// File: address-utils.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

/**
 * @dev Utility library of inline functions on addresses.
 * @notice Based on:
 * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol
 * Requires EIP-1052.
 */
library AddressUtils
{

  /**
   * @dev Returns whether the target address is a contract.
   * @param _addr Address to check.
   * @return addressCheck True if _addr is a contract, false if not.
   */
  function isContract(
    address _addr
  )
    internal
    view
    returns (bool addressCheck)
  {
    // This method relies in extcodesize, which returns 0 for contracts in
    // construction, since the code is only stored at the end of the
    // constructor execution.

    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
    // for accounts without code, i.e. `keccak256('')`
    bytes32 codehash;
    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
 //   assembly { codehash := extcodehash(_addr) } // solhint-disable-line
    addressCheck = (codehash != 0x0 && codehash != accountHash);
  }

}

// File: EpigeonInterfaces.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.4.11;

//----------------------------------------------------------------------------------------------------
interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function transfer(address recipient, uint256 amount) external returns (bool);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
}
//----------------------------------------------------------------------------------------------------
interface IERC777 {
    function name() external view returns (string memory);
    function symbol() external view returns (string memory);
    function granularity() external view returns (uint256);
    function totalSupply() external view returns (uint256);
    function balanceOf(address owner) external view returns (uint256);
    function send(address recipient, uint256 amount, bytes data) external;
    function burn(uint256 amount, bytes data) external;
    function isOperatorFor(address operator, address tokenHolder) external view returns (bool);
    function authorizeOperator(address operator) external;
    function revokeOperator(address operator) external;
    function defaultOperators() external view returns (address[] memory);
    function operatorSend(address sender, address recipient, uint256 amount, bytes data, bytes operatorData) external;
    function operatorBurn(address account, uint256 amount, bytes data, bytes operatorData) external;
    event Sent( address indexed operator, address indexed from, address indexed to, uint256 amount, bytes data, bytes operatorData);
    event Minted(address indexed operator, address indexed to, uint256 amount, bytes data, bytes operatorData);
    event Burned(address indexed operator, address indexed from, uint256 amount, bytes data, bytes operatorData);
    event AuthorizedOperator(address indexed operator, address indexed tokenHolder);
    event RevokedOperator(address indexed operator, address indexed tokenHolder);
}
//----------------------------------------------------------------------------------------------------
interface ILockable {
    function lock(address to, uint256 amount, bytes32 hash) external;
    function operatorLock(address from, address to, uint256 amount, bytes32 hash, bytes data, bytes operatorData) external;
    function unlock(string unlockerPhrase) external;
    function operatorUnlock(address to, string unlockerPhrase, bytes data, bytes operatorData) external;
    function reclaim(address to, string unlockerPhrase) external;
    function operatorReclaim(address from, address to, string unlockerPhrase, bytes data, bytes operatorData) external;
    function unlockByLockedCoinContract(address to, bytes32 hash) external;
    function reclaimByLockedCoinContract(address from, address to, bytes32 hash) external;
    function lockedSupply() external view returns (uint256 locked_supply);
    function lockedAmount(address from, bytes32 hash) external view returns (uint256 amount);
    function lockedBalanceOf(address account) external view returns (uint256);
}
//----------------------------------------------------------------------------------------------------
interface IPigeonFactory {
    function createCryptoPigeon(address to) external returns (ICryptoPigeon pigeonAddress);    
    function iAmFactory() external pure returns (bool);
    function amIEpigeon() external returns (bool);
    function factoryId() external view returns (uint256 id);
    function getMetaDataForPigeon(address pigeon) external view returns (string metadata);
    function mintingPrice() external view returns (uint256 price);
    function totalSupply() external view returns (uint256 supply);
    function maxSupply() external view returns (uint256 supply);
    function getFactoryTokenPrice(address ERC20Token) external view returns (uint256 price);
}
//----------------------------------------------------------------------------------------------------
interface ICryptoPigeon {
    function burnPigeon() external;    
    function iAmPigeon() external pure returns (bool); 
    function transferPigeon(address newOwner) external; 
    function hasFlown() external view returns (bool);
    function toAddress() external view returns (address addressee);   
    function owner() external view returns (address ownerAddress);
    function manager() external view returns (address managerAddress);
    function factoryId() external view returns (uint256 id);
}
//----------------------------------------------------------------------------------------------------
interface IEpigeon {
    function pigeonDestinations() external view returns (IPigeonDestinationDirectory destinations);
    function nameAndKeyDirectory() external view returns (INameAndPublicKeyDirectory directory);
    function getLastFactoryId() external view returns (uint256 id);
    function getFactoryAddresstoId(uint256 id) external view returns (address factoryAddress);
    function getPigeonPriceForFactory(uint256 factoryId) external view returns (uint256 price);
    function getPigeonTokenPriceForFactory(address ERC20Token, uint256 factoryId) external view returns (uint256 price);
    function createCryptoPigeonNFT(address to, uint256 factoryId) external returns (address pigeonaddress);
    function transferPigeon(address from, address to, address pigeon) external;
    function burnPigeon(address pigeon) external;
    function nftContractAddress() external view returns (address nftContract);
    function validPigeon(address pigeon, address pigeonOwner) external view returns (bool);
}
//----------------------------------------------------------------------------------------------------
interface IEpigeonNFT {
    function isTokenizedPigeon(address pigeon) external view returns (bool);
}
//----------------------------------------------------------------------------------------------------
interface INameAndPublicKeyDirectory {
    function getPublicKeyForAddress (address owner) external view returns (string key); 
    function getUserNameForAddress (address owner) external view returns (string name);
}
//----------------------------------------------------------------------------------------------------
interface IPigeonDestinationDirectory{
    function changeToAddress(address newToAddress, address oldToAddress) external;
    function setToAddress(address newToAddress) external;
    function deleteToAddress(address oldToAddress) external;
    function deleteToAddressByEpigeon(address pigeon) external;
    function pigeonsSentToAddressLenght(address toAddress) external view returns (uint256 length);
    function pigeonSentToAddressByIndex(address toAddress, uint index) external view returns (address pigeonAddress);   
}
//----------------------------------------------------------------------------------------------------
interface IPigeonManagerDirectory{
    function changeManager(address newManager, address oldManager) external;
    function deleteManager(address oldManager) external;
    function setManager(address newManager) external;
    function pigeonsOfManagerLenght(address toAddress) external view returns (uint256 length);
    function pigeonOfManagerByIndex(address toAddress, uint index) external view returns (address pigeonAddress);   
}
//----------------------------------------------------------------------------------------------------


// File: EpigeonNFT.sol



// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.4.11;

import "./nf-token-enumerable.sol";
import "./EpigeonInterfaces.sol";

//----------------------------------------------------------------------------------

contract EpigeonNFT is NFTokenEnumerable{
    IEpigeon public epigeon;
      
    address public owner;
    string public name;
    string public symbol;
    mapping (uint256 => address) internal idtoCryptoPigeon;
    mapping (address => uint256) internal cryptoPigeonToId;
    uint256 public mintingPrice = 1000000000000000;
    uint256 public highestTokenId;
    mapping (address => uint256) internal approvedTokenPrice;
    
    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    
    constructor (string memory _name, string memory _symbol, address _epigeon){
        owner = msg.sender;
        epigeon = IEpigeon(_epigeon);
        name = _name;
        symbol = _symbol;
        highestTokenId = 0;
    }
    
    function burn(uint256 tokenId) public {
        require(msg.sender == ICryptoPigeon(idtoCryptoPigeon[tokenId]).owner());
        require(epigeon.nftContractAddress() == address(this));
        epigeon.burnPigeon(idtoCryptoPigeon[tokenId]);
        delete cryptoPigeonToId[idtoCryptoPigeon[tokenId]];
        delete idtoCryptoPigeon[tokenId];
        super._burn(tokenId);
    }
    
    function burnPigeonToken(uint256 tokenId) public {
        require(msg.sender == ICryptoPigeon(idtoCryptoPigeon[tokenId]).owner());
        require(epigeon.nftContractAddress() == address(this));
        delete cryptoPigeonToId[idtoCryptoPigeon[tokenId]];
        delete idtoCryptoPigeon[tokenId];
        super._burn(tokenId);
    }
    
    function isTokenizedPigeon(address pigeon) public view returns (bool tokenized){
        return idtoCryptoPigeon[cryptoPigeonToId[pigeon]] == pigeon;
    }
    
    function mintingTokenPrice(address ERC20Token) public view returns (uint256 price){
        return approvedTokenPrice[ERC20Token];
    }
    
    function mintForEther(uint256 factoryId) public payable {
        require(msg.value >= mintingPrice + epigeon.getPigeonPriceForFactory(factoryId), "Not enough value");      
        _mintForAddress(msg.sender, factoryId);
    }
    
    function mintForToken(address ERC20Token, uint256 factoryId) public returns (bool){
        require (approvedTokenPrice[ERC20Token] > 0);
        require (epigeon.getPigeonTokenPriceForFactory(ERC20Token, factoryId) > 0);
        uint256 price = approvedTokenPrice[ERC20Token] + epigeon.getPigeonTokenPriceForFactory(ERC20Token, factoryId);
        if (IERC20(ERC20Token).transferFrom(msg.sender, owner, price) == true)
        {
            _mintForAddress(msg.sender, factoryId);
            return true;
        }
        else{
            return false;
        }
    }
    
    function payout() public {
        require(msg.sender == owner);
        owner.transfer(address(this).balance);
    }
    
    function pigeonAddressToToken(address pigeon) public view returns (uint256  tokenId){
        return cryptoPigeonToId[pigeon];
    }
    
    function setMintingPrice(uint256 price) public {
        require(msg.sender == owner);
        mintingPrice = price;
    }
    
    function setMintingPrice(address ERC20Token, uint256 price) public {
        require(msg.sender == owner);
        approvedTokenPrice[ERC20Token] = price;
    }
    
    function tokenContractAddress(uint256  tokenId) public view validNFToken(tokenId) returns (address rpigeon){
        return idtoCryptoPigeon[tokenId];
    }
    
    function tokenizePigeon(address pigeon) public payable{
        require(msg.value >= mintingPrice, "Not enough value");
        require(cryptoPigeonToId[pigeon] == 0);
        require(ICryptoPigeon(pigeon).owner() == msg.sender);
        require(ICryptoPigeon(pigeon).iAmPigeon());
        require(epigeon.validPigeon(pigeon, msg.sender));
        require(epigeon.nftContractAddress() == address(this));
        highestTokenId++;
        uint256 tokenId = highestTokenId;
        super._mint(msg.sender, tokenId);
        _setTokenContractAddress(tokenId, pigeon);
    }
    
    function tokenURI(uint256 tokenId) public view returns (string metadata){
        metadata = IPigeonFactory(epigeon.getFactoryAddresstoId(ICryptoPigeon(idtoCryptoPigeon[tokenId]).factoryId())).getMetaDataForPigeon(idtoCryptoPigeon[tokenId]);
        return metadata;
    }
    
    function _mintForAddress(address to, uint256 factoryId) internal {
        require(epigeon.nftContractAddress() == address(this));
        highestTokenId++;
        uint256 tokenId = highestTokenId;
        address pigeon = epigeon.createCryptoPigeonNFT(to, factoryId);
        super._mint(to, tokenId);
        _setTokenContractAddress(tokenId, pigeon);
    }
    
    function _setTokenContractAddress(uint256  tokenId, address  pigeon) internal validNFToken(tokenId) {
        idtoCryptoPigeon[tokenId] = pigeon;
        cryptoPigeonToId[pigeon] = tokenId;
    }
    
    function transferOwnership(address newOwner) public {    
        require(owner == msg.sender, "Only owner");
        require(newOwner != address(0), "Zero address");
        emit OwnershipTransferred(owner, newOwner);
        owner.transfer(address(this).balance);
        owner = newOwner;
    }
    
    function _transfer(address to, uint256 tokenId) internal {
        require(epigeon.nftContractAddress() == address(this));
        epigeon.transferPigeon(ICryptoPigeon(idtoCryptoPigeon[tokenId]).owner(), to, idtoCryptoPigeon[tokenId]);
        super._transfer(to, tokenId);
    }
}



// File: erc165.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

/**
 * @dev A standard for detecting smart contract interfaces. 
 * See: https://eips.ethereum.org/EIPS/eip-165.
 */
interface ERC165
{

  /**
   * @dev Checks if the smart contract includes a specific interface.
   * This function uses less than 30,000 gas.
   * @param _interfaceID The interface identifier, as specified in ERC-165.
   * @return True if _interfaceID is supported, false otherwise.
   */
  function supportsInterface(
    bytes4 _interfaceID
  )
    external
    view
    returns (bool);
    
}

// File: erc721-enumerable.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

/**
 * @dev Optional enumeration extension for ERC-721 non-fungible token standard.
 * See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md.
 */
interface ERC721Enumerable
{

  /**
   * @dev Returns a count of valid NFTs tracked by this contract, where each one of them has an
   * assigned and queryable owner not equal to the zero address.
   * @return Total supply of NFTs.
   */
  function totalSupply()
    external
    view
    returns (uint256);

  /**
   * @dev Returns the token identifier for the `_index`th NFT. Sort order is not specified.
   * @param _index A counter less than `totalSupply()`.
   * @return Token id.
   */
  function tokenByIndex(
    uint256 _index
  )
    external
    view
    returns (uint256);

  /**
   * @dev Returns the token identifier for the `_index`th NFT assigned to `_owner`. Sort order is
   * not specified. It throws if `_index` >= `balanceOf(_owner)` or if `_owner` is the zero address,
   * representing invalid NFTs.
   * @param _owner An address where we are interested in NFTs owned by them.
   * @param _index A counter less than `balanceOf(_owner)`.
   * @return Token id.
   */
  function tokenOfOwnerByIndex(
    address _owner,
    uint256 _index
  )
    external
    view
    returns (uint256);

}

// File: erc721-token-receiver.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

/**
 * @dev ERC-721 interface for accepting safe transfers.
 * See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md.
 */
interface ERC721TokenReceiver
{

  /**
   * @dev Handle the receipt of a NFT. The ERC721 smart contract calls this function on the
   * recipient after a `transfer`. This function MAY throw to revert and reject the transfer. Return
   * of other than the magic value MUST result in the transaction being reverted.
   * Returns `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))` unless throwing.
   * @notice The contract address is always the message sender. A wallet/broker/auction application
   * MUST implement the wallet interface if it will accept safe transfers.
   * @param _operator The address which called `safeTransferFrom` function.
   * @param _from The address which previously owned the token.
   * @param _tokenId The NFT identifier which is being transferred.
   * @param _data Additional data with no specified format.
   * @return Returns `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`.
   */
  function onERC721Received(
    address _operator,
    address _from,
    uint256 _tokenId,
    bytes _data
  )
    external
    returns(bytes4);

}

// File: erc721.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

/**
 * @dev ERC-721 non-fungible token standard.
 * See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md.
 */
interface ERC721
{

  /**
   * @dev Emits when ownership of any NFT changes by any mechanism. This event emits when NFTs are
   * created (`from` == 0) and destroyed (`to` == 0). Exception: during contract creation, any
   * number of NFTs may be created and assigned without emitting Transfer. At the time of any
   * transfer, the approved address for that NFT (if any) is reset to none.
   */
  event Transfer(
    address indexed _from,
    address indexed _to,
    uint256 indexed _tokenId
  );

  /**
   * @dev This emits when the approved address for an NFT is changed or reaffirmed. The zero
   * address indicates there is no approved address. When a Transfer event emits, this also
   * indicates that the approved address for that NFT (if any) is reset to none.
   */
  event Approval(
    address indexed _owner,
    address indexed _approved,
    uint256 indexed _tokenId
  );

  /**
   * @dev This emits when an operator is enabled or disabled for an owner. The operator can manage
   * all NFTs of the owner.
   */
  event ApprovalForAll(
    address indexed _owner,
    address indexed _operator,
    bool _approved
  );

  /**
   * @dev Transfers the ownership of an NFT from one address to another address.
   * @notice Throws unless `msg.sender` is the current owner, an authorized operator, or the
   * approved address for this NFT. Throws if `_from` is not the current owner. Throws if `_to` is
   * the zero address. Throws if `_tokenId` is not a valid NFT. When transfer is complete, this
   * function checks if `_to` is a smart contract (code size > 0). If so, it calls
   * `onERC721Received` on `_to` and throws if the return value is not
   * `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`.
   * @param _from The current owner of the NFT.
   * @param _to The new owner.
   * @param _tokenId The NFT to transfer.
   * @param _data Additional data with no specified format, sent in call to `_to`.
   */
  function safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId,
    bytes _data
  )
    external;

  /**
   * @dev Transfers the ownership of an NFT from one address to another address.
   * @notice This works identically to the other function with an extra data parameter, except this
   * function just sets data to ""
   * @param _from The current owner of the NFT.
   * @param _to The new owner.
   * @param _tokenId The NFT to transfer.
   */
  function safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId
  )
    external;

  /**
   * @dev Throws unless `msg.sender` is the current owner, an authorized operator, or the approved
   * address for this NFT. Throws if `_from` is not the current owner. Throws if `_to` is the zero
   * address. Throws if `_tokenId` is not a valid NFT.
   * @notice The caller is responsible to confirm that `_to` is capable of receiving NFTs or else
   * they mayb be permanently lost.
   * @param _from The current owner of the NFT.
   * @param _to The new owner.
   * @param _tokenId The NFT to transfer.
   */
  function transferFrom(
    address _from,
    address _to,
    uint256 _tokenId
  )
    external;

  /**
   * @dev Set or reaffirm the approved address for an NFT.
   * @notice The zero address indicates there is no approved address. Throws unless `msg.sender` is
   * the current NFT owner, or an authorized operator of the current owner.
   * @param _approved The new approved NFT controller.
   * @param _tokenId The NFT to approve.
   */
  function approve(
    address _approved,
    uint256 _tokenId
  )
    external;

  /**
   * @dev Enables or disables approval for a third party ("operator") to manage all of
   * `msg.sender`'s assets. It also emits the ApprovalForAll event.
   * @notice The contract MUST allow multiple operators per owner.
   * @param _operator Address to add to the set of authorized operators.
   * @param _approved True if the operators is approved, false to revoke approval.
   */
  function setApprovalForAll(
    address _operator,
    bool _approved
  )
    external;

  /**
   * @dev Returns the number of NFTs owned by `_owner`. NFTs assigned to the zero address are
   * considered invalid, and this function throws for queries about the zero address.
   * @param _owner Address for whom to query the balance.
   * @return Balance of _owner.
   */
  function balanceOf(
    address _owner
  )
    external
    view
    returns (uint256);

  /**
   * @dev Returns the address of the owner of the NFT. NFTs assigned to zero address are considered
   * invalid, and queries about them do throw.
   * @param _tokenId The identifier for an NFT.
   * @return Address of _tokenId owner.
   */
  function ownerOf(
    uint256 _tokenId
  )
    external
    view
    returns (address);

  /**
   * @dev Get the approved address for a single NFT.
   * @notice Throws if `_tokenId` is not a valid NFT.
   * @param _tokenId The NFT to find the approved address for.
   * @return Address that _tokenId is approved for.
   */
  function getApproved(
    uint256 _tokenId
  )
    external
    view
    returns (address);

  /**
   * @dev Returns true if `_operator` is an approved operator for `_owner`, false otherwise.
   * @param _owner The address that owns the NFTs.
   * @param _operator The address that acts on behalf of the owner.
   * @return True if approved for all, false otherwise.
   */
  function isApprovedForAll(
    address _owner,
    address _operator
  )
    external
    view
    returns (bool);

}

// File: nf-token-enumerable.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

import "./nf-token.sol";
import "./erc721-enumerable.sol";

/**
 * @dev Optional enumeration implementation for ERC-721 non-fungible token standard.
 */
contract NFTokenEnumerable is
  NFToken,
  ERC721Enumerable
{

  /**
   * @dev List of revert message codes. Implementing dApp should handle showing the correct message.
   * Based on 0xcert framework error codes.
   */
  string constant INVALID_INDEX = "005007";

  /**
   * @dev Array of all NFT IDs.
   */
  uint256[] internal tokens;

  /**
   * @dev Mapping from token ID to its index in global tokens array.
   */
  mapping(uint256 => uint256) internal idToIndex;

  /**
   * @dev Mapping from owner to list of owned NFT IDs.
   */
  mapping(address => uint256[]) internal ownerToIds;

  /**
   * @dev Mapping from NFT ID to its index in the owner tokens list.
   */
  mapping(uint256 => uint256) internal idToOwnerIndex;

  /**
   * @dev Contract constructor.
   */
  constructor()
  {
    supportedInterfaces[0x780e9d63] = true; // ERC721Enumerable
  }

  /**
   * @dev Returns the count of all existing NFTokens.
   * @return Total supply of NFTs.
   */
  function totalSupply()
    external
    //override
    view
    returns (uint256)
  {
    return tokens.length;
  }

  /**
   * @dev Returns NFT ID by its index.
   * @param _index A counter less than `totalSupply()`.
   * @return Token id.
   */
  function tokenByIndex(
    uint256 _index
  )
    external
    //override
    view
    returns (uint256)
  {
    require(_index < tokens.length, INVALID_INDEX);
    return tokens[_index];
  }

  /**
   * @dev returns the n-th NFT ID from a list of owner's tokens.
   * @param _owner Token owner's address.
   * @param _index Index number representing n-th token in owner's list of tokens.
   * @return Token id.
   */
  function tokenOfOwnerByIndex(
    address _owner,
    uint256 _index
  )
    external
   // override
    view
    returns (uint256)
  {
    require(_index < ownerToIds[_owner].length, INVALID_INDEX);
    return ownerToIds[_owner][_index];
  }

  /**
   * @dev Mints a new NFT.
   * @notice This is an internal function which should be called from user-implemented external
   * mint function. Its purpose is to show and properly initialize data structures when using this
   * implementation.
   * @param _to The address that will own the minted NFT.
   * @param _tokenId of the NFT to be minted by the msg.sender.
   */
  function _mint(
    address _to,
    uint256 _tokenId
  )
    internal
    //override
    //virtual
  {
    super._mint(_to, _tokenId);
    tokens.push(_tokenId);
    idToIndex[_tokenId] = tokens.length - 1;
  }

  /**
   * @dev Burns a NFT.
   * @notice This is an internal function which should be called from user-implemented external
   * burn function. Its purpose is to show and properly initialize data structures when using this
   * implementation. Also, note that this burn implementation allows the minter to re-mint a burned
   * NFT.
   * @param _tokenId ID of the NFT to be burned.
   */
  function _burn(
    uint256 _tokenId
  )
    internal
  //  override
   // virtual
  {
    super._burn(_tokenId);

    uint256 tokenIndex = idToIndex[_tokenId];
    uint256 lastTokenIndex = tokens.length - 1;
    uint256 lastToken = tokens[lastTokenIndex];

    tokens[tokenIndex] = lastToken;

    //tokens.pop();
    delete tokens[lastTokenIndex];
    tokens.length--;
    // This wastes gas if you are burning the last token but saves a little gas if you are not.
    idToIndex[lastToken] = tokenIndex;
    idToIndex[_tokenId] = 0;
  }

  /**
   * @dev Removes a NFT from an address.
   * @notice Use and override this function with caution. Wrong usage can have serious consequences.
   * @param _from Address from wich we want to remove the NFT.
   * @param _tokenId Which NFT we want to remove.
   */
  function _removeNFToken(
    address _from,
    uint256 _tokenId
  )
    internal
  //  override
  //  virtual
  {
    require(idToOwner[_tokenId] == _from, NOT_OWNER);
    delete idToOwner[_tokenId];

    uint256 tokenToRemoveIndex = idToOwnerIndex[_tokenId];
    uint256 lastTokenIndex = ownerToIds[_from].length - 1;

    if (lastTokenIndex != tokenToRemoveIndex)
    {
      uint256 lastToken = ownerToIds[_from][lastTokenIndex];
      ownerToIds[_from][tokenToRemoveIndex] = lastToken;
      idToOwnerIndex[lastToken] = tokenToRemoveIndex;
    }

    //ownerToIds[_from].pop();
    delete ownerToIds[_from][lastTokenIndex];
    ownerToIds[_from].length--;
  }

  /**
   * @dev Assignes a new NFT to an address.
   * @notice Use and override this function with caution. Wrong usage can have serious consequences.
   * @param _to Address to wich we want to add the NFT.
   * @param _tokenId Which NFT we want to add.
   */
  function _addNFToken(
    address _to,
    uint256 _tokenId
  )
    internal
 //   override
  //  virtual
  {
    require(idToOwner[_tokenId] == address(0), NFT_ALREADY_EXISTS);
    idToOwner[_tokenId] = _to;

    ownerToIds[_to].push(_tokenId);
    idToOwnerIndex[_tokenId] = ownerToIds[_to].length - 1;
  }

  /**
   * @dev Helper function that gets NFT count of owner. This is needed for overriding in enumerable
   * extension to remove double storage(gas optimization) of owner nft count.
   * @param _owner Address for whom to query the count.
   * @return Number of _owner NFTs.
   */
  function _getOwnerNFTCount(
    address _owner
  )
    internal
 //   override
  //  virtual
    view
    returns (uint256)
  {
    return ownerToIds[_owner].length;
  }
}

// File: nf-token.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

import "./erc721.sol";
import "./erc721-token-receiver.sol";
import "./supports-interface.sol";
import "./address-utils.sol";

/**
 * @dev Implementation of ERC-721 non-fungible token standard.
 */
contract NFToken is
  ERC721,
  SupportsInterface
{
  using AddressUtils for address;

  /**
   * @dev List of revert message codes. Implementing dApp should handle showing the correct message.
   * Based on 0xcert framework error codes.
   */
  string constant ZERO_ADDRESS = "003001";
  string constant NOT_VALID_NFT = "003002";
  string constant NOT_OWNER_OR_OPERATOR = "003003";
  string constant NOT_OWNER_APPROVED_OR_OPERATOR = "003004";
  string constant NOT_ABLE_TO_RECEIVE_NFT = "003005";
  string constant NFT_ALREADY_EXISTS = "003006";
  string constant NOT_OWNER = "003007";
  string constant IS_OWNER = "003008";

  /**
   * @dev Magic value of a smart contract that can recieve NFT.
   * Equal to: bytes4(keccak256("onERC721Received(address,address,uint256,bytes)")).
   */
  bytes4 internal constant MAGIC_ON_ERC721_RECEIVED = 0x150b7a02;

  /**
   * @dev A mapping from NFT ID to the address that owns it.
   */
  mapping (uint256 => address) internal idToOwner;

  /**
   * @dev Mapping from NFT ID to approved address.
   */
  mapping (uint256 => address) internal idToApproval;

   /**
   * @dev Mapping from owner address to count of his tokens.
   */
  mapping (address => uint256) private ownerToNFTokenCount;

  /**
   * @dev Mapping from owner address to mapping of operator addresses.
   */
  mapping (address => mapping (address => bool)) internal ownerToOperators;

  /**
   * @dev Guarantees that the msg.sender is an owner or operator of the given NFT.
   * @param _tokenId ID of the NFT to validate.
   */
  modifier canOperate(
    uint256 _tokenId
  )
  {
    address tokenOwner = idToOwner[_tokenId];
    require(
      tokenOwner == msg.sender || ownerToOperators[tokenOwner][msg.sender],
      NOT_OWNER_OR_OPERATOR
    );
    _;
  }

  /**
   * @dev Guarantees that the msg.sender is allowed to transfer NFT.
   * @param _tokenId ID of the NFT to transfer.
   */
  modifier canTransfer(
    uint256 _tokenId
  )
  {
    address tokenOwner = idToOwner[_tokenId];
    require(
      tokenOwner == msg.sender
      || idToApproval[_tokenId] == msg.sender
      || ownerToOperators[tokenOwner][msg.sender],
      NOT_OWNER_APPROVED_OR_OPERATOR
    );
    _;
  }

  /**
   * @dev Guarantees that _tokenId is a valid Token.
   * @param _tokenId ID of the NFT to validate.
   */
  modifier validNFToken(
    uint256 _tokenId
  )
  {
    require(idToOwner[_tokenId] != address(0), NOT_VALID_NFT);
    _;
  }

  /**
   * @dev Contract constructor.
   */
  constructor()
  {
    supportedInterfaces[0x80ac58cd] = true; // ERC721
  }

  /**
   * @dev Transfers the ownership of an NFT from one address to another address. This function can
   * be changed to payable.
   * @notice Throws unless `msg.sender` is the current owner, an authorized operator, or the
   * approved address for this NFT. Throws if `_from` is not the current owner. Throws if `_to` is
   * the zero address. Throws if `_tokenId` is not a valid NFT. When transfer is complete, this
   * function checks if `_to` is a smart contract (code size > 0). If so, it calls
   * `onERC721Received` on `_to` and throws if the return value is not
   * `bytes4(keccak256("onERC721Received(address,uint256,bytes)"))`.
   * @param _from The current owner of the NFT.
   * @param _to The new owner.
   * @param _tokenId The NFT to transfer.
   * @param _data Additional data with no specified format, sent in call to `_to`.
   */
  function safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId,
    bytes  _data
  )
    external
   // override
  {
    _safeTransferFrom(_from, _to, _tokenId, _data);
  }

  /**
   * @dev Transfers the ownership of an NFT from one address to another address. This function can
   * be changed to payable.
   * @notice This works identically to the other function with an extra data parameter, except this
   * function just sets data to ""
   * @param _from The current owner of the NFT.
   * @param _to The new owner.
   * @param _tokenId The NFT to transfer.
   */
  function safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId
  )
    external
    //override
  {
    _safeTransferFrom(_from, _to, _tokenId, "");
  }

  /**
   * @dev Throws unless `msg.sender` is the current owner, an authorized operator, or the approved
   * address for this NFT. Throws if `_from` is not the current owner. Throws if `_to` is the zero
   * address. Throws if `_tokenId` is not a valid NFT. This function can be changed to payable.
   * @notice The caller is responsible to confirm that `_to` is capable of receiving NFTs or else
   * they maybe be permanently lost.
   * @param _from The current owner of the NFT.
   * @param _to The new owner.
   * @param _tokenId The NFT to transfer.
   */
  function transferFrom(
    address _from,
    address _to,
    uint256 _tokenId
  )
    external
  //  override
    canTransfer(_tokenId)
    validNFToken(_tokenId)
  {
    address tokenOwner = idToOwner[_tokenId];
    require(tokenOwner == _from, NOT_OWNER);
    require(_to != address(0), ZERO_ADDRESS);

    _transfer(_to, _tokenId);
  }

  /**
   * @dev Set or reaffirm the approved address for an NFT. This function can be changed to payable.
   * @notice The zero address indicates there is no approved address. Throws unless `msg.sender` is
   * the current NFT owner, or an authorized operator of the current owner.
   * @param _approved Address to be approved for the given NFT ID.
   * @param _tokenId ID of the token to be approved.
   */
  function approve(
    address _approved,
    uint256 _tokenId
  )
    external
//    override
    canOperate(_tokenId)
    validNFToken(_tokenId)
  {
    address tokenOwner = idToOwner[_tokenId];
    require(_approved != tokenOwner, IS_OWNER);

    idToApproval[_tokenId] = _approved;
    emit Approval(tokenOwner, _approved, _tokenId);
  }

  /**
   * @dev Enables or disables approval for a third party ("operator") to manage all of
   * `msg.sender`'s assets. It also emits the ApprovalForAll event.
   * @notice This works even if sender doesn't own any tokens at the time.
   * @param _operator Address to add to the set of authorized operators.
   * @param _approved True if the operators is approved, false to revoke approval.
   */
  function setApprovalForAll(
    address _operator,
    bool _approved
  )
    external
//    override
  {
    ownerToOperators[msg.sender][_operator] = _approved;
    emit ApprovalForAll(msg.sender, _operator, _approved);
  }

  /**
   * @dev Returns the number of NFTs owned by `_owner`. NFTs assigned to the zero address are
   * considered invalid, and this function throws for queries about the zero address.
   * @param _owner Address for whom to query the balance.
   * @return Balance of _owner.
   */
  function balanceOf(
    address _owner
  )
    external
 //   override
    view
    returns (uint256)
  {
    require(_owner != address(0), ZERO_ADDRESS);
    return _getOwnerNFTCount(_owner);
  }

  /**
   * @dev Returns the address of the owner of the NFT. NFTs assigned to zero address are considered
   * invalid, and queries about them do throw.
   * @param _tokenId The identifier for an NFT.
   * @return _owner Address of _tokenId owner.
   */
  function ownerOf(
    uint256 _tokenId
  )
    external
//    override
    view
    returns (address _owner)
  {
    _owner = idToOwner[_tokenId];
    require(_owner != address(0), NOT_VALID_NFT);
  }

  /**
   * @dev Get the approved address for a single NFT.
   * @notice Throws if `_tokenId` is not a valid NFT.
   * @param _tokenId ID of the NFT to query the approval of.
   * @return Address that _tokenId is approved for.
   */
  function getApproved(
    uint256 _tokenId
  )
    external
//    override
    view
    validNFToken(_tokenId)
    returns (address)
  {
    return idToApproval[_tokenId];
  }

  /**
   * @dev Checks if `_operator` is an approved operator for `_owner`.
   * @param _owner The address that owns the NFTs.
   * @param _operator The address that acts on behalf of the owner.
   * @return True if approved for all, false otherwise.
   */
  function isApprovedForAll(
    address _owner,
    address _operator
  )
    external
//    override
    view
    returns (bool)
  {
    return ownerToOperators[_owner][_operator];
  }

  /**
   * @dev Actually preforms the transfer.
   * @notice Does NO checks.
   * @param _to Address of a new owner.
   * @param _tokenId The NFT that is being transferred.
   */
  function _transfer(
    address _to,
    uint256 _tokenId
  )
    internal
//    virtual
  {
    address from = idToOwner[_tokenId];
    _clearApproval(_tokenId);

    _removeNFToken(from, _tokenId);
    _addNFToken(_to, _tokenId);

    emit Transfer(from, _to, _tokenId);
  }

  /**
   * @dev Mints a new NFT.
   * @notice This is an internal function which should be called from user-implemented external
   * mint function. Its purpose is to show and properly initialize data structures when using this
   * implementation.
   * @param _to The address that will own the minted NFT.
   * @param _tokenId of the NFT to be minted by the msg.sender.
   */
  function _mint(
    address _to,
    uint256 _tokenId
  )
    internal
//    virtual
  {
    require(_to != address(0), ZERO_ADDRESS);
    require(idToOwner[_tokenId] == address(0), NFT_ALREADY_EXISTS);

    _addNFToken(_to, _tokenId);

    emit Transfer(address(0), _to, _tokenId);
  }

  /**
   * @dev Burns a NFT.
   * @notice This is an internal function which should be called from user-implemented external burn
   * function. Its purpose is to show and properly initialize data structures when using this
   * implementation. Also, note that this burn implementation allows the minter to re-mint a burned
   * NFT.
   * @param _tokenId ID of the NFT to be burned.
   */
  function _burn(
    uint256 _tokenId
  )
    internal
//    virtual
    validNFToken(_tokenId)
  {
    address tokenOwner = idToOwner[_tokenId];
    _clearApproval(_tokenId);
    _removeNFToken(tokenOwner, _tokenId);
    emit Transfer(tokenOwner, address(0), _tokenId);
  }

  /**
   * @dev Removes a NFT from owner.
   * @notice Use and override this function with caution. Wrong usage can have serious consequences.
   * @param _from Address from wich we want to remove the NFT.
   * @param _tokenId Which NFT we want to remove.
   */
  function _removeNFToken(
    address _from,
    uint256 _tokenId
  )
    internal
//    virtual
  {
    require(idToOwner[_tokenId] == _from, NOT_OWNER);
    ownerToNFTokenCount[_from] = ownerToNFTokenCount[_from] - 1;
    delete idToOwner[_tokenId];
  }

  /**
   * @dev Assignes a new NFT to owner.
   * @notice Use and override this function with caution. Wrong usage can have serious consequences.
   * @param _to Address to wich we want to add the NFT.
   * @param _tokenId Which NFT we want to add.
   */
  function _addNFToken(
    address _to,
    uint256 _tokenId
  )
    internal
//    virtual
  {
    require(idToOwner[_tokenId] == address(0), NFT_ALREADY_EXISTS);

    idToOwner[_tokenId] = _to;
    ownerToNFTokenCount[_to] = ownerToNFTokenCount[_to] + 1;
  }

  /**
   * @dev Helper function that gets NFT count of owner. This is needed for overriding in enumerable
   * extension to remove double storage (gas optimization) of owner nft count.
   * @param _owner Address for whom to query the count.
   * @return Number of _owner NFTs.
   */
  function _getOwnerNFTCount(
    address _owner
  )
    internal
//    virtual
    view
    returns (uint256)
  {
    return ownerToNFTokenCount[_owner];
  }

  /**
   * @dev Actually perform the safeTransferFrom.
   * @param _from The current owner of the NFT.
   * @param _to The new owner.
   * @param _tokenId The NFT to transfer.
   * @param _data Additional data with no specified format, sent in call to `_to`.
   */
  function _safeTransferFrom(
    address _from,
    address _to,
    uint256 _tokenId,
    bytes memory _data
  )
    private
    canTransfer(_tokenId)
    validNFToken(_tokenId)
  {
    address tokenOwner = idToOwner[_tokenId];
    require(tokenOwner == _from, NOT_OWNER);
    require(_to != address(0), ZERO_ADDRESS);

    _transfer(_to, _tokenId);

    if (_to.isContract())
    {
      bytes4 retval = ERC721TokenReceiver(_to).onERC721Received(msg.sender, _from, _tokenId, _data);
      require(retval == MAGIC_ON_ERC721_RECEIVED, NOT_ABLE_TO_RECEIVE_NFT);
    }
  }

  /**
   * @dev Clears the current approval of a given NFT ID.
   * @param _tokenId ID of the NFT to be transferred.
   */
  function _clearApproval(
    uint256 _tokenId
  )
    private
  {
    if (idToApproval[_tokenId] != address(0))
    {
      delete idToApproval[_tokenId];
    }
  }

}

// File: supports-interface.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.4.11;

import "./erc165.sol";

/**
 * @dev Implementation of standard for detect smart contract interfaces.
 */
contract SupportsInterface is
  ERC165
{

  /**
   * @dev Mapping of supported intefraces. You must not set element 0xffffffff to true.
   */
  mapping(bytes4 => bool) internal supportedInterfaces;

  /**
   * @dev Contract constructor.
   */
  constructor()
  {
    supportedInterfaces[0x01ffc9a7] = true; // ERC165
  }

  /**
   * @dev Function to check which interfaces are suported by this contract.
   * @param _interfaceID Id of the interface.
   * @return True if _interfaceID is supported, false otherwise.
   */
  function supportsInterface(
    bytes4 _interfaceID
  )
    external
    //override
    view
    returns (bool)
  {
    return supportedInterfaces[_interfaceID];
  }

}