// Sources flattened with hardhat v2.6.6 https://hardhat.org

// File @openzeppelin/contracts/utils/Context.sol@v4.3.2

// License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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 Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}


// File @openzeppelin/contracts/access/Ownable.sol@v4.3.2

// License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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 Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor() {
        _setOwner(_msgSender());
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        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 {
        _setOwner(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");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}


// File contracts/Compensation.sol

// SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.0;

contract Compensation is Ownable {
    address public verifier;
    mapping(address => bool) public claimed;

    constructor(address initialVerifier) {
        require(initialVerifier != address(0), "address_is_null");
        verifier = initialVerifier;
    }

    function setVerifier(address newVerifier) public onlyOwner {
        require(newVerifier != address(0), "address_is_null");
        verifier = newVerifier;
    }

    function withdraw(uint256 amount) public onlyOwner {
        payable(msg.sender).transfer(amount);
    }

    function claim(uint256 amount, uint8 v, bytes32 r, bytes32 s) public {
        require(!claimed[msg.sender], "already_claimed");

        bytes32 hash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", keccak256(abi.encodePacked(msg.sender, amount))));
        address recoveredVerifier = ecrecover(hash, v, r, s);

        require(verifier == recoveredVerifier, "bad_signature");

        claimed[msg.sender] = true;
        payable(msg.sender).transfer(amount);
    }

    receive() external payable {
        // Do nothing.
    }
}