contract DiamondFacet is IDiamondCut, IDiamondLoupe, IERC165 {
    // Standard diamondCut external function
    /// @notice Add/replace/remove any number of functions and optionally execute
    ///         a function with delegatecall
    /// @param _diamondCut Contains the facet addresses and function selectors
    /// @param _init The address of the contract or facet to execute _calldata
    /// @param _calldata A function call, including function selector and arguments
    ///                  _calldata is executed with delegatecall on _init
    function diamondCut(
        FacetCut[] calldata _diamondCut,
        address _init,
        bytes calldata _calldata
    ) external override {
        LibDiamondStorageDerivaDEX.DiamondStorageDerivaDEX storage dsDerivaDEX =
            LibDiamondStorageDerivaDEX.diamondStorageDerivaDEX();
        require(msg.sender == dsDerivaDEX.admin, "DiamondFacet: Must own the contract");
        require(_diamondCut.length > 0, "DiamondFacet: No facets to cut");
        for (uint256 facetIndex; facetIndex < _diamondCut.length; facetIndex++) {
            LibDiamondCut.addReplaceRemoveFacetSelectors(
                _diamondCut[facetIndex].facetAddress,
                _diamondCut[facetIndex].action,
                _diamondCut[facetIndex].functionSelectors
            );
        }
        emit DiamondCut(_diamondCut, _init, _calldata);
        LibDiamondCut.initializeDiamondCut(_init, _calldata);
    }

    // Diamond Loupe Functions
    ////////////////////////////////////////////////////////////////////
    /// These functions are expected to be called frequently by tools.
    //
    // struct Facet {
    //     address facetAddress;
    //     bytes4[] functionSelectors;
    // }
    //
    /// @notice Gets all facets and their selectors.
    /// @return facets_ Facet
    function facets() external view override returns (Facet[] memory facets_) {
        LibDiamondStorage.DiamondStorage storage ds = LibDiamondStorage.diamondStorage();
        uint256 numFacets = ds.facetAddresses.length;
        facets_ = new Facet[](numFacets);
        for (uint256 i; i < numFacets; i++) {
            address facetAddress_ = ds.facetAddresses[i];
            facets_[i].facetAddress = facetAddress_;
            facets_[i].functionSelectors = ds.facetFunctionSelectors[facetAddress_].functionSelectors;
        }
    }

    /// @notice Gets all the function selectors provided by a facet.
    /// @param _facet The facet address.
    /// @return facetFunctionSelectors_
    function facetFunctionSelectors(address _facet)
        external
        view
        override
        returns (bytes4[] memory facetFunctionSelectors_)
    {
        LibDiamondStorage.DiamondStorage storage ds = LibDiamondStorage.diamondStorage();
        facetFunctionSelectors_ = ds.facetFunctionSelectors[_facet].functionSelectors;
    }

    /// @notice Get all the facet addresses used by a diamond.
    /// @return facetAddresses_
    function facetAddresses() external view override returns (address[] memory facetAddresses_) {
        LibDiamondStorage.DiamondStorage storage ds = LibDiamondStorage.diamondStorage();
        facetAddresses_ = ds.facetAddresses;
    }

    /// @notice Gets the facet that supports the given selector.
    /// @dev If facet is not found return address(0).
    /// @param _functionSelector The function selector.
    /// @return facetAddress_ The facet address.
    function facetAddress(bytes4 _functionSelector) external view override returns (address facetAddress_) {
        LibDiamondStorage.DiamondStorage storage ds = LibDiamondStorage.diamondStorage();
        facetAddress_ = ds.selectorToFacetAndPosition[_functionSelector].facetAddress;
    }

    // This implements ERC-165.
    function supportsInterface(bytes4 _interfaceId) external view override returns (bool) {
        LibDiamondStorage.DiamondStorage storage ds = LibDiamondStorage.diamondStorage();
        return ds.supportedInterfaces[_interfaceId];
    }
}
function supportsInterface(bytes4 _interfaceId) external view override returns (bool) {
    LibDiamondStorage.DiamondStorage storage ds = LibDiamondStorage.diamondStorage();
    return ds.supportedInterfaces[_interfaceId];
}

// This implements ERC-165.