// File: contracts/TokenBridge.sol



// contracts/TokenBridge.sol
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "./Governable.sol";

contract TokenBridge is Governable {

    event Deposit(address indexed src, uint256 amount, address indexed token);
    event Withdrawal(address indexed src, uint256 amount, address indexed token);

    function deposit(uint256 amount, address token) public {
        require (amount > 0, "!amount");
        require (IERC20(token).transferFrom(_msgSender(), address(this), amount), "!transfer");
        emit Deposit(_msgSender(), amount, token);
    }

    function withdraw(address to, uint256 amount, address token) public onlyGovernance {
        require (amount > 0, "!amount");
        require (IERC20(token).balanceOf(address(this)) >= amount, "!balance");
        require (IERC20(token).transfer(to, amount), "!transfer");
        emit Withdrawal(to, amount, token);
    }
}
// File: contracts/Governable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Governable.sol)

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Context.sol";

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (a governance) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the governance account will be the one that deploys the contract. This
 * can later be changed with {transferGovernance}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyGovernance`, which can be applied to your functions to restrict their use to
 * the governance.
 */
abstract contract Governable is Context {
    address private _governance;

    event GovernanceTransferred(address indexed previousGovernance, address indexed newGovernance);

    /**
     * @dev Initializes the contract setting the deployer as the initial governance.
     */
    constructor() {
        _transferGovernance(_msgSender());
    }

    /**
     * @dev Returns the address of the current governance.
     */
    function governance() public view virtual returns (address) {
        return _governance;
    }

    /**
     * @dev Throws if called by any account other than the governance.
     */
    modifier onlyGovernance() {
        require(governance() == _msgSender(), "Governable: caller is not the governance");
        _;
    }

    /**
     * @dev Leaves the contract without governance. It will not be possible to call
     * `onlyGovernance` functions anymore. Can only be called by the current governance.
     *
     * NOTE: Renouncing governanceship will leave the contract without an governance,
     * thereby removing any functionality that is only available to the governance.
     */
    function renounceGovernance() public virtual onlyGovernance {
        _transferGovernance(address(0));
    }

    /**
     * @dev Transfers governanceship of the contract to a new account (`newGovernance`).
     * Can only be called by the current governance.
     */
    function transferGovernance(address newGovernance) public virtual onlyGovernance {
        require(newGovernance != address(0), "Governable: new governance is the zero address");
        _transferGovernance(newGovernance);
    }

    /**
     * @dev Transfers governanceship of the contract to a new account (`newGovernance`).
     * Internal function without access restriction.
     */
    function _transferGovernance(address newGovernance) internal virtual {
        address oldGovernance = _governance;
        _governance = newGovernance;
        emit GovernanceTransferred(oldGovernance, newGovernance);
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);

    /**
     * @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);
}

// 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;
    }
}