// Contract: BearStaking
// Target function: function onERC721Received(
Ownership(_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);
    }
}

 
// OpenZeppelin Contracts v4.4.1 (token/ERC721/IERC721Receiver.sol)
/**
 * @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);
}

 
// OpenZeppelin Contracts v4.4.1 (utils/math/SafeMath.sol)
// CAUTION
// This version of SafeMath should only be used with Solidity 0.8 or later,
// because it relies on the compiler's built in overflow checks.
/**
 * @dev Wrappers over Solidity's arithmetic operations.
 *
 * NOTE: `SafeMath` is generally not needed starting with Solidity 0.8, since the compiler
 * now has built in overflow checking.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            uint256 c = a + b;
            if (c < a) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b > a) return (false, 0);
            return (true, a - b);
        }
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) return (true, 0);
            uint256 c = a * b;
            if (c / a != b) return (false, 0);
            return (true, c);
        }
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a / b);
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        unchecked {
            if (b == 0) return (false, 0);
            return (true, a % b);
        }
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        return a + b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        return a * b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator.
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b <= a, errorMessage);
            return a - b;
        }
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a / b;
        }
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(
        uint256 a,
        uint256 b,
        string memory errorMessage
    ) internal pure returns (uint256) {
        unchecked {
            require(b > 0, errorMessage);
            return a % b;
        }
    }
}

contract BearStaking is Ownable, IERC721Receiver{
  using SafeMath for uint256;

  bytes4 private constant _ERC721_RECEIVED = 0x150b7a02;

  //StakedBear Struct
  struct StakedBear{
    address owner;
    uint256 lastClaimed;
    bool isStaked;
    bool isEmergencyOut;
    uint256 emergencyOutTime;
  }

  //event 
  event RewardClaimed(uint256 tokenID, address owner);
  event Staked(address staker, uint256 tokenID, uint256 stakedTime);
  event UnStaked(uint256 tokenID, uint256 unstakedTime);

  // token_id => StakedBear
  mapping(uint256 => StakedBear) public stakedBear;
  uint256[] public bears;

  //NFT address
  address public bearNFT = 0x838E240c0FcBd12fBfFdB327d35A32DD2E73C7ea;
  //ERC20 address
  address public honey = 0x4F0c5042A11830fEaBA227840402e2409b0FC9dC;

  //reward discription 
  uint256 public rate = 10 * 10**18;
  //reward interval
  uint256 public rewardPeroid = 1 days;

  // reward = delta * rate / peroid
  function calculateReward(uint256 _lastClaimed, uint256 _rewardEndTime) view internal returns(uint256){
    return _rewardEndTime.sub(_lastClaimed).mul(rate).div(rewardPeroid); 
  }

  function batchStakeNFT(uint256[] memory _tokenIds) external {
      for(uint256 i=0;i<_tokenIds.length;i++){
          stakeNFT(_tokenIds[i]);
      }
  }  
  function stakeNFT(uint256 _tokenId) public {
    require(!stakedBear[_tokenId].isStaked, "Staking: NFT already on staked!");
    require(IERC721(bearNFT).ownerOf(_tokenId)==msg.sender, "Staking: Not the NFT owner!");
    require(
        address(this) == IERC721(bearNFT).getApproved(_tokenId) || IERC721(bearNFT).isApprovedForAll(msg.sender, address(this)), 
        "Staking: NFT not approved for the staking address OR Staking not set as operator!"
    );
    IERC721(bearNFT).safeTransferFrom(msg.sender, address(this), _tokenId, " ");
    _stakeNFT(_tokenId);
  }

  function batchUnstakeNFT(uint256[] memory _tokenIds) external {
      for(uint256 i=0;i<_tokenIds.length;i++){
          unstakeNFT(_tokenIds[i]);
      }
  }  
  function unstakeNFT(uint256 _tokenId) public {
    require(stakedBear[_tokenId].isStaked, "Staking: NFT not on staked!");
    IERC721(bearNFT).safeTransferFrom(address(this), msg.sender, _tokenId, " ");
    claimReward(_tokenId);
    _unstakeNFT(_tokenId);
  }

  function batchUnstakeWithoutRewardNFT(uint256[] memory _tokenIds) external{
      for(uint256 i=0;i<_tokenIds.length; i++){
          unstakeWithoutRewardNFT(_tokenIds[i]);
      }
  }
  function unstakeWithoutRewardNFT(uint256 _tokenId) public {
    stakedBear[_tokenId].emergencyOutTime = block.timestamp;
    stakedBear[_tokenId].isEmergencyOut = true;
    require(stakedBear[_tokenId].isStaked, "Staking: NFT not on staked!");
    IERC721(bearNFT).safeTransferFrom(address(this), msg.sender, _tokenId, " ");
    _unstakeNFT(_tokenId);
  }

  function _stakeNFT(uint256 _tokenId) internal{
    StakedBear storage bear = stakedBear[_tokenId];
    require(!bear.isStaked, "Staking: NFT already in staking!");
    bear.isStaked = true;
    bear.owner = msg.sender;
    bear.lastClaimed = block.timestamp;
    bear.isEmergencyOut = false;
    //add bear
    bears.push(_tokenId);
    emit Staked(msg.sender, _tokenId, block.timestamp);
  }

  function _unstakeNFT(uint256 _tokenId) internal {
    StakedBear storage bear = stakedBear[_tokenId];
    require(bear.isStaked, "Staking: NFT not staked!");
    require(bear.owner == msg.sender, "Staking: Not the owner of NFT!");
    bear.isStaked = false;

    emit UnStaked(_tokenId, block.timestamp);
    //remove from bears.
    for(uint256 i=0; i<bears.length; i++){
        if(bears[i] == _tokenId){
            bears[i] = bears[bears.length-1];
            bears.pop();
            return;
        }
    }
  }

  function claimReward(uint256 _tokenId) public {
    StakedBear storage bear = stakedBear[_tokenId];
    require(bear.owner != address(0), "Staking: Bear not in staking!"); 
    require(bear.owner == msg.sender, "Staking: Not the owner of NFT!"); 
    uint256 reward = 0;
    if(bear.isEmergencyOut){
        require(bear.emergencyOutTime > bear.lastClaimed, "Staking: Already Claimed Reward!");
        reward = calculateReward(bear.lastClaimed, bear.emergencyOutTime);

    }else{
        require(bear.isStaked, "Staking: Not in staking!");
        reward = calculateReward(bear.lastClaimed, block.timestamp);
    }
    bear.lastClaimed = block.timestamp;
    //transfer honey
    IERC20(honey).transfer(msg.sender, reward);
    emit RewardClaimed(_tokenId, msg.sender);
  }

  function claimBatchReward(uint256[] memory _tokenIds) external{
    for(uint i=0; i<_tokenIds.length; i++){
      claimReward(_tokenIds[i]);
    }
  }

  function getStakedBear(address wallet)  public view returns(uint256[] memory){
      uint256[] memory stakedBears = new uint256[](bears.length);
      uint256 count=0;
      for(uint256 i=0; i<bears.length; i++){
        StakedBear memory _bear = stakedBear[bears[i]];
        if(_bear.owner==wallet && _bear.isStaked){
            stakedBears[count] = bears[i];
            count++;
        }
      }
      uint256[] memory userStakedBears = new uint256[](count);
      for(uint256 i=0; i<count; i++){
          userStakedBears[i] = stakedBears[i];
      }
      return userStakedBears;
  }

  function getClaimableToken(address wallet) external view returns(uint256){
      uint256[] memory stakedBears = getStakedBear(wallet);
      uint256 reward = 0;
      for(uint256 i=0; i<stakedBears.length; i++){
          if(stakedBear[stakedBears[i]].isEmergencyOut)
            reward += calculateReward(stakedBear[stakedBears[i]].lastClaimed, stakedBear[stakedBears[i]].emergencyOutTime);
          else
            reward += calculateReward(stakedBear[stakedBears[i]].lastClaimed, block.timestamp);
      }
      return reward;
  }

  function getTotalStakedBears() external view returns(uint256){
      return bears.length;
  }
  
  //----------- Rescue Ether and tokens ------------//
  function withdraw() external payable onlyOwner {
    (bool os, ) = payable(owner()).call{value: address(this).balance}("");
    require(os);
  }

  function withdrawToken(uint256 amount) external onlyOwner{
    IERC20(honey).transfer(msg.sender, amount);
  }


  //------ Callbacks -------------------//