// SPDX-License-Identifier: MIT OR Apache-2.0
pragma solidity >=0.6.11;

// ============ Internal Imports ============
import {IInterchainGasPaymaster} from "../interfaces/IInterchainGasPaymaster.sol";
import {IInterchainSecurityModule} from "../interfaces/IInterchainSecurityModule.sol";
import {IHyperlaneConnectionClient} from "../interfaces/IHyperlaneConnectionClient.sol";
import {IMailbox} from "../interfaces/IMailbox.sol";

// ============ External Imports ============
import {OwnableUpgradeable} from "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import {Address} from "@openzeppelin/contracts/utils/Address.sol";

abstract contract HyperlaneConnectionClient is
    OwnableUpgradeable,
    IHyperlaneConnectionClient
{
    // ============ Mutable Storage ============

    IMailbox public mailbox;
    // Interchain Gas Paymaster contract. The relayer associated with this contract
    // must be willing to relay messages dispatched from the current Mailbox contract,
    // otherwise payments made to the paymaster will not result in relayed messages.
    IInterchainGasPaymaster public interchainGasPaymaster;

    IInterchainSecurityModule public interchainSecurityModule;

    uint256[48] private __GAP; // gap for upgrade safety

    // ============ Events ============
    /**
     * @notice Emitted when a new mailbox is set.
     * @param mailbox The address of the mailbox contract
     */
    event MailboxSet(address indexed mailbox);

    /**
     * @notice Emitted when a new Interchain Gas Paymaster is set.
     * @param interchainGasPaymaster The address of the Interchain Gas Paymaster.
     */
    event InterchainGasPaymasterSet(address indexed interchainGasPaymaster);

    event InterchainSecurityModuleSet(address indexed module);

    // ============ Modifiers ============

    /**
     * @notice Only accept messages from an Hyperlane Mailbox contract
     */
    modifier onlyMailbox() {
        require(msg.sender == address(mailbox), "!mailbox");
        _;
    }

    /**
     * @notice Only accept addresses that at least have contract code
     */
    modifier onlyContract(address _contract) {
        require(Address.isContract(_contract), "!contract");
        _;
    }

    // ======== Initializer =========

    function __HyperlaneConnectionClient_initialize(address _mailbox)
        internal
        onlyInitializing
    {
        _setMailbox(_mailbox);
        __Ownable_init();
    }

    function __HyperlaneConnectionClient_initialize(
        address _mailbox,
        address _interchainGasPaymaster
    ) internal onlyInitializing {
        _setInterchainGasPaymaster(_interchainGasPaymaster);
        __HyperlaneConnectionClient_initialize(_mailbox);
    }

    function __HyperlaneConnectionClient_initialize(
        address _mailbox,
        address _interchainGasPaymaster,
        address _interchainSecurityModule
    ) internal onlyInitializing {
        _setInterchainSecurityModule(_interchainSecurityModule);
        __HyperlaneConnectionClient_initialize(
            _mailbox,
            _interchainGasPaymaster
        );
    }

    function __HyperlaneConnectionClient_initialize(
        address _mailbox,
        address _interchainGasPaymaster,
        address _interchainSecurityModule,
        address _owner
    ) internal onlyInitializing {
        _setMailbox(_mailbox);
        _setInterchainGasPaymaster(_interchainGasPaymaster);
        _setInterchainSecurityModule(_interchainSecurityModule);
        _transferOwnership(_owner);
    }

    // ============ External functions ============

    /**
     * @notice Sets the address of the application's Mailbox.
     * @param _mailbox The address of the Mailbox contract.
     */
    function setMailbox(address _mailbox) external virtual onlyOwner {
        _setMailbox(_mailbox);
    }

    /**
     * @notice Sets the address of the application's InterchainGasPaymaster.
     * @param _interchainGasPaymaster The address of the InterchainGasPaymaster contract.
     */
    function setInterchainGasPaymaster(address _interchainGasPaymaster)
        external
        virtual
        onlyOwner
    {
        _setInterchainGasPaymaster(_interchainGasPaymaster);
    }

    function setInterchainSecurityModule(address _module)
        external
        virtual
        onlyOwner
    {
        _setInterchainSecurityModule(_module);
    }

    // ============ Internal functions ============

    /**
     * @notice Sets the address of the application's InterchainGasPaymaster.
     * @param _interchainGasPaymaster The address of the InterchainGasPaymaster contract.
     */
    function _setInterchainGasPaymaster(address _interchainGasPaymaster)
        internal
        onlyContract(_interchainGasPaymaster)
    {
        interchainGasPaymaster = IInterchainGasPaymaster(
            _interchainGasPaymaster
        );
        emit InterchainGasPaymasterSet(_interchainGasPaymaster);
    }

    /**
     * @notice Modify the contract the Application uses to validate Mailbox contracts
     * @param _mailbox The address of the mailbox contract
     */
    function _setMailbox(address _mailbox) internal onlyContract(_mailbox) {
        mailbox = IMailbox(_mailbox);
        emit MailboxSet(_mailbox);
    }

    function _setInterchainSecurityModule(address _module) internal {
        require(
            _module == address(0) || Address.isContract(_module),
            "!contract"
        );
        interchainSecurityModule = IInterchainSecurityModule(_module);
        emit InterchainSecurityModuleSet(_module);
    }
}