AnyswapV6ERC20.sol

// SPDX-License-Identifier: GPL-3.0-or-later

pragma solidity ^0.8.2;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    function totalSupply() external view returns (uint256);
    function decimals() external view returns (uint8);
    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);
}

library Address {
    function isContract(address account) internal view returns (bool) {
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        // solhint-disable-next-line no-inline-assembly
        assembly { codehash := extcodehash(account) }
        return (codehash != 0x0 && codehash != accountHash);
    }
}

library SafeERC20 {
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint value) internal {
        callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    function safeApprove(IERC20 token, address spender, uint value) internal {
        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));
    }
    function callOptionalReturn(IERC20 token, bytes memory data) private {
        require(address(token).isContract(), "SafeERC20: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = address(token).call(data);
        require(success, "SafeERC20: low-level call failed");

        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

contract AnyswapV6ERC20 is IERC20 {
    using SafeERC20 for IERC20;
    string public name;
    string public symbol;
    uint8  public immutable override decimals;

    address public immutable underlying;
    bool public constant underlyingIsMinted = false;

    /// @dev Records amount of AnyswapV6ERC20 token owned by account.
    mapping (address => uint256) public override balanceOf;
    uint256 private _totalSupply;

    // init flag for setting immediate vault, needed for CREATE2 support
    bool private _init;

    // flag to enable/disable swapout vs vault.burn so multiple events are triggered
    bool private _vaultOnly;

    // delay for timelock functions
    uint public constant DELAY = 2 days;

    // set of minters, can be this bridge or other bridges
    mapping(address => bool) public isMinter;
    address[] public minters;

    // primary controller of the token contract
    address public vault;

    address public pendingMinter;
    uint public delayMinter;

    address public pendingVault;
    uint public delayVault;

    modifier onlyAuth() {
        require(isMinter[msg.sender], "AnyswapV6ERC20: FORBIDDEN");
        _;
    }

    modifier onlyVault() {
        require(msg.sender == vault, "AnyswapV6ERC20: FORBIDDEN");
        _;
    }

    function owner() external view returns (address) {
        return vault;
    }

    function mpc() external view returns (address) {
        return vault;
    }

    function setVaultOnly(bool enabled) external onlyVault {
        _vaultOnly = enabled;
    }

    function initVault(address _vault) external onlyVault {
        require(_init);
        _init = false;
        vault = _vault;
        isMinter[_vault] = true;
        minters.push(_vault);
    }

    function setVault(address _vault) external onlyVault {
        require(_vault != address(0), "AnyswapV6ERC20: address(0)");
        pendingVault = _vault;
        delayVault = block.timestamp + DELAY;
    }

    function applyVault() external onlyVault {
        require(pendingVault != address(0) && block.timestamp >= delayVault);
        vault = pendingVault;

        pendingVault = address(0);
        delayVault = 0;
    }

    function setMinter(address _auth) external onlyVault {
        require(_auth != address(0), "AnyswapV6ERC20: address(0)");
        pendingMinter = _auth;
        delayMinter = block.timestamp + DELAY;
    }

    function applyMinter() external onlyVault {
        require(pendingMinter != address(0) && block.timestamp >= delayMinter);
        isMinter[pendingMinter] = true;
        minters.push(pendingMinter);

        pendingMinter = address(0);
        delayMinter = 0;
    }

    // No time delay revoke minter emergency function
    function revokeMinter(address _auth) external onlyVault {
        isMinter[_auth] = false;
    }

    function getAllMinters() external view returns (address[] memory) {
        return minters;
    }

    function changeVault(address newVault) external onlyVault returns (bool) {
        require(newVault != address(0), "AnyswapV6ERC20: address(0)");
        emit LogChangeVault(vault, newVault, block.timestamp);
        vault = newVault;
        pendingVault = address(0);
        delayVault = 0;
        return true;
    }

    function mint(address to, uint256 amount) external onlyAuth returns (bool) {
        _mint(to, amount);
        return true;
    }

    function burn(address from, uint256 amount) external onlyAuth returns (bool) {
        _burn(from, amount);
        return true;
    }

    function Swapin(bytes32 txhash, address account, uint256 amount) external onlyAuth returns (bool) {
        if (underlying != address(0) && IERC20(underlying).balanceOf(address(this)) >= amount) {
            IERC20(underlying).safeTransfer(account, amount);
        } else {
            _mint(account, amount);
        }
        emit LogSwapin(txhash, account, amount);
        return true;
    }

    function Swapout(uint256 amount, address bindaddr) external returns (bool) {
        require(!_vaultOnly, "AnyswapV6ERC20: vaultOnly");
        require(bindaddr != address(0), "AnyswapV6ERC20: address(0)");
        if (underlying != address(0) && balanceOf[msg.sender] < amount) {
            IERC20(underlying).safeTransferFrom(msg.sender, address(this), amount);
        } else {
            _burn(msg.sender, amount);
        }
        emit LogSwapout(msg.sender, bindaddr, amount);
        return true;
    }

    /// @dev Records number of AnyswapV6ERC20 token that account (second) will be allowed to spend on behalf of another account (first) through {transferFrom}.
    mapping (address => mapping (address => uint256)) public override allowance;

    event LogChangeVault(address indexed oldVault, address indexed newVault, uint indexed effectiveTime);
    event LogSwapin(bytes32 indexed txhash, address indexed account, uint amount);
    event LogSwapout(address indexed account, address indexed bindaddr, uint amount);

    constructor(string memory _name, string memory _symbol, uint8 _decimals, address _underlying, address _vault) {
        name = _name;
        symbol = _symbol;
        decimals = _decimals;
        underlying = _underlying;
        if (_underlying != address(0)) {
            require(_decimals == IERC20(_underlying).decimals());
        }

        // Use init to allow for CREATE2 accross all chains
        _init = true;

        // Disable/Enable swapout for v1 tokens vs mint/burn for v3 tokens
        _vaultOnly = false;

        vault = _vault;
    }

    /// @dev Returns the total supply of AnyswapV6ERC20 token as the ETH held in this contract.
    function totalSupply() external view override returns (uint256) {
        return _totalSupply;
    }

    function deposit() external returns (uint) {
        uint _amount = IERC20(underlying).balanceOf(msg.sender);
        IERC20(underlying).safeTransferFrom(msg.sender, address(this), _amount);
        return _deposit(_amount, msg.sender);
    }

    function deposit(uint amount) external returns (uint) {
        IERC20(underlying).safeTransferFrom(msg.sender, address(this), amount);
        return _deposit(amount, msg.sender);
    }

    function deposit(uint amount, address to) external returns (uint) {
        IERC20(underlying).safeTransferFrom(msg.sender, address(this), amount);
        return _deposit(amount, to);
    }

    function depositVault(uint amount, address to) external onlyVault returns (uint) {
        return _deposit(amount, to);
    }

    function _deposit(uint amount, address to) internal returns (uint) {
        require(!underlyingIsMinted);
        require(underlying != address(0) && underlying != address(this));
        _mint(to, amount);
        return amount;
    }

    function withdraw() external returns (uint) {
        return _withdraw(msg.sender, balanceOf[msg.sender], msg.sender);
    }

    function withdraw(uint amount) external returns (uint) {
        return _withdraw(msg.sender, amount, msg.sender);
    }

    function withdraw(uint amount, address to) external returns (uint) {
        return _withdraw(msg.sender, amount, to);
    }

    function withdrawVault(address from, uint amount, address to) external onlyVault returns (uint) {
        return _withdraw(from, amount, to);
    }

    function _withdraw(address from, uint amount, address to) internal returns (uint) {
        require(!underlyingIsMinted);
        require(underlying != address(0) && underlying != address(this));
        _burn(from, amount);
        IERC20(underlying).safeTransfer(to, amount);
        return amount;
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

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

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        uint256 balance = balanceOf[account];
        require(balance >= amount, "ERC20: burn amount exceeds balance");

        balanceOf[account] = balance - amount;
        _totalSupply -= amount;
        emit Transfer(account, address(0), amount);
    }

    /// @dev Sets `value` as allowance of `spender` account over caller account's AnyswapV6ERC20 token.
    /// Emits {Approval} event.
    /// Returns boolean value indicating whether operation succeeded.
    function approve(address spender, uint256 value) external override returns (bool) {
        allowance[msg.sender][spender] = value;
        emit Approval(msg.sender, spender, value);

        return true;
    }

    /// @dev Moves `value` AnyswapV6ERC20 token from caller's account to account (`to`).
    /// Emits {Transfer} event.
    /// Returns boolean value indicating whether operation succeeded.
    /// Requirements:
    ///   - caller account must have at least `value` AnyswapV6ERC20 token.
    function transfer(address to, uint256 value) external override returns (bool) {
        require(to != address(0) && to != address(this));
        uint256 balance = balanceOf[msg.sender];
        require(balance >= value, "AnyswapV6ERC20: transfer amount exceeds balance");

        balanceOf[msg.sender] = balance - value;
        balanceOf[to] += value;
        emit Transfer(msg.sender, to, value);

        return true;
    }

    /// @dev Moves `value` AnyswapV6ERC20 token from account (`from`) to account (`to`) using allowance mechanism.
    /// `value` is then deducted from caller account's allowance, unless set to `type(uint256).max`.
    /// Emits {Approval} event to reflect reduced allowance `value` for caller account to spend from account (`from`),
    /// unless allowance is set to `type(uint256).max`
    /// Emits {Transfer} event.
    /// Returns boolean value indicating whether operation succeeded.
    /// Requirements:
    ///   - `from` account must have at least `value` balance of AnyswapV6ERC20 token.
    ///   - `from` account must have approved caller to spend at least `value` of AnyswapV6ERC20 token, unless `from` and caller are the same account.
    function transferFrom(address from, address to, uint256 value) external override returns (bool) {
        require(to != address(0) && to != address(this));
        if (from != msg.sender) {
            uint256 allowed = allowance[from][msg.sender];
            if (allowed != type(uint256).max) {
                require(allowed >= value, "AnyswapV6ERC20: request exceeds allowance");
                uint256 reduced = allowed - value;
                allowance[from][msg.sender] = reduced;
                emit Approval(from, msg.sender, reduced);
            }
        }

        uint256 balance = balanceOf[from];
        require(balance >= value, "AnyswapV6ERC20: transfer amount exceeds balance");

        balanceOf[from] = balance - value;
        balanceOf[to] += value;
        emit Transfer(from, to, value);

        return true;
    }
}