// SPDX-License-Identifier: MIT

pragma solidity 0.8.17;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
import "@openzeppelin-upgradeable/contracts/utils/StringsUpgradeable.sol";
import "@openzeppelin-upgradeable/contracts/access/Ownable2StepUpgradeable.sol";
import "@openzeppelin-upgradeable/contracts/security/PausableUpgradeable.sol";
import "@openzeppelin-upgradeable/contracts/token/ERC721/ERC721Upgradeable.sol";
import "@openzeppelin-upgradeable/contracts/security/ReentrancyGuardUpgradeable.sol";
import "./Shared.sol";

/**
 * @title Subscription Token Protocol Version 1
 * @author Fabric Inc.
 * @notice An NFT contract which allows users to mint time and access token gated content while time remains.
 * @dev The balanceOf function returns the number of seconds remaining in the subscription. Token gated systems leverage
 *      the balanceOf function to determine if a user has the token, and if no time remains, the balance is 0. NFT holders
 *      can mint additional time. The creator/owner of the contract can withdraw the funds at any point. There are
 *      additional functionalities for granting time, refunding accounts, fees, rewards, etc. This contract is designed to be used with
 *      Clones, but is not designed to be upgradeable. Added functionality will come with new versions.
 */

contract SubscriptionTokenV1 is
    ERC721Upgradeable,
    Ownable2StepUpgradeable,
    ReentrancyGuardUpgradeable,
    PausableUpgradeable
{
    using SafeERC20 for IERC20;
    using StringsUpgradeable for uint256;

    /// @dev The maximum number of reward halvings (limiting this prevents overflow)
    uint256 private constant _MAX_REWARD_HALVINGS = 32;

    /// @dev Maximum protocol fee basis points (12.5%)
    uint16 private constant _MAX_FEE_BIPS = 1250;

    /// @dev Maximum basis points (100%)
    uint16 private constant _MAX_BIPS = 10000;

    /// @dev Guard to ensure the purchase amount is valid
    modifier validAmount(uint256 amount) {
        require(amount >= _minimumPurchase, "Amount must be >= minimum purchase");
        _;
    }

    /// @dev Emitted when the owner withdraws available funds
    event Withdraw(address indexed account, uint256 tokensTransferred);

    /// @dev Emitted when a subscriber withdraws their rewards
    event RewardWithdraw(address indexed account, uint256 tokensTransferred);

    /// @dev Emitted when a subscriber slashed the rewards of another subscriber
    event RewardPointsSlashed(address indexed account, address indexed slasher, uint256 rewardPointsSlashed);

    /// @dev Emitted when tokens are allocated to the reward pool
    event RewardsAllocated(uint256 tokens);

    /// @dev Emitted when time is purchased (new nft or renewed)
    event Purchase(
        address indexed account,
        uint256 indexed tokenId,
        uint256 tokensTransferred,
        uint256 timePurchased,
        uint256 rewardPoints,
        uint256 expiresAt
    );

    /// @dev Emitted when a subscriber is granted time by the creator
    event Grant(address indexed account, uint256 indexed tokenId, uint256 secondsGranted, uint256 expiresAt);

    /// @dev Emitted when the creator refunds a subscribers remaining time
    event Refund(address indexed account, uint256 indexed tokenId, uint256 tokensTransferred, uint256 timeReclaimed);

    /// @dev Emitted when the creator tops up the contract balance on refund
    event RefundTopUp(uint256 tokensIn);

    /// @dev Emitted when the fees are transferred to the collector
    event FeeTransfer(address indexed from, address indexed to, uint256 tokensTransferred);

    /// @dev Emitted when the fee collector is updated
    event FeeCollectorChange(address indexed from, address indexed to);

    /// @dev Emitted when tokens are allocated to the fee pool
    event FeeAllocated(uint256 tokens);

    /// @dev Emitted when a referral fee is paid out
    event ReferralPayout(
        uint256 indexed tokenId, address indexed referrer, uint256 indexed referralId, uint256 rewardAmount
    );

    /// @dev Emitted when a new referral code is created
    event ReferralCreated(uint256 id, uint16 rewardBps);

    /// @dev Emitted when a referral code is deleted
    event ReferralDestroyed(uint256 id);

    /// @dev Emitted when the supply cap is updated
    event SupplyCapChange(uint256 supplyCap);

    /// @dev Emitted when the transfer recipient is updated
    event TransferRecipientChange(address indexed recipient);

    /// @dev The subscription struct which holds the state of a subscription for an account
    struct Subscription {
        /// @dev The tokenId for the subscription
        uint256 tokenId;
        /// @dev The number of seconds purchased
        uint256 secondsPurchased;
        /// @dev The number of seconds granted by the creator
        uint256 secondsGranted;
        /// @dev A time offset used to adjust expiration for grants
        uint256 grantOffset;
        /// @dev A time offset used to adjust expiration for purchases
        uint256 purchaseOffset;
        /// @dev The number of reward points earned
        uint256 rewardPoints;
        /// @dev The number of rewards withdrawn
        uint256 rewardsWithdrawn;
    }

    /// @dev The metadata URI for the contract
    string private _contractURI;

    /// @dev The metadata URI for the tokens. Note: if it ends with /, then we append the tokenId
    string private _tokenURI;

    /// @dev The cost of one second in denominated token (wei or other base unit)
    uint256 private _tokensPerSecond;

    /// @dev Minimum number of seconds to purchase. Also, this is the number of seconds until the reward multiplier is halved.
    uint256 private _minPurchaseSeconds;

    /// @dev The minimum number of tokens accepted for a time purchase
    uint256 private _minimumPurchase;

    /// @dev The token contract address, or 0x0 for native tokens
    IERC20 private _token;

    /// @dev The total number of tokens transferred in (accounting)
    uint256 private _tokensIn;

    /// @dev The total number of tokens transferred out (accounting)
    uint256 private _tokensOut;

    /// @dev The token counter for mint id generation and enforcing supply caps
    uint256 private _tokenCounter;

    /// @dev The total number of tokens allocated for the fee collector (accounting)
    uint256 private _feeBalance;

    /// @dev The protocol fee basis points (10000 = 100%, max = _MAX_FEE_BIPS)
    uint16 private _feeBps;

    /// @dev The protocol fee collector address (for withdraws or sponsored transfers)
    address private _feeCollector;

    /// @dev Flag which determines if the contract is erc20 denominated
    bool private _erc20;

    /// @dev The block timestamp of the contract deployment (used for reward halvings)
    uint256 private _deployBlockTime;

    /// @dev The reward pool size (used to calculate reward withdraws accurately)
    uint256 private _totalRewardPoints;

    /// @dev The reward pool balance (accounting)
    uint256 private _rewardPoolBalance;

    /// @dev The reward pool total (used to calculate reward withdraws accurately)
    uint256 private _rewardPoolTotal;

    /// @dev The reward pool tokens slashed (used to calculate reward withdraws accurately)
    uint256 private _rewardPoolSlashed;

    /// @dev The basis points for reward allocations
    uint16 private _rewardBps;

    /// @dev The number of reward halvings. This is used to calculate the reward multiplier for early supporters, if the creator chooses to reward them.
    uint256 private _numRewardHalvings;

    /// @dev The maximum number of tokens which can be minted (adjustable over time, but will not allow setting below current count)
    uint256 private _supplyCap;

    /// @dev The address of the account which can receive transfers via sponsored calls
    address private _transferRecipient;

    /// @dev The subscription state for each account
    mapping(address => Subscription) private _subscriptions;

    /// @dev The collection of referral codes for referral rewards
    mapping(uint256 => uint16) private _referralCodes;

    ////////////////////////////////////

    /// @dev Disable initializers on the logic contract
    constructor() {
        _disableInitializers();
    }

    /// @dev Fallback function to mint time for native token contracts
    receive() external payable {
        mintFor(msg.sender, msg.value);
    }

    /**
     * @dev Initialize acts as the constructor, as this contract is intended to work with proxy contracts.
     * @param params the init params (See Common.InitParams)
     */
    function initialize(Shared.InitParams memory params) public initializer {
        require(bytes(params.name).length > 0, "Name cannot be empty");
        require(bytes(params.symbol).length > 0, "Symbol cannot be empty");
        require(bytes(params.contractUri).length > 0, "Contract URI cannot be empty");
        require(bytes(params.tokenUri).length > 0, "Token URI cannot be empty");
        require(params.owner != address(0), "Owner address cannot be 0x0");
        require(params.tokensPerSecond > 0, "Tokens per second must be > 0");
        require(params.minimumPurchaseSeconds > 0, "Min purchase seconds must be > 0");
        require(params.feeBps <= _MAX_FEE_BIPS, "Fee bps too high");
        require(params.rewardBps <= _MAX_BIPS, "Reward bps too high");
        require(params.numRewardHalvings <= _MAX_REWARD_HALVINGS, "Reward halvings too high");
        if (params.feeRecipient != address(0)) {
            require(params.feeBps > 0, "Fees required when fee recipient is present");
        }
        if (params.rewardBps > 0) {
            require(params.numRewardHalvings > 0, "Reward halvings too low");
        }

        __ERC721_init(params.name, params.symbol);
        _transferOwnership(params.owner);
        __Pausable_init_unchained();
        __ReentrancyGuard_init();
        _contractURI = params.contractUri;
        _tokenURI = params.tokenUri;
        _tokensPerSecond = params.tokensPerSecond;
        _minimumPurchase = params.minimumPurchaseSeconds * params.tokensPerSecond;
        _minPurchaseSeconds = params.minimumPurchaseSeconds;
        _rewardBps = params.rewardBps;
        _numRewardHalvings = params.numRewardHalvings;
        _feeBps = params.feeBps;
        _feeCollector = params.feeRecipient;
        _token = IERC20(params.erc20TokenAddr);
        _erc20 = params.erc20TokenAddr != address(0);
        _deployBlockTime = block.timestamp;
    }

    /////////////////////////
    // Subscriber Calls
    /////////////////////////

    /**
     * @notice Mint or renew a subscription for sender
     * @param numTokens the amount of ERC20 tokens or native tokens to transfer
     */
    function mint(uint256 numTokens) external payable {
        mintFor(msg.sender, numTokens);
    }

    /**
     * @notice Mint or renew a subscription for sender, with referral rewards for a referrer
     * @param numTokens the amount of ERC20 tokens or native tokens to transfer
     * @param referralCode the referral code to use
     * @param referrer the referrer address and reward recipient
     */
    function mintWithReferral(uint256 numTokens, uint256 referralCode, address referrer) external payable {
        mintWithReferralFor(msg.sender, numTokens, referralCode, referrer);
    }

    /**
     * @notice Withdraw available rewards. This is only possible if the subscription is active.
     */
    function withdrawRewards() external {
        Subscription memory sub = _subscriptions[msg.sender];
        require(_isActive(sub), "Subscription not active");
        uint256 rewardAmount = _rewardBalance(sub);
        require(rewardAmount > 0, "No rewards to withdraw");
        sub.rewardsWithdrawn += rewardAmount;
        _subscriptions[msg.sender] = sub;
        _rewardPoolBalance -= rewardAmount;
        _transferOut(msg.sender, rewardAmount);
        emit RewardWithdraw(msg.sender, rewardAmount);
    }

    /**
     * @notice Slash the reward points for an expired subscription after a grace period which is 50% of the purchased time
     *         Any slashable points are burned, increasing the value of remaining points.
     * @param account the account of the subscription to slash
     */
    function slashRewards(address account) external {
        require(_rewardBps > 0, "Rewards disabled");
        Subscription memory slasher = _subscriptions[msg.sender];
        require(_isActive(slasher), "Subscription not active");

        Subscription memory sub = _subscriptions[account];
        require(sub.rewardPoints > 0, "No reward points to slash");

        // Expiration + grace period (50% of purchased time)
        uint256 slashPoint = _subscriptionExpiresAt(sub) + (sub.secondsPurchased / 2);
        require(block.timestamp >= slashPoint, "Not slashable");

        // Deflate the reward points pool and account for prior reward withdrawals
        _totalRewardPoints -= sub.rewardPoints;
        _rewardPoolSlashed += sub.rewardsWithdrawn;

        // If all points are slashed, move left-over funds to creator
        if (_totalRewardPoints == 0) {
            _rewardPoolBalance = 0;
        }

        emit RewardPointsSlashed(account, msg.sender, sub.rewardPoints);
        sub.rewardPoints = 0;
        sub.rewardsWithdrawn = 0;
        _subscriptions[account] = sub;
    }

    /////////////////////////
    // Creator Calls
    /////////////////////////

    /**
     * @notice Withdraw available funds as the owner
     */
    function withdraw() external {
        withdrawTo(msg.sender);
    }

    /**
     * @notice Withdraw available funds and transfer fees as the owner
     */
    function withdrawAndTransferFees() external {
        withdrawTo(msg.sender);
        _transferFees();
    }

    /**
     * @notice Withdraw available funds as the owner to a specific account
     * @param account the account to transfer funds to
     */
    function withdrawTo(address account) public onlyOwner {
        require(account != address(0), "Account cannot be 0x0");
        uint256 balance = creatorBalance();
        require(balance > 0, "No Balance");
        _transferToCreator(account, balance);
    }

    /**
     * @notice Refund one or more accounts remaining purchased time and revoke any granted time
     * @dev This refunds accounts using creator balance, and can also transfer in to top up the fund. Any excess value is withdrawable.
     * @param numTokensIn an optional amount of tokens to transfer in before refunding
     * @param accounts the list of accounts to refund and revoke grants for
     */
    function refund(uint256 numTokensIn, address[] memory accounts) external payable onlyOwner {
        require(accounts.length > 0, "No accounts to refund");
        if (numTokensIn > 0) {
            uint256 finalAmount = _transferIn(msg.sender, numTokensIn);
            emit RefundTopUp(finalAmount);
        } else if (msg.value > 0) {
            revert("Unexpected value transfer");
        }
        require(canRefund(accounts), "Insufficient balance for refund");
        for (uint256 i = 0; i < accounts.length; i++) {
            _refund(accounts[i]);
        }
    }

    /**
     * @notice Update the contract metadata
     * @param contractUri the collection metadata URI
     * @param tokenUri the token metadata URI
     */
    function updateMetadata(string memory contractUri, string memory tokenUri) external onlyOwner {
        require(bytes(contractUri).length > 0, "Contract URI cannot be empty");
        require(bytes(tokenUri).length > 0, "Token URI cannot be empty");
        _contractURI = contractUri;
        _tokenURI = tokenUri;
    }

    /**
     * @notice Grant time to a list of accounts, so they can access content without paying
     * @param accounts the list of accounts to grant time to
     * @param secondsToAdd the number of seconds to grant for each account
     */
    function grantTime(address[] memory accounts, uint256 secondsToAdd) external onlyOwner {
        require(secondsToAdd > 0, "Seconds to add must be > 0");
        require(accounts.length > 0, "No accounts to grant time to");
        for (uint256 i = 0; i < accounts.length; i++) {
            _grantTime(accounts[i], secondsToAdd);
        }
    }

    /**
     * @notice Pause minting to allow for migrations or other actions
     */
    function pause() external onlyOwner {
        _pause();
    }

    /**
     * @notice Unpause to resume subscription minting
     */
    function unpause() external onlyOwner {
        _unpause();
    }

    /**
     * @notice Update the maximum number of tokens (subscriptions)
     * @param supplyCap the new supply cap (must be greater than token count or 0 for unlimited)
     */
    function setSupplyCap(uint256 supplyCap) external onlyOwner {
        require(supplyCap == 0 || supplyCap >= _tokenCounter, "Supply cap must be >= current count or 0");
        _supplyCap = supplyCap;
        emit SupplyCapChange(supplyCap);
    }

    /**
     * @notice Set a transfer recipient for automated/sponsored transfers
     * @param recipient the recipient address
     */
    function setTransferRecipient(address recipient) external onlyOwner {
        _transferRecipient = recipient;
        emit TransferRecipientChange(recipient);
    }

    /////////////////////////
    // Sponsored Calls
    /////////////////////////

    /**
     * @notice Mint or renew a subscription for a specific account. Intended for automated renewals.
     * @param account the account to mint or renew time for
     * @param numTokens the amount of ERC20 tokens or native tokens to transfer
     */
    function mintFor(address account, uint256 numTokens) public payable whenNotPaused validAmount(numTokens) {
        uint256 finalAmount = _transferIn(msg.sender, numTokens);
        _purchaseTime(account, finalAmount);
    }

    /**
     * @notice Mint or renew a subscription for a specific account, with referral details
     * @param account the account to mint or renew time for
     * @param numTokens the amount of ERC20 tokens or native tokens to transfer
     * @param referralCode the referral code to use for rewards
     * @param referrer the referrer address and reward recipient
     */
    function mintWithReferralFor(address account, uint256 numTokens, uint256 referralCode, address referrer)
        public
        payable
        whenNotPaused
        validAmount(numTokens)
    {
        require(referrer != address(0), "Referrer cannot be 0x0");

        uint256 finalAmount = _transferIn(msg.sender, numTokens);
        uint256 tokenId = _purchaseTime(account, finalAmount);

        // Calculate rewards and transfer rewards out
        uint256 payout = _referralAmount(finalAmount, referralCode);
        if (payout > 0) {
            _transferOut(referrer, payout);
            emit ReferralPayout(tokenId, referrer, referralCode, payout);
        }
    }

    /**
     * @notice Transfer any available fees to the fee collector
     */
    function transferFees() external {
        require(_feeBalance > 0, "No fees to collect");
        _transferFees();
    }

    /**
     * @notice Transfer all balances to the transfer recipient and fee collector (if applicable)
     * @dev This is a way for EOAs to pay gas fees on behalf of the creator (automation, etc)
     */
    function transferAllBalances() external {
        require(_transferRecipient != address(0), "Transfer recipient not set");
        _transferAllBalances(_transferRecipient);
    }

    /////////////////////////
    // Fee Management
    /////////////////////////

    /**
     * @notice Fetch the current fee schedule
     * @return feeCollector the feeCollector address
     * @return feeBps the fee basis points
     */
    function feeSchedule() external view returns (address feeCollector, uint16 feeBps) {
        return (_feeCollector, _feeBps);
    }

    /**
     * @notice Fetch the accumulated fee balance
     * @return balance the accumulated fees which have not yet been transferred
     */
    function feeBalance() external view returns (uint256 balance) {
        return _feeBalance;
    }

    /**
     * @notice Update the fee collector address. Can be set to 0x0 to disable fees permanently.
     * @param newCollector the new fee collector address
     */
    function updateFeeRecipient(address newCollector) external {
        require(msg.sender == _feeCollector, "Unauthorized");
        // Give tokens back to creator and set fee rate to 0
        if (newCollector == address(0)) {
            _feeBalance = 0;
            _feeBps = 0;
        }
        _feeCollector = newCollector;
        emit FeeCollectorChange(msg.sender, newCollector);
    }

    /////////////////////////
    // Referral Rewards
    /////////////////////////

    /**
     * @notice Create a referral code for giving rewards to referrers on mint
     * @param code the unique integer code for the referral
     * @param bps the reward basis points
     */
    function createReferralCode(uint256 code, uint16 bps) external onlyOwner {
        require(bps <= _MAX_BIPS, "bps too high");
        require(bps > 0, "bps must be > 0");
        uint16 existing = _referralCodes[code];
        require(existing == 0, "Referral code exists");
        _referralCodes[code] = bps;
        emit ReferralCreated(code, bps);
    }

    /**
     * @notice Delete a referral code
     * @param code the unique integer code for the referral
     */
    function deleteReferralCode(uint256 code) external onlyOwner {
        delete _referralCodes[code];
        emit ReferralDestroyed(code);
    }

    /**
     * @notice Fetch the reward basis points for a given referral code
     * @param code the unique integer code for the referral
     * @return bps the reward basis points
     */
    function referralCodeBps(uint256 code) external view returns (uint16 bps) {
        return _referralCodes[code];
    }

    ////////////////////////
    // Core Internal Logic
    ////////////////////////

    /// @dev Add time to a given account (transfer happens before this is called)
    function _purchaseTime(address account, uint256 amount) internal returns (uint256) {
        require(account != address(0), "Account cannot be 0x0");

        Subscription memory sub = _fetchSubscription(account);

        // Adjust offset to account for existing time
        if (block.timestamp > sub.purchaseOffset + sub.secondsPurchased) {
            sub.purchaseOffset = block.timestamp - sub.secondsPurchased;
        }

        uint256 rp = amount * rewardMultiplier();
        uint256 tv = timeValue(amount);
        sub.secondsPurchased += tv;
        sub.rewardPoints += rp;
        _subscriptions[account] = sub;
        _totalRewardPoints += rp;

        // If fees or rewards are enabled, allocate a portion of the purchase to those pools
        _allocateFeesAndRewards(amount);

        // Mint the NFT if it does not exist before purchase event for indexers
        _maybeMint(account, sub.tokenId);

        emit Purchase(account, sub.tokenId, amount, tv, rp, _subscriptionExpiresAt(sub));
        return sub.tokenId;
    }

    /// @dev Get or build a new subscription
    function _fetchSubscription(address account) internal returns (Subscription memory) {
        Subscription memory sub = _subscriptions[account];
        if (sub.tokenId == 0) {
            require(_supplyCap == 0 || _tokenCounter < _supplyCap, "Supply cap reached");
            _tokenCounter += 1;
            sub = Subscription(_tokenCounter, 0, 0, block.timestamp, block.timestamp, 0, 0);
        }
        return sub;
    }

    /// @dev Mint the NFT if it does not exist. Used after grant/purchase state changes (check effects)
    function _maybeMint(address account, uint256 tokenId) private {
        if (_ownerOf(tokenId) == address(0)) {
            _safeMint(account, tokenId);
        }
    }

    /// @dev If fees or rewards are present, allocate a portion of the amount to the relevant pools
    function _allocateFeesAndRewards(uint256 amount) private {
        _allocateRewards(_allocateFees(amount));
    }

    /// @dev Allocate tokens to the fee collector
    function _allocateFees(uint256 amount) internal returns (uint256) {
        if (_feeBps == 0) {
            return amount;
        }
        uint256 fee = (amount * _feeBps) / _MAX_BIPS;
        _feeBalance += fee;
        emit FeeAllocated(fee);
        return amount - fee;
    }

    /// @dev Allocate tokens to the reward pool
    function _allocateRewards(uint256 amount) internal returns (uint256) {
        if (_rewardBps == 0 || _totalRewardPoints == 0) {
            return amount;
        }
        uint256 rewards = (amount * _rewardBps) / _MAX_BIPS;
        _rewardPoolBalance += rewards;
        _rewardPoolTotal += rewards;
        emit RewardsAllocated(rewards);
        return amount - rewards;
    }

    /// @dev Transfer tokens into the contract, either native or ERC20
    function _transferIn(address from, uint256 amount) internal nonReentrant returns (uint256) {
        if (!_erc20) {
            require(msg.value == amount, "Purchase amount must match value sent");
            _tokensIn += amount;
            return amount;
        }

        // Note: We support tokens which take fees, but do not support rebasing tokens
        require(msg.value == 0, "Native tokens not accepted for ERC20 subscriptions");
        uint256 preBalance = _token.balanceOf(from);
        uint256 allowance = _token.allowance(from, address(this));
        require(preBalance >= amount && allowance >= amount, "Insufficient Balance or Allowance");
        _token.safeTransferFrom(from, address(this), amount);
        uint256 postBalance = _token.balanceOf(from);
        uint256 finalAmount = preBalance - postBalance;
        _tokensIn += finalAmount;
        return finalAmount;
    }

    /// @dev Transfer tokens to the creator, after allocating protocol fees and rewards
    function _transferToCreator(address to, uint256 amount) internal {
        emit Withdraw(to, amount);
        _transferOut(to, amount);
    }

    /// @dev Transfer tokens out of the contract, either native or ERC20
    function _transferOut(address to, uint256 amount) internal nonReentrant {
        _tokensOut += amount;
        if (_erc20) {
            _token.safeTransfer(to, amount);
        } else {
            (bool sent,) = payable(to).call{value: amount}("");
            require(sent, "Failed to transfer Ether");
        }
    }

    /// @dev Transfer fees to the fee collector
    function _transferFees() internal {
        if (_feeBalance == 0) {
            return;
        }
        uint256 balance = _feeBalance;
        _feeBalance = 0;
        _transferOut(_feeCollector, balance);
        emit FeeTransfer(msg.sender, _feeCollector, balance);
    }

    /// @dev Transfer all remaining balances to the creator and fee collector (if applicable)
    function _transferAllBalances(address balanceRecipient) internal {
        uint256 balance = creatorBalance();
        if (balance > 0) {
            _transferToCreator(balanceRecipient, balance);
        }

        // Transfer protocol fees
        _transferFees();
    }

    /// @dev Grant time to a given account
    function _grantTime(address account, uint256 numSeconds) internal {
        Subscription memory sub = _fetchSubscription(account);
        // Adjust offset to account for existing time
        if (block.timestamp > sub.grantOffset + sub.secondsGranted) {
            sub.grantOffset = block.timestamp - sub.secondsGranted;
        }

        sub.secondsGranted += numSeconds;
        _subscriptions[account] = sub;

        // Mint the NFT if it does not exist before grant event for indexers
        _maybeMint(account, sub.tokenId);

        emit Grant(account, sub.tokenId, numSeconds, _subscriptionExpiresAt(sub));
    }

    /// @dev The amount of granted time remaining for a given subscription
    function _grantTimeRemaining(Subscription memory sub) internal view returns (uint256) {
        uint256 expiresAt = sub.grantOffset + sub.secondsGranted;
        if (expiresAt <= block.timestamp) {
            return 0;
        }
        return expiresAt - block.timestamp;
    }

    /// @dev The amount of purchased time remaining for a given subscription
    function _purchaseTimeRemaining(Subscription memory sub) internal view returns (uint256) {
        uint256 expiresAt = sub.purchaseOffset + sub.secondsPurchased;
        if (expiresAt <= block.timestamp) {
            return 0;
        }
        return expiresAt - block.timestamp;
    }

    /// @dev Refund the remaining time for the given accounts subscription, and clear grants
    function _refund(address account) internal {
        Subscription memory sub = _subscriptions[account];
        if (sub.secondsPurchased == 0 && sub.secondsGranted == 0) {
            return;
        }

        sub.secondsGranted = 0;
        uint256 balance = refundableBalanceOf(account);
        uint256 tokens = balance * _tokensPerSecond;
        if (balance > 0) {
            sub.secondsPurchased -= balance;
            _subscriptions[account] = sub;
            _transferOut(account, tokens);
        } else {
            _subscriptions[account] = sub;
        }

        emit Refund(account, sub.tokenId, tokens, balance);
    }

    /// @dev Compute the reward amount for a given token amount and referral code
    function _referralAmount(uint256 tokenAmount, uint256 referralCode) internal view returns (uint256) {
        uint16 referralBps = _referralCodes[referralCode];
        if (referralBps == 0) {
            return 0;
        }
        return (tokenAmount * referralBps) / _MAX_BIPS;
    }

    /// @dev The timestamp when the subscription expires
    function _subscriptionExpiresAt(Subscription memory sub) internal pure returns (uint256) {
        uint256 purchase = sub.purchaseOffset + sub.secondsPurchased;
        uint256 grant = sub.grantOffset + sub.secondsGranted;
        return purchase > grant ? purchase : grant;
    }

    /// @dev The reward balance for a given subscription
    function _rewardBalance(Subscription memory sub) internal view returns (uint256) {
        uint256 userShare = (_rewardPoolTotal - _rewardPoolSlashed) * sub.rewardPoints / _totalRewardPoints;
        if (userShare <= sub.rewardsWithdrawn) {
            return 0;
        }
        return userShare - sub.rewardsWithdrawn;
    }

    /// @dev Determine if a subscription is active
    function _isActive(Subscription memory sub) internal view returns (bool) {
        return _subscriptionExpiresAt(sub) > block.timestamp;
    }

    ////////////////////////
    // Informational
    ////////////////////////

    /**
     * @notice Determine the total cost for refunding the given accounts
     * @dev The value will change from block to block, so this is only an estimate
     * @param accounts the list of accounts to refund
     * @return numTokens total number of tokens for refund
     */
    function refundableTokenBalanceOfAll(address[] memory accounts) public view returns (uint256 numTokens) {
        uint256 amount;
        for (uint256 i = 0; i < accounts.length; i++) {
            amount += refundableBalanceOf(accounts[i]);
        }
        return amount * _tokensPerSecond;
    }

    /**
     * @notice Determines if a refund can be processed for the given accounts with the current balance
     * @param accounts the list of accounts to refund
     * @return refundable true if the refund can be processed from the current balance
     */
    function canRefund(address[] memory accounts) public view returns (bool refundable) {
        return creatorBalance() >= refundableTokenBalanceOfAll(accounts);
    }

    /**
     * @notice The current reward multiplier used to calculate reward points on mint. This is halved every _minPurchaseSeconds and goes to 0 after N halvings.
     * @return multiplier the current value
     */
    function rewardMultiplier() public view returns (uint256 multiplier) {
        if (_numRewardHalvings == 0) {
            return 0;
        }
        uint256 halvings = (block.timestamp - _deployBlockTime) / _minPurchaseSeconds;
        if (halvings > _numRewardHalvings) {
            return 0;
        }
        return (2 ** _numRewardHalvings) / (2 ** halvings);
    }

    /**
     * @notice The amount of time exchanged for the given number of tokens
     * @param numTokens the number of tokens to exchange for time
     * @return numSeconds the number of seconds purchased
     */
    function timeValue(uint256 numTokens) public view returns (uint256 numSeconds) {
        return numTokens / _tokensPerSecond;
    }

    /**
     * @notice The creators withdrawable balance
     * @return balance the number of tokens available for withdraw
     */
    function creatorBalance() public view returns (uint256 balance) {
        return _tokensIn - _tokensOut - _feeBalance - _rewardPoolBalance;
    }

    /**
     * @notice The sum of all deposited tokens over time. Fees and refunds are not accounted for.
     * @return total the total number of tokens deposited
     */
    function totalCreatorEarnings() public view returns (uint256 total) {
        return _tokensIn;
    }

    /**
     * @notice Relevant subscription information for a given account
     * @return tokenId the tokenId for the account
     * @return refundableAmount the number of seconds which can be refunded
     * @return rewardPoints the number of reward points earned
     * @return expiresAt the timestamp when the subscription expires
     */
    function subscriptionOf(address account)
        external
        view
        returns (uint256 tokenId, uint256 refundableAmount, uint256 rewardPoints, uint256 expiresAt)
    {
        Subscription memory sub = _subscriptions[account];
        return (sub.tokenId, sub.secondsPurchased, sub.rewardPoints, _subscriptionExpiresAt(sub));
    }

    /**
     * @notice The percentage (as basis points) of creator earnings which are rewarded to subscribers
     * @return bps reward basis points
     */
    function rewardBps() external view returns (uint16 bps) {
        return _rewardBps;
    }

    /**
     * @notice The number of reward points allocated to all subscribers (used to calculate rewards)
     * @return numPoints total number of reward points
     */
    function totalRewardPoints() external view returns (uint256 numPoints) {
        return _totalRewardPoints;
    }

    /**
     * @notice The balance of the reward pool (for reward withdraws)
     * @return numTokens number of tokens in the reward pool
     */
    function rewardPoolBalance() external view returns (uint256 numTokens) {
        return _rewardPoolBalance;
    }

    /**
     * @notice The number of tokens available to withdraw from the reward pool, for a given account
     * @param account the account to check
     * @return numTokens number of tokens available to withdraw
     */
    function rewardBalanceOf(address account) external view returns (uint256 numTokens) {
        Subscription memory sub = _subscriptions[account];
        return _rewardBalance(sub);
    }

    /**
     * @notice The ERC-20 address used for purchases, or 0x0 for native
     * @return erc20 address or 0x0 for native
     */
    function erc20Address() public view returns (address erc20) {
        return address(_token);
    }

    /**
     * @notice The refundable time balance for a given account
     * @param account the account to check
     * @return numSeconds the number of seconds which can be refunded
     */
    function refundableBalanceOf(address account) public view returns (uint256 numSeconds) {
        Subscription memory sub = _subscriptions[account];
        return _purchaseTimeRemaining(sub);
    }

    /**
     * @notice The contract metadata URI for accessing collection metadata
     * @return uri the collection URI
     */
    function contractURI() public view returns (string memory uri) {
        return _contractURI;
    }

    /**
     * @notice The base token URI for accessing token metadata
     * @return uri the base token URI
     */
    function baseTokenURI() public view returns (string memory uri) {
        return _tokenURI;
    }

    /**
     * @notice The number of tokens required for a single second of time
     * @return numTokens per second
     */
    function tps() external view returns (uint256 numTokens) {
        return _tokensPerSecond;
    }

    /**
     * @notice The minimum number of seconds required for a purchase
     * @return numSeconds minimum
     */
    function minPurchaseSeconds() external view returns (uint256 numSeconds) {
        return _minPurchaseSeconds;
    }

    /**
     * @notice Fetch the current supply cap (0 for unlimited)
     * @return count the current number
     * @return cap the max number of subscriptions
     */
    function supplyDetail() external view returns (uint256 count, uint256 cap) {
        return (_tokenCounter, _supplyCap);
    }

    /**
     * @notice Fetch the current transfer recipient address
     * @return recipient the address or 0x0 address for none
     */
    function transferRecipient() external view returns (address recipient) {
        return _transferRecipient;
    }

    /**
     * @notice Fetch the metadata URI for a given token
     * @dev If _tokenURI ends with a / then the tokenId is appended
     * @param tokenId the tokenId to fetch the metadata URI for
     * @return uri the URI for the token
     */
    function tokenURI(uint256 tokenId) public view override returns (string memory uri) {
        _requireMinted(tokenId);

        bytes memory str = bytes(_tokenURI);
        uint256 len = str.length;
        if (str[len - 1] == "/") {
            return string(abi.encodePacked(_tokenURI, tokenId.toString()));
        }

        return _tokenURI;
    }

    //////////////////////
    // Overrides
    //////////////////////

    /**
     * @notice Override the default balanceOf behavior to account for time remaining
     * @param account the account to fetch the balance of
     * @return numSeconds the number of seconds remaining in the subscription
     */
    function balanceOf(address account) public view override returns (uint256 numSeconds) {
        Subscription memory sub = _subscriptions[account];
        return _purchaseTimeRemaining(sub) + _grantTimeRemaining(sub);
    }

    /**
     * @notice Renounce ownership of the contract, transferring all remaining funds to the creator and fee collector
     *         and pausing the contract to prevent further inflows.
     */
    function renounceOwnership() public override onlyOwner {
        _transferAllBalances(msg.sender);
        _pause();
        _transferOwnership(address(0));
    }

    /// @dev Transfers may occur if the destination does not have a subscription
    function _beforeTokenTransfer(address from, address to, uint256, /* tokenId */ uint256 /* batchSize */ )
        internal
        override
    {
        if (from == address(0)) {
            return;
        }

        require(_subscriptions[to].tokenId == 0, "Cannot transfer to existing subscribers");
        if (to != address(0)) {
            _subscriptions[to] = _subscriptions[from];
        }

        delete _subscriptions[from];
    }

    //////////////////////
    // Recovery Functions
    //////////////////////

    /**
     * @notice Reconcile the ERC20 balance of the contract with the internal state
     * @dev The prevents lost funds if ERC20 tokens are transferred to the contract directly
     */
    function reconcileERC20Balance() external onlyOwner {
        require(_erc20, "Only for ERC20 tokens");
        uint256 balance = _token.balanceOf(address(this));
        uint256 expectedBalance = _tokensIn - _tokensOut;
        require(balance > expectedBalance, "Tokens already reconciled");
        _tokensIn += balance - expectedBalance;
    }

    /**
     * @notice Recover ERC20 tokens which were accidentally sent to the contract
     * @param tokenAddress the address of the token to recover
     * @param recipientAddress the address to send the tokens to
     * @param tokenAmount the amount of tokens to send
     */
    function recoverERC20(address tokenAddress, address recipientAddress, uint256 tokenAmount) external onlyOwner {
        require(tokenAddress != erc20Address(), "Cannot recover subscription token");
        IERC20(tokenAddress).safeTransfer(recipientAddress, tokenAmount);
    }

    /**
     * @notice Recover native tokens which bypassed receive. Only callable for erc20 denominated contracts.
     * @param recipient the address to send the tokens to
     */
    function recoverNativeTokens(address recipient) external onlyOwner {
        require(_erc20, "Not supported, use reconcileNativeBalance");
        uint256 balance = address(this).balance;
        require(balance > 0, "No balance to recover");
        (bool sent,) = payable(recipient).call{value: balance}("");
        require(sent, "Failed to transfer Ether");
    }

    /**
     * @notice Reconcile native tokens which bypassed receive/mint. Only callable for native denominated contracts.
     */
    function reconcileNativeBalance() external onlyOwner {
        require(!_erc20, "Not supported, use recoverNativeTokens");
        uint256 balance = address(this).balance;
        require(balance > 0, "No balance to recover");
        uint256 expectedBalance = _tokensIn - _tokensOut;
        require(balance > expectedBalance, "Balance reconciled");
        _tokensIn += balance - expectedBalance;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `from` to `to` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 amount) external returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../extensions/IERC20Permit.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    /**
     * @dev Transfer `value` amount of `token` from the calling contract to `to`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    /**
     * @dev Transfer `value` amount of `token` from `from` to `to`, spending the approval given by `from` to the
     * calling contract. If `token` returns no value, non-reverting calls are assumed to be successful.
     */
    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    /**
     * @dev Increase the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 oldAllowance = token.allowance(address(this), spender);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance + value));
    }

    /**
     * @dev Decrease the calling contract's allowance toward `spender` by `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful.
     */
    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, oldAllowance - value));
        }
    }

    /**
     * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
     * non-reverting calls are assumed to be successful. Compatible with tokens that require the approval to be set to
     * 0 before setting it to a non-zero value.
     */
    function forceApprove(IERC20 token, address spender, uint256 value) internal {
        bytes memory approvalCall = abi.encodeWithSelector(token.approve.selector, spender, value);

        if (!_callOptionalReturnBool(token, approvalCall)) {
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, 0));
            _callOptionalReturn(token, approvalCall);
        }
    }

    /**
     * @dev Use a ERC-2612 signature to set the `owner` approval toward `spender` on `token`.
     * Revert on invalid signature.
     */
    function safePermit(
        IERC20Permit token,
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) internal {
        uint256 nonceBefore = token.nonces(owner);
        token.permit(owner, spender, value, deadline, v, r, s);
        uint256 nonceAfter = token.nonces(owner);
        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address-functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        require(returndata.length == 0 || abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     *
     * This is a variant of {_callOptionalReturn} that silents catches all reverts and returns a bool instead.
     */
    function _callOptionalReturnBool(IERC20 token, bytes memory data) private returns (bool) {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We cannot use {Address-functionCall} here since this should return false
        // and not revert is the subcall reverts.

        (bool success, bytes memory returndata) = address(token).call(data);
        return
            success && (returndata.length == 0 || abi.decode(returndata, (bool))) && Address.isContract(address(token));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)

pragma solidity ^0.8.0;

import "./math/MathUpgradeable.sol";
import "./math/SignedMathUpgradeable.sol";

/**
 * @dev String operations.
 */
library StringsUpgradeable {
    bytes16 private constant _SYMBOLS = "0123456789abcdef";
    uint8 private constant _ADDRESS_LENGTH = 20;

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        unchecked {
            uint256 length = MathUpgradeable.log10(value) + 1;
            string memory buffer = new string(length);
            uint256 ptr;
            /// @solidity memory-safe-assembly
            assembly {
                ptr := add(buffer, add(32, length))
            }
            while (true) {
                ptr--;
                /// @solidity memory-safe-assembly
                assembly {
                    mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                }
                value /= 10;
                if (value == 0) break;
            }
            return buffer;
        }
    }

    /**
     * @dev Converts a `int256` to its ASCII `string` decimal representation.
     */
    function toString(int256 value) internal pure returns (string memory) {
        return string(abi.encodePacked(value < 0 ? "-" : "", toString(SignedMathUpgradeable.abs(value))));
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        unchecked {
            return toHexString(value, MathUpgradeable.log256(value) + 1);
        }
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }

    /**
     * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
     */
    function toHexString(address addr) internal pure returns (string memory) {
        return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
    }

    /**
     * @dev Returns true if the two strings are equal.
     */
    function equal(string memory a, string memory b) internal pure returns (bool) {
        return keccak256(bytes(a)) == keccak256(bytes(b));
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (access/Ownable2Step.sol)

pragma solidity ^0.8.0;

import "./OwnableUpgradeable.sol";
import "../proxy/utils/Initializable.sol";

/**
 * @dev Contract module which provides access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership} and {acceptOwnership}.
 *
 * This module is used through inheritance. It will make available all functions
 * from parent (Ownable).
 */
abstract contract Ownable2StepUpgradeable is Initializable, OwnableUpgradeable {
    function __Ownable2Step_init() internal onlyInitializing {
        __Ownable_init_unchained();
    }

    function __Ownable2Step_init_unchained() internal onlyInitializing {
    }
    address private _pendingOwner;

    event OwnershipTransferStarted(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Returns the address of the pending owner.
     */
    function pendingOwner() public view virtual returns (address) {
        return _pendingOwner;
    }

    /**
     * @dev Starts the ownership transfer of the contract to a new account. Replaces the pending transfer if there is one.
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual override onlyOwner {
        _pendingOwner = newOwner;
        emit OwnershipTransferStarted(owner(), newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`) and deletes any pending owner.
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual override {
        delete _pendingOwner;
        super._transferOwnership(newOwner);
    }

    /**
     * @dev The new owner accepts the ownership transfer.
     */
    function acceptOwnership() public virtual {
        address sender = _msgSender();
        require(pendingOwner() == sender, "Ownable2Step: caller is not the new owner");
        _transferOwnership(sender);
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[49] private __gap;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (security/Pausable.sol)

pragma solidity ^0.8.0;

import "../utils/ContextUpgradeable.sol";
import "../proxy/utils/Initializable.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
abstract contract PausableUpgradeable is Initializable, ContextUpgradeable {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    function __Pausable_init() internal onlyInitializing {
        __Pausable_init_unchained();
    }

    function __Pausable_init_unchained() internal onlyInitializing {
        _paused = false;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        _requireNotPaused();
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        _requirePaused();
        _;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view virtual returns (bool) {
        return _paused;
    }

    /**
     * @dev Throws if the contract is paused.
     */
    function _requireNotPaused() internal view virtual {
        require(!paused(), "Pausable: paused");
    }

    /**
     * @dev Throws if the contract is not paused.
     */
    function _requirePaused() internal view virtual {
        require(paused(), "Pausable: not paused");
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[49] private __gap;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/ERC721.sol)

pragma solidity ^0.8.0;

import "./IERC721Upgradeable.sol";
import "./IERC721ReceiverUpgradeable.sol";
import "./extensions/IERC721MetadataUpgradeable.sol";
import "../../utils/AddressUpgradeable.sol";
import "../../utils/ContextUpgradeable.sol";
import "../../utils/StringsUpgradeable.sol";
import "../../utils/introspection/ERC165Upgradeable.sol";
import "../../proxy/utils/Initializable.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721Upgradeable is Initializable, ContextUpgradeable, ERC165Upgradeable, IERC721Upgradeable, IERC721MetadataUpgradeable {
    using AddressUpgradeable for address;
    using StringsUpgradeable for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    function __ERC721_init(string memory name_, string memory symbol_) internal onlyInitializing {
        __ERC721_init_unchained(name_, symbol_);
    }

    function __ERC721_init_unchained(string memory name_, string memory symbol_) internal onlyInitializing {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165Upgradeable, IERC165Upgradeable) returns (bool) {
        return
            interfaceId == type(IERC721Upgradeable).interfaceId ||
            interfaceId == type(IERC721MetadataUpgradeable).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: address zero is not a valid owner");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _ownerOf(tokenId);
        require(owner != address(0), "ERC721: invalid token ID");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        _requireMinted(tokenId);

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overridden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721Upgradeable.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not token owner or approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        _requireMinted(tokenId);

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        _setApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(address from, address to, uint256 tokenId) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner or approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner or approved");
        _safeTransfer(from, to, tokenId, data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(address from, address to, uint256 tokenId, bytes memory data) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns the owner of the `tokenId`. Does NOT revert if token doesn't exist
     */
    function _ownerOf(uint256 tokenId) internal view virtual returns (address) {
        return _owners[tokenId];
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _ownerOf(tokenId) != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        address owner = ERC721Upgradeable.ownerOf(tokenId);
        return (spender == owner || isApprovedForAll(owner, spender) || getApproved(tokenId) == spender);
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(address to, uint256 tokenId, bytes memory data) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId, 1);

        // Check that tokenId was not minted by `_beforeTokenTransfer` hook
        require(!_exists(tokenId), "ERC721: token already minted");

        unchecked {
            // Will not overflow unless all 2**256 token ids are minted to the same owner.
            // Given that tokens are minted one by one, it is impossible in practice that
            // this ever happens. Might change if we allow batch minting.
            // The ERC fails to describe this case.
            _balances[to] += 1;
        }

        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);

        _afterTokenTransfer(address(0), to, tokenId, 1);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     * This is an internal function that does not check if the sender is authorized to operate on the token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721Upgradeable.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId, 1);

        // Update ownership in case tokenId was transferred by `_beforeTokenTransfer` hook
        owner = ERC721Upgradeable.ownerOf(tokenId);

        // Clear approvals
        delete _tokenApprovals[tokenId];

        unchecked {
            // Cannot overflow, as that would require more tokens to be burned/transferred
            // out than the owner initially received through minting and transferring in.
            _balances[owner] -= 1;
        }
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);

        _afterTokenTransfer(owner, address(0), tokenId, 1);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(address from, address to, uint256 tokenId) internal virtual {
        require(ERC721Upgradeable.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId, 1);

        // Check that tokenId was not transferred by `_beforeTokenTransfer` hook
        require(ERC721Upgradeable.ownerOf(tokenId) == from, "ERC721: transfer from incorrect owner");

        // Clear approvals from the previous owner
        delete _tokenApprovals[tokenId];

        unchecked {
            // `_balances[from]` cannot overflow for the same reason as described in `_burn`:
            // `from`'s balance is the number of token held, which is at least one before the current
            // transfer.
            // `_balances[to]` could overflow in the conditions described in `_mint`. That would require
            // all 2**256 token ids to be minted, which in practice is impossible.
            _balances[from] -= 1;
            _balances[to] += 1;
        }
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);

        _afterTokenTransfer(from, to, tokenId, 1);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits an {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721Upgradeable.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Approve `operator` to operate on all of `owner` tokens
     *
     * Emits an {ApprovalForAll} event.
     */
    function _setApprovalForAll(address owner, address operator, bool approved) internal virtual {
        require(owner != operator, "ERC721: approve to caller");
        _operatorApprovals[owner][operator] = approved;
        emit ApprovalForAll(owner, operator, approved);
    }

    /**
     * @dev Reverts if the `tokenId` has not been minted yet.
     */
    function _requireMinted(uint256 tokenId) internal view virtual {
        require(_exists(tokenId), "ERC721: invalid token ID");
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721ReceiverUpgradeable(to).onERC721Received(_msgSender(), from, tokenId, data) returns (bytes4 retval) {
                return retval == IERC721ReceiverUpgradeable.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    /// @solidity memory-safe-assembly
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting and burning. If {ERC721Consecutive} is
     * used, the hook may be called as part of a consecutive (batch) mint, as indicated by `batchSize` greater than 1.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s tokens will be transferred to `to`.
     * - When `from` is zero, the tokens will be minted for `to`.
     * - When `to` is zero, ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     * - `batchSize` is non-zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 /* firstTokenId */,
        uint256 batchSize
    ) internal virtual {
        if (batchSize > 1) {
            if (from != address(0)) {
                _balances[from] -= batchSize;
            }
            if (to != address(0)) {
                _balances[to] += batchSize;
            }
        }
    }

    /**
     * @dev Hook that is called after any token transfer. This includes minting and burning. If {ERC721Consecutive} is
     * used, the hook may be called as part of a consecutive (batch) mint, as indicated by `batchSize` greater than 1.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s tokens were transferred to `to`.
     * - When `from` is zero, the tokens were minted for `to`.
     * - When `to` is zero, ``from``'s tokens were burned.
     * - `from` and `to` are never both zero.
     * - `batchSize` is non-zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(address from, address to, uint256 firstTokenId, uint256 batchSize) internal virtual {}

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[44] private __gap;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (security/ReentrancyGuard.sol)

pragma solidity ^0.8.0;
import "../proxy/utils/Initializable.sol";

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuardUpgradeable is Initializable {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    function __ReentrancyGuard_init() internal onlyInitializing {
        __ReentrancyGuard_init_unchained();
    }

    function __ReentrancyGuard_init_unchained() internal onlyInitializing {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and making it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        _nonReentrantBefore();
        _;
        _nonReentrantAfter();
    }

    function _nonReentrantBefore() private {
        // On the first call to nonReentrant, _status will be _NOT_ENTERED
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;
    }

    function _nonReentrantAfter() private {
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
     * `nonReentrant` function in the call stack.
     */
    function _reentrancyGuardEntered() internal view returns (bool) {
        return _status == _ENTERED;
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[49] private __gap;
}

// SPDX-License-Identifier: MIT

pragma solidity 0.8.17;

/// @dev Shared constructs for the Subscription Token Protocol contracts
library Shared {
    /// @dev The initialization parameters for a subscription token
    struct InitParams {
        /// @dev the name of the collection
        string name;
        /// @dev the symbol of the collection
        string symbol;
        /// @dev the metadata URI for the collection
        string contractUri;
        /// @dev the metadata URI for the tokens
        string tokenUri;
        /// @dev the address of the owner of the collection
        address owner;
        /// @dev the number of base tokens required for a single second of time
        uint256 tokensPerSecond;
        /// @dev the minimum number of seconds an account can purchase
        uint256 minimumPurchaseSeconds;
        /// @dev the basis points for reward allocations
        uint16 rewardBps;
        /// @dev the number of times the reward rate is halved (until it reaches one). 6 = 64,32,16,16,8,4,2,1 .. then 0
        uint8 numRewardHalvings;
        /// @dev the basis points for fee allocations
        uint16 feeBps;
        /// @dev the address of the fee recipient
        address feeRecipient;
        /// @dev the address of the ERC20 token used for purchases, or the 0x0 for native
        address erc20TokenAddr;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Permit.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 Permit extension allowing approvals to be made via signatures, as defined in
 * https://eips.ethereum.org/EIPS/eip-2612[EIP-2612].
 *
 * Adds the {permit} method, which can be used to change an account's ERC20 allowance (see {IERC20-allowance}) by
 * presenting a message signed by the account. By not relying on {IERC20-approve}, the token holder account doesn't
 * need to send a transaction, and thus is not required to hold Ether at all.
 */
interface IERC20Permit {
    /**
     * @dev Sets `value` as the allowance of `spender` over ``owner``'s tokens,
     * given ``owner``'s signed approval.
     *
     * IMPORTANT: The same issues {IERC20-approve} has related to transaction
     * ordering also apply here.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `deadline` must be a timestamp in the future.
     * - `v`, `r` and `s` must be a valid `secp256k1` signature from `owner`
     * over the EIP712-formatted function arguments.
     * - the signature must use ``owner``'s current nonce (see {nonces}).
     *
     * For more information on the signature format, see the
     * https://eips.ethereum.org/EIPS/eip-2612#specification[relevant EIP
     * section].
     */
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;

    /**
     * @dev Returns the current nonce for `owner`. This value must be
     * included whenever a signature is generated for {permit}.
     *
     * Every successful call to {permit} increases ``owner``'s nonce by one. This
     * prevents a signature from being used multiple times.
     */
    function nonces(address owner) external view returns (uint256);

    /**
     * @dev Returns the domain separator used in the encoding of the signature for {permit}, as defined by {EIP712}.
     */
    // solhint-disable-next-line func-name-mixedcase
    function DOMAIN_SEPARATOR() external view returns (bytes32);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     *
     * Furthermore, `isContract` will also return true if the target contract within
     * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
     * which only has an effect at the end of a transaction.
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard math utilities missing in the Solidity language.
 */
library MathUpgradeable {
    enum Rounding {
        Down, // Toward negative infinity
        Up, // Toward infinity
        Zero // Toward zero
    }

    /**
     * @dev Returns the largest of two numbers.
     */
    function max(uint256 a, uint256 b) internal pure returns (uint256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two numbers.
     */
    function min(uint256 a, uint256 b) internal pure returns (uint256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two numbers. The result is rounded towards
     * zero.
     */
    function average(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b) / 2 can overflow.
        return (a & b) + (a ^ b) / 2;
    }

    /**
     * @dev Returns the ceiling of the division of two numbers.
     *
     * This differs from standard division with `/` in that it rounds up instead
     * of rounding down.
     */
    function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
        // (a + b - 1) / b can overflow on addition, so we distribute.
        return a == 0 ? 0 : (a - 1) / b + 1;
    }

    /**
     * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
     * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
     * with further edits by Uniswap Labs also under MIT license.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
        unchecked {
            // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
            // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
            // variables such that product = prod1 * 2^256 + prod0.
            uint256 prod0; // Least significant 256 bits of the product
            uint256 prod1; // Most significant 256 bits of the product
            assembly {
                let mm := mulmod(x, y, not(0))
                prod0 := mul(x, y)
                prod1 := sub(sub(mm, prod0), lt(mm, prod0))
            }

            // Handle non-overflow cases, 256 by 256 division.
            if (prod1 == 0) {
                return prod0 / denominator;
            }

            // Make sure the result is less than 2^256. Also prevents denominator == 0.
            require(denominator > prod1, "Math: mulDiv overflow");

            ///////////////////////////////////////////////
            // 512 by 256 division.
            ///////////////////////////////////////////////

            // Make division exact by subtracting the remainder from [prod1 prod0].
            uint256 remainder;
            assembly {
                // Compute remainder using mulmod.
                remainder := mulmod(x, y, denominator)

                // Subtract 256 bit number from 512 bit number.
                prod1 := sub(prod1, gt(remainder, prod0))
                prod0 := sub(prod0, remainder)
            }

            // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
            // See https://cs.stackexchange.com/q/138556/92363.

            // Does not overflow because the denominator cannot be zero at this stage in the function.
            uint256 twos = denominator & (~denominator + 1);
            assembly {
                // Divide denominator by twos.
                denominator := div(denominator, twos)

                // Divide [prod1 prod0] by twos.
                prod0 := div(prod0, twos)

                // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                twos := add(div(sub(0, twos), twos), 1)
            }

            // Shift in bits from prod1 into prod0.
            prod0 |= prod1 * twos;

            // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
            // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
            // four bits. That is, denominator * inv = 1 mod 2^4.
            uint256 inverse = (3 * denominator) ^ 2;

            // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
            // in modular arithmetic, doubling the correct bits in each step.
            inverse *= 2 - denominator * inverse; // inverse mod 2^8
            inverse *= 2 - denominator * inverse; // inverse mod 2^16
            inverse *= 2 - denominator * inverse; // inverse mod 2^32
            inverse *= 2 - denominator * inverse; // inverse mod 2^64
            inverse *= 2 - denominator * inverse; // inverse mod 2^128
            inverse *= 2 - denominator * inverse; // inverse mod 2^256

            // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
            // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
            // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
            // is no longer required.
            result = prod0 * inverse;
            return result;
        }
    }

    /**
     * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
     */
    function mulDiv(uint256 x, uint256 y, uint256 denominator, Rounding rounding) internal pure returns (uint256) {
        uint256 result = mulDiv(x, y, denominator);
        if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
            result += 1;
        }
        return result;
    }

    /**
     * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
     *
     * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
     */
    function sqrt(uint256 a) internal pure returns (uint256) {
        if (a == 0) {
            return 0;
        }

        // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
        //
        // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
        // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
        //
        // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
        // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
        // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
        //
        // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
        uint256 result = 1 << (log2(a) >> 1);

        // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
        // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
        // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
        // into the expected uint128 result.
        unchecked {
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            result = (result + a / result) >> 1;
            return min(result, a / result);
        }
    }

    /**
     * @notice Calculates sqrt(a), following the selected rounding direction.
     */
    function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = sqrt(a);
            return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 2, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 128;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 64;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 32;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 16;
            }
            if (value >> 8 > 0) {
                value >>= 8;
                result += 8;
            }
            if (value >> 4 > 0) {
                value >>= 4;
                result += 4;
            }
            if (value >> 2 > 0) {
                value >>= 2;
                result += 2;
            }
            if (value >> 1 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log2(value);
            return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 10, rounded down, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >= 10 ** 64) {
                value /= 10 ** 64;
                result += 64;
            }
            if (value >= 10 ** 32) {
                value /= 10 ** 32;
                result += 32;
            }
            if (value >= 10 ** 16) {
                value /= 10 ** 16;
                result += 16;
            }
            if (value >= 10 ** 8) {
                value /= 10 ** 8;
                result += 8;
            }
            if (value >= 10 ** 4) {
                value /= 10 ** 4;
                result += 4;
            }
            if (value >= 10 ** 2) {
                value /= 10 ** 2;
                result += 2;
            }
            if (value >= 10 ** 1) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log10(value);
            return result + (rounding == Rounding.Up && 10 ** result < value ? 1 : 0);
        }
    }

    /**
     * @dev Return the log in base 256, rounded down, of a positive value.
     * Returns 0 if given 0.
     *
     * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
     */
    function log256(uint256 value) internal pure returns (uint256) {
        uint256 result = 0;
        unchecked {
            if (value >> 128 > 0) {
                value >>= 128;
                result += 16;
            }
            if (value >> 64 > 0) {
                value >>= 64;
                result += 8;
            }
            if (value >> 32 > 0) {
                value >>= 32;
                result += 4;
            }
            if (value >> 16 > 0) {
                value >>= 16;
                result += 2;
            }
            if (value >> 8 > 0) {
                result += 1;
            }
        }
        return result;
    }

    /**
     * @dev Return the log in base 256, following the selected rounding direction, of a positive value.
     * Returns 0 if given 0.
     */
    function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
        unchecked {
            uint256 result = log256(value);
            return result + (rounding == Rounding.Up && 1 << (result << 3) < value ? 1 : 0);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/math/SignedMath.sol)

pragma solidity ^0.8.0;

/**
 * @dev Standard signed math utilities missing in the Solidity language.
 */
library SignedMathUpgradeable {
    /**
     * @dev Returns the largest of two signed numbers.
     */
    function max(int256 a, int256 b) internal pure returns (int256) {
        return a > b ? a : b;
    }

    /**
     * @dev Returns the smallest of two signed numbers.
     */
    function min(int256 a, int256 b) internal pure returns (int256) {
        return a < b ? a : b;
    }

    /**
     * @dev Returns the average of two signed numbers without overflow.
     * The result is rounded towards zero.
     */
    function average(int256 a, int256 b) internal pure returns (int256) {
        // Formula from the book "Hacker's Delight"
        int256 x = (a & b) + ((a ^ b) >> 1);
        return x + (int256(uint256(x) >> 255) & (a ^ b));
    }

    /**
     * @dev Returns the absolute unsigned value of a signed value.
     */
    function abs(int256 n) internal pure returns (uint256) {
        unchecked {
            // must be unchecked in order to support `n = type(int256).min`
            return uint256(n >= 0 ? n : -n);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.7.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/ContextUpgradeable.sol";
import "../proxy/utils/Initializable.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract OwnableUpgradeable is Initializable, ContextUpgradeable {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    function __Ownable_init() internal onlyInitializing {
        __Ownable_init_unchained();
    }

    function __Ownable_init_unchained() internal onlyInitializing {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(address(0));
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[49] private __gap;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (proxy/utils/Initializable.sol)

pragma solidity ^0.8.2;

import "../../utils/AddressUpgradeable.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since proxied contracts do not make use of a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
 * reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
 * case an upgrade adds a module that needs to be initialized.
 *
 * For example:
 *
 * [.hljs-theme-light.nopadding]
 * ```solidity
 * contract MyToken is ERC20Upgradeable {
 *     function initialize() initializer public {
 *         __ERC20_init("MyToken", "MTK");
 *     }
 * }
 *
 * contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
 *     function initializeV2() reinitializer(2) public {
 *         __ERC20Permit_init("MyToken");
 *     }
 * }
 * ```
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {ERC1967Proxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 *
 * [CAUTION]
 * ====
 * Avoid leaving a contract uninitialized.
 *
 * An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
 * contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
 * the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
 *
 * [.hljs-theme-light.nopadding]
 * ```
 * /// @custom:oz-upgrades-unsafe-allow constructor
 * constructor() {
 *     _disableInitializers();
 * }
 * ```
 * ====
 */
abstract contract Initializable {
    /**
     * @dev Indicates that the contract has been initialized.
     * @custom:oz-retyped-from bool
     */
    uint8 private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Triggered when the contract has been initialized or reinitialized.
     */
    event Initialized(uint8 version);

    /**
     * @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
     * `onlyInitializing` functions can be used to initialize parent contracts.
     *
     * Similar to `reinitializer(1)`, except that functions marked with `initializer` can be nested in the context of a
     * constructor.
     *
     * Emits an {Initialized} event.
     */
    modifier initializer() {
        bool isTopLevelCall = !_initializing;
        require(
            (isTopLevelCall && _initialized < 1) || (!AddressUpgradeable.isContract(address(this)) && _initialized == 1),
            "Initializable: contract is already initialized"
        );
        _initialized = 1;
        if (isTopLevelCall) {
            _initializing = true;
        }
        _;
        if (isTopLevelCall) {
            _initializing = false;
            emit Initialized(1);
        }
    }

    /**
     * @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
     * contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
     * used to initialize parent contracts.
     *
     * A reinitializer may be used after the original initialization step. This is essential to configure modules that
     * are added through upgrades and that require initialization.
     *
     * When `version` is 1, this modifier is similar to `initializer`, except that functions marked with `reinitializer`
     * cannot be nested. If one is invoked in the context of another, execution will revert.
     *
     * Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
     * a contract, executing them in the right order is up to the developer or operator.
     *
     * WARNING: setting the version to 255 will prevent any future reinitialization.
     *
     * Emits an {Initialized} event.
     */
    modifier reinitializer(uint8 version) {
        require(!_initializing && _initialized < version, "Initializable: contract is already initialized");
        _initialized = version;
        _initializing = true;
        _;
        _initializing = false;
        emit Initialized(version);
    }

    /**
     * @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
     * {initializer} and {reinitializer} modifiers, directly or indirectly.
     */
    modifier onlyInitializing() {
        require(_initializing, "Initializable: contract is not initializing");
        _;
    }

    /**
     * @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
     * Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
     * to any version. It is recommended to use this to lock implementation contracts that are designed to be called
     * through proxies.
     *
     * Emits an {Initialized} event the first time it is successfully executed.
     */
    function _disableInitializers() internal virtual {
        require(!_initializing, "Initializable: contract is initializing");
        if (_initialized != type(uint8).max) {
            _initialized = type(uint8).max;
            emit Initialized(type(uint8).max);
        }
    }

    /**
     * @dev Returns the highest version that has been initialized. See {reinitializer}.
     */
    function _getInitializedVersion() internal view returns (uint8) {
        return _initialized;
    }

    /**
     * @dev Returns `true` if the contract is currently initializing. See {onlyInitializing}.
     */
    function _isInitializing() internal view returns (bool) {
        return _initializing;
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^0.8.0;
import "../proxy/utils/Initializable.sol";

/**
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract ContextUpgradeable is Initializable {
    function __Context_init() internal onlyInitializing {
    }

    function __Context_init_unchained() internal onlyInitializing {
    }
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[50] private __gap;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC721/IERC721.sol)

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165Upgradeable.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721Upgradeable is IERC165Upgradeable {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of tokens in ``owner``'s account.
     */
    function balanceOf(address owner) external view returns (uint256 balance);

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Note that the caller is responsible to confirm that the recipient is capable of receiving ERC721
     * or else they may be permanently lost. Usage of {safeTransferFrom} prevents loss, though the caller must
     * understand this adds an external call which potentially creates a reentrancy vulnerability.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(address from, address to, uint256 tokenId) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool approved) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC721/IERC721Receiver.sol)

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721ReceiverUpgradeable {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC721Upgradeable.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721MetadataUpgradeable is IERC721Upgradeable {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     *
     * Furthermore, `isContract` will also return true if the target contract within
     * the same transaction is already scheduled for destruction by `SELFDESTRUCT`,
     * which only has an effect at the end of a transaction.
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://consensys.net/diligence/blog/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResultFromTarget(target, success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
     * the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
     *
     * _Available since v4.8._
     */
    function verifyCallResultFromTarget(
        address target,
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        if (success) {
            if (returndata.length == 0) {
                // only check isContract if the call was successful and the return data is empty
                // otherwise we already know that it was a contract
                require(isContract(target), "Address: call to non-contract");
            }
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    /**
     * @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason or using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            _revert(returndata, errorMessage);
        }
    }

    function _revert(bytes memory returndata, string memory errorMessage) private pure {
        // Look for revert reason and bubble it up if present
        if (returndata.length > 0) {
            // The easiest way to bubble the revert reason is using memory via assembly
            /// @solidity memory-safe-assembly
            assembly {
                let returndata_size := mload(returndata)
                revert(add(32, returndata), returndata_size)
            }
        } else {
            revert(errorMessage);
        }
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

pragma solidity ^0.8.0;

import "./IERC165Upgradeable.sol";
import "../../proxy/utils/Initializable.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165Upgradeable is Initializable, IERC165Upgradeable {
    function __ERC165_init() internal onlyInitializing {
    }

    function __ERC165_init_unchained() internal onlyInitializing {
    }
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165Upgradeable).interfaceId;
    }

    /**
     * @dev This empty reserved space is put in place to allow future versions to add new
     * variables without shifting down storage in the inheritance chain.
     * See https://docs.openzeppelin.com/contracts/4.x/upgradeable#storage_gaps
     */
    uint256[50] private __gap;
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165Upgradeable {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

{
  "remappings": [
    "@openzeppelin/=lib/openzeppelin-contracts/",
    "@openzeppelin-upgradeable/=lib/openzeppelin-contracts-upgradeable/",
    "@forge/=lib/forge-std/src/",
    "ds-test/=lib/forge-std/lib/ds-test/src/",
    "erc4626-tests/=lib/openzeppelin-contracts-upgradeable/lib/erc4626-tests/",
    "forge-std/=lib/forge-std/src/",
    "openzeppelin-contracts-upgradeable/=lib/openzeppelin-contracts-upgradeable/",
    "openzeppelin-contracts/=lib/openzeppelin-contracts/"
  ],
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "metadata": {
    "useLiteralContent": false,
    "bytecodeHash": "ipfs"
  },
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "devdoc",
        "userdoc",
        "metadata",
        "abi"
      ]
    }
  },
  "evmVersion": "london",
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