// Contract: TransferProxy
// Target function: function _setTokenURI(uint256 tokenId, string memory uri) internal
 owner, uint256 index) public view returns (uint256) {
        require(index < balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
        return _ownedTokens[owner][index];
    }

    /**
     * @dev Gets the total amount of tokens stored by the contract.
     * @return uint256 representing the total amount of tokens
     */
    function totalSupply() public view returns (uint256) {
        return _allTokens.length;
    }

    /**
     * @dev Gets the token ID at a given index of all the tokens in this contract
     * Reverts if the index is greater or equal to the total number of tokens.
     * @param index uint256 representing the index to be accessed of the tokens list
     * @return uint256 token ID at the given index of the tokens list
     */
    function tokenByIndex(uint256 index) public view returns (uint256) {
        require(index < totalSupply(), "ERC721Enumerable: global index out of bounds");
        return _allTokens[index];
    }

    /**
     * @dev Internal function to transfer ownership of a given token ID to another address.
     * As opposed to transferFrom, this imposes no restrictions on msg.sender.
     * @param from current owner of the token
     * @param to address to receive the ownership of the given token ID
     * @param tokenId uint256 ID of the token to be transferred
     */
    function _transferFrom(address from, address to, uint256 tokenId) internal {
        super._transferFrom(from, to, tokenId);

        _removeTokenFromOwnerEnumeration(from, tokenId);

        _addTokenToOwnerEnumeration(to, tokenId);
    }

    /**
     * @dev Internal function to mint a new token.
     * Reverts if the given token ID already exists.
     * @param to address the beneficiary that will own the minted token
     * @param tokenId uint256 ID of the token to be minted
     */
    function _mint(address to, uint256 tokenId) internal {
        super._mint(to, tokenId);

        _addTokenToOwnerEnumeration(to, tokenId);

        _addTokenToAllTokensEnumeration(tokenId);
    }

    /**
     * @dev Internal function to burn a specific token.
     * Reverts if the token does not exist.
     * Deprecated, use {ERC721-_burn} instead.
     * @param owner owner of the token to burn
     * @param tokenId uint256 ID of the token being burned
     */
    function _burn(address owner, uint256 tokenId) internal {
        super._burn(owner, tokenId);

        _removeTokenFromOwnerEnumeration(owner, tokenId);
        // Since tokenId will be deleted, we can clear its slot in _ownedTokensIndex to trigger a gas refund
        _ownedTokensIndex[tokenId] = 0;

        _removeTokenFromAllTokensEnumeration(tokenId);
    }

    /**
     * @dev Gets the list of token IDs of the requested owner.
     * @param owner address owning the tokens
     * @return uint256[] List of token IDs owned by the requested address
     */
    function _tokensOfOwner(address owner) internal view returns (uint256[] storage) {
        return _ownedTokens[owner];
    }

    /**
     * @dev Private function to add a token to this extension's ownership-tracking data structures.
     * @param to address representing the new owner of the given token ID
     * @param tokenId uint256 ID of the token to be added to the tokens list of the given address
     */
    function _addTokenToOwnerEnumeration(address to, uint256 tokenId) private {
        _ownedTokensIndex[tokenId] = _ownedTokens[to].length;
        _ownedTokens[to].push(tokenId);
    }

    /**
     * @dev Private function to add a token to this extension's token tracking data structures.
     * @param tokenId uint256 ID of the token to be added to the tokens list
     */
    function _addTokenToAllTokensEnumeration(uint256 tokenId) private {
        _allTokensIndex[tokenId] = _allTokens.length;
        _allTokens.push(tokenId);
    }

    /**
     * @dev Private function to remove a token from this extension's ownership-tracking data structures. Note that
     * while the token is not assigned a new owner, the `_ownedTokensIndex` mapping is _not_ updated: this allows for
     * gas optimizations e.g. when performing a transfer operation (avoiding double writes).
     * This has O(1) time complexity, but alters the order of the _ownedTokens array.
     * @param from address representing the previous owner of the given token ID
     * @param tokenId uint256 ID of the token to be removed from the tokens list of the given address
     */
    function _removeTokenFromOwnerEnumeration(address from, uint256 tokenId) private {
        // To prevent a gap in from's tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _ownedTokens[from].length.sub(1);
        uint256 tokenIndex = _ownedTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary
        if (tokenIndex != lastTokenIndex) {
            uint256 lastTokenId = _ownedTokens[from][lastTokenIndex];

            _ownedTokens[from][tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
            _ownedTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index
        }

        // This also deletes the contents at the last position of the array
        _ownedTokens[from].length--;

        // Note that _ownedTokensIndex[tokenId] hasn't been cleared: it still points to the old slot (now occupied by
        // lastTokenId, or just over the end of the array if the token was the last one).
    }

    /**
     * @dev Private function to remove a token from this extension's token tracking data structures.
     * This has O(1) time complexity, but alters the order of the _allTokens array.
     * @param tokenId uint256 ID of the token to be removed from the tokens list
     */
    function _removeTokenFromAllTokensEnumeration(uint256 tokenId) private {
        // To prevent a gap in the tokens array, we store the last token in the index of the token to delete, and
        // then delete the last slot (swap and pop).

        uint256 lastTokenIndex = _allTokens.length.sub(1);
        uint256 tokenIndex = _allTokensIndex[tokenId];

        // When the token to delete is the last token, the swap operation is unnecessary. However, since this occurs so
        // rarely (when the last minted token is burnt) that we still do the swap here to avoid the gas cost of adding
        // an 'if' statement (like in _removeTokenFromOwnerEnumeration)
        uint256 lastTokenId = _allTokens[lastTokenIndex];

        _allTokens[tokenIndex] = lastTokenId; // Move the last token to the slot of the to-delete token
        _allTokensIndex[lastTokenId] = tokenIndex; // Update the moved token's index

        // This also deletes the contents at the last position of the array
        _allTokens.length--;
        _allTokensIndex[tokenId] = 0;
    }
}

library UintLibrary {
    function toString(uint256 _i) internal pure returns (string memory) {
        if (_i == 0) {
            return "0";
        }
        uint j = _i;
        uint len;
        while (j != 0) {
            len++;
            j /= 10;
        }
        bytes memory bstr = new bytes(len);
        uint k = len - 1;
        while (_i != 0) {
            bstr[k--] = byte(uint8(48 + _i % 10));
            _i /= 10;
        }
        return string(bstr);
    }
}

library StringLibrary {
    using UintLibrary for uint256;

    function append(string memory _a, string memory _b) internal pure returns (string memory) {
        bytes memory _ba = bytes(_a);
        bytes memory _bb = bytes(_b);
        bytes memory bab = new bytes(_ba.length + _bb.length);
        uint k = 0;
        for (uint i = 0; i < _ba.length; i++) bab[k++] = _ba[i];
        for (uint i = 0; i < _bb.length; i++) bab[k++] = _bb[i];
        return string(bab);
    }

    function append(string memory _a, string memory _b, string memory _c) internal pure returns (string memory) {
        bytes memory _ba = bytes(_a);
        bytes memory _bb = bytes(_b);
        bytes memory _bc = bytes(_c);
        bytes memory bbb = new bytes(_ba.length + _bb.length + _bc.length);
        uint k = 0;
        for (uint i = 0; i < _ba.length; i++) bbb[k++] = _ba[i];
        for (uint i = 0; i < _bb.length; i++) bbb[k++] = _bb[i];
        for (uint i = 0; i < _bc.length; i++) bbb[k++] = _bc[i];
        return string(bbb);
    }

    function recover(string memory message, uint8 v, bytes32 r, bytes32 s) internal pure returns (address) {
        bytes memory msgBytes = bytes(message);
        bytes memory fullMessage = concat(
            bytes("\x19Ethereum Signed Message:\n"),
            bytes(msgBytes.length.toString()),
            msgBytes,
            new bytes(0), new bytes(0), new bytes(0), new bytes(0)
        );
        return ecrecover(keccak256(fullMessage), v, r, s);
    }

    function concat(bytes memory _ba, bytes memory _bb, bytes memory _bc, bytes memory _bd, bytes memory _be, bytes memory _bf, bytes memory _bg) internal pure returns (bytes memory) {
        bytes memory resultBytes = new bytes(_ba.length + _bb.length + _bc.length + _bd.length + _be.length + _bf.length + _bg.length);
        uint k = 0;
        for (uint i = 0; i < _ba.length; i++) resultBytes[k++] = _ba[i];
        for (uint i = 0; i < _bb.length; i++) resultBytes[k++] = _bb[i];
        for (uint i = 0; i < _bc.length; i++) resultBytes[k++] = _bc[i];
        for (uint i = 0; i < _bd.length; i++) resultBytes[k++] = _bd[i];
        for (uint i = 0; i < _be.length; i++) resultBytes[k++] = _be[i];
        for (uint i = 0; i < _bf.length; i++) resultBytes[k++] = _bf[i];
        for (uint i = 0; i < _bg.length; i++) resultBytes[k++] = _bg[i];
        return resultBytes;
    }
}

contract HasContractURI is ERC165 {

    string public contractURI;

    /*
     * bytes4(keccak256('contractURI()')) == 0xe8a3d485
     */
    bytes4 private constant _INTERFACE_ID_CONTRACT_URI = 0xe8a3d485;

    constructor(string memory _contractURI) public {
        contractURI = _contractURI;
        _registerInterface(_INTERFACE_ID_CONTRACT_URI);
    }

    /**
     * @dev Internal function to set the contract URI
     * @param _contractURI string URI prefix to assign
     */
    function _setContractURI(string memory _contractURI) internal {
        contractURI = _contractURI;
    }
}

contract HasTokenURI {
    using StringLibrary for string;

    //Token URI prefix
    string public tokenURIPrefix;

    // Optional mapping for token URIs
    mapping(uint256 => string) private _tokenURIs;

    constructor(string memory _tokenURIPrefix) public {
        tokenURIPrefix = _tokenURIPrefix;
    }

    /**
     * @dev Returns an URI for a given token ID.
     * Throws if the token ID does not exist. May return an empty string.
     * @param tokenId uint256 ID of the token to query
     */
    function _tokenURI(uint256 tokenId) internal view returns (string memory) {
        return tokenURIPrefix.append(_tokenURIs[tokenId]);
    }

    /**
     * @dev Internal function to set the token URI for a given token.
     * Reverts if the token ID does not exist.
     * @param tokenId uint256 ID of the token to set its URI
     * @param uri string URI to assign
     */
    function _setTokenURI(uint256 tokenId, string memory uri) internal {
        _tokenURIs[tokenId] = uri;
    }

    /**
     * @dev Internal function to set the token URI prefix.
     * @param _tokenURIPrefix string URI prefix to assign
     */
    function _setTokenURIPrefix(string memory _tokenURIPrefix) internal {
        tokenURIPrefix = _tokenURIPrefix;
    }

    function _clearTokenURI(uint256 tokenId) internal {
        if (bytes(_tokenURIs[tokenId]).length != 0) {
            delete _tokenURIs[tokenId];
        }
    }
}

contract HasSecondarySaleFees is ERC165 {

    event SecondarySaleFees(uint256 tokenId, address[] recipients, uint[] bps);

    /*
     * bytes4(keccak256('getFeeBps(uint256)')) == 0x0ebd4c7f
     * bytes4(keccak256('getFeeRecipients(uint256)')) == 0xb9c4d9fb
     *
     * => 0x0ebd4c7f ^ 0xb9c4d9fb == 0xb7799584
     */
    bytes4 private constant _INTERFACE_ID_FEES = 0xb7799584;

    constructor() public {
        _registerInterface(_INTERFACE_ID_FEES);
    }

    function getFeeRecipients(uint256 id) public view returns (address payable[] memory);
    function getFeeBps(uint256 id) public view returns (uint[] memory);
}

/**
 * @title Full ERC721 Token with support for tokenURIPrefix
 * This implementation includes all the required and some optional functionality of the ERC721 standard
 * Moreover, it includes approve all functionality using operator terminology
 * @dev see https://eips.ethereum.org/EIPS/eip-721
 */
contract ERC721Base is HasSecondarySaleFees, ERC721, HasContractURI, HasTokenURI, ERC721Enumerable {
    // Token name
    string public name;

    // Token symbol
    string public symbol;

    struct Fee {
        address payable recipient;
        uint256 value;
    }

    // id => fees
    mapping (uint256 => Fee[]) public fees;

    /*
     *     bytes4(keccak256('name()')) == 0x06fdde03
     *     bytes4(keccak256('symbol()')) == 0x95d89b41
     *     bytes4(keccak256('tokenURI(uint256)')) == 0xc87b56dd
     *
     *     => 0x06fdde03 ^ 0x95d89b41 ^ 0xc87b56dd == 0x5b5e139f
     */
    bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;

    /**
     * @dev Constructor function
     */
    constructor (string memory _name, string memory _symbol, string memory contractURI, string memory _tokenURIPrefix) HasContractURI(contractURI) HasTokenURI(_tokenURIPrefix) public {
        name = _name;
        symbol = _symbol;

        // register the supported interfaces to conform to ERC721 via ERC165
        _registerInterface(_INTERFACE_ID_ERC721_METADATA);
    }

    function getFeeRecipients(uint256 id) public view returns (address payable[] memory) {
        Fee[] memory _fees = fees[id];
        address payable[] memory result = new address payable[](_fees.length);
        for (uint i = 0; i < _fees.length; i++) {
            result[i] = _fees[i].recipient;
        }
        return result;
    }

    function getFeeBps(uint256 id) public view returns (uint[] memory) {
        Fee[] memory _fees = fees[id];
        uint[] memory result = new uint[](_fees.length);
        for (uint i = 0; i < _fees.length; i++) {
            result[i] = _fees[i].value;
        }
        return result;
    }

    function _mint(address to, uint256 tokenId, Fee[] memory _fees) internal {
        _mint(to, tokenId);
        address[] memory recipients = new address[](_fees.length);
        uint[] memory bps = new uint[](_fees.length);
        for (uint i = 0; i < _fees.length; i++) {
            require(_fees[i].recipient != address(0x0), "Recipient should be present");
            require(_fees[i].value != 0, "Fee value should be positive");
            fees[tokenId].push(_fees[i]);
            recipients[i] = _fees[i].recipient;
            bps[i] = _fees[i].value;
        }
        if (_fees.length > 0) {
            emit SecondarySaleFees(tokenId, recipients, bps);
        }
    }

    /**
     * @dev Returns an URI for a given token ID.
     * Throws if the token ID does not exist. May return an empty string.
     * @param tokenId uint256 ID of the token to query
     */
    function tokenURI(uint256 tokenId) external view returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");
        return super._tokenURI(tokenId);
    }