// SPDX-License-Identifier: MIT
pragma solidity 0.8.16;

/// @dev The ETH transfer has failed.
error ETHTransferFailed();

/// @dev Sends `amount` (in wei) ETH to `to`.
/// Reverts upon failure.
function safeTransferETH(address to, uint256 amount) {
    assembly {
        // Transfer the ETH and check if it succeeded or not.
        if iszero(call(gas(), to, amount, 0, 0, 0, 0)) {
            // Store the function selector of `ETHTransferFailed()`.
            mstore(0x00, 0xb12d13eb)
            // Revert with (offset, size).
            revert(0x1c, 0x04)
        }
    }
}

contract Escrow {
    address public owner;
    address public claimer;

    error OnlyOwner();
    error OnlyClaimer();
    event Claimed(uint256 balance);
    event ClaimerChanged(address oldClaimer, address newClaimer);
    event Received(uint256 amount);

    constructor(address _owner, address _claimer) payable {
        owner = _owner;
        claimer = _claimer;
    }

    function claim(address recipient) public payable returns (bool) {
        if (msg.sender != claimer) revert OnlyClaimer();
        
        emit Claimed(address(this).balance);
        
        return safeTransferETH(recipient, address(this).balance);
    }

    function setClaimer(address _claimer) public payable {
        if (msg.sender != owner) revert OnlyOwner();

        claimer = _claimer;
    }

    receive() external payable {
        emit Received(msg.value);
    }
}