// File: contracts/Router.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/utils/introspection/IERC165.sol";
import "./interfaces/IDiamondLoupe.sol";
import "./interfaces/IDiamondCut.sol";
import "./interfaces/IERC173.sol";
import "./libraries/LibDiamond.sol";

contract Router {
    struct DiamondArgs {
        address owner;
    }

    constructor(
        IDiamondCut.FacetCut[] memory _diamondCut,
        DiamondArgs memory _args
    ) {
        LibDiamond.diamondCut(_diamondCut, address(0), new bytes(0));
        LibDiamond.setContractOwner(_args.owner);

        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();

        // adding ERC165 data
        ds.supportedInterfaces[type(IERC165).interfaceId] = true;
        ds.supportedInterfaces[type(IDiamondCut).interfaceId] = true;
        ds.supportedInterfaces[type(IDiamondLoupe).interfaceId] = true;
        ds.supportedInterfaces[type(IERC173).interfaceId] = true;
    }

    // Find facet for function that is called and execute the
    // function if a facet is found and return any value.
    fallback() external payable {
        LibDiamond.DiamondStorage storage ds = LibDiamond.diamondStorage();
        address facet = ds.selectorToFacetAndPosition[msg.sig].facetAddress;
        require(facet != address(0), "Diamond: Function does not exist");
        assembly {
            calldatacopy(0, 0, calldatasize())
            let result := delegatecall(gas(), facet, 0, calldatasize(), 0, 0)
            returndatacopy(0, 0, returndatasize())
            switch result
            case 0 {
                revert(0, returndatasize())
            }
            default {
                return(0, returndatasize())
            }
        }
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// File: @openzeppelin/contracts/utils/introspection/IERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC165 standard, as defined in the
 * https://eips.ethereum.org/EIPS/eip-165[EIP].
 *
 * Implementers can declare support of contract interfaces, which can then be
 * queried by others ({ERC165Checker}).
 *
 * For an implementation, see {ERC165}.
 */
interface IERC165 {
    /**
     * @dev Returns true if this contract implements the interface defined by
     * `interfaceId`. See the corresponding
     * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
     * to learn more about how these ids are created.
     *
     * This function call must use less than 30 000 gas.
     */
    function supportsInterface(bytes4 interfaceId) external view returns (bool);
}

// File: contracts/interfaces/IDiamondLoupe.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

// A loupe is a small magnifying glass used to look at diamonds.
// These functions look at diamonds
interface IDiamondLoupe {
    /// These functions are expected to be called frequently
    /// by tools.

    struct Facet {
        address facetAddress;
        bytes4[] functionSelectors;
    }

    /// @notice Gets all facet addresses and their four byte function selectors.
    /// @return facets_ Facet
    function facets() external view returns (Facet[] memory facets_);

    /// @notice Gets all the function selectors supported by a specific facet.
    /// @param _facet The facet address.
    /// @return facetFunctionSelectors_
    function facetFunctionSelectors(address _facet)
        external
        view
        returns (bytes4[] memory facetFunctionSelectors_);

    /// @notice Get all the facet addresses used by a diamond.
    /// @return facetAddresses_
    function facetAddresses()
        external
        view
        returns (address[] memory 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
        returns (address facetAddress_);
}

// File: contracts/interfaces/IDiamondCut.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

interface IDiamondCut {
    enum FacetCutAction {
        Add,
        Replace,
        Remove
    }
    // Add=0, Replace=1, Remove=2

    struct FacetCut {
        address facetAddress;
        FacetCutAction action;
        bytes4[] functionSelectors;
    }

    /// @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;

    event DiamondCut(FacetCut[] _diamondCut, address _init, bytes _calldata);
}

// File: contracts/interfaces/IERC173.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

/// @title ERC-173 Contract Ownership Standard
///  Note: the ERC-165 identifier for this interface is 0x7f5828d0
/* is ERC165 */
interface IERC173 {
    /// @dev This emits when ownership of a contract changes.
    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    /// @notice Get the address of the owner
    /// @return owner_ The address of the owner.
    function owner() external view returns (address owner_);

    /// @notice Set the address of the new owner of the contract
    /// @dev Set _newOwner to address(0) to renounce any ownership.
    /// @param _newOwner The address of the new owner of the contract
    function transferOwnership(address _newOwner) external;
}

// File: contracts/libraries/LibDiamond.sol



// SPDX-License-Identifier: MIT
pragma solidity 0.8.3;

import "../interfaces/IDiamondCut.sol";

library LibDiamond {
    bytes32 constant DIAMOND_STORAGE_POSITION =
        keccak256("diamond.standard.diamond.storage");

    struct FacetAddressAndPosition {
        address facetAddress;
        uint16 functionSelectorPosition; // position in facetFunctionSelectors.functionSelectors array
    }

    struct FacetFunctionSelectors {
        bytes4[] functionSelectors;
        uint16 facetAddressPosition; // position of facetAddress in facetAddresses array
    }

    struct DiamondStorage {
        // maps function selector to the facet address and
        // the position of the selector in the facetFunctionSelectors.selectors array
        mapping(bytes4 => FacetAddressAndPosition) selectorToFacetAndPosition;
        // maps facet addresses to function selectors
        mapping(address => FacetFunctionSelectors) facetFunctionSelectors;
        // facet addresses
        address[] facetAddresses;
        // Used to query if a contract implements an interface.
        // Used to implement ERC-165.
        mapping(bytes4 => bool) supportedInterfaces;
        // owner of the contract
        address contractOwner;
    }

    function diamondStorage()
        internal
        pure
        returns (DiamondStorage storage ds)
    {
        bytes32 position = DIAMOND_STORAGE_POSITION;
        assembly {
            ds.slot := position
        }
    }

    event OwnershipTransferred(
        address indexed previousOwner,
        address indexed newOwner
    );

    function setContractOwner(address _newOwner) internal {
        DiamondStorage storage ds = diamondStorage();
        address previousOwner = ds.contractOwner;
        ds.contractOwner = _newOwner;
        emit OwnershipTransferred(previousOwner, _newOwner);
    }

    function contractOwner() internal view returns (address contractOwner_) {
        contractOwner_ = diamondStorage().contractOwner;
    }

    function enforceIsContractOwner() internal view {
        require(
            msg.sender == diamondStorage().contractOwner,
            "LibDiamond: Must be contract owner"
        );
    }

    event DiamondCut(
        IDiamondCut.FacetCut[] _diamondCut,
        address _init,
        bytes _calldata
    );

    // Internal function version of diamondCut
    function diamondCut(
        IDiamondCut.FacetCut[] memory _diamondCut,
        address _init,
        bytes memory _calldata
    ) internal {
        for (
            uint256 facetIndex;
            facetIndex < _diamondCut.length;
            facetIndex++
        ) {
            IDiamondCut.FacetCutAction action = _diamondCut[facetIndex].action;
            if (action == IDiamondCut.FacetCutAction.Add) {
                addFunctions(
                    _diamondCut[facetIndex].facetAddress,
                    _diamondCut[facetIndex].functionSelectors
                );
            } else if (action == IDiamondCut.FacetCutAction.Replace) {
                replaceFunctions(
                    _diamondCut[facetIndex].facetAddress,
                    _diamondCut[facetIndex].functionSelectors
                );
            } else if (action == IDiamondCut.FacetCutAction.Remove) {
                removeFunctions(
                    _diamondCut[facetIndex].facetAddress,
                    _diamondCut[facetIndex].functionSelectors
                );
            } else {
                revert("LibDiamondCut: Incorrect FacetCutAction");
            }
        }
        emit DiamondCut(_diamondCut, _init, _calldata);
        initializeDiamondCut(_init, _calldata);
    }

    function addFunctions(
        address _facetAddress,
        bytes4[] memory _functionSelectors
    ) internal {
        require(
            _functionSelectors.length > 0,
            "LibDiamondCut: No selectors in facet to cut"
        );
        DiamondStorage storage ds = diamondStorage();
        // uint16 selectorCount = uint16(diamondStorage().selectors.length);
        require(
            _facetAddress != address(0),
            "LibDiamondCut: Add facet can't be address(0)"
        );
        uint16 selectorPosition = uint16(
            ds.facetFunctionSelectors[_facetAddress].functionSelectors.length
        );
        // add new facet address if it does not exist
        if (selectorPosition == 0) {
            enforceHasContractCode(
                _facetAddress,
                "LibDiamondCut: New facet has no code"
            );
            ds
                .facetFunctionSelectors[_facetAddress]
                .facetAddressPosition = uint16(ds.facetAddresses.length);
            ds.facetAddresses.push(_facetAddress);
        }
        for (
            uint256 selectorIndex;
            selectorIndex < _functionSelectors.length;
            selectorIndex++
        ) {
            bytes4 selector = _functionSelectors[selectorIndex];
            address oldFacetAddress = ds
                .selectorToFacetAndPosition[selector]
                .facetAddress;
            require(
                oldFacetAddress == address(0),
                "LibDiamondCut: Can't add function that already exists"
            );
            addFunction(ds, selector, selectorPosition, _facetAddress);
            selectorPosition++;
        }
    }

    function replaceFunctions(
        address _facetAddress,
        bytes4[] memory _functionSelectors
    ) internal {
        require(
            _functionSelectors.length > 0,
            "LibDiamondCut: No selectors in facet to cut"
        );
        DiamondStorage storage ds = diamondStorage();
        require(
            _facetAddress != address(0),
            "LibDiamondCut: Add facet can't be address(0)"
        );
        uint16 selectorPosition = uint16(
            ds.facetFunctionSelectors[_facetAddress].functionSelectors.length
        );
        // add new facet address if it does not exist
        if (selectorPosition == 0) {
            enforceHasContractCode(
                _facetAddress,
                "LibDiamondCut: New facet has no code"
            );
            ds
                .facetFunctionSelectors[_facetAddress]
                .facetAddressPosition = uint16(ds.facetAddresses.length);
            ds.facetAddresses.push(_facetAddress);
        }
        for (
            uint256 selectorIndex;
            selectorIndex < _functionSelectors.length;
            selectorIndex++
        ) {
            bytes4 selector = _functionSelectors[selectorIndex];
            address oldFacetAddress = ds
                .selectorToFacetAndPosition[selector]
                .facetAddress;
            require(
                oldFacetAddress != _facetAddress,
                "LibDiamondCut: Can't replace function with same function"
            );
            removeFunction(ds, oldFacetAddress, selector);
            // add function
            addFunction(ds, selector, selectorPosition, _facetAddress);
            selectorPosition++;
        }
    }

    function removeFunctions(
        address _facetAddress,
        bytes4[] memory _functionSelectors
    ) internal {
        require(
            _functionSelectors.length > 0,
            "LibDiamondCut: No selectors in facet to cut"
        );
        DiamondStorage storage ds = diamondStorage();
        // if function does not exist then do nothing and return
        require(
            _facetAddress == address(0),
            "LibDiamondCut: Remove facet address must be address(0)"
        );
        for (
            uint256 selectorIndex;
            selectorIndex < _functionSelectors.length;
            selectorIndex++
        ) {
            bytes4 selector = _functionSelectors[selectorIndex];
            address oldFacetAddress = ds
                .selectorToFacetAndPosition[selector]
                .facetAddress;
            removeFunction(ds, oldFacetAddress, selector);
        }
    }

    function addFunction(
        DiamondStorage storage ds,
        bytes4 _selector,
        uint16 _selectorPosition,
        address _facetAddress
    ) internal {
        ds
            .selectorToFacetAndPosition[_selector]
            .functionSelectorPosition = _selectorPosition;
        ds.facetFunctionSelectors[_facetAddress].functionSelectors.push(
            _selector
        );
        ds.selectorToFacetAndPosition[_selector].facetAddress = _facetAddress;
    }

    function removeFunction(
        DiamondStorage storage ds,
        address _facetAddress,
        bytes4 _selector
    ) internal {
        require(
            _facetAddress != address(0),
            "LibDiamondCut: Can't remove function that doesn't exist"
        );
        // an immutable function is a function defined directly in a diamond
        require(
            _facetAddress != address(this),
            "LibDiamondCut: Can't remove immutable function"
        );
        // replace selector with last selector, then delete last selector
        uint256 selectorPosition = ds
            .selectorToFacetAndPosition[_selector]
            .functionSelectorPosition;
        uint256 lastSelectorPosition = ds
            .facetFunctionSelectors[_facetAddress]
            .functionSelectors
            .length - 1;
        // if not the same then replace _selector with lastSelector
        if (selectorPosition != lastSelectorPosition) {
            bytes4 lastSelector = ds
                .facetFunctionSelectors[_facetAddress]
                .functionSelectors[lastSelectorPosition];
            ds.facetFunctionSelectors[_facetAddress].functionSelectors[
                    selectorPosition
                ] = lastSelector;
            ds
                .selectorToFacetAndPosition[lastSelector]
                .functionSelectorPosition = uint16(selectorPosition);
        }
        // delete the last selector
        ds.facetFunctionSelectors[_facetAddress].functionSelectors.pop();
        delete ds.selectorToFacetAndPosition[_selector];

        // if no more selectors for facet address then delete the facet address
        if (lastSelectorPosition == 0) {
            // replace facet address with last facet address and delete last facet address
            uint256 lastFacetAddressPosition = ds.facetAddresses.length - 1;
            uint256 facetAddressPosition = ds
                .facetFunctionSelectors[_facetAddress]
                .facetAddressPosition;
            if (facetAddressPosition != lastFacetAddressPosition) {
                address lastFacetAddress = ds.facetAddresses[
                    lastFacetAddressPosition
                ];
                ds.facetAddresses[facetAddressPosition] = lastFacetAddress;
                ds
                    .facetFunctionSelectors[lastFacetAddress]
                    .facetAddressPosition = uint16(facetAddressPosition);
            }
            ds.facetAddresses.pop();
            delete ds
                .facetFunctionSelectors[_facetAddress]
                .facetAddressPosition;
        }
    }

    function initializeDiamondCut(address _init, bytes memory _calldata)
        internal
    {
        if (_init == address(0)) {
            require(
                _calldata.length == 0,
                "LibDiamondCut: _init is address(0) but_calldata is not empty"
            );
        } else {
            require(
                _calldata.length > 0,
                "LibDiamondCut: _calldata is empty but _init is not address(0)"
            );
            if (_init != address(this)) {
                enforceHasContractCode(
                    _init,
                    "LibDiamondCut: _init address has no code"
                );
            }
            (bool success, bytes memory error) = _init.delegatecall(_calldata);
            if (!success) {
                if (error.length > 0) {
                    // bubble up the error
                    revert(string(error));
                } else {
                    revert("LibDiamondCut: _init function reverted");
                }
            }
        }
    }

    function enforceHasContractCode(
        address _contract,
        string memory _errorMessage
    ) internal view {
        uint256 contractSize;
        assembly {
            contractSize := extcodesize(_contract)
        }
        require(contractSize > 0, _errorMessage);
    }
}