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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

// Contract for digital signature and staking
contract A0Signatures {
    // Instance of the A0T token (must be ERC20-compatible)
    IERC20 public immutable token;

    // Structure for digital signatures
    struct Signature {
        bytes32 identifier;
        bytes32 data;
        address signer;
        uint256 timestamp;
        uint256 stake;
        uint256 stakeLock;
    }

    // Mapping from signature identifier to stored Signature
    mapping(bytes32 => Signature) public signatures;

    // Event emitted when a new signature is recorded.
    event SignatureCreated(
        bytes32 indexed identifier,
        address indexed signer,
        uint256 timestamp
    );

    // Event emitted when a signature is unstaked.
    event SignatureUnstaked(
        bytes32 indexed identifier,
        address indexed signer,
        uint256 timestamp,
        uint256 unstakedAmount
    );

    // constructor to set the token instance
    constructor(address tokenAddress) {
        token = IERC20(tokenAddress);
    }

    // function to issue a digital signature, foundation for off-chain dApps
    // can be used for time-locking A0T tokens
    function sign(Signature[] calldata signaturesIn) external {
        uint256 totalStakeNeeded = 0;
        uint256 len = signaturesIn.length;
        for (uint256 i = 0; i < len; i++) {
            totalStakeNeeded += signaturesIn[i].stake;
        }

        // Transfer the total stake from the user to this contract using allowance.
        require(
            token.transferFrom(msg.sender, address(this), totalStakeNeeded),
            "Token transfer failed, check allowance and balance"
        );

        // Process each signature.
        for (uint256 i = 0; i < len; i++) {
            bytes32 id = signaturesIn[i].identifier;
            // Ensure the identifier has not been used yet.
            require(signatures[id].timestamp == 0, "Identifier already signed");

            Signature memory sig = signaturesIn[i];
            sig.signer = msg.sender;
            sig.timestamp = block.timestamp;
            // Store the signature.
            signatures[id] = sig;

            emit SignatureCreated(id, msg.sender, block.timestamp);
        }
    }

    // function to return staked tokens from signatures
    // can be used after stake is no longer needed and stakeLock timestamp has passed
    function unstake(bytes32[] calldata identifiers) external {
        uint256 totalToUnstake = 0;
        uint256 len = identifiers.length;

        for (uint256 i = 0; i < len; i++) {
            Signature storage sig = signatures[identifiers[i]];
            require(sig.timestamp != 0, "Signature does not exist");
            require(sig.signer == msg.sender, "Not the signature owner");
            require(sig.stake > 0, "No stake to unstake");
            require(sig.stakeLock <= block.timestamp, "Stake is still locked");

            totalToUnstake += sig.stake;
            uint256 stakedAmount = sig.stake;
            // Mark the signature's stake as claimed.
            sig.stake = 0;

            emit SignatureUnstaked(
                identifiers[i],
                msg.sender,
                block.timestamp,
                stakedAmount
            );
        }

        require(totalToUnstake > 0, "Nothing to unstake");
        require(
            token.transfer(msg.sender, totalToUnstake),
            "Token transfer failed"
        );
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v5.1.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.20;

/**
 * @dev Interface of the ERC-20 standard as defined in the ERC.
 */
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 value of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

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

    /**
     * @dev Moves a `value` amount of 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 value) 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 a `value` amount of tokens 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 value) external returns (bool);

    /**
     * @dev Moves a `value` amount of tokens from `from` to `to` using the
     * allowance mechanism. `value` 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 value) external returns (bool);
}

{
  "optimizer": {
    "enabled": true,
    "runs": 2000
  },
  "outputSelection": {
    "*": {
      "*": [
        "evm.bytecode",
        "evm.deployedBytecode",
        "devdoc",
        "userdoc",
        "metadata",
        "abi"
      ]
    }
  },
  "remappings": []
}

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[{"inputs":[{"internalType":"address","name":"tokenAddress","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"bytes32","name":"identifier","type":"bytes32"},{"indexed":true,"internalType":"address","name":"signer","type":"address"},{"indexed":false,"internalType":"uint256","name":"timestamp","type":"uint256"}],"name":"SignatureCreated","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"bytes32","name":"identifier","type":"bytes32"},{"indexed":true,"internalType":"address","name":"signer","type":"address"},{"indexed":false,"internalType":"uint256","name":"timestamp","type":"uint256"},{"indexed":false,"internalType":"uint256","name":"unstakedAmount","type":"uint256"}],"name":"SignatureUnstaked","type":"event"},{"inputs":[{"components":[{"internalType":"bytes32","name":"identifier","type":"bytes32"},{"internalType":"bytes32","name":"data","type":"bytes32"},{"internalType":"address","name":"signer","type":"address"},{"internalType":"uint256","name":"timestamp","type":"uint256"},{"internalType":"uint256","name":"stake","type":"uint256"},{"internalType":"uint256","name":"stakeLock","type":"uint256"}],"internalType":"struct A0Signatures.Signature[]","name":"signaturesIn","type":"tuple[]"}],"name":"sign","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"bytes32","name":"","type":"bytes32"}],"name":"signatures","outputs":[{"internalType":"bytes32","name":"identifier","type":"bytes32"},{"internalType":"bytes32","name":"data","type":"bytes32"},{"internalType":"address","name":"signer","type":"address"},{"internalType":"uint256","name":"timestamp","type":"uint256"},{"internalType":"uint256","name":"stake","type":"uint256"},{"internalType":"uint256","name":"stakeLock","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"token","outputs":[{"internalType":"contract IERC20","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"bytes32[]","name":"identifiers","type":"bytes32[]"}],"name":"unstake","outputs":[],"stateMutability":"nonpayable","type":"function"}]

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000000000000000000000000cc4adb618253ed0d4d8a188fb901d70c54735e03

-----Decoded View---------------
Arg [0] : tokenAddress (address): 0xCc4ADB618253ED0d4d8A188fB901d70C54735e03

-----Encoded View---------------
1 Constructor Arguments found :
Arg [0] : 000000000000000000000000cc4adb618253ed0d4d8a188fb901d70c54735e03