// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./LzApp.sol";
import "./ExcessivelySafeCall.sol";

/*
 * the default LayerZero messaging behaviour is blocking, i.e. any failed message will block the channel
 * this abstract class try-catch all fail messages and store locally for future retry. hence, non-blocking
 * NOTE: if the srcAddress is not configured properly, it will still block the message pathway from (srcChainId, srcAddress)
 */
abstract contract NonblockingLzApp is LzApp {
    using ExcessivelySafeCall for address;

    constructor(address _endpoint) LzApp(_endpoint) {}

    mapping(uint16 => mapping(bytes => mapping(uint64 => bytes32)))
        public failedMessages;

    event MessageFailed(
        uint16 _srcChainId,
        bytes _srcAddress,
        uint64 _nonce,
        bytes _payload,
        bytes _reason
    );
    event RetryMessageSuccess(
        uint16 _srcChainId,
        bytes _srcAddress,
        uint64 _nonce,
        bytes32 _payloadHash
    );

    // overriding the virtual function in LzReceiver
    function _blockingLzReceive(
        uint16 _srcChainId,
        bytes memory _srcAddress,
        uint64 _nonce,
        bytes memory _payload
    ) internal virtual override {
        (bool success, bytes memory reason) = address(this).excessivelySafeCall(
            gasleft(),
            150,
            abi.encodeWithSelector(
                this.nonblockingLzReceive.selector,
                _srcChainId,
                _srcAddress,
                _nonce,
                _payload
            )
        );
        // try-catch all errors/exceptions
        if (!success) {
            _storeFailedMessage(
                _srcChainId,
                _srcAddress,
                _nonce,
                _payload,
                reason
            );
        }
    }

    function _storeFailedMessage(
        uint16 _srcChainId,
        bytes memory _srcAddress,
        uint64 _nonce,
        bytes memory _payload,
        bytes memory _reason
    ) internal virtual {
        failedMessages[_srcChainId][_srcAddress][_nonce] = keccak256(_payload);
        emit MessageFailed(_srcChainId, _srcAddress, _nonce, _payload, _reason);
    }

    function nonblockingLzReceive(
        uint16 _srcChainId,
        bytes calldata _srcAddress,
        uint64 _nonce,
        bytes calldata _payload
    ) public virtual {
        // only internal transaction
        require(
            _msgSender() == address(this),
            "NonblockingLzApp: caller must be LzApp"
        );
        _nonblockingLzReceive(_srcChainId, _srcAddress, _nonce, _payload);
    }

    //@notice override this function
    function _nonblockingLzReceive(
        uint16 _srcChainId,
        bytes memory _srcAddress,
        uint64 _nonce,
        bytes memory _payload
    ) internal virtual;

    function retryMessage(
        uint16 _srcChainId,
        bytes calldata _srcAddress,
        uint64 _nonce,
        bytes calldata _payload
    ) public payable virtual {
        // assert there is message to retry
        bytes32 payloadHash = failedMessages[_srcChainId][_srcAddress][_nonce];
        require(
            payloadHash != bytes32(0),
            "NonblockingLzApp: no stored message"
        );
        require(
            keccak256(_payload) == payloadHash,
            "NonblockingLzApp: invalid payload"
        );
        // clear the stored message
        failedMessages[_srcChainId][_srcAddress][_nonce] = bytes32(0);
        // execute the message. revert if it fails again
        _nonblockingLzReceive(_srcChainId, _srcAddress, _nonce, _payload);
        emit RetryMessageSuccess(_srcChainId, _srcAddress, _nonce, payloadHash);
    }
}