// File: /contracts/MEFaverse.sol




// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Strings.sol";
import './Blimpie/Delegated.sol';
import './Blimpie/Merkle.sol';
import './Blimpie/ERC721Batch.sol';
import './Blimpie/PaymentSplitterMod.sol';

contract MEFaverse is Delegated, ERC721Batch, Merkle, PaymentSplitterMod {
  using Strings for uint256;

  uint public MAX_MINT   = 2;
  uint public MAX_ORDER  = 2;
  uint public MAX_SUPPLY = 8500;
  uint public PRICE      = 0.08 ether;

  bool public isPresaleActive = false;
  bool public isMainsaleActive = false;

  string private _tokenURIPrefix;
  string private _tokenURISuffix;

  address[] private _accounts = [
    0xE57048340ddf7a28244E1cdC63AA9056187E2665,
    0xbE8Fdf8Ca08c10082b8aD24e2Eb01592153dC8B2,
    0x5B7556FA084116e33aaeB273a511Fdfb35BE0DA0,
    0x42a06F7bB64fd3B862A74e5BcBADc3CFb3F907a4,
    0xf092E151480c9CBf372de602E6c8d048C212a979,
    0x3ff0D4b04D8ef29198C7F8ce597F6FCbA0aF3931,
    0x557e5F91f60dc99aB499F6ffdbedFfBa44b441D9
  ];

  uint[] private _shares = [
    40,
    23,
     8,
    10,
     5,
     4,
    10
  ];

  constructor()
    Delegated()
    ERC721B("MEFaverse", "MEF", 0)
    PaymentSplitterMod( _accounts, _shares ){
  }

  //safety first
  fallback() external payable {}


  //view: IERC721Metadata
  function tokenURI( uint tokenId ) external view override returns( string memory ){
    require(_exists(tokenId), "MEFaverse: query for nonexistent token");
    return string(abi.encodePacked(_tokenURIPrefix, tokenId.toString(), _tokenURISuffix));
  }

  //payable
  function mint( uint quantity, bytes32[] calldata proof ) external payable {
    require( 0 < quantity && quantity <= MAX_ORDER,  "MEFaverse: order too big"             );
    require( msg.value >= PRICE * quantity,          "MEFaverse: ether sent is not correct" );
    require( owners[msg.sender].purchased + quantity <= MAX_MINT, "MEFaverse: don't be greedy" );

    uint supply = totalSupply();
    require( supply + quantity <= MAX_SUPPLY, "MEFaverse: mint/order exceeds supply" );

    if( isMainsaleActive ){
      //no-op
      
    }
    else if( isPresaleActive ){
      verifyProof( keccak256( abi.encodePacked( msg.sender ) ), proof );
    }
    else{
      revert( "MEFaverse: sale is not active" );
    }

    owners[msg.sender].balance += uint16(quantity);
    owners[msg.sender].purchased += uint16(quantity);
    for( uint i; i < quantity; ++i ){
      _safeMint( msg.sender, supply++, "" );
    }
  }


  //onlyDelegates
  function mintTo(uint[] calldata quantity, address[] calldata recipient) external payable onlyDelegates{
    require(quantity.length == recipient.length, "MEFaverse: must provide equal quantities and recipients" );

    unchecked{
      uint totalQuantity;
      for(uint i; i < quantity.length; ++i){
        totalQuantity += quantity[i];
      }
      uint supply = totalSupply();
      require( supply + totalQuantity <= MAX_SUPPLY, "MEFaverse: mint/order exceeds supply" );

      for(uint i; i < recipient.length; ++i){
        if( quantity[i] > 0 ){
          owners[recipient[i]].balance += uint16(quantity[i]);
          for( uint j; j < quantity[i]; ++j ){
            _mint( recipient[i], supply++ );
          }
        }
      }
    }
  }

  function setActive(bool isPresaleActive_, bool isMainsaleActive_) external onlyDelegates{
    isPresaleActive = isPresaleActive_;
    isMainsaleActive = isMainsaleActive_;
  }

  function setBaseURI(string calldata _newPrefix, string calldata _newSuffix) external onlyDelegates{
    _tokenURIPrefix = _newPrefix;
    _tokenURISuffix = _newSuffix;
  }

  function setConfig(uint maxOrder, uint maxSupply, uint maxMint, uint price) external onlyDelegates{
    require( maxSupply >= totalSupply(), "MEFaverse: specified supply is lower than current balance" );
    MAX_ORDER  = maxOrder;
    MAX_SUPPLY = maxSupply;
    MAX_MINT   = maxMint;
    PRICE      = price;
  }


  //private
  function _mint( address to, uint tokenId ) internal override {
    tokens.push( Token( to ) );
    emit Transfer( address(0), to, tokenId );
  }
}

// File: /contracts/Blimpie/PaymentSplitterMod.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/Context.sol";

/**
 * @title PaymentSplitter
 * @dev This contract allows to split Ether payments among a group of accounts. The sender does not need to be aware
 * that the Ether will be split in this way, since it is handled transparently by the contract.
 *
 * The split can be in equal parts or in any other arbitrary proportion. The way this is specified is by assigning each
 * account to a number of shares. Of all the Ether that this contract receives, each account will then be able to claim
 * an amount proportional to the percentage of total shares they were assigned.
 *
 * `PaymentSplitter` follows a _pull payment_ model. This means that payments are not automatically forwarded to the
 * accounts but kept in this contract, and the actual transfer is triggered as a separate step by calling the {release}
 * function.
 */
contract PaymentSplitterMod is Context {
    event PayeeAdded(address account, uint256 shares);
    event PaymentReleased(address to, uint256 amount);
    event PaymentReceived(address from, uint256 amount);

    uint256 private _totalShares;
    uint256 private _totalReleased;

    mapping(address => uint256) private _shares;
    mapping(address => uint256) private _released;
    address[] private _payees;

    /**
     * @dev Creates an instance of `PaymentSplitter` where each account in `payees` is assigned the number of shares at
     * the matching position in the `shares` array.
     *
     * All addresses in `payees` must be non-zero. Both arrays must have the same non-zero length, and there must be no
     * duplicates in `payees`.
     */
    constructor(address[] memory payees, uint256[] memory shares_) payable {
        require(payees.length == shares_.length, "PaymentSplitter: payees and shares length mismatch");
        require(payees.length > 0, "PaymentSplitter: no payees");

        for (uint256 i = 0; i < payees.length; i++) {
            _addPayee(payees[i], shares_[i]);
        }
    }

    /**
     * @dev The Ether received will be logged with {PaymentReceived} events. Note that these events are not fully
     * reliable: it's possible for a contract to receive Ether without triggering this function. This only affects the
     * reliability of the events, and not the actual splitting of Ether.
     *
     * To learn more about this see the Solidity documentation for
     * https://solidity.readthedocs.io/en/latest/contracts.html#fallback-function[fallback
     * functions].
     */
    receive() external payable {
        emit PaymentReceived(_msgSender(), msg.value);
    }

    /**
     * @dev Getter for the total shares held by payees.
     */
    function totalShares() public view returns (uint256) {
        return _totalShares;
    }

    /**
     * @dev Getter for the total amount of Ether already released.
     */
    function totalReleased() public view returns (uint256) {
        return _totalReleased;
    }

    /**
     * @dev Getter for the amount of shares held by an account.
     */
    function shares(address account) public view returns (uint256) {
        return _shares[account];
    }

    /**
     * @dev Getter for the amount of Ether already released to a payee.
     */
    function released(address account) public view returns (uint256) {
        return _released[account];
    }

    /**
     * @dev Getter for the address of the payee number `index`.
     */
    function payee(uint256 index) public view returns (address) {
        return _payees[index];
    }

    /**
     * @dev Triggers a transfer to `account` of the amount of Ether they are owed, according to their percentage of the
     * total shares and their previous withdrawals.
     */
    function release(address payable account) public virtual {
        require(_shares[account] > 0, "PaymentSplitter: account has no shares");

        uint256 totalReceived = address(this).balance + _totalReleased;
        uint256 payment = (totalReceived * _shares[account]) / _totalShares - _released[account];
        require(payment != 0, "PaymentSplitter: account is not due payment");

        _released[account] = _released[account] + payment;
        _totalReleased = _totalReleased + payment;

        Address.sendValue(account, payment);
        emit PaymentReleased(account, payment);
    }

    function _addPayee(address account, uint256 shares_) internal {
        require(account != address(0), "PaymentSplitter: account is the zero address");
        require(shares_ > 0, "PaymentSplitter: shares are 0");
        require(_shares[account] == 0, "PaymentSplitter: account already has shares");

        _payees.push(account);
        _shares[account] = shares_;
        _totalShares = _totalShares + shares_;
        emit PayeeAdded(account, shares_);
    }

    function _resetCounters() internal {
        _totalReleased = 0;
        for(uint i; i < _payees.length; ++i ){
            _released[ _payees[i] ] = 0;
        }
    }

    function _setPayee( uint index, address account, uint newShares ) internal {
        _totalShares = _totalShares - _shares[ account ] + newShares;
        _shares[ account ] = newShares;
        _payees[ index ] = account;
    }
}

// File: /contracts/Blimpie/Merkle.sol




// SPDX-License-Identifier: BSD-3

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";
import './Delegated.sol';

contract Merkle is Delegated{
  bytes32 internal merkleRoot;

  function setMerkleRoot( bytes32 merkleRoot_ ) external onlyOwner{
    merkleRoot = merkleRoot_;
  }

  function verifyProof(bytes32 leaf, bytes32[] memory proof) internal view{
    require( MerkleProof.processProof( proof, leaf ) == merkleRoot, "Merkle Proof verification failed" );
  }
}
// File: /contracts/Blimpie/IERC721Batch.sol



// SPDX-License-Identifier: BSD-3-Clause

pragma solidity ^0.8.0;

interface IERC721Batch {
  function isOwnerOf( address account, uint[] calldata tokenIds ) external view returns( bool );
  function transferBatch( address from, address to, uint[] calldata tokenIds, bytes calldata data ) external;
  function walletOfOwner( address account ) external view returns( uint[] memory );
}

// File: /contracts/Blimpie/ERC721EnumerableB.sol



// SPDX-License-Identifier: BSD-3-Clause

pragma solidity ^0.8.0;

/****************************************
 * @author: squeebo_nft                 *
 ****************************************
 *   Blimpie-ERC721 provides low-gas    *
 *       mints + transfers              *
 ****************************************/

import "@openzeppelin/contracts/token/ERC721/extensions/IERC721Enumerable.sol";
import "./ERC721B.sol";

abstract contract ERC721EnumerableB is ERC721B, IERC721Enumerable {
  function supportsInterface( bytes4 interfaceId ) public view virtual override(IERC165, ERC721B) returns( bool isSupported ){
    return interfaceId == type(IERC721Enumerable).interfaceId || super.supportsInterface(interfaceId);
  }

  function tokenOfOwnerByIndex( address owner, uint index ) external view override returns( uint tokenId ){
    uint count;
    for( uint i; i < tokens.length; ++i ){
      if( owner == tokens[i].owner ){
        if( count == index )
          return i;
        else
          ++count;
      }
    }

    revert("ERC721EnumerableB: owner index out of bounds");
  }

  function tokenByIndex( uint index ) external view override returns( uint tokenId ){
    require( index < totalSupply(), "ERC721EnumerableB: query for nonexistent token");
    return index + _offset;
  }

  function totalSupply() public view override( ERC721B, IERC721Enumerable ) returns( uint ){
    return ERC721B.totalSupply();
  }
}

// File: /contracts/Blimpie/ERC721Batch.sol




// SPDX-License-Identifier: BSD-3-Clause

pragma solidity ^0.8.0;

/****************************************
 * @author: squeebo_nft                 *
 ****************************************
 *   Blimpie-FF721 provides low-gas     *
 *       mints + transfers              *
 ****************************************/

import "../Blimpie/IERC721Batch.sol";
import "./ERC721EnumerableB.sol";

abstract contract ERC721Batch is ERC721EnumerableB, IERC721Batch {
  function isOwnerOf( address account, uint[] calldata tokenIds ) external view override returns( bool ){
    for(uint i; i < tokenIds.length; ++i ){
      if( account != tokens[ tokenIds[i] ].owner )
        return false;
    }

    return true;
  }

  function transferBatch( address from, address to, uint[] calldata tokenIds, bytes calldata data ) external override{
    for(uint i; i < tokenIds.length; ++i ){
      safeTransferFrom( from, to, tokenIds[i], data );
    }
  }

  function walletOfOwner( address account ) external view override returns( uint[] memory wallet ){
    uint count;
    uint quantity = owners[ account ].balance;
    wallet = new uint[]( quantity );
    for( uint i; i < tokens.length; ++i ){
      if( account == tokens[i].owner ){
        wallet[ count++ ] = i;
        if( count == quantity )
          break;
      }
    }
    return wallet;
  }
}
// File: /contracts/Blimpie/ERC721B.sol



// SPDX-License-Identifier: BSD-3-Clause

pragma solidity ^0.8.0;

/****************************************
 * @author: squeebo_nft         *
 ****************************************
 *   Blimpie-FF721 provides low-gas  *
 *     mints + transfers        *
 ****************************************/

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/IERC721Metadata.sol";
import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/utils/Context.sol";
import "@openzeppelin/contracts/utils/introspection/ERC165.sol";


abstract contract ERC721B is Context, ERC165, IERC721, IERC721Metadata {
  using Address for address;

  struct Owner{
    uint16 balance;
    uint16 purchased;
  }

  struct Token{
    address owner;
  }

  Token[] public tokens;
  mapping(address => Owner) public owners;

  uint internal _burned;
  uint internal _offset;
  string private _name;
  string private _symbol;

  mapping(uint => address) internal _tokenApprovals;
  mapping(address => mapping(address => bool)) private _operatorApprovals;

  constructor(string memory name_, string memory symbol_, uint offset_ ){
    _name = name_;
    _symbol = symbol_;

    _offset = offset_;
    for(uint i; i < _offset; ++i ){
      tokens.push();
    }
  }

  //public view
  function balanceOf(address owner) external view override returns( uint balance ){
    return owners[owner].balance;
  }

  function name() external view override returns( string memory name_ ){
    return _name;
  }

  function ownerOf(uint tokenId) public view override returns( address owner ){
    require(_exists(tokenId), "ERC721B: query for nonexistent token");
    return tokens[tokenId].owner;
  }

  function supportsInterface(bytes4 interfaceId) public view virtual override(ERC165, IERC165) returns( bool isSupported ){
    return
      interfaceId == type(IERC721).interfaceId ||
      interfaceId == type(IERC721Metadata).interfaceId ||
      super.supportsInterface(interfaceId);
  }

  function symbol() external view override returns( string memory symbol_ ){
    return _symbol;
  }

  function totalSupply() public view virtual returns (uint) {
    return tokens.length - (_burned + _offset);
  }


  //approvals
  function approve(address to, uint tokenId) external override {
    address owner = ownerOf(tokenId);
    require(to != owner, "ERC721B: approval to current owner");

    require(
      _msgSender() == owner || isApprovedForAll(owner, _msgSender()),
      "ERC721B: caller is not owner nor approved for all"
    );

    _approve(to, tokenId);
  }

  function getApproved(uint tokenId) public view override returns( address approver ){
    require(_exists(tokenId), "ERC721: query for nonexistent token");
    return _tokenApprovals[tokenId];
  }

  function isApprovedForAll(address owner, address operator) public view override returns( bool isApproved ){
    return _operatorApprovals[owner][operator];
  }

  function setApprovalForAll(address operator, bool approved) external override {
    _operatorApprovals[_msgSender()][operator] = approved;
    emit ApprovalForAll(_msgSender(), operator, approved);
  }


  //transfers
  function safeTransferFrom(address from, address to, uint tokenId) external override{
    safeTransferFrom(from, to, tokenId, "");
  }

  function safeTransferFrom(address from, address to, uint tokenId, bytes memory _data) public override {
    require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721B: caller is not owner nor approved");
    _safeTransfer(from, to, tokenId, _data);
  }

  function transferFrom(address from, address to, uint tokenId) external override {
    //solhint-disable-next-line max-line-length
    require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721B: caller is not owner nor approved");
    _transfer(from, to, tokenId);
  }


  //internal
  function _approve(address to, uint tokenId) internal{
    _tokenApprovals[tokenId] = to;
    emit Approval(ownerOf(tokenId), to, tokenId);
  }

  function _beforeTokenTransfer(address from, address to) internal virtual {
    if( from != address(0) )
      --owners[from].balance;

    if( to != address(0) )
      ++owners[to].balance;
  }


  function _burn(uint tokenId) internal {
    address owner = ownerOf(tokenId);

    _beforeTokenTransfer(owner, address(0));

    // Clear approvals
    _approve(address(0), tokenId);
    tokens[tokenId].owner = address(0);

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

  function _checkOnERC721Received(address from, address to, uint 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("ERC721B: transfer to non ERC721Receiver implementer");
        } else {
          assembly {
            revert(add(32, reason), mload(reason))
          }
        }
      }
    } else {
      return true;
    }
  }

  function _exists(uint tokenId) internal view returns( bool ){
    return tokenId < tokens.length && tokens[tokenId].owner != address(0);
  }

  function _isApprovedOrOwner(address spender, uint tokenId) internal view returns( bool isApproved ){
    require(_exists(tokenId), "ERC721B: query for nonexistent token");
    address owner = ownerOf(tokenId);
    return (spender == owner || getApproved(tokenId) == spender || isApprovedForAll(owner, spender));
  }

  function _mint(address to, uint tokenId) internal virtual;

  function _next() internal view virtual returns(uint){
    return tokens.length + _offset;
  }

  function _safeMint(address to, uint tokenId) internal {
    _safeMint(to, tokenId, "");
  }

  function _safeMint(address to, uint tokenId, bytes memory _data) internal {
    _mint(to, tokenId);
    require(
      _checkOnERC721Received(address(0), to, tokenId, _data),
      "ERC721B: transfer to non ERC721Receiver implementer"
    );
  }

  function _safeTransfer(address from, address to, uint tokenId, bytes memory _data) internal{
    _transfer(from, to, tokenId);
    require(_checkOnERC721Received(from, to, tokenId, _data), "ERC721B: transfer to non ERC721Receiver implementer");
  }

  function _transfer(address from, address to, uint tokenId) internal {
    require(ownerOf(tokenId) == from, "ERC721B: transfer of token that is not own");
    _beforeTokenTransfer(from, to);

    // Clear approvals from the previous owner
    _approve(address(0), tokenId);
    tokens[tokenId].owner = to;

    emit Transfer(from, to, tokenId);
  }
}

// File: /contracts/Blimpie/Delegated.sol




// SPDX-License-Identifier: BSD-3-Clause

pragma solidity ^0.8.0;

/***********************
* @author: squeebo_nft *
************************/

import "@openzeppelin/contracts/access/Ownable.sol";

contract Delegated is Ownable{
  mapping(address => bool) internal _delegates;

  constructor(){
    _delegates[owner()] = true;
  }

  modifier onlyDelegates {
    require(_delegates[msg.sender], "Invalid delegate" );
    _;
  }

  //onlyOwner
  function isDelegate( address addr ) external view onlyOwner returns ( bool ){
    return _delegates[addr];
  }

  function setDelegate( address addr, bool isDelegate_ ) external onlyOwner{
    _delegates[addr] = isDelegate_;
  }

  function transferOwnership(address newOwner) public virtual override onlyOwner {
    _delegates[newOwner] = true;
    super.transferOwnership( newOwner );
  }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)

pragma solidity ^0.8.0;

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

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)

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/cryptography/MerkleProof.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/cryptography/MerkleProof.sol)

pragma solidity ^0.8.0;

/**
 * @dev These functions deal with verification of Merkle Trees proofs.
 *
 * The proofs can be generated using the JavaScript library
 * https://github.com/miguelmota/merkletreejs[merkletreejs].
 * Note: the hashing algorithm should be keccak256 and pair sorting should be enabled.
 *
 * See `test/utils/cryptography/MerkleProof.test.js` for some examples.
 */
library MerkleProof {
    /**
     * @dev Returns true if a `leaf` can be proved to be a part of a Merkle tree
     * defined by `root`. For this, a `proof` must be provided, containing
     * sibling hashes on the branch from the leaf to the root of the tree. Each
     * pair of leaves and each pair of pre-images are assumed to be sorted.
     */
    function verify(
        bytes32[] memory proof,
        bytes32 root,
        bytes32 leaf
    ) internal pure returns (bool) {
        return processProof(proof, leaf) == root;
    }

    /**
     * @dev Returns the rebuilt hash obtained by traversing a Merklee tree up
     * from `leaf` using `proof`. A `proof` is valid if and only if the rebuilt
     * hash matches the root of the tree. When processing the proof, the pairs
     * of leafs & pre-images are assumed to be sorted.
     *
     * _Available since v4.4._
     */
    function processProof(bytes32[] memory proof, bytes32 leaf) internal pure returns (bytes32) {
        bytes32 computedHash = leaf;
        for (uint256 i = 0; i < proof.length; i++) {
            bytes32 proofElement = proof[i];
            if (computedHash <= proofElement) {
                // Hash(current computed hash + current element of the proof)
                computedHash = _efficientHash(computedHash, proofElement);
            } else {
                // Hash(current element of the proof + current computed hash)
                computedHash = _efficientHash(proofElement, computedHash);
            }
        }
        return computedHash;
    }

    function _efficientHash(bytes32 a, bytes32 b) private pure returns (bytes32 value) {
        assembly {
            mstore(0x00, a)
            mstore(0x20, b)
            value := keccak256(0x00, 0x40)
        }
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Strings.sol)

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/Context.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

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/utils/Address.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (utils/Address.sol)

pragma solidity ^0.8.1;

/**
 * @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
     * ====
     *
     * [IMPORTANT]
     * ====
     * You shouldn't rely on `isContract` to protect against flash loan attacks!
     *
     * Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
     * like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
     * constructor.
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize/address.code.length, which returns 0
        // for contracts in construction, since the code is only stored at the end
        // of the constructor execution.

        return account.code.length > 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/token/ERC721/extensions/IERC721Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/extensions/IERC721Metadata.sol)

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/token/ERC721/extensions/IERC721Enumerable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC721/extensions/IERC721Enumerable.sol)

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);

    /**
     * @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/IERC721Receiver.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721Receiver.sol)

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/IERC721.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721.sol)

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/access/Ownable.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)

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() {
        _transferOwnership(_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 {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}