// File: contracts/openzeppelin/contracts/token/ERC20/IERC20.sol



// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/IERC20.sol)



pragma solidity ^0.8.0;



/**

 * @dev Interface of the ERC20 standard as defined in the EIP.

 */

interface IERC20 {

    /**

     * @dev Returns the amount of tokens in existence.

     */

    function totalSupply() external view returns (uint256);



    /**

     * @dev Returns the amount of tokens owned by `account`.

     */

    function balanceOf(address account) external view returns (uint256);



    /**

     * @dev Moves `amount` 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 amount) 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 `amount` 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 amount) external returns (bool);



    /**

     * @dev Moves `amount` tokens from `from` to `to` using the

     * allowance mechanism. `amount` 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 amount

    ) external returns (bool);



    /**

     * @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);

}


// File: contracts/openzeppelin/contracts/utils/Context.sol



// 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/openzeppelin/contracts/access/Ownable.sol



// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)



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() {

        _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: contracts/GovernanceExchanger.sol



pragma solidity ^0.8.13;





contract GovernanceExchanger is Ownable {

    address public immutable governanceToken;

    address public immutable utilityToken;

    address private immutable holdingAccount;

    uint256 private immutable endDate;



    // This event is triggered whenever a call to #exchange succeeds.

    event Exchanged(address account, uint256 amount);



    constructor(address governanceToken_, address utilityToken_, address holdingAccount_) {

        governanceToken = governanceToken_;

        utilityToken = utilityToken_;

        holdingAccount = holdingAccount_;



        endDate = block.timestamp + 3 days;

    }



    function exchange(uint256 amount) external {

        require(block.timestamp <= endDate, "GovernanceExchanger::exchange: Exchange period has ended.");

        

        uint256 allowance = IERC20(utilityToken).allowance(msg.sender, address(this));

        

        require(allowance >= amount, "GovernanceExchanger::exchange: Token allowance too small.");



        uint256 utilityTokenBalance = IERC20(utilityToken).balanceOf(msg.sender);



        require(utilityTokenBalance >= amount, "GovernanceExchanger::exchange: Sender's balance must be greater than or equal to the amount requested.");

        require(IERC20(utilityToken).transferFrom(msg.sender, holdingAccount, amount), "GovernanceExchanger::exchange: Transfer of utility tokens failed.");

        require(IERC20(governanceToken).transfer(msg.sender, amount), "GovernanceExchanger::exchange: Transfer of governance tokens failed.");

        emit Exchanged(msg.sender, amount);

    }



    function withdrawGovernance() public onlyOwner {

      require(IERC20(governanceToken).transfer(holdingAccount, IERC20(governanceToken).balanceOf(address(this))), "GovernanceExchanger::withdrawGovernance: Withdraw failed.");

    }



    function withdrawUtility() public onlyOwner {

      require(IERC20(utilityToken).transfer(holdingAccount, IERC20(utilityToken).balanceOf(address(this))), "GovernanceExchanger::withdrawUtility: Withdraw failed.");

    }

}