// File: contracts/GiveForever.sol



// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

interface ILido is IERC20 {
  function submit(address _referral) external payable returns (uint256 StETH);
  function withdraw(uint256 _amount, bytes32 _pubkeyHash) external; // wont be available until post-merge
  function sharesOf(address _owner) external returns (uint balance);
}

contract GiveForever {
    address public charity; // Givewell 0x7cF2eBb5Ca55A8bd671A020F8BDbAF07f60F26C1;
    address public lidoAddress; // Goerli 0x1643E812aE58766192Cf7D2Cf9567dF2C37e9B7F; 
    uint public donated;

    constructor (address _charityAddress, address _lidoAddress) {
      charity = _charityAddress;
      lidoAddress = _lidoAddress;
    }

    function deposit() payable public {
        ILido(lidoAddress).submit{value: msg.value}(address(this));
        donated += msg.value;
    }

    function lidoBalance() public view returns (uint) {
        return ILido(lidoAddress).balanceOf(address(this));
    }

    function withdraw() public {
        uint balance = ILido(lidoAddress).balanceOf(address(this));
        uint surplus = balance - donated;
        require(surplus > 0, "Nothing to return");
        ILido(lidoAddress).transfer(charity, surplus);
    }

    function updateWallet(address _newAddress) public {
        require(msg.sender == charity, "Only charity can update wallet");
        charity = _newAddress;
    }
        
} 
// 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);
}