// SPDX-License-Identifier: MIT

pragma solidity ^0.8.20;

library OFTMsgCodec {
    // Offset constants for encoding and decoding OFT messages
    uint8 private constant SEND_TO_OFFSET = 32;
    uint8 private constant SEND_AMOUNT_SD_OFFSET = 40;

    /**
     * @dev Encodes an OFT LayerZero message.
     * @param _sendTo The recipient address.
     * @param _amountShared The amount in shared decimals.
     * @param _composeMsg The composed message.
     * @return _msg The encoded message.
     * @return hasCompose A boolean indicating whether the message has a composed payload.
     */
    function encode(
        bytes32 _sendTo,
        uint64 _amountShared,
        bytes memory _composeMsg
    ) internal view returns (bytes memory _msg, bool hasCompose) {
        hasCompose = _composeMsg.length > 0;
        // @dev Remote chains will want to know the composed function caller ie. msg.sender on the src.
        _msg = hasCompose
            ? abi.encodePacked(_sendTo, _amountShared, addressToBytes32(msg.sender), _composeMsg)
            : abi.encodePacked(_sendTo, _amountShared);
    }

    /**
     * @dev Checks if the OFT message is composed.
     * @param _msg The OFT message.
     * @return A boolean indicating whether the message is composed.
     */
    function isComposed(bytes calldata _msg) internal pure returns (bool) {
        return _msg.length > SEND_AMOUNT_SD_OFFSET;
    }

    /**
     * @dev Retrieves the recipient address from the OFT message.
     * @param _msg The OFT message.
     * @return The recipient address.
     */
    function sendTo(bytes calldata _msg) internal pure returns (bytes32) {
        return bytes32(_msg[:SEND_TO_OFFSET]);
    }

    /**
     * @dev Retrieves the amount in shared decimals from the OFT message.
     * @param _msg The OFT message.
     * @return The amount in shared decimals.
     */
    function amountSD(bytes calldata _msg) internal pure returns (uint64) {
        return uint64(bytes8(_msg[SEND_TO_OFFSET:SEND_AMOUNT_SD_OFFSET]));
    }

    /**
     * @dev Retrieves the composed message from the OFT message.
     * @param _msg The OFT message.
     * @return The composed message.
     */
    function composeMsg(bytes calldata _msg) internal pure returns (bytes memory) {
        return _msg[SEND_AMOUNT_SD_OFFSET:];
    }

    /**
     * @dev Converts an address to bytes32.
     * @param _addr The address to convert.
     * @return The bytes32 representation of the address.
     */
    function addressToBytes32(address _addr) internal pure returns (bytes32) {
        return bytes32(uint256(uint160(_addr)));
    }

    /**
     * @dev Converts bytes32 to an address.
     * @param _b The bytes32 value to convert.
     * @return The address representation of bytes32.
     */
    function bytes32ToAddress(bytes32 _b) internal pure returns (address) {
        return address(uint160(uint256(_b)));
    }
}