// SPDX-License-Identifier: MIT
pragma solidity 0.8.17;

import { LibDiamond } from "../Libraries/LibDiamond.sol";
import { IDiamondLoupe } from "../Interfaces/IDiamondLoupe.sol";
import { IERC165 } from "../Interfaces/IERC165.sol";

/// @title Diamond Loupe Facet
/// @author LI.FI (https://li.fi)
/// @notice Core EIP-2535 Facet for inspecting Diamond Proxies.
/// @custom:version 1.0.0
contract DiamondLoupeFacet is IDiamondLoupe, IERC165 {
    // 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_) {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        uint256 numFacets = ds.facetAddresses.length;
        facets_ = new Facet[](numFacets);
        for (uint256 i = 0; i < numFacets; ) {
            address facetAddress_ = ds.facetAddresses[i];
            facets_[i].facetAddress = facetAddress_;
            facets_[i].functionSelectors = ds
                .facetFunctionSelectors[facetAddress_]
                .functionSelectors;
            unchecked {
                ++i;
            }
        }
    }

    /// @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_)
    {
        LibDiamond.DiamondStorage storage ds = LibDiamond.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_)
    {
        LibDiamond.DiamondStorage storage ds = LibDiamond.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_) {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        facetAddress_ = ds
            .selectorToFacetAndPosition[_functionSelector]
            .facetAddress;
    }

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