pragma solidity 0.5.11;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
contract Context {
    // Empty internal constructor, to prevent people from mistakenly deploying
    // an instance of this contract, which should be used via inheritance.
    constructor () internal { }
    // solhint-disable-previous-line no-empty-blocks

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}


/**
 * @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);
}

/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () internal {
        _owner = _msgSender();
        emit OwnershipTransferred(address(0), _owner);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Returns true if the caller is the current owner.
     */
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     */
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}


/**
 * @dev Required interface of an ERC721 compliant contract.
 */
contract IERC721 is IERC165 {
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

    /**
     * @dev Returns the number of NFTs in `owner`'s account.
     */
    function balanceOf(address owner) public view returns (uint256 balance);

    /**
     * @dev Returns the owner of the NFT specified by `tokenId`.
     */
    function ownerOf(uint256 tokenId) public view returns (address owner);

    /**
     * @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
     * another (`to`).
     *
     *
     *
     * Requirements:
     * - `from`, `to` cannot be zero.
     * - `tokenId` must be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this
     * NFT by either {approve} or {setApprovalForAll}.
     */
    function safeTransferFrom(address from, address to, uint256 tokenId) public;
    /**
     * @dev Transfers a specific NFT (`tokenId`) from one account (`from`) to
     * another (`to`).
     *
     * Requirements:
     * - If the caller is not `from`, it must be approved to move this NFT by
     * either {approve} or {setApprovalForAll}.
     */
    function transferFrom(address from, address to, uint256 tokenId) public;
    function approve(address to, uint256 tokenId) public;
    function getApproved(uint256 tokenId) public view returns (address operator);

    function setApprovalForAll(address operator, bool _approved) public;
    function isApprovedForAll(address owner, address operator) public view returns (bool);


    function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory data) public;
}


contract ICards is IERC721 {

    struct Batch {
        uint48 userID;
        uint16 size;
    }

    function batches(uint index) public view returns (uint48 userID, uint16 size);

    function userIDToAddress(uint48 id) public view returns (address);

    function getDetails(
        uint tokenId
    )
        public
        view
        returns (
        uint16 proto,
        uint8 quality
    );

    function setQuality(
        uint tokenId,
        uint8 quality
    ) public;

    function mintCards(
        address to,
        uint16[] memory _protos,
        uint8[] memory _qualities
    )
        public
        returns (uint);

    function mintCard(
        address to,
        uint16 _proto,
        uint8 _quality
    )
        public
        returns (uint);

    function burn(uint tokenId) public;

    function batchSize()
        public
        view
        returns (uint);
}


contract Forge is Ownable {

    ICards cards;

    uint8 constant diamond = 1;

    bool public locked = true;

    event LockSet(bool status);
    event ForgedCards(uint finalId, uint[] all);

    constructor(ICards _cards) public {
        cards = _cards;
    }

    function forge(uint[] memory _ids) public {
        require(
            locked == false,
            "Forge: contract must be unlocked"
        );

        require(
            _ids.length == 5,
            "Forge: must forge 5 at a time"
        );

        (uint16 proto, uint8 quality) = cards.getDetails(_ids[0]);
        address owner = cards.ownerOf(_ids[0]);

        require(
            owner == msg.sender || cards.isApprovedForAll(owner, msg.sender) == true,
            "Forge: cannot forge without authorisation"
        );

        require(
            quality > diamond,
            "Forge: cannot forge diamond cards"
        );

        for (uint i = 1; i < 5; i++) {
            (uint16 nextProto, uint8 nextQuality) = cards.getDetails(_ids[i]);

            require(
                proto == nextProto,
                "Forge: different protos"
            );

            require(
                quality == nextQuality,
                "Forge: different qualities"
            );

            require(
                cards.ownerOf(_ids[i]) == owner,
                "Forge: different owners"
            );

            cards.burn(_ids[i]);
        }

        cards.setQuality(_ids[0], quality - 1);

        emit ForgedCards(_ids[0], _ids);
    }

    function setLock(bool status)
        public
        onlyOwner
    {
        locked = status;
        emit LockSet(status);
    }

}