// File: contracts/others/BaltoNftStaking.sol



// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

/**
 * @author Brewlabs
 * This contract has been developed by brewlabs.info
 */
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";
import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";

contract BaltoNftStaking is Ownable, IERC721Receiver, ReentrancyGuard {
    using SafeERC20 for IERC20;

    bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;
    uint256 private constant BLOCKS_PER_DAY = 6426;
    uint256 private PRECISION_FACTOR;

    // Whether it is initialized
    bool public isInitialized;
    uint256 public duration = 365; // 365 days

    // The block number when staking starts.
    uint256 public startBlock;
    // The block number when staking ends.
    uint256 public bonusEndBlock;
    // tokens created per block.
    uint256[2] public rewardsPerBlock;
    // The block number of the last pool update
    uint256 public lastRewardBlock;

    address public treasury = 0x64961Ffd0d84b2355eC2B5d35B0d8D8825A774dc;
    uint256 public performanceFee = 0.00089 ether;

    // The staked token
    IERC721 public stakingNft;
    // The earned token
    address[2] public earnedTokens;
    // Accrued token per share
    uint256[2] public accTokenPerShares;
    uint256 public oneTimeLimit = 40;

    uint256 public totalStaked;
    uint256[2] private paidRewards;
    uint256[2] private shouldTotalPaid;

    struct UserInfo {
        uint256 amount; // number of staked NFTs
        uint256[] tokenIds; // staked tokenIds
        uint256[2] rewardDebt; // Reward debt
    }
    // Info of each user that stakes tokenIds

    mapping(address => UserInfo) public userInfo;

    event Deposit(address indexed user, uint256[] tokenIds);
    event Withdraw(address indexed user, uint256[] tokenIds);
    event Claim(address indexed user, address indexed token, uint256 amount);
    event EmergencyWithdraw(address indexed user, uint256[] tokenIds);
    event AdminTokenRecovered(address tokenRecovered, uint256 amount);

    event NewStartAndEndBlocks(uint256 startBlock, uint256 endBlock);
    event NewRewardsPerBlock(uint256[2] rewardsPerBlock);
    event RewardsStop(uint256 blockNumber);
    event EndBlockUpdated(uint256 blockNumber);

    event ServiceInfoUpadted(address _addr, uint256 _fee);
    event DurationUpdated(uint256 _duration);

    constructor() {}

    /*
    * @notice Initialize the contract
    * @param _stakingNft: nft address to stake
    * @param _earnedToken: earned token address
    * @param _rewardsPerBlock: reward per block (in earnedToken)
    */
    function initialize(IERC721 _stakingNft, address[2] memory _earnedTokens, uint256[2] memory _rewardsPerBlock)
        external
        onlyOwner
    {
        require(!isInitialized, "Already initialized");

        // Make this contract initialized
        isInitialized = true;

        stakingNft = _stakingNft;
        earnedTokens = _earnedTokens;
        rewardsPerBlock = _rewardsPerBlock;

        PRECISION_FACTOR = uint256(10 ** 30);
    }

    /*
    * @notice Deposit staked tokens and collect reward tokens (if any)
    * @param _amount: amount to withdraw (in earnedToken)
    */
    function deposit(uint256[] memory _tokenIds) external payable nonReentrant {
        require(startBlock > 0 && startBlock < block.number, "Staking hasn't started yet");
        require(_tokenIds.length > 0, "must add at least one tokenId");
        require(_tokenIds.length <= oneTimeLimit, "cannot exceed one-time limit");

        _transferPerformanceFee();
        _updatePool();

        UserInfo storage user = userInfo[msg.sender];
        if (user.amount > 0) {
            _transferRewards(msg.sender, 0);
            _transferRewards(msg.sender, 1);
        }

        for (uint256 i = 0; i < _tokenIds.length; i++) {
            uint256 tokenId = _tokenIds[i];
            stakingNft.safeTransferFrom(msg.sender, address(this), tokenId);
            user.tokenIds.push(tokenId);
        }
        user.amount = user.amount + _tokenIds.length;
        user.rewardDebt[0] = (user.amount * accTokenPerShares[0]) / PRECISION_FACTOR;
        user.rewardDebt[1] = (user.amount * accTokenPerShares[1]) / PRECISION_FACTOR;

        totalStaked = totalStaked + _tokenIds.length;
        emit Deposit(msg.sender, _tokenIds);

        // update rate for second rewards
        uint256 remainRewards = address(this).balance;
        if (earnedTokens[1] != address(0x0)) {
            remainRewards = IERC20(earnedTokens[1]).balanceOf(address(this));
        }
        remainRewards += paidRewards[1];
        if (remainRewards > shouldTotalPaid[1]) {
            remainRewards = remainRewards - shouldTotalPaid[1];

            uint256 remainBlocks = bonusEndBlock - block.number;
            rewardsPerBlock[1] = remainRewards / remainBlocks;
            emit NewRewardsPerBlock(rewardsPerBlock);
        }
    }

    /*
    * @notice Withdraw staked tokenIds and collect reward tokens
    * @param _amount: number of tokenIds to unstake
    */
    function withdraw(uint256 _amount) external payable nonReentrant {
        require(_amount > 0, "Amount should be greator than 0");
        require(_amount <= oneTimeLimit, "cannot exceed one-time limit");

        UserInfo storage user = userInfo[msg.sender];
        require(user.amount >= _amount, "Amount to withdraw too high");

        _transferPerformanceFee();
        _updatePool();

        if (user.amount > 0) {
            _transferRewards(msg.sender, 0);
            _transferRewards(msg.sender, 1);
        }

        uint256[] memory _tokenIds = new uint256[](_amount);
        for (uint256 i = 0; i < _amount; i++) {
            uint256 tokenId = user.tokenIds[user.tokenIds.length - 1];
            user.tokenIds.pop();

            _tokenIds[i] = tokenId;
            stakingNft.safeTransferFrom(address(this), msg.sender, tokenId);
        }
        user.amount = user.amount - _amount;
        user.rewardDebt[0] = (user.amount * accTokenPerShares[0]) / PRECISION_FACTOR;
        user.rewardDebt[1] = (user.amount * accTokenPerShares[1]) / PRECISION_FACTOR;

        totalStaked = totalStaked - _amount;
        emit Withdraw(msg.sender, _tokenIds);
    }

    function claimReward(uint8 _index) external payable nonReentrant {
        UserInfo storage user = userInfo[msg.sender];

        _transferPerformanceFee();
        _updatePool();

        if (user.amount == 0) return;

        _transferRewards(msg.sender, _index);

        user.rewardDebt[_index] = (user.amount * accTokenPerShares[_index]) / PRECISION_FACTOR;
    }

    function claimRewardAll() external payable nonReentrant {
        _transferPerformanceFee();
        _updatePool();

        if (userInfo[msg.sender].amount == 0) return;

        _transferRewards(msg.sender, 0);
        _transferRewards(msg.sender, 1);

        UserInfo storage user = userInfo[msg.sender];
        user.rewardDebt[0] = (user.amount * accTokenPerShares[0]) / PRECISION_FACTOR;
        user.rewardDebt[1] = (user.amount * accTokenPerShares[1]) / PRECISION_FACTOR;
    }

    function _transferRewards(address _user, uint8 _index) internal {
        UserInfo memory user = userInfo[_user];
        uint256 pending = (user.amount * accTokenPerShares[_index]) / PRECISION_FACTOR - user.rewardDebt[_index];
        if (pending == 0) return;

        require(availableRewardTokens(_index) >= pending, "Insufficient reward tokens");
        paidRewards[_index] += pending;

        if (earnedTokens[_index] == address(0x0)) {
            payable(_user).transfer(pending);
        } else {
            IERC20(earnedTokens[_index]).safeTransfer(_user, pending);
        }

        emit Claim(_user, earnedTokens[_index], pending);
    }

    /*
    * @notice Withdraw staked NFTs without caring about rewards
    * @dev Needs to be for emergency.
    */
    function emergencyWithdraw() external nonReentrant {
        UserInfo storage user = userInfo[msg.sender];
        uint256 _amount = user.amount;
        if (_amount > oneTimeLimit) _amount = oneTimeLimit;

        uint256[] memory _tokenIds = new uint256[](_amount);
        for (uint256 i = 0; i < _amount; i++) {
            uint256 tokenId = user.tokenIds[user.tokenIds.length - 1];
            user.tokenIds.pop();

            _tokenIds[i] = tokenId;
            stakingNft.safeTransferFrom(address(this), msg.sender, tokenId);
        }
        user.amount = user.amount - _amount;
        user.rewardDebt[0] = (user.amount * accTokenPerShares[0]) / PRECISION_FACTOR;
        user.rewardDebt[1] = (user.amount * accTokenPerShares[1]) / PRECISION_FACTOR;
        totalStaked = totalStaked - _amount;

        emit EmergencyWithdraw(msg.sender, _tokenIds);
    }

    function stakedInfo(address _user) external view returns (uint256, uint256[] memory) {
        return (userInfo[_user].amount, userInfo[_user].tokenIds);
    }

    /**
     * @notice Available amount of reward token
     */
    function availableRewardTokens(uint8 _index) public view returns (uint256) {
        if (earnedTokens[_index] == address(0x0)) return address(this).balance;
        return IERC20(earnedTokens[_index]).balanceOf(address(this));
    }

    function insufficientRewards() external view returns (uint256) {
        uint256 adjustedShouldTotalPaid = shouldTotalPaid[0];
        uint256 remainRewards = availableRewardTokens(0) + paidRewards[0];

        if (startBlock == 0) {
            adjustedShouldTotalPaid += rewardsPerBlock[0] * duration * BLOCKS_PER_DAY;
        } else {
            uint256 remainBlocks = _getMultiplier(lastRewardBlock, bonusEndBlock);
            adjustedShouldTotalPaid += rewardsPerBlock[0] * remainBlocks;
        }

        if (remainRewards >= adjustedShouldTotalPaid) return 0;
        return adjustedShouldTotalPaid - remainRewards;
    }

    /*
    * @notice View function to see pending reward on frontend.
    * @param _user: user address
    * @param _index: index of earning token (0 - earning token, 1 - eth) 
    * @return Pending reward for a given user
    */
    function pendingReward(address _user, uint8 _index) external view returns (uint256) {
        UserInfo storage user = userInfo[_user];

        uint256 adjustedTokenPerShare = accTokenPerShares[_index];
        if (block.number > lastRewardBlock && totalStaked > 0 && lastRewardBlock > 0) {
            uint256 multiplier = _getMultiplier(lastRewardBlock, block.number);
            uint256 rewards = multiplier * rewardsPerBlock[_index];

            adjustedTokenPerShare += (rewards * PRECISION_FACTOR) / totalStaked;
        }

        return (user.amount * adjustedTokenPerShare) / PRECISION_FACTOR - user.rewardDebt[_index];
    }

    /**
     * Admin Methods
     */
    function increaseEmissionRate(uint256 _amount) external onlyOwner {
        require(startBlock > 0, "pool is not started");
        require(bonusEndBlock > block.number, "pool was already finished");
        require(_amount > 0, "invalid amount");

        _updatePool();

        IERC20(earnedTokens[0]).safeTransferFrom(msg.sender, address(this), _amount);

        uint256 remainRewards = availableRewardTokens(0) + paidRewards[0];
        if (remainRewards > shouldTotalPaid[0]) {
            remainRewards = remainRewards - shouldTotalPaid[0];

            uint256 remainBlocks = bonusEndBlock - block.number;
            rewardsPerBlock[0] = remainRewards / remainBlocks;
            emit NewRewardsPerBlock(rewardsPerBlock);
        }
    }

    /*
    * @notice Withdraw reward token
    * @dev Only callable by owner. Needs to be for emergency.
    */
    function emergencyRewardWithdraw(uint256 _amount, uint8 _index) external onlyOwner {
        require(block.number > bonusEndBlock, "Pool is running");
        if (_index == 0) {
            require(availableRewardTokens(0) >= _amount, "Insufficient reward tokens");
            if (_amount == 0) _amount = availableRewardTokens(0);
            IERC20(earnedTokens[0]).safeTransfer(address(msg.sender), _amount);
        } else {
            if (earnedTokens[1] == address(0x0)) {
                payable(msg.sender).transfer(address(this).balance);
            } else {
                IERC20(earnedTokens[1]).safeTransfer(msg.sender, IERC20(earnedTokens[1]).balanceOf(address(this)));
            }
        }
    }

    function startReward() external onlyOwner {
        require(startBlock == 0, "Pool was already started");

        startBlock = block.number + 100;
        bonusEndBlock = startBlock + duration * BLOCKS_PER_DAY;
        lastRewardBlock = startBlock;

        emit NewStartAndEndBlocks(startBlock, bonusEndBlock);
    }

    function stopReward() external onlyOwner {
        _updatePool();

        uint256 remainRewards = availableRewardTokens(0) + paidRewards[0];
        if (remainRewards > shouldTotalPaid[0]) {
            remainRewards = remainRewards - shouldTotalPaid[0];
            IERC20(earnedTokens[0]).transfer(msg.sender, remainRewards);
        }

        remainRewards = address(this).balance;
        if (earnedTokens[1] != address(0x0)) {
            remainRewards = IERC20(earnedTokens[1]).balanceOf(address(this));
        }

        remainRewards += paidRewards[1];
        if (remainRewards > shouldTotalPaid[1]) {
            remainRewards = remainRewards - shouldTotalPaid[1];

            if (earnedTokens[1] == address(0x0)) {
                payable(msg.sender).transfer(remainRewards);
            } else {
                IERC20(earnedTokens[1]).safeTransfer(msg.sender, remainRewards);
            }
        }

        bonusEndBlock = block.number;
        emit RewardsStop(bonusEndBlock);
    }

    function updateEndBlock(uint256 _endBlock) external onlyOwner {
        require(startBlock > 0, "Pool is not started");
        require(bonusEndBlock > block.number, "Pool was already finished");
        require(_endBlock > block.number && _endBlock > startBlock, "Invalid end block");

        bonusEndBlock = _endBlock;
        emit EndBlockUpdated(_endBlock);
    }

    /*
    * @notice Update reward per block
    * @dev Only callable by owner.
    * @param _rewardsPerBlock: the reward per block
    * @param _index: index of reward token
    */
    function updateRewardsPerBlock(uint256 _rewardsPerBlock, uint8 _index) external onlyOwner {
        _updatePool();
        rewardsPerBlock[_index] = _rewardsPerBlock;
        emit NewRewardsPerBlock(rewardsPerBlock);
    }

    function setDuration(uint256 _duration) external onlyOwner {
        require(_duration >= 30, "lower limit reached");

        _updatePool();
        duration = _duration;
        if (startBlock > 0) {
            bonusEndBlock = startBlock + duration * BLOCKS_PER_DAY;
            require(bonusEndBlock > block.number, "invalid duration");
        }
        emit DurationUpdated(_duration);
    }

    function setServiceInfo(address _treasury, uint256 _fee) external {
        require(msg.sender == treasury, "setServiceInfo: FORBIDDEN");
        require(_treasury != address(0x0), "Invalid address");

        treasury = _treasury;
        performanceFee = _fee;
        emit ServiceInfoUpadted(_treasury, _fee);
    }

    /**
     * @notice It allows the admin to recover wrong tokens sent to the contract
     * @param _token: the address of the token to withdraw
     * @dev This function is only callable by admin.
     */
    function rescueTokens(address _token) external onlyOwner {
        require(_token != address(earnedTokens[0]), "Cannot be reward token");
        require(_token != address(earnedTokens[1]), "Cannot be reward token");

        uint256 amount = address(this).balance;
        if (_token == address(0x0)) {
            payable(msg.sender).transfer(amount);
        } else {
            amount = IERC20(_token).balanceOf(address(this));
            IERC20(_token).safeTransfer(address(msg.sender), amount);
        }

        emit AdminTokenRecovered(_token, amount);
    }

    /**
     * Internal Methods
     */
    /*
    * @notice Update reward variables of the given pool to be up-to-date.
    */
    function _updatePool() internal {
        if (block.number <= lastRewardBlock || lastRewardBlock == 0) return;
        if (totalStaked == 0) {
            lastRewardBlock = block.number;
            return;
        }

        uint256 multiplier = _getMultiplier(lastRewardBlock, block.number);
        uint256 _reward = multiplier * rewardsPerBlock[0];
        accTokenPerShares[0] += (_reward * PRECISION_FACTOR) / totalStaked;
        shouldTotalPaid[0] += _reward;

        _reward = multiplier * rewardsPerBlock[1];
        accTokenPerShares[1] += (_reward * PRECISION_FACTOR) / totalStaked;
        shouldTotalPaid[1] += _reward;

        lastRewardBlock = block.number;
    }

    /*
    * @notice Return reward multiplier over the given _from to _to block.
    * @param _from: block to start
    * @param _to: block to finish
    */
    function _getMultiplier(uint256 _from, uint256 _to) internal view returns (uint256) {
        if (_to <= bonusEndBlock) {
            return _to - _from;
        } else if (_from >= bonusEndBlock) {
            return 0;
        } else {
            return bonusEndBlock - _from;
        }
    }

    function _transferPerformanceFee() internal {
        require(msg.value >= performanceFee, "should pay small gas");

        payable(treasury).transfer(performanceFee);
        if (msg.value > performanceFee) {
            payable(msg.sender).transfer(msg.value - performanceFee);
        }
    }

    /**
     * onERC721Received(address operator, address from, uint256 tokenId, bytes data) → bytes4
     * 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.
     */
    function onERC721Received(address, address, uint256, bytes calldata) external view override returns (bytes4) {
        require(msg.sender == address(stakingNft), "not enabled NFT");
        return _ERC721_RECEIVED;
    }

    receive() external payable {}
}

// 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);
    }
}

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



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (security/ReentrancyGuard.sol)

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 making 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/ERC20/extensions/IERC20Metadata.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";

/**
 * @dev Interface for the optional metadata functions from the ERC20 standard.
 *
 * _Available since v4.1._
 */
interface IERC20Metadata is IERC20 {
    /**
     * @dev Returns the name of the token.
     */
    function name() external view returns (string memory);

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

    /**
     * @dev Returns the decimals places of the token.
     */
    function decimals() external view returns (uint8);
}

// 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/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/ERC20/utils/SafeERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)

pragma solidity ^0.8.0;

import "../IERC20.sol";
import "../../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using Address for address;

    function safeTransfer(
        IERC20 token,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 value
    ) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        require(
            (value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        uint256 newAllowance = token.allowance(address(this), spender) + value;
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(
        IERC20 token,
        address spender,
        uint256 value
    ) internal {
        unchecked {
            uint256 oldAllowance = token.allowance(address(this), spender);
            require(oldAllowance >= value, "SafeERC20: decreased allowance below zero");
            uint256 newAllowance = oldAllowance - value;
            _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
        }
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) {
            // Return data is optional
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}

// 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/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (token/ERC20/IERC20.sol)

pragma solidity ^0.8.0;

/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

// 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/Address.sol



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

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);
            }
        }
    }
}