// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

/// @dev Minimal non-upgradeable delegatecall proxy for testing upgradeable
/// contracts (WTFControllerV2 uses an initializer + _disableInitializers()).
contract TestProxy {
    bytes32 private constant _IMPLEMENTATION_SLOT =
        bytes32(uint256(keccak256("test.proxy.implementation")) - 1);

    constructor(address implementation_) {
        bytes32 slot = _IMPLEMENTATION_SLOT;
        assembly {
            sstore(slot, implementation_)
        }
    }

    fallback() external payable {
        bytes32 slot = _IMPLEMENTATION_SLOT;
        address impl;
        assembly {
            impl := sload(slot)
        }
        assembly {
            calldatacopy(0, 0, calldatasize())
            let result := delegatecall(gas(), impl, 0, calldatasize(), 0, 0)
            returndatacopy(0, 0, returndatasize())
            switch result
            case 0 {
                revert(0, returndatasize())
            }
            default {
                return(0, returndatasize())
            }
        }
    }
}