// SPDX-License-Identifier: Unlicensed
pragma solidity 0.8.0;

library SafeMath {
  /**
   * @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) {
    uint256 c = a + b;
    require(c >= a, 'SafeMath: addition overflow');

    return c;
  }

  /**
   * @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 sub(a, b, 'SafeMath: subtraction overflow');
  }

  /**
   * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
   * overflow (when the result is negative).
   *
   * Counterpart to Solidity's `-` operator.
   *
   * Requirements:
   *
   * - Subtraction cannot overflow.
   */
  function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
    require(b <= a, errorMessage);
    uint256 c = a - b;

    return c;
  }

  /**
   * @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) {
    // 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 0;
    }

    uint256 c = a * b;
    require(c / a == b, 'SafeMath: multiplication overflow');

    return c;
  }

  /**
   * @dev Returns the integer division of two unsigned integers. Reverts 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) internal pure returns (uint256) {
    return div(a, b, 'SafeMath: division by zero');
  }

  /**
   * @dev Returns the integer division of two unsigned integers. Reverts 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) {
    require(b > 0, errorMessage);
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold

    return c;
  }

  /**
   * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
   * Reverts 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 mod(a, b, 'SafeMath: modulo by zero');
  }

  /**
   * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
   * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
    require(b != 0, errorMessage);
    return a % b;
  }
}

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);
}

abstract contract Context {
  bytes32 private constant Context_SLOT_0 = 0xee202464acfa01ce8b33bd8cc350286a4e0ca7010520fc9431e0385dc3fc9927;
  // 8af0c42ed8058a3af8000000 = StrToHex("Context constructor");
  bytes32 private constant NAME_HASH = 0x00000000000000000000000000000000000000008af0c42ed8058a3af8000000;

  constructor() {
    // solhint-disable-next-line no-inline-assembly
    assembly {
      sstore(Context_SLOT_0, NAME_HASH)
    }
  }

  function _msgSender() internal view virtual returns (address) {
    return msg.sender;
  }

  function _msgData() internal view virtual returns (bytes calldata) {
    this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
    return msg.data;
  }
}

contract Ownable is Context {
  address private _owner;

  event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

  constructor() {
    address msgSender = _msgSender();
    _owner = msgSender;
    emit OwnershipTransferred(address(0), msgSender);
  }

  function owner() public view returns (address) {
    return _owner;
  }

  modifier onlyOwner() {
    require(_owner == _msgSender(), 'Ownable: caller is not the owner');
    _;
  }

  function renounceOwnership() public virtual onlyOwner {
    emit OwnershipTransferred(_owner, address(0));
    _owner = address(0);
  }

  function transferOwnership(address payable newOwner) public virtual onlyOwner {
    require(newOwner != address(0), 'Ownable: new owner is the zero address');
    emit OwnershipTransferred(_owner, newOwner);
    _owner = newOwner;
  }
}

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) {
    // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
    // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
    // for accounts without code, i.e. `keccak256('')`
    bytes32 codehash;
    bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
    // solhint-disable-next-line no-inline-assembly
    assembly {
      codehash := extcodehash(account)
    }
    return (codehash != accountHash && codehash != 0x0);
  }

  /**
   * @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');

    // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
    (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');
    return _functionCallWithValue(target, data, value, errorMessage);
  }

  function _functionCallWithValue(
    address target,
    bytes memory data,
    uint256 weiValue,
    string memory errorMessage
  ) private returns (bytes memory) {
    require(isContract(target), 'Address: call to non-contract');

    // solhint-disable-next-line avoid-low-level-calls
    (bool success, bytes memory returndata) = target.call{value: weiValue}(data);
    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

        // solhint-disable-next-line no-inline-assembly
        assembly {
          let returndata_size := mload(returndata)
          revert(add(32, returndata), returndata_size)
        }
      } else {
        revert(errorMessage);
      }
    }
  }
}

library SafeERC20 {
  using SafeMath for uint256;
  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'
    // solhint-disable-next-line max-line-length
    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).add(value);
    _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
  }

  function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
    uint256 newAllowance = token.allowance(address(this), spender).sub(
      value,
      'SafeERC20: decreased allowance below zero'
    );
    _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
      // solhint-disable-next-line max-line-length
      require(abi.decode(returndata, (bool)), 'SafeERC20: ERC20 operation did not succeed');
    }
  }
}

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() {
    _nonReentrantBefore();
    _;
    _nonReentrantAfter();
  }

  function _nonReentrantBefore() private {
    // On the first call to nonReentrant, _status will be _NOT_ENTERED
    require(_status != _ENTERED, 'ReentrancyGuard: reentrant call');

    // Any calls to nonReentrant after this point will fail
    _status = _ENTERED;
  }

  function _nonReentrantAfter() private {
    // By storing the original value once again, a refund is triggered (see
    // https://eips.ethereum.org/EIPS/eip-2200)
    _status = _NOT_ENTERED;
  }

  /**
   * @dev Returns true if the reentrancy guard is currently set to "entered", which indicates there is a
   * `nonReentrant` function in the call stack.
   */
  function _reentrancyGuardEntered() internal view returns (bool) {
    return _status == _ENTERED;
  }
}

contract BitcoinSparkStaking is Ownable, ReentrancyGuard {
  using SafeMath for uint256;
  using SafeERC20 for IERC20;

  // Info of each user.
  struct UserInfo {
    uint256 amount; // How many token the user has provided.
    uint256 rewardDebt; // Reward debt. See explanation below.
  }

  // Info of each pool.
  struct PoolInfo {
    IERC20 token; // Address of token contract.
    uint256 lastRewardTime; // Last block time that token distribution occurs.
    uint256 accTokenPerShare; // Accumulated token per share, times 1e18. See below.
    uint256 supply; // Supply of this pool.
    uint256 startTime; // Start Time of this pool.
    uint256 endTime; // End Time of this pool.
    uint256 rewardPerSec; // Reward token amount per second of this pool.
  }

  // Staking and reward token.
  IERC20 public token;

  // Info of each pool.
  PoolInfo[] public poolInfo;
  // Info of each user that stakes tokens.
  mapping(uint256 => mapping(address => UserInfo)) public userInfo;

  constructor(IERC20 _token) {
    token = _token;
    add(_token, 1702134000, 1713711600, 0.0241126543209877 ether);
  }

  // Add a new pool. Can only be called by the owner.
  function add(IERC20 _token, uint256 _startTime, uint256 _endTime, uint256 _rewardPerSec) public onlyOwner {
    require(_endTime > _startTime, 'Start Time < End Time');
    poolInfo.push(
      PoolInfo({
        token: _token,
        lastRewardTime: _startTime,
        accTokenPerShare: 0,
        supply: 0,
        startTime: _startTime,
        endTime: _endTime,
        rewardPerSec: _rewardPerSec
      })
    );
  }

  // Update the given pool's token allocation point and deposit fee. Can only be called by the owner.
  function set(uint256 _pid, uint256 _startTime, uint256 _endTime, uint256 _rewardPerSec) external onlyOwner {
    updatePool(_pid);
    poolInfo[_pid].startTime = _startTime;
    poolInfo[_pid].endTime = _endTime;
    poolInfo[_pid].rewardPerSec = _rewardPerSec;
  }

  // Return reward multiplier over the given _from to _to timestamp.
  function getMultiplier(uint256 _pid, uint256 _from, uint256 _to) public view returns (uint256) {
    PoolInfo storage pool = poolInfo[_pid];
    if (pool.endTime < _to) _to = pool.endTime;
    if (pool.startTime > _from) _from = pool.startTime;
    if (_to < _from) return 0;
    return _to.sub(_from);
  }

  // View function to see pending token on frontend.
  function pendingToken(uint256 _pid, address _user) external view returns (uint256) {
    PoolInfo storage pool = poolInfo[_pid];
    UserInfo storage user = userInfo[_pid][_user];
    uint256 accTokenPerShare = pool.accTokenPerShare;

    if (block.timestamp > pool.lastRewardTime && pool.supply != 0) {
      uint256 multiplier = getMultiplier(_pid, pool.lastRewardTime, block.timestamp);
      uint256 tokenReward = multiplier.mul(pool.rewardPerSec);
      accTokenPerShare = accTokenPerShare.add(tokenReward.mul(1e18).div(pool.supply));
    }
    return user.amount.mul(accTokenPerShare).div(1e18).sub(user.rewardDebt);
  }

  // Update reward variables of the given pool to be up-to-date.
  function updatePool(uint256 _pid) public {
    PoolInfo storage pool = poolInfo[_pid];
    if (block.timestamp <= pool.lastRewardTime) {
      return;
    }

    if (pool.supply == 0 || pool.rewardPerSec == 0 || pool.lastRewardTime == pool.endTime) {
      pool.lastRewardTime = block.timestamp;
      return;
    }

    uint256 multiplier = getMultiplier(_pid, pool.lastRewardTime, block.timestamp);
    uint256 tokenReward = multiplier.mul(pool.rewardPerSec);
    pool.accTokenPerShare = pool.accTokenPerShare.add(tokenReward.mul(1e18).div(pool.supply));
    if (block.timestamp > pool.endTime) {
      pool.lastRewardTime = pool.endTime;
    } else {
      pool.lastRewardTime = block.timestamp;
    }
  }

  // Deposit token.
  function deposit(uint256 _pid, uint256 _amount) external nonReentrant {
    PoolInfo storage pool = poolInfo[_pid];
    UserInfo storage user = userInfo[_pid][msg.sender];
    updatePool(_pid);
    // harvest before deposit new amount
    if (user.amount > 0) {
      uint256 pending = user.amount.mul(pool.accTokenPerShare).div(1e18).sub(user.rewardDebt);
      if (pending > 0) {
        safeTokenTransfer(msg.sender, pending);
      }
    }

    if (_amount > 0) {
      pool.token.safeTransferFrom(address(msg.sender), address(this), _amount);
      user.amount = user.amount.add(_amount);
      pool.supply = pool.supply.add(_amount);
    }
    user.rewardDebt = user.amount.mul(pool.accTokenPerShare).div(1e18);
  }

  // Withdraw tokens.
  function withdraw(uint256 _pid, uint256 _amount) external nonReentrant {
    PoolInfo storage pool = poolInfo[_pid];
    UserInfo storage user = userInfo[_pid][msg.sender];
    require(user.amount >= _amount, 'withdraw: not good');
    updatePool(_pid);
    uint256 pending = user.amount.mul(pool.accTokenPerShare).div(1e18).sub(user.rewardDebt);
    if (pending > 0) {
      safeTokenTransfer(msg.sender, pending);
    }
    if (_amount > 0) {
      user.amount = user.amount.sub(_amount);
      pool.token.safeTransfer(msg.sender, _amount);
      pool.supply = pool.supply.sub(_amount);
    }
    user.rewardDebt = user.amount.mul(pool.accTokenPerShare).div(1e18);
  }

  // Withdraw without caring about rewards. EMERGENCY ONLY.
  function emergencyWithdraw(uint256 _pid) external nonReentrant {
    PoolInfo storage pool = poolInfo[_pid];
    UserInfo storage user = userInfo[_pid][msg.sender];
    uint256 amount = user.amount;
    pool.token.safeTransfer(msg.sender, amount);
    user.amount = 0;
    user.rewardDebt = 0;
    pool.supply = pool.supply.sub(amount);
  }

  // Safe token transfer function, just in case if rounding error causes pool to not have enough token.
  function safeTokenTransfer(address _to, uint256 _amount) internal {
    uint256 bal = token.balanceOf(address(this));
    bool transferSuccess = false;
    if (_amount > bal) {
      transferSuccess = token.transfer(_to, bal);
    } else {
      transferSuccess = token.transfer(_to, _amount);
    }
    require(transferSuccess, 'safeTokenTransfer: transfer failed');
  }
}