// File: contracts/FoxGameNFT.sol



/*
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██╔════╝██╔═══██╗╚██╗██╔╝    ██╔════╝ ██╔══██╗████╗ ████║██╔════╝
█████╗  ██║   ██║ ╚███╔╝     ██║  ███╗███████║██╔████╔██║█████╗  
██╔══╝  ██║   ██║ ██╔██╗     ██║   ██║██╔══██║██║╚██╔╝██║██╔══╝  
██║     ╚██████╔╝██╔╝ ██╗    ╚██████╔╝██║  ██║██║ ╚═╝ ██║███████╗
╚═╝      ╚═════╝ ╚═╝  ╚═╝     ╚═════╝ ╚═╝  ╚═╝╚═╝     ╚═╝╚══════╝
*/

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.10;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";

import "./IFoxGameNFTTraits.sol";
import "./IFoxGameCarrot.sol";
import "./IFoxGameNFT.sol";
import "./IFoxGame.sol";

contract FoxGameNFT is IFoxGameNFT, ERC721Enumerable, Ownable, ReentrancyGuard {
  // Presale status
  bool public presaleActive;
  bool public saleActive;

  // Flag to allow smart contacts if ever needed
  bool private eosOnlyEnabled = true;

  // Rarity trait probabilities
  uint8[][29] private rarities;
  uint8[][29] private aliases;

  // Mumber of players minted
  uint16 public minted;

  // Maximum players in the game
  uint16 public constant MAX_TOKENS = 50000;

  // Number of GEN 0 tokens
  uint16 public constant MAX_GEN0_TOKENS = 10000;

  // Maximum mint per transaction (per account during whitelist)
  uint32 public maxMint = 10;

  // Time denominator for seeding randomness.
  uint32 private seedRotationSeconds = 90 days;

  // External contracts
  IFoxGameCarrot private immutable foxCarrot;
  IFoxGame private immutable foxGame;
  IFoxGameNFTTraits private foxTraits;

  // GEN 0 mint price
  uint256 public constant MINT_PRICE = 0.0649 ether;

  // Mapping of token ID to player traits
  mapping(uint16 => Traits) private tokenTraits;

  // Whitelist mint count
  mapping (address => uint32) public presaleMinted;

  // Store previous trait combinations to prevent duplicates
  mapping(uint256 => bool) private knownCombinations;

  // isApprovedForAll registry
  mapping(address => bool) private approvedWhitelist;

  // Events
  event Mint(string kind, address owner, uint16 tokenId);
  event PresaleActive(bool active);
  event SaleActive(bool active);

  // Initialize
  constructor(address carrot, address game, address traits) ERC721("FoxGame NFT", "FOXGAME") {
    foxCarrot = IFoxGameCarrot(carrot);
    foxGame = IFoxGame(game);
    foxTraits = IFoxGameNFTTraits(traits);

    // Precomputed rarity probabilities on chain.
    // (via walker's alias algorithm)

    // RABBIT

    // Fur
    rarities[0] = [ 255, 204, 153, 153 ];
    aliases[0] = [ 0, 0, 1, 1 ];
    // Paws
    rarities[1] = [ 255, 255, 229, 204, 229, 204, 179, 255, 255, 128 ];
    aliases[1] = [ 0, 0, 1, 2, 3, 2, 3, 0, 0, 4 ];
    // Mouth
    rarities[2] = [ 255, 204, 204, 204, 127, 102, 51, 255, 255, 26 ];
    aliases[2] = [ 0, 0, 1, 0, 2, 0, 1, 0, 0, 4 ];
    // Nose
    rarities[3] = [ 255, 102, 255, 255, 204, 153, 102, 255, 51, 51, 255, 204, 255, 204, 153, 204, 153, 51, 255, 51 ];
    aliases[3] = [ 0, 2, 0, 2, 3, 2, 4, 6, 6, 6, 0, 7, 11, 12, 13, 7, 11, 13, 0, 14 ];
    // Eyes
    rarities[4] = [ 56, 255, 179, 153, 158, 112, 133, 112, 112, 56, 250, 224, 199, 122, 240, 214, 189, 112, 112, 163, 112, 138 ];
    aliases[4] = [ 1, 0, 1, 2, 3, 1, 4, 3, 6, 12, 6, 10, 11, 12, 13, 14, 15, 12, 13, 16, 21, 19 ];
    // Ears
    rarities[5] = [ 153, 153, 255, 102, 77, 230 ];
    aliases[5] = [ 2, 2, 0, 2, 3, 3 ];
    // Head
    rarities[6] = [ 61, 184, 122, 122, 61, 255, 204, 122, 224, 255, 214, 184, 235, 61, 184, 184, 184, 122, 122, 184, 153, 245, 143, 224 ];
    aliases[6] = [ 6, 8, 8, 9, 10, 0, 5, 15, 6, 8, 9, 15, 10, 20, 20, 12, 21, 22, 23, 23, 15, 20, 21, 22 ];

    // FOX

    // Furr
    rarities[7] = [ 191, 77, 191, 255, 38, 115, 204, 153, 191, 38, 64, 115, 77, 115, 128 ];
    aliases[7] = [ 3, 3, 3, 0, 7, 7, 3, 6, 7, 10, 8, 13, 14, 10, 13 ];
    // Feet
    rarities[8] = [ 255, 242, 153, 204, 115, 230, 230, 115, 115 ];
    aliases[8] = [ 0, 0, 1, 2, 0, 0, 0, 2, 3 ];
    // Neck
    rarities[9] = [ 77, 255, 128, 77, 153, 153, 153, 77, 153, 230, 77, 77, 77, 204, 179, 230, 77, 179, 128, 179, 153, 230, 77, 77, 102, 77, 153, 153, 204, 77 ];
    aliases[9] = [ 3, 0, 1, 2, 13, 13, 13, 13, 14, 14, 18, 19, 20, 3, 13, 20, 24, 14, 17, 18, 19, 20, 25, 25, 21, 24, 25, 26, 26, 28 ];
    // Mouth
    rarities[10] = [ 41, 61, 102, 204, 255, 102, 204, 204 ];
    aliases[10] = [ 5, 5, 5, 5, 0, 4, 5, 5 ];
    // Eyes
    rarities[11] = [ 87, 255, 130, 245, 173, 173, 191, 87, 176, 128, 217, 43, 173, 217, 92, 217, 43 ];
    aliases[11] = [ 1, 0, 3, 1, 6, 6, 3, 9, 6, 8, 9, 9, 9, 9, 9, 9, 14 ];
    // Cunning
    rarities[12] = [ 255, 153, 204, 102 ];
    aliases[12] = [ 0, 0, 0, 1 ];

    // HUNTER

    // Clothes
    rarities[13] = [ 128, 255, 128, 64, 255 ];
    aliases[13] = [ 2, 0, 1, 2, 0 ];
    // Neck
    rarities[14] = [ 102, 255, 26, 153, 255 ];
    aliases[14] = [ 1, 0, 3, 1, 0 ];
    // Mouth
    rarities[15] = [ 255, 229, 179, 179, 89, 179, 217 ];
    aliases[15] = [ 0, 0, 0, 6, 6, 6, 1 ];
    // Hat
    rarities[16] = [ 191, 38, 89, 255, 191 ];
    aliases[16] = [ 3, 4, 4, 0, 3 ];
    // Eyes
    rarities[17] = [ 191, 255, 38, 77, 191, 77, 217, 38, 153, 191, 77, 191, 204, 77, 77 ];
    aliases[17] = [ 1, 0, 4, 4, 1, 4, 5, 5, 6, 5, 5, 6, 8, 8, 12 ];
    // Marksman
    rarities[18] = [ 255, 153, 204, 102 ];
    aliases[18] = [ 0, 0, 0, 1 ];
  }

  /**
   * Upload rarity propbabilties. Only used in emergencies.
   * @param traitTypeId trait name id (0 corresponds to "fur")
   * @param _rarities walker rarity probailities
   * @param _aliases walker aliases index
   */
  function uploadTraits(uint8 traitTypeId, uint8[] calldata _rarities, uint8[] calldata _aliases) external onlyOwner {
    rarities[traitTypeId] = _rarities;
    aliases[traitTypeId] = _aliases;
  }

  /**
   * Enable Presale.
   */
  function togglePresale() external onlyOwner {
    presaleActive = !presaleActive;
    emit PresaleActive(presaleActive);
  }

  /**
   * Enable Sale.
   */
  function toggleSale() external onlyOwner {
    saleActive = !saleActive;
    emit PresaleActive(saleActive);
  }

  /**
   * Update the ERC-721 trait contract address.
   */
  function setTraitsContract(address _address) external onlyOwner {
    foxTraits = IFoxGameNFTTraits(_address);
  }

  /**
   * Set the max mints per account during persale and per tx during public sale
   */
  function setMaxMintAmount(uint32 _maxMint) external onlyOwner {
    maxMint = _maxMint;
  }

  /**
   * Expose traits to trait contract.
   */
  function getTraits(uint16 tokenId) external view override returns (Traits memory) {
    return tokenTraits[tokenId];
  }

  /**
   * Expose maximum GEN 0 tokens.
   */
  function getMaxGEN0Players() external pure override returns (uint16) {
    return MAX_GEN0_TOKENS;
  }

  /**
   * Internal helper for minting.
   */
  function _mint(uint32 amount, bool stake, uint256 originSeed) internal {
    Kind kind;
    uint16[] memory tokenIdsToStake = stake ? new uint16[](amount) : new uint16[](0);
    uint256 carrotCost;
    uint256 seed;
    for (uint32 i = 0; i < amount; i++) {
      minted++;
      seed = _reseedWithIndex(originSeed, i);
      carrotCost += getMintCarrotCost(minted);
      kind = _generateAndStoreTraits(minted, seed, 0).kind;
      address recipient = _selectRecipient(seed);
      if (!stake || recipient != msg.sender) {
        _safeMint(recipient, minted);
      } else {
        tokenIdsToStake[i] = minted;
        _safeMint(address(foxGame), minted);
      }
      emit Mint(kind == Kind.RABBIT ? "RABBIT" : kind == Kind.FOX ? "FOX" : "HUNTER", recipient, minted);
    }
    if (carrotCost > 0) {
      foxCarrot.burn(msg.sender, carrotCost);
    }
    if (stake) {
      foxGame.stakeTokens(msg.sender, tokenIdsToStake);
    }
  }

  /**
   * Mint your players.
   * @param amount number of tokens to mint
   * @param stake mint directly to staking
   * @param membership wheather user is membership or not
   * @param seed account seed
   * @param sig signature 
   */
  function presaleMint(uint32 amount, bool stake, bool membership, uint48 expiration, uint256 seed, bytes calldata sig) external payable nonReentrant _eosOnly {
    require(presaleActive, "minting is not active");
    require(minted + amount <= MAX_TOKENS, "minted out");
    require(expiration > block.timestamp, "signature has expired");
    require(membership, "only members allowed");
    require(foxGame.isValidSignature(msg.sender, membership, expiration, seed, sig), "invalid signature");

    // Require ETH for GEN 0 only
    if (minted < MAX_GEN0_TOKENS) {
      require(minted + amount <= MAX_GEN0_TOKENS, "not enough available gen0 mints");
      require(amount * MINT_PRICE == msg.value, "invalid payment amount");
    } else {
      require(msg.value == 0, "only carrots required");
    }

    // Allow only 10 per account during presale
    uint32 claimed = presaleMinted[msg.sender];
    require(amount > 0 && amount <= maxMint - claimed, "cannot exceed presale mints");
    presaleMinted[msg.sender] = claimed + amount;

    _mint(amount, stake, seed);
  }

  /**
   * Mint your players.
   * @param amount number of tokens to mint
   * @param stake mint directly to staking
   * @param seed random seed per mint
   * @param sig signature 
   */
  function mint(uint32 amount, bool stake, uint256 seed, uint48 expiration, bytes calldata sig) external payable nonReentrant _eosOnly {
    require(saleActive, "minting is not active");
    require(amount > 0 && amount <= maxMint, "invalid mint amount");
    require(amount * MINT_PRICE == msg.value, "Invalid payment amount");
    require(minted + amount <= MAX_TOKENS, "minted out");
    require(expiration > block.timestamp, "signature has expired");
    require(foxGame.isValidSignature(msg.sender, false, expiration, seed, sig), "invalid signature");

    _mint(amount, stake, seed);
  }

  /**
   * Calculate the foxCarrot cost:
   * - the first 20% are paid in ETH
   * - the next 20% are 20000 $CARROT
   * - the next 40% are 40000 $CARROT
   * - the final 20% are 80000 $CARROT
   * @param tokenId the ID to check the cost of to mint
   * @return the cost of the given token ID
   */
  function getMintCarrotCost(uint16 tokenId) public pure returns (uint256) {
    if (tokenId <= MAX_GEN0_TOKENS) return 0;
    if (tokenId <= MAX_TOKENS * 2 / 5) return 20000 ether;
    if (tokenId <= MAX_TOKENS * 4 / 5) return 40000 ether;
    return 80000 ether;
  }

  /**
   * Generate and store player traits. Recursively called to ensure uniqueness.
   * Give users 3 attempts, bit shifting the seed each time (uses 5 bytes of entropy before failing)
   * @param tokenId id of the token to generate traits
   * @param seed random 256 bit seed to derive traits
   * @return t player trait struct
   */
  function _generateAndStoreTraits(uint16 tokenId, uint256 seed, uint8 attempt) internal returns (Traits memory t) {
    require(attempt < 6, "unable to generate unique traits");
    t = _selectTraits(tokenId, seed);
    if (!knownCombinations[_structToHash(t)]) {
      tokenTraits[tokenId] = t;
      knownCombinations[_structToHash(t)] = true;
      return t;
    }
    return _generateAndStoreTraits(tokenId, seed >> attempt, attempt + 1);
  }

  /**
   * uses A.J. Walker's Alias algorithm for O(1) rarity table lookup
   * ensuring O(1) instead of O(n) reduces mint cost by more than 50%
   * probability & alias tables are generated off-chain beforehand
   * @param seed portion of the 256 bit seed to remove trait correlation
   * @param traitType the trait type to select a trait for 
   * @return the ID of the randomly selected trait
   */
  function _selectTrait(uint16 seed, uint8 traitType) internal view returns (uint8) {
    uint8 trait = uint8(seed) % uint8(rarities[traitType].length);
    if (seed >> 8 < rarities[traitType][trait]) return trait;
    return aliases[traitType][trait];
  }

  /**
   * the first 20% (ETH purchases) go to the minter
   * the remaining 80% have a 10% chance to be given to a random staked fox
   * @param seed a random value to select a recipient from
   * @return the address of the recipient (either the minter or the fox thief's owner)
   */
  function _selectRecipient(uint256 seed) internal view returns (address) {
    if (minted <= MAX_GEN0_TOKENS || ((seed >> 245) % 10) != 0) {
      return msg.sender; // top 10 bits haven't been used
    }
    // 144 bits reserved for trait selection
    address thief = foxGame.randomFoxOwner(seed >> 144);
    if (thief == address(0x0)) {
      return msg.sender;
    }
    return thief;
  }

  /**
   * selects the species and all of its traits based on the seed value
   * @param seed a pseudorandom 256 bit number to derive traits from
   * @return t struct of randomly selected traits
   */
  function _selectTraits(uint16 tokenId, uint256 seed) internal view returns (Traits memory t) {
    // No Hunters until GEN 1 (RABBIT=0, FOX=1, HUNTER=2)
    if (tokenId <= MAX_GEN0_TOKENS) {
      t.kind = Kind((seed & 0xFFFF) % 10 == 0 ? 1 : 0);
    } else {
      uint mod = (seed & 0xFFFF) % 50;
      t.kind = Kind(mod == 0 ? 2 : mod < 5 ? 1 : 0);
    }
    // Use 128 bytes of seed entropy to define traits.
    uint8 offset = uint8(t.kind) * 7;                                           // RABBIT FOX     HUNTER
    seed >>= 16; t.traits[0] = _selectTrait(uint16(seed & 0xFFFF), 0 + offset); // Fur    Tail    Clothes
    seed >>= 16; t.traits[1] = _selectTrait(uint16(seed & 0xFFFF), 1 + offset); // Head   Fur     Eyes
    seed >>= 16; t.traits[2] = _selectTrait(uint16(seed & 0xFFFF), 2 + offset); // Ears   Eyes    Hat
    seed >>= 16; t.traits[3] = _selectTrait(uint16(seed & 0xFFFF), 3 + offset); // Eyes   Mouth   Mouth
    seed >>= 16; t.traits[4] = _selectTrait(uint16(seed & 0xFFFF), 4 + offset); // Nose   Neck    Neck
    seed >>= 16; t.traits[5] = _selectTrait(uint16(seed & 0xFFFF), 5 + offset); // Mouth  Feet    Weapon
    seed >>= 16; t.traits[6] = _selectTrait(uint16(seed & 0xFFFF), 6 + offset); // Paws   Cunning Marksman
    t.advantage = t.traits[6];
  }

  /**
   * converts a struct to a 256 bit hash to check for uniqueness
   * @param t the struct to pack into a hash
   * @return the 256 bit hash of the struct
   */
  function _structToHash(Traits memory t) internal pure returns (uint256) {
    return uint256(bytes32(
      abi.encodePacked(
        t.kind,
        t.advantage,
        t.traits[0],
        t.traits[1],
        t.traits[2],
        t.traits[3],
        t.traits[4],
        t.traits[5],
        t.traits[6]
      )
    ));
  }

  /**
   * Reseeds entropy with mint amount offset.
   * @param seed random seed
   * @param offset additional entropy during mint
   * @return rotated seed
   */
  function _reseedWithIndex(uint256 seed, uint32 offset) internal pure returns (uint256) {
    return uint256(keccak256(abi.encodePacked(seed, offset)));
  }

  /**
   * Allow private sales.
   */
  function mintToAddress(uint256 amount, address recipient, uint256 originSeed) external onlyOwner {
    require(minted + amount <= MAX_TOKENS, "minted out");
    require(amount > 0, "invalid mint amount");
    
    Kind kind;
    uint256 seed;
    for (uint32 i = 0; i < amount; i++) {
      minted++;
      seed = _reseedWithIndex(originSeed, i);
      kind = _generateAndStoreTraits(minted, seed, 0).kind;
      _safeMint(recipient, minted);
      emit Mint(kind == Kind.RABBIT ? "RABBIT" : kind == Kind.FOX ? "FOX" : "HUNTER", recipient, minted);
    }
  }

  /**
   * Allows owner to withdraw funds from minting.
   */
  function withdraw() external onlyOwner {
    payable(owner()).transfer(address(this).balance);
  }

  /**
   * Override transfer to avoid the approval step during staking.
   */
  function transferFrom(address from, address to, uint256 tokenId) public override(ERC721, IFoxGameNFT) {
    if (msg.sender != address(foxGame)) {
      require(_isApprovedOrOwner(msg.sender, tokenId), "transfer not owner nor approved");
    }
    _transfer(from, to, tokenId);
  }

  /**
   * Override NFT token uri. Calls into traits contract.
   */
  function tokenURI(uint256 tokenId) public view override returns (string memory) {
    require(_exists(tokenId), "nonexistent token");
    return foxTraits.tokenURI(uint16(tokenId));
  }

  /**
   * Ennumerate tokens by owner.
   */
  function tokensOf(address owner) external view returns (uint16[] memory) {
    uint32 tokenCount = uint32(balanceOf(owner));
    uint16[] memory tokensId = new uint16[](tokenCount);
    for (uint32 i = 0; i < tokenCount; i++){
      tokensId[i] = uint16(tokenOfOwnerByIndex(owner, i));
    }
    return tokensId;
  }

  /**
   * Overridden to resolve multiple inherited interfaces.
   */
  function ownerOf(uint256 tokenId) public view override(ERC721, IFoxGameNFT) returns (address) {
    return super.ownerOf(tokenId);
  }

  /**
   * Overridden to resolve multiple inherited interfaces.
   */
  function safeTransferFrom(address from, address to, uint256 tokenId, bytes memory _data) public override(ERC721, IFoxGameNFT) {
    super.safeTransferFrom(from, to, tokenId, _data);
  }

  /**
   * Modifier to reject smart contracts.
   */
  modifier _eosOnly() {
    require(!eosOnlyEnabled || tx.origin == msg.sender, "eos only");
    _;
  }
}

// File: @openzeppelin/contracts/access/Ownable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../utils/Context.sol";

/**
 * @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.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * 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.
 */
abstract 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() {
        _setOwner(_msgSender());
    }

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

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the 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 virtual onlyOwner {
        _setOwner(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 virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        _setOwner(newOwner);
    }

    function _setOwner(address newOwner) private {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// File: @openzeppelin/contracts/security/ReentrancyGuard.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor() {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}

// File: @openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../ERC721.sol";
import "./IERC721Enumerable.sol";

/**
 * @dev This implements an optional extension of {ERC721} defined in the EIP that adds
 * enumerability of all the token ids in the contract as well as all token ids owned by each
 * account.
 */
abstract contract ERC721Enumerable is ERC721, IERC721Enumerable {
    // Mapping from owner to list of owned token IDs
    mapping(address => mapping(uint256 => uint256)) private _ownedTokens;

    // Mapping from token ID to index of the owner tokens list
    mapping(uint256 => uint256) private _ownedTokensIndex;

    // Array with all token ids, used for enumeration
    uint256[] private _allTokens;

    // Mapping from token id to position in the allTokens array
    mapping(uint256 => uint256) private _allTokensIndex;

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(IERC165, ERC721) returns (bool) {
        return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721Enumerable-tokenOfOwnerByIndex}.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721.balanceOf(owner), "ERC721Enumerable: owner index out of bounds");
        return _ownedTokens[owner][index];
    }

    /**
     * @dev See {IERC721Enumerable-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _allTokens.length;
    }

    /**
     * @dev See {IERC721Enumerable-tokenByIndex}.
     */
    function tokenByIndex(uint256 index) public view virtual override returns (uint256) {
        require(index < ERC721Enumerable.totalSupply(), "ERC721Enumerable: global index out of bounds");
        return _allTokens[index];
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual override {
        super._beforeTokenTransfer(from, to, tokenId);

        if (from == address(0)) {
            _addTokenToAllTokensEnumeration(tokenId);
        } else if (from != to) {
            _removeTokenFromOwnerEnumeration(from, tokenId);
        }
        if (to == address(0)) {
            _removeTokenFromAllTokensEnumeration(tokenId);
        } else if (to != from) {
            _addTokenToOwnerEnumeration(to, tokenId);
        }
    }

    /**
     * @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 {
        uint256 length = ERC721.balanceOf(to);
        _ownedTokens[to][length] = tokenId;
        _ownedTokensIndex[tokenId] = length;
    }

    /**
     * @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 = ERC721.balanceOf(from) - 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
        delete _ownedTokensIndex[tokenId];
        delete _ownedTokens[from][lastTokenIndex];
    }

    /**
     * @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 - 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
        delete _allTokensIndex[tokenId];
        _allTokens.pop();
    }
}

// File: contracts/IFoxGameNFTTraits.sol



/*
███████╗ ██████╗ ██╗  ██╗     ██████╗  █████╗ ███╗   ███╗███████╗
██╔════╝██╔═══██╗╚██╗██╔╝    ██╔════╝ ██╔══██╗████╗ ████║██╔════╝
█████╗  ██║   ██║ ╚███╔╝     ██║  ███╗███████║██╔████╔██║█████╗  
██╔══╝  ██║   ██║ ██╔██╗     ██║   ██║██╔══██║██║╚██╔╝██║██╔══╝  
██║     ╚██████╔╝██╔╝ ██╗    ╚██████╔╝██║  ██║██║ ╚═╝ ██║███████╗
╚═╝      ╚═════╝ ╚═╝  ╚═╝     ╚═════╝ ╚═╝  ╚═╝╚═╝     ╚═╝╚══════╝
*/

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.10;

interface IFoxGameNFTTraits {
  function tokenURI(uint16 tokenId) external view returns (string memory);
}

// File: contracts/IFoxGameCarrot.sol



/*
███████╗ ██████╗ ██╗  ██╗     ██████╗  █████╗ ███╗   ███╗███████╗
██╔════╝██╔═══██╗╚██╗██╔╝    ██╔════╝ ██╔══██╗████╗ ████║██╔════╝
█████╗  ██║   ██║ ╚███╔╝     ██║  ███╗███████║██╔████╔██║█████╗  
██╔══╝  ██║   ██║ ██╔██╗     ██║   ██║██╔══██║██║╚██╔╝██║██╔══╝  
██║     ╚██████╔╝██╔╝ ██╗    ╚██████╔╝██║  ██║██║ ╚═╝ ██║███████╗
╚═╝      ╚═════╝ ╚═╝  ╚═╝     ╚═════╝ ╚═╝  ╚═╝╚═╝     ╚═╝╚══════╝
*/

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.10;

interface IFoxGameCarrot {
  function mint(address to, uint256 amount) external;
  function burn(address from, uint256 amount) external;
}

// File: contracts/IFoxGameNFT.sol



/*
███████╗ ██████╗ ██╗  ██╗     ██████╗  █████╗ ███╗   ███╗███████╗
██╔════╝██╔═══██╗╚██╗██╔╝    ██╔════╝ ██╔══██╗████╗ ████║██╔════╝
█████╗  ██║   ██║ ╚███╔╝     ██║  ███╗███████║██╔████╔██║█████╗  
██╔══╝  ██║   ██║ ██╔██╗     ██║   ██║██╔══██║██║╚██╔╝██║██╔══╝  
██║     ╚██████╔╝██╔╝ ██╗    ╚██████╔╝██║  ██║██║ ╚═╝ ██║███████╗
╚═╝      ╚═════╝ ╚═╝  ╚═╝     ╚═════╝ ╚═╝  ╚═╝╚═╝     ╚═╝╚══════╝
*/

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.10;

interface IFoxGameNFT {
  enum Kind { RABBIT, FOX, HUNTER }
  struct Traits { Kind kind; uint8 advantage; uint8[7] traits; }
  function getMaxGEN0Players() external pure returns (uint16);
  function getTraits(uint16) external view returns (Traits memory);
  function ownerOf(uint256) external view returns (address owner);
  function transferFrom(address, address, uint256) external;
  function safeTransferFrom(address, address, uint256, bytes memory) external;
}

// File: contracts/IFoxGame.sol



/*
███████╗ ██████╗ ██╗  ██╗     ██████╗  █████╗ ███╗   ███╗███████╗
██╔════╝██╔═══██╗╚██╗██╔╝    ██╔════╝ ██╔══██╗████╗ ████║██╔════╝
█████╗  ██║   ██║ ╚███╔╝     ██║  ███╗███████║██╔████╔██║█████╗  
██╔══╝  ██║   ██║ ██╔██╗     ██║   ██║██╔══██║██║╚██╔╝██║██╔══╝  
██║     ╚██████╔╝██╔╝ ██╗    ╚██████╔╝██║  ██║██║ ╚═╝ ██║███████╗
╚═╝      ╚═════╝ ╚═╝  ╚═╝     ╚═════╝ ╚═╝  ╚═╝╚═╝     ╚═╝╚══════╝
*/

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.10;

interface IFoxGame {
  function stakeTokens(address, uint16[] calldata) external;
  function randomFoxOwner(uint256) external view returns (address);
  function isValidSignature(address, bool, uint48, uint256, bytes memory) external view returns (bool);
}

// File: @openzeppelin/contracts/utils/Context.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @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 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.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}

// File: @openzeppelin/contracts/token/ERC721/ERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC721.sol";
import "./IERC721Receiver.sol";
import "./extensions/IERC721Metadata.sol";
import "../../utils/Address.sol";
import "../../utils/Context.sol";
import "../../utils/Strings.sol";
import "../../utils/introspection/ERC165.sol";

/**
 * @dev Implementation of https://eips.ethereum.org/EIPS/eip-721[ERC721] Non-Fungible Token Standard, including
 * the Metadata extension, but not including the Enumerable extension, which is available separately as
 * {ERC721Enumerable}.
 */
contract ERC721 is Context, ERC165, IERC721, IERC721Metadata {
    using Address for address;
    using Strings for uint256;

    // Token name
    string private _name;

    // Token symbol
    string private _symbol;

    // Mapping from token ID to owner address
    mapping(uint256 => address) private _owners;

    // Mapping owner address to token count
    mapping(address => uint256) private _balances;

    // Mapping from token ID to approved address
    mapping(uint256 => address) private _tokenApprovals;

    // Mapping from owner to operator approvals
    mapping(address => mapping(address => bool)) private _operatorApprovals;

    /**
     * @dev Initializes the contract by setting a `name` and a `symbol` to the token collection.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }

    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns (bool) {
        return
            interfaceId == type(IERC721).interfaceId ||
            interfaceId == type(IERC721Metadata).interfaceId ||
            super.supportsInterface(interfaceId);
    }

    /**
     * @dev See {IERC721-balanceOf}.
     */
    function balanceOf(address owner) public view virtual override returns (uint256) {
        require(owner != address(0), "ERC721: balance query for the zero address");
        return _balances[owner];
    }

    /**
     * @dev See {IERC721-ownerOf}.
     */
    function ownerOf(uint256 tokenId) public view virtual override returns (address) {
        address owner = _owners[tokenId];
        require(owner != address(0), "ERC721: owner query for nonexistent token");
        return owner;
    }

    /**
     * @dev See {IERC721Metadata-name}.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }

    /**
     * @dev See {IERC721Metadata-symbol}.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }

    /**
     * @dev See {IERC721Metadata-tokenURI}.
     */
    function tokenURI(uint256 tokenId) public view virtual override returns (string memory) {
        require(_exists(tokenId), "ERC721Metadata: URI query for nonexistent token");

        string memory baseURI = _baseURI();
        return bytes(baseURI).length > 0 ? string(abi.encodePacked(baseURI, tokenId.toString())) : "";
    }

    /**
     * @dev Base URI for computing {tokenURI}. If set, the resulting URI for each
     * token will be the concatenation of the `baseURI` and the `tokenId`. Empty
     * by default, can be overriden in child contracts.
     */
    function _baseURI() internal view virtual returns (string memory) {
        return "";
    }

    /**
     * @dev See {IERC721-approve}.
     */
    function approve(address to, uint256 tokenId) public virtual override {
        address owner = ERC721.ownerOf(tokenId);
        require(to != owner, "ERC721: approval to current owner");

        require(
            _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
            "ERC721: approve caller is not owner nor approved for all"
        );

        _approve(to, tokenId);
    }

    /**
     * @dev See {IERC721-getApproved}.
     */
    function getApproved(uint256 tokenId) public view virtual override returns (address) {
        require(_exists(tokenId), "ERC721: approved query for nonexistent token");

        return _tokenApprovals[tokenId];
    }

    /**
     * @dev See {IERC721-setApprovalForAll}.
     */
    function setApprovalForAll(address operator, bool approved) public virtual override {
        require(operator != _msgSender(), "ERC721: approve to caller");

        _operatorApprovals[_msgSender()][operator] = approved;
        emit ApprovalForAll(_msgSender(), operator, approved);
    }

    /**
     * @dev See {IERC721-isApprovedForAll}.
     */
    function isApprovedForAll(address owner, address operator) public view virtual override returns (bool) {
        return _operatorApprovals[owner][operator];
    }

    /**
     * @dev See {IERC721-transferFrom}.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        //solhint-disable-next-line max-line-length
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");

        _transfer(from, to, tokenId);
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) public virtual override {
        safeTransferFrom(from, to, tokenId, "");
    }

    /**
     * @dev See {IERC721-safeTransferFrom}.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) public virtual override {
        require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: transfer caller is not owner nor approved");
        _safeTransfer(from, to, tokenId, _data);
    }

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * `_data` is additional data, it has no specified format and it is sent in call to `to`.
     *
     * This internal function is equivalent to {safeTransferFrom}, and can be used to e.g.
     * implement alternative mechanisms to perform token transfer, such as signature-based.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeTransfer(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _transfer(from, to, tokenId);
        require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721: transfer to non ERC721Receiver implementer");
    }

    /**
     * @dev Returns whether `tokenId` exists.
     *
     * Tokens can be managed by their owner or approved accounts via {approve} or {setApprovalForAll}.
     *
     * Tokens start existing when they are minted (`_mint`),
     * and stop existing when they are burned (`_burn`).
     */
    function _exists(uint256 tokenId) internal view virtual returns (bool) {
        return _owners[tokenId] != address(0);
    }

    /**
     * @dev Returns whether `spender` is allowed to manage `tokenId`.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function _isApprovedOrOwner(address spender, uint256 tokenId) internal view virtual returns (bool) {
        require(_exists(tokenId), "ERC721: operator query for nonexistent token");
        address owner = ERC721.ownerOf(tokenId);
        return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
    }

    /**
     * @dev Safely mints `tokenId` and transfers it to `to`.
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function _safeMint(address to, uint256 tokenId) internal virtual {
        _safeMint(to, tokenId, "");
    }

    /**
     * @dev Same as {xref-ERC721-_safeMint-address-uint256-}[`_safeMint`], with an additional `data` parameter which is
     * forwarded in {IERC721Receiver-onERC721Received} to contract recipients.
     */
    function _safeMint(
        address to,
        uint256 tokenId,
        bytes memory _data
    ) internal virtual {
        _mint(to, tokenId);
        require(
            _checkOnERC721Received(address(0), to, tokenId, _data),
            "ERC721: transfer to non ERC721Receiver implementer"
        );
    }

    /**
     * @dev Mints `tokenId` and transfers it to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {_safeMint} whenever possible
     *
     * Requirements:
     *
     * - `tokenId` must not exist.
     * - `to` cannot be the zero address.
     *
     * Emits a {Transfer} event.
     */
    function _mint(address to, uint256 tokenId) internal virtual {
        require(to != address(0), "ERC721: mint to the zero address");
        require(!_exists(tokenId), "ERC721: token already minted");

        _beforeTokenTransfer(address(0), to, tokenId);

        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(address(0), to, tokenId);
    }

    /**
     * @dev Destroys `tokenId`.
     * The approval is cleared when the token is burned.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     *
     * Emits a {Transfer} event.
     */
    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Clear approvals
        _approve(address(0), tokenId);

        _balances[owner] -= 1;
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);
    }

    /**
     * @dev Transfers `tokenId` from `from` to `to`.
     *  As opposed to {transferFrom}, this imposes no restrictions on msg.sender.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     *
     * Emits a {Transfer} event.
     */
    function _transfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {
        require(ERC721.ownerOf(tokenId) == from, "ERC721: transfer of token that is not own");
        require(to != address(0), "ERC721: transfer to the zero address");

        _beforeTokenTransfer(from, to, tokenId);

        // Clear approvals from the previous owner
        _approve(address(0), tokenId);

        _balances[from] -= 1;
        _balances[to] += 1;
        _owners[tokenId] = to;

        emit Transfer(from, to, tokenId);
    }

    /**
     * @dev Approve `to` to operate on `tokenId`
     *
     * Emits a {Approval} event.
     */
    function _approve(address to, uint256 tokenId) internal virtual {
        _tokenApprovals[tokenId] = to;
        emit Approval(ERC721.ownerOf(tokenId), to, tokenId);
    }

    /**
     * @dev Internal function to invoke {IERC721Receiver-onERC721Received} on a target address.
     * The call is not executed if the target address is not a contract.
     *
     * @param from address representing the previous owner of the given token ID
     * @param to target address that will receive the tokens
     * @param tokenId uint256 ID of the token to be transferred
     * @param _data bytes optional data to send along with the call
     * @return bool whether the call correctly returned the expected magic value
     */
    function _checkOnERC721Received(
        address from,
        address to,
        uint256 tokenId,
        bytes memory _data
    ) private returns (bool) {
        if (to.isContract()) {
            try IERC721Receiver(to).onERC721Received(_msgSender(), from, tokenId, _data) returns (bytes4 retval) {
                return retval == IERC721Receiver.onERC721Received.selector;
            } catch (bytes memory reason) {
                if (reason.length == 0) {
                    revert("ERC721: transfer to non ERC721Receiver implementer");
                } else {
                    assembly {
                        revert(add(32, reason), mload(reason))
                    }
                }
            }
        } else {
            return true;
        }
    }

    /**
     * @dev Hook that is called before any token transfer. This includes minting
     * and burning.
     *
     * Calling conditions:
     *
     * - When `from` and `to` are both non-zero, ``from``'s `tokenId` will be
     * transferred to `to`.
     * - When `from` is zero, `tokenId` will be minted for `to`.
     * - When `to` is zero, ``from``'s `tokenId` will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 tokenId
    ) internal virtual {}
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional enumeration extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Enumerable is IERC721 {
    /**
     * @dev Returns the total amount of tokens stored by the contract.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns a token ID owned by `owner` at a given `index` of its token list.
     * Use along with {balanceOf} to enumerate all of ``owner``'s tokens.
     */
    function tokenOfOwnerByIndex(address owner, uint256 index) external view returns (uint256 tokenId);

    /**
     * @dev Returns a token ID at a given `index` of all the tokens stored by the contract.
     * Use along with {totalSupply} to enumerate all tokens.
     */
    function tokenByIndex(uint256 index) external view returns (uint256);
}

// File: @openzeppelin/contracts/token/ERC721/IERC721.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../../utils/introspection/IERC165.sol";

/**
 * @dev Required interface of an ERC721 compliant contract.
 */
interface IERC721 is IERC165 {
    /**
     * @dev Emitted when `tokenId` token is transferred from `from` to `to`.
     */
    event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables `approved` to manage the `tokenId` token.
     */
    event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);

    /**
     * @dev Emitted when `owner` enables or disables (`approved`) `operator` to manage all of its assets.
     */
    event ApprovalForAll(address indexed owner, address indexed operator, bool approved);

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

    /**
     * @dev Returns the owner of the `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function ownerOf(uint256 tokenId) external view returns (address owner);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`, checking first that contract recipients
     * are aware of the ERC721 protocol to prevent tokens from being forever locked.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be have been allowed to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Transfers `tokenId` token from `from` to `to`.
     *
     * WARNING: Usage of this method is discouraged, use {safeTransferFrom} whenever possible.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address from,
        address to,
        uint256 tokenId
    ) external;

    /**
     * @dev Gives permission to `to` to transfer `tokenId` token to another account.
     * The approval is cleared when the token is transferred.
     *
     * Only a single account can be approved at a time, so approving the zero address clears previous approvals.
     *
     * Requirements:
     *
     * - The caller must own the token or be an approved operator.
     * - `tokenId` must exist.
     *
     * Emits an {Approval} event.
     */
    function approve(address to, uint256 tokenId) external;

    /**
     * @dev Returns the account approved for `tokenId` token.
     *
     * Requirements:
     *
     * - `tokenId` must exist.
     */
    function getApproved(uint256 tokenId) external view returns (address operator);

    /**
     * @dev Approve or remove `operator` as an operator for the caller.
     * Operators can call {transferFrom} or {safeTransferFrom} for any token owned by the caller.
     *
     * Requirements:
     *
     * - The `operator` cannot be the caller.
     *
     * Emits an {ApprovalForAll} event.
     */
    function setApprovalForAll(address operator, bool _approved) external;

    /**
     * @dev Returns if the `operator` is allowed to manage all of the assets of `owner`.
     *
     * See {setApprovalForAll}
     */
    function isApprovedForAll(address owner, address operator) external view returns (bool);

    /**
     * @dev Safely transfers `tokenId` token from `from` to `to`.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `tokenId` token must exist and be owned by `from`.
     * - If the caller is not `from`, it must be approved to move this token by either {approve} or {setApprovalForAll}.
     * - If `to` refers to a smart contract, it must implement {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
     *
     * Emits a {Transfer} event.
     */
    function safeTransferFrom(
        address from,
        address to,
        uint256 tokenId,
        bytes calldata data
    ) external;
}

// File: @openzeppelin/contracts/token/ERC721/IERC721Receiver.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @title ERC721 token receiver interface
 * @dev Interface for any contract that wants to support safeTransfers
 * from ERC721 asset contracts.
 */
interface IERC721Receiver {
    /**
     * @dev Whenever an {IERC721} `tokenId` token is transferred to this contract via {IERC721-safeTransferFrom}
     * by `operator` from `from`, this function is called.
     *
     * It must return its Solidity selector to confirm the token transfer.
     * If any other value is returned or the interface is not implemented by the recipient, the transfer will be reverted.
     *
     * The selector can be obtained in Solidity with `IERC721.onERC721Received.selector`.
     */
    function onERC721Received(
        address operator,
        address from,
        uint256 tokenId,
        bytes calldata data
    ) external returns (bytes4);
}

// File: @openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "../IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional metadata extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
interface IERC721Metadata is IERC721 {
    /**
     * @dev Returns the token collection name.
     */
    function name() external view returns (string memory);

    /**
     * @dev Returns the token collection symbol.
     */
    function symbol() external view returns (string memory);

    /**
     * @dev Returns the Uniform Resource Identifier (URI) for `tokenId` token.
     */
    function tokenURI(uint256 tokenId) external view returns (string memory);
}

// File: @openzeppelin/contracts/utils/Address.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        assembly {
            size := extcodesize(account)
        }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain `call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value
    ) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(
        address target,
        bytes memory data,
        uint256 value,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        (bool success, bytes memory returndata) = target.call{value: value}(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        (bool success, bytes memory returndata) = target.staticcall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(
        address target,
        bytes memory data,
        string memory errorMessage
    ) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        (bool success, bytes memory returndata) = target.delegatecall(data);
        return verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Tool to verifies that a low level call was successful, and revert if it wasn't, either by bubbling the
     * revert reason using the provided one.
     *
     * _Available since v4.3._
     */
    function verifyCallResult(
        bool success,
        bytes memory returndata,
        string memory errorMessage
    ) internal pure returns (bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}

// File: @openzeppelin/contracts/utils/Strings.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

/**
 * @dev String operations.
 */
library Strings {
    bytes16 private constant _HEX_SYMBOLS = "0123456789abcdef";

    /**
     * @dev Converts a `uint256` to its ASCII `string` decimal representation.
     */
    function toString(uint256 value) internal pure returns (string memory) {
        // Inspired by OraclizeAPI's implementation - MIT licence
        // https://github.com/oraclize/ethereum-api/blob/b42146b063c7d6ee1358846c198246239e9360e8/oraclizeAPI_0.4.25.sol

        if (value == 0) {
            return "0";
        }
        uint256 temp = value;
        uint256 digits;
        while (temp != 0) {
            digits++;
            temp /= 10;
        }
        bytes memory buffer = new bytes(digits);
        while (value != 0) {
            digits -= 1;
            buffer[digits] = bytes1(uint8(48 + uint256(value % 10)));
            value /= 10;
        }
        return string(buffer);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
     */
    function toHexString(uint256 value) internal pure returns (string memory) {
        if (value == 0) {
            return "0x00";
        }
        uint256 temp = value;
        uint256 length = 0;
        while (temp != 0) {
            length++;
            temp >>= 8;
        }
        return toHexString(value, length);
    }

    /**
     * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
     */
    function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
        bytes memory buffer = new bytes(2 * length + 2);
        buffer[0] = "0";
        buffer[1] = "x";
        for (uint256 i = 2 * length + 1; i > 1; --i) {
            buffer[i] = _HEX_SYMBOLS[value & 0xf];
            value >>= 4;
        }
        require(value == 0, "Strings: hex length insufficient");
        return string(buffer);
    }
}

// File: @openzeppelin/contracts/utils/introspection/ERC165.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "./IERC165.sol";

/**
 * @dev Implementation of the {IERC165} interface.
 *
 * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
 * for the additional interface id that will be supported. For example:
 *
 * ```solidity
 * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
 *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
 * }
 * ```
 *
 * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
 */
abstract contract ERC165 is IERC165 {
    /**
     * @dev See {IERC165-supportsInterface}.
     */
    function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
        return interfaceId == type(IERC165).interfaceId;
    }
}

// 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);
}