MultichainImmutable.sol

// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

import {Initializable} from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
import {TransparentUpgradeableProxy} from "@openzeppelin/contracts/proxy/transparent/TransparentUpgradeableProxy.sol";

contract Implementation is Initializable {
    address internal weth;

    constructor() {
        _disableInitializers();
    }

    function init(address _weth) external initializer {
        weth = _weth;
    }
}

contract ProxyFactory {
    error ZeroAdmin();
    error Unauthorized();

    event NewProxy(address proxy, address implementation);

    address immutable admin;

    constructor(address _admin) {
        if (_admin == address(0)) revert ZeroAdmin();
        admin = _admin;
    }

    function createProxy(IWETH _weth, address _proxyAdmin) external {
        if (msg.sender != admin) revert Unauthorized();

        address firstImpl = address(new Implementation());

        bytes memory proxyInitCalldata = abi.encodeCall(
            Implementation.init,
            (_weth)
        );

        address proxy = address(
            new TransparentUpgradeableProxy(
                firstImpl,
                _proxyAdmin,
                proxyInitCalldata
            )
        );

        emit NewProxy(proxy, firstImpl);
    }
}


contract ProxyFactoryDeployer {
    error AlreadyDeployed();
    
    address constant SAFE_SINGLETON_FACTORY =
      0x914d7Fec6aaC8cd542e72Bca78B30650d45643d7;
      
    bytes32 constant SALT = keccak256("<custom-salt>");

    address public immutable factoryAddress;

    address constant ADMIN = <multichain proxy admin address>;

    constructor() {
        (bool success, bytes memory result) = SAFE_SINGLETON_FACTORY.call(
            abi.encodePacked(
                SALT,
                type(ProxyFactory).creationCode,
                abi.encode(ADMIN)
            )
        );

        if (!success) {
            revert AlreadyDeployed();
        }

        factoryAddress = address(bytes20(result));
    }
}