// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

pragma solidity ^0.8.0;

import "../utils/Context.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 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() {
        _transferOwnership(_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 {
        _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);
    }
}

// File: @openzeppelin/contracts/utils/Context.sol



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

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: contracts/timelock/Timelock.sol



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

pragma solidity >=0.8.0 <0.9.0;

import "@openzeppelin/contracts/access/Ownable.sol";

contract Timelock is Ownable {
    event NewAdmin(address indexed newAdmin);
    event NewPendingAdmin(address indexed newPendingAdmin);
    event NewDelay(uint256 indexed newDelay);
    event CancelTransaction(
        bytes32 indexed txHash,
        address indexed target,
        uint256 value,
        string signature,
        bytes data,
        uint256 eta
    );
    event ExecuteTransaction(
        bytes32 indexed txHash,
        address indexed target,
        uint256 value,
        string signature,
        bytes data,
        uint256 eta
    );
    event QueueTransaction(
        bytes32 indexed txHash,
        address indexed target,
        uint256 value,
        string signature,
        bytes data,
        uint256 eta
    );

    uint256 public constant GRACE_PERIOD = 14 days;
    uint256 public constant MINIMUM_DELAY = 12 hours;
    uint256 public constant MAXIMUM_DELAY = 30 days;

    address public admin;
    address public pendingAdmin;
    uint256 public delay;
    bool public admin_initialized;

    mapping(bytes32 => bool) public queuedTransactions;

    modifier onlyAdmin() {
        require(
            admin == msg.sender,
            "Timelock::queueTransaction: Call must come from admin."
        );
        _;
    }

    constructor(address admin_, uint256 delay_) {
        require(
            delay_ >= MINIMUM_DELAY,
            "Timelock::constructor: Delay must exceed minimum delay."
        );
        require(
            delay_ <= MAXIMUM_DELAY,
            "Timelock::constructor: Delay must not exceed maximum delay."
        );

        admin = admin_;
        delay = delay_;
        admin_initialized = false;
    }

    // XXX: function() external payable { }
    receive() external payable {}

    function setDelay(uint256 delay_) public {
        require(
            msg.sender == address(this),
            "Timelock::setDelay: Call must come from Timelock."
        );
        require(
            delay_ >= MINIMUM_DELAY,
            "Timelock::setDelay: Delay must exceed minimum delay."
        );
        require(
            delay_ <= MAXIMUM_DELAY,
            "Timelock::setDelay: Delay must not exceed maximum delay."
        );
        delay = delay_;

        emit NewDelay(delay);
    }

    function acceptAdmin() public {
        require(
            msg.sender == pendingAdmin,
            "Timelock::acceptAdmin: Call must come from pendingAdmin."
        );
        admin = msg.sender;
        pendingAdmin = address(0);

        emit NewAdmin(admin);
    }

    function setPendingAdmin(address pendingAdmin_) public {
        // allows one time setting of admin for deployment purposes
        if (admin_initialized) {
            require(
                msg.sender == address(this),
                "Timelock::setPendingAdmin: Call must come from Timelock."
            );
        } else {
            require(
                msg.sender == admin,
                "Timelock::setPendingAdmin: First call must come from admin."
            );
            admin_initialized = true;
        }
        pendingAdmin = pendingAdmin_;

        emit NewPendingAdmin(pendingAdmin);
    }

    function queueTransaction(
        address target,
        uint256 value,
        string memory signature,
        bytes memory data,
        uint256 eta
    ) public onlyAdmin returns (bytes32) {
        require(
            eta >= getBlockTimestamp() + delay,
            "Timelock::queueTransaction: Estimated execution block must satisfy delay."
        );

        bytes32 txHash = keccak256(
            abi.encode(target, value, signature, data, eta)
        );
        queuedTransactions[txHash] = true;
        emit QueueTransaction(txHash, target, value, signature, data, eta);
        return txHash;
    }

    function cancelTransaction(
        address target,
        uint256 value,
        string memory signature,
        bytes memory data,
        uint256 eta
    ) public onlyAdmin {
        bytes32 txHash = keccak256(
            abi.encode(target, value, signature, data, eta)
        );
        queuedTransactions[txHash] = false;

        emit CancelTransaction(txHash, target, value, signature, data, eta);
    }

    function executeTransaction(
        address target,
        uint256 value,
        string memory signature,
        bytes memory data,
        uint256 eta
    ) public payable onlyAdmin returns (bytes memory) {
        bytes32 txHash = keccak256(
            abi.encode(target, value, signature, data, eta)
        );
        require(
            queuedTransactions[txHash],
            "Timelock::executeTransaction: Transaction hasn't been queued."
        );
        require(
            getBlockTimestamp() >= eta,
            "Timelock::executeTransaction: Transaction hasn't surpassed time lock."
        );
        require(
            getBlockTimestamp() <= eta + GRACE_PERIOD,
            "Timelock::executeTransaction: Transaction is stale."
        );

        queuedTransactions[txHash] = false;

        bytes memory callData;

        if (bytes(signature).length == 0) {
            callData = data;
        } else {
            callData = abi.encodePacked(
                bytes4(keccak256(bytes(signature))),
                data
            );
        }

        // solium-disable-next-line security/no-call-value
        (bool success, bytes memory returnData) = target.call{value: value}(
            callData
        );
        require(
            success,
            "Timelock::executeTransaction: Transaction execution reverted."
        );

        emit ExecuteTransaction(txHash, target, value, signature, data, eta);

        return returnData;
    }

    function getBlockTimestamp() internal view returns (uint256) {
        // solium-disable-next-line security/no-block-members
        return block.timestamp;
    }
}