// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
pragma experimental ABIEncoderV2;
import "./libraries/BoringMath.sol";
import "./libraries/SignedSafeMath.sol";
import "./libraries/BoringERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
/************************************************************************************************
Originally from
https://github.com/sushiswap/sushiswap/blob/master/contracts/MasterChefV2.sol
and
https://github.com/sdaoswap/sushiswap/blob/master/contracts/MasterChef.sol
This source code has been modified from the original, which was copied from the github repository
at commit hash 10148a31d9192bc803dac5d24fe0319b52ae99a4.
*************************************************************************************************/
contract SDAOTokenStaking is Ownable,ReentrancyGuard {
  using BoringMath for uint256;
  using BoringERC20 for IERC20;
  using SignedSafeMath for int256;
  //==========  Structs  ==========
  
  /// @dev Info of each user.
  /// @param amount LP token amount the user has provided.
  /// @param rewardDebt The amount of rewards entitled to the user.
  struct UserInfo {
    uint256 amount;
    int256 rewardDebt;
  }
  /// @dev Info of each rewards pool.
  /// @param tokenPerBlock Reward tokens per block number.
  /// @param lpSupply Total staked amount.
  /// @param accRewardsPerShare Total rewards accumulated per staked token.
  /// @param lastRewardBlock Last time rewards were updated for the pool.
  /// @param endOfEpochBlock End of epoc block number for compute and to avoid deposits.
  struct PoolInfo {
    uint256 tokenPerBlock;
    uint256 lpSupply;
    uint256 accRewardsPerShare;
    uint256 lastRewardBlock;
    uint256 endOfEpochBlock;
  }
  //==========  Constants  ==========
  /// @dev For percision calculation while computing the rewards.
  uint256 private constant ACC_REWARDS_PRECISION = 1e18;
  /// @dev ERC20 token used to distribute rewards.   
  IERC20 public immutable rewardsToken;
  /** ==========  Storage  ========== */
  /// @dev Indicates whether a staking pool exists for a given staking token.
  //mapping(address => bool) public stakingPoolExists;
  
  /// @dev Info of each staking pool.
  PoolInfo[] public poolInfo;
  
  /// @dev Address of the LP token for each staking pool.
  mapping(uint256 => IERC20) public lpToken;
  
  /// @dev Info of each user that stakes tokens.
  mapping(uint256 => mapping(address => UserInfo)) public userInfo;
  /// @dev Total rewards received from governance for distribution.
  /// Used to return remaining rewards if staking is canceled.
  uint256 public totalRewardsReceived;
  // ==========  Events  ==========
  event Deposit(address indexed user, uint256 indexed pid, uint256 amount, address indexed to);
  event Withdraw(address indexed user, uint256 indexed pid, uint256 amount, address indexed to);
  event EmergencyWithdraw(address indexed user, uint256 indexed pid, uint256 amount, address indexed to);
  event Harvest(address indexed user, uint256 indexed pid, uint256 amount);
  event LogPoolAddition(uint256 indexed pid, IERC20 indexed lpToken);
  event LogUpdatePool(uint256 indexed pid, uint256 lastRewardBlock, uint256 lpSupply, uint256 accRewardsPerShare);
  event RewardsAdded(uint256 amount);
  event ExtendPool(uint256 indexed pid, uint256 rewardBlock, uint256 endOfEpochBlock);
  // ==========  Constructor  ==========
  /// @dev During the deployment of the contract pass the ERC-20 contract address used for rewards.
  constructor(address _rewardsToken) public {
    rewardsToken = IERC20(_rewardsToken);
  }
  /// @dev Add rewards to be distributed.
  /// Note: This function must be used to add rewards if the owner
  /// wants to retain the option to cancel distribution and reclaim
  /// undistributed tokens.  
  function addRewards(uint256 amount) external onlyOwner {
    
    require(rewardsToken.balanceOf(msg.sender) > 0, "ERC20: not enough tokens to transfer");
    totalRewardsReceived = totalRewardsReceived.add(amount);
    rewardsToken.safeTransferFrom(msg.sender, address(this), amount);
    
    emit RewardsAdded(amount);
  }
  // ==========  Pools  ==========
  
  /// @dev Add a new LP to the pool.
  /// Can only be called by the owner or the points allocator.
  /// @param _lpToken Address of the LP ERC-20 token.
  /// @param _sdaoPerBlock Rewards per block.
  /// @param _endOfEpochBlock Epocs end block number.
  function add(IERC20 _lpToken, uint256 _sdaoPerBlock, uint256 _endOfEpochBlock) public onlyOwner {
    //This is not needed as we are going to use the contract for multiple pools with the same LP Tokens
    //require(!stakingPoolExists[address(_lpToken)], " Staking pool already exists.");
    
    require(_endOfEpochBlock > block.number, "Cannot create the pool for past time.");
    uint256 pid = poolInfo.length;
    lpToken[pid] = _lpToken;
    poolInfo.push(PoolInfo({
      tokenPerBlock: _sdaoPerBlock,
      endOfEpochBlock:_endOfEpochBlock,
      lastRewardBlock: block.number,
      lpSupply:0,
      accRewardsPerShare: 0
    }));
    //stakingPoolExists[address(_lpToken)] = true;
    emit LogPoolAddition(pid, _lpToken);
  }
  /// @dev Add a new LP to the pool.
  /// Can only be called by the owner or the points allocator.
  /// @param _pid Pool Id to extend the schedule.
  /// @param _sdaoPerBlock Rewards per block.
  /// @param _endOfEpochBlock Epocs end block number.
  function extendPool(uint256 _pid, uint256 _sdaoPerBlock, uint256 _endOfEpochBlock) public onlyOwner {
    
    require(_endOfEpochBlock > block.number && _endOfEpochBlock > poolInfo[_pid].endOfEpochBlock, "Cannot extend the pool for past time.");
    // Update the accumulated rewards
    PoolInfo memory pool = updatePool(_pid);
    pool.tokenPerBlock = _sdaoPerBlock;
    pool.endOfEpochBlock = _endOfEpochBlock;
    pool.lastRewardBlock = block.number;
    // Update the Pool Storage
    poolInfo[_pid] = pool;
    emit ExtendPool(_pid, _sdaoPerBlock, _endOfEpochBlock);
  }
  /// @dev To get the rewards per block.
  function sdaoPerBlock(uint256 _pid) public view returns (uint256 amount) {
      PoolInfo memory pool = poolInfo[_pid];
      amount = pool.tokenPerBlock;
  }
  /// @dev Update reward variables for all pools in `pids`.
  /// Note: This can become very expensive.
  /// @param pids Pool IDs of all to be updated. Make sure to update all active pools.
  function massUpdatePools(uint256[] calldata pids) external onlyOwner {
    uint256 len = pids.length;
    for (uint256 i = 0; i < len; ++i) {
      updatePool(pids[i]);
    }
  }
  /// @dev Update reward variables of the given pool.
  /// @param _pid The index of the pool. See `poolInfo`.
  /// @return pool Returns the pool that was updated.
 function updatePool(uint256 _pid) private returns (PoolInfo memory pool) {
    pool = poolInfo[_pid];
    uint256 lpSupply = pool.lpSupply;
    if (block.number > pool.lastRewardBlock && pool.lastRewardBlock < pool.endOfEpochBlock) {
       if(lpSupply > 0){
         
           uint256 blocks;
           if(block.number < pool.endOfEpochBlock) {
             blocks = block.number.sub(pool.lastRewardBlock);
           } else {
             blocks = pool.endOfEpochBlock.sub(pool.lastRewardBlock);
          }
          uint256 sdaoReward = blocks.mul(sdaoPerBlock(_pid));
          pool.accRewardsPerShare = pool.accRewardsPerShare.add((sdaoReward.mul(ACC_REWARDS_PRECISION) / lpSupply));
       }
       pool.lastRewardBlock = block.number;
       poolInfo[_pid] = pool;
       emit LogUpdatePool(_pid, pool.lastRewardBlock, lpSupply, pool.accRewardsPerShare);
    }
  }
  // ==========  Users  ==========
  /// @dev View function to see pending rewards on frontend.
  /// @param _pid The index of the pool. See `poolInfo`.
  /// @param _user Address of user.
  /// @return pending rewards for a given user.
  function pendingRewards(uint256 _pid, address _user) external view returns (uint256 pending) {
    PoolInfo memory pool = poolInfo[_pid];
    UserInfo storage user = userInfo[_pid][_user];
    uint256 accRewardsPerShare = pool.accRewardsPerShare;
    uint256 lpSupply = pool.lpSupply;
    if (block.number > pool.lastRewardBlock && pool.lastRewardBlock < pool.endOfEpochBlock) {
      if(lpSupply > 0){
        uint256 blocks;
        if(block.number < pool.endOfEpochBlock) {
            blocks = block.number.sub(pool.lastRewardBlock);
        } else {
          blocks = pool.endOfEpochBlock.sub(pool.lastRewardBlock);
        }
        
        uint256 sdaoReward = blocks.mul(sdaoPerBlock(_pid));
        accRewardsPerShare = accRewardsPerShare.add(sdaoReward.mul(ACC_REWARDS_PRECISION) / lpSupply);
      }
    }
    pending = int256(user.amount.mul(accRewardsPerShare) / ACC_REWARDS_PRECISION).sub(user.rewardDebt).toUInt256();
  }
  /// @dev Deposit LP tokens to earn rewards.
  /// @param _pid The index of the pool. See `poolInfo`.
  /// @param _amount LP token amount to deposit.
  /// @param _to The receiver of `_amount` deposit benefit.
  function deposit(uint256 _pid, uint256 _amount, address _to) external nonReentrant {
    // Input Validation
    require(_amount > 0 && _to != address(0), "Invalid inputs for deposit.");
    PoolInfo memory pool = updatePool(_pid);
    UserInfo storage user = userInfo[_pid][_to];
    // check if epoch as ended or if pool doesnot exist 
    require (pool.endOfEpochBlock > block.number,"This pool epoch has ended. Please join staking new session.");
    
    user.amount = user.amount.add(_amount);
    user.rewardDebt = user.rewardDebt.add(int256(_amount.mul(pool.accRewardsPerShare) / ACC_REWARDS_PRECISION));
    // Add to total supply
    pool.lpSupply = pool.lpSupply.add(_amount);
    // Update the pool back
    poolInfo[_pid] = pool;
    // Interactions
    lpToken[_pid].safeTransferFrom(msg.sender, address(this), _amount);
    emit Deposit(msg.sender, _pid, _amount, _to);
  }
  /// @dev Withdraw LP tokens from the staking contract.
  /// @param _pid The index of the pool. See `poolInfo`.
  /// @param _amount LP token amount to withdraw.
  /// @param _to Receiver of the LP tokens.
  function withdraw(uint256 _pid, uint256 _amount, address _to) external nonReentrant {
    require(_to != address(0), "ERC20: transfer to the zero address");
    PoolInfo memory pool = updatePool(_pid);
    UserInfo storage user = userInfo[_pid][msg.sender];
    // Check whether user has deposited stake
    require(user.amount >= _amount && _amount > 0, "Invalid amount to withdraw.");
    // Effects
    user.rewardDebt = user.rewardDebt.sub(int256(_amount.mul(pool.accRewardsPerShare) / ACC_REWARDS_PRECISION));
    user.amount = user.amount.sub(_amount);
    // Subtract from total supply
    pool.lpSupply = pool.lpSupply.sub(_amount);
    // Update the pool back
    poolInfo[_pid] = pool;
    // Interactions
    lpToken[_pid].safeTransfer(_to, _amount);
    emit Withdraw(msg.sender, _pid, _amount, _to);
  }
   /// @dev Harvest proceeds for transaction sender to `_to`.
   /// @param _pid The index of the pool. See `poolInfo`.
   /// @param _to Receiver of rewards.
   function harvest(uint256 _pid, address _to) external nonReentrant {
    
    require(_to != address(0), "ERC20: transfer to the zero address");
    PoolInfo memory pool = updatePool(_pid);
    UserInfo storage user = userInfo[_pid][msg.sender];
    int256 accumulatedRewards = int256(user.amount.mul(pool.accRewardsPerShare) / ACC_REWARDS_PRECISION);
    uint256 _pendingRewards = accumulatedRewards.sub(user.rewardDebt).toUInt256();
    // Effects
    user.rewardDebt = accumulatedRewards;
    // Interactions
    if(_pendingRewards > 0 ) {
      rewardsToken.safeTransfer(_to, _pendingRewards);
    }
    
    emit Harvest(msg.sender, _pid, _pendingRewards);
  }
  //// @dev Withdraw LP tokens and harvest accumulated rewards, sending both to `to`.
  /// @param _pid The index of the pool. See `poolInfo`.
  /// @param _amount LP token amount to withdraw.
  /// @param _to Receiver of the LP tokens and rewards.
  function withdrawAndHarvest(uint256 _pid, uint256 _amount, address _to) external nonReentrant {
    require(_to != address(0), "ERC20: transfer to the zero address");
    PoolInfo memory pool = updatePool(_pid);
    UserInfo storage user = userInfo[_pid][msg.sender];
    // Check if the user has stake in the pool
    require(user.amount >= _amount && _amount > 0, "Cannot withdraw more than staked.");
    int256 accumulatedRewards = int256(user.amount.mul(pool.accRewardsPerShare) / ACC_REWARDS_PRECISION);
    uint256 _pendingRewards = accumulatedRewards.sub(user.rewardDebt).toUInt256();
    // Effects
    user.rewardDebt = accumulatedRewards.sub(int256(_amount.mul(pool.accRewardsPerShare) / ACC_REWARDS_PRECISION));
    user.amount = user.amount.sub(_amount);
    // Subtract from total supply
    pool.lpSupply = pool.lpSupply.sub(_amount);
    // Update the pool back
    poolInfo[_pid] = pool;
    // Interactions
    if(_pendingRewards > 0) {
      rewardsToken.safeTransfer(_to, _pendingRewards);
    }
    lpToken[_pid].safeTransfer(_to, _amount);
    emit Harvest(msg.sender, _pid, _pendingRewards);
    emit Withdraw(msg.sender, _pid, _amount, _to);
  }
  /// @dev Withdraw without caring about rewards. EMERGENCY ONLY.
  /// @param _pid The index of the pool. See `poolInfo`.
  /// @param _to Receiver of the LP tokens.  
  function emergencyWithdraw(uint256 _pid, address _to) external nonReentrant { 
    require(_to != address(0), "ERC20: transfer to the zero address");
    UserInfo storage user = userInfo[_pid][msg.sender];
    uint256 amount = user.amount;
    user.amount = 0;
    user.rewardDebt = 0;
    PoolInfo memory pool = updatePool(_pid);
    pool.lpSupply = pool.lpSupply.sub(amount);
    // Update the pool back
    poolInfo[_pid] = pool;
    // Note: transfer can fail or succeed if `amount` is zero.
    lpToken[_pid].safeTransfer(_to, amount);
    emit EmergencyWithdraw(msg.sender, _pid, amount, _to);
  }
  function withdrawETHAndAnyTokens(address token) external onlyOwner {
    msg.sender.send(address(this).balance);
    IERC20 Token = IERC20(token);
    uint256 currentTokenBalance = Token.balanceOf(address(this));
    Token.safeTransfer(msg.sender, currentTokenBalance); 
  }
  // ==========  Getter Functions  ==========
  function poolLength() external view returns (uint256) {
    return poolInfo.length;
  }
}// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
library SignedSafeMath {
  int256 constant private _INT256_MIN = -2**255;
  /**
    * @dev Returns the multiplication of two signed integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `*` operator.
    *
    * Requirements:
    *
    * - Multiplication cannot overflow.
    */
  function mul(int256 a, int256 b) internal pure returns (int256) {
    // 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;
    }
    require(!(a == -1 && b == _INT256_MIN), "SignedSafeMath: multiplication overflow");
    int256 c = a * b;
    require(c / a == b, "SignedSafeMath: multiplication overflow");
    return c;
  }
  /**
    * @dev Returns the integer division of two signed 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(int256 a, int256 b) internal pure returns (int256) {
    require(b != 0, "SignedSafeMath: division by zero");
    require(!(b == -1 && a == _INT256_MIN), "SignedSafeMath: division overflow");
    int256 c = a / b;
    return c;
  }
  /**
    * @dev Returns the subtraction of two signed integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `-` operator.
    *
    * Requirements:
    *
    * - Subtraction cannot overflow.
    */
  function sub(int256 a, int256 b) internal pure returns (int256) {
    int256 c = a - b;
    require((b >= 0 && c <= a) || (b < 0 && c > a), "SignedSafeMath: subtraction overflow");
    return c;
  }
  /**
    * @dev Returns the addition of two signed integers, reverting on
    * overflow.
    *
    * Counterpart to Solidity's `+` operator.
    *
    * Requirements:
    *
    * - Addition cannot overflow.
    */
  function add(int256 a, int256 b) internal pure returns (int256) {
    int256 c = a + b;
    require((b >= 0 && c >= a) || (b < 0 && c < a), "SignedSafeMath: addition overflow");
    return c;
  }
  function toUInt256(int256 a) internal pure returns (uint256) {
    require(a >= 0, "Integer < 0");
    return uint256(a);
  }
}// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
/// @notice A library for performing overflow-/underflow-safe math,
/// updated with awesomeness from of DappHub (https://github.com/dapphub/ds-math).
library BoringMath {
    function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
        require((c = a + b) >= b, "BoringMath: Add Overflow");
    }
    function sub(uint256 a, uint256 b) internal pure returns (uint256 c) {
        require((c = a - b) <= a, "BoringMath: Underflow");
    }
    function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
        require(b == 0 || (c = a * b) / b == a, "BoringMath: Mul Overflow");
    }
    function to128(uint256 a) internal pure returns (uint128 c) {
        require(a <= uint128(-1), "BoringMath: uint128 Overflow");
        c = uint128(a);
    }
    function to64(uint256 a) internal pure returns (uint64 c) {
        require(a <= uint64(-1), "BoringMath: uint64 Overflow");
        c = uint64(a);
    }
    function to32(uint256 a) internal pure returns (uint32 c) {
        require(a <= uint32(-1), "BoringMath: uint32 Overflow");
        c = uint32(a);
    }
}
/// @notice A library for performing overflow-/underflow-safe addition and subtraction on uint128.
library BoringMath128 {
    function add(uint128 a, uint128 b) internal pure returns (uint128 c) {
        require((c = a + b) >= b, "BoringMath: Add Overflow");
    }
    function sub(uint128 a, uint128 b) internal pure returns (uint128 c) {
        require((c = a - b) <= a, "BoringMath: Underflow");
    }
}
/// @notice A library for performing overflow-/underflow-safe addition and subtraction on uint64.
library BoringMath64 {
    function add(uint64 a, uint64 b) internal pure returns (uint64 c) {
        require((c = a + b) >= b, "BoringMath: Add Overflow");
    }
    function sub(uint64 a, uint64 b) internal pure returns (uint64 c) {
        require((c = a - b) <= a, "BoringMath: Underflow");
    }
}
/// @notice A library for performing overflow-/underflow-safe addition and subtraction on uint32.
library BoringMath32 {
    function add(uint32 a, uint32 b) internal pure returns (uint32 c) {
        require((c = a + b) >= b, "BoringMath: Add Overflow");
    }
    function sub(uint32 a, uint32 b) internal pure returns (uint32 c) {
        require((c = a - b) <= a, "BoringMath: Underflow");
    }
}// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
import "../interfaces/IERC20.sol";
// solhint-disable avoid-low-level-calls
library BoringERC20 {
    bytes4 private constant SIG_SYMBOL = 0x95d89b41; // symbol()
    bytes4 private constant SIG_NAME = 0x06fdde03; // name()
    bytes4 private constant SIG_DECIMALS = 0x313ce567; // decimals()
    bytes4 private constant SIG_TRANSFER = 0xa9059cbb; // transfer(address,uint256)
    bytes4 private constant SIG_TRANSFER_FROM = 0x23b872dd; // transferFrom(address,address,uint256)
    function returnDataToString(bytes memory data) internal pure returns (string memory) {
        if (data.length >= 64) {
            return abi.decode(data, (string));
        } else if (data.length == 32) {
            uint8 i = 0;
            while(i < 32 && data[i] != 0) {
                i++;
            }
            bytes memory bytesArray = new bytes(i);
            for (i = 0; i < 32 && data[i] != 0; i++) {
                bytesArray[i] = data[i];
            }
            return string(bytesArray);
        } else {
            return "???";
        }
    }
    /// @notice Provides a safe ERC20.symbol version which returns '???' as fallback string.
    /// @param token The address of the ERC-20 token contract.
    /// @return (string) Token symbol.
    function safeSymbol(IERC20 token) internal view returns (string memory) {
        (bool success, bytes memory data) = address(token).staticcall(abi.encodeWithSelector(SIG_SYMBOL));
        return success ? returnDataToString(data) : "???";
    }
    /// @notice Provides a safe ERC20.name version which returns '???' as fallback string.
    /// @param token The address of the ERC-20 token contract.
    /// @return (string) Token name.
    function safeName(IERC20 token) internal view returns (string memory) {
        (bool success, bytes memory data) = address(token).staticcall(abi.encodeWithSelector(SIG_NAME));
        return success ? returnDataToString(data) : "???";
    }
    /// @notice Provides a safe ERC20.decimals version which returns '18' as fallback value.
    /// @param token The address of the ERC-20 token contract.
    /// @return (uint8) Token decimals.
    function safeDecimals(IERC20 token) internal view returns (uint8) {
        (bool success, bytes memory data) = address(token).staticcall(abi.encodeWithSelector(SIG_DECIMALS));
        return success && data.length == 32 ? abi.decode(data, (uint8)) : 18;
    }
    /// @notice Provides a safe ERC20.transfer version for different ERC-20 implementations.
    /// Reverts on a failed transfer.
    /// @param token The address of the ERC-20 token.
    /// @param to Transfer tokens to.
    /// @param amount The token amount.
    function safeTransfer(
        IERC20 token,
        address to,
        uint256 amount
    ) internal {
        (bool success, bytes memory data) = address(token).call(abi.encodeWithSelector(SIG_TRANSFER, to, amount));
        require(success && (data.length == 0 || abi.decode(data, (bool))), "BoringERC20: Transfer failed");
    }
    /// @notice Provides a safe ERC20.transferFrom version for different ERC-20 implementations.
    /// Reverts on a failed transfer.
    /// @param token The address of the ERC-20 token.
    /// @param from Transfer tokens from.
    /// @param to Transfer tokens to.
    /// @param amount The token amount.
    function safeTransferFrom(
        IERC20 token,
        address from,
        address to,
        uint256 amount
    ) internal {
        (bool success, bytes memory data) = address(token).call(abi.encodeWithSelector(SIG_TRANSFER_FROM, from, to, amount));
        require(success && (data.length == 0 || abi.decode(data, (bool))), "BoringERC20: TransferFrom failed");
    }
}// SPDX-License-Identifier: MIT
pragma solidity 0.6.12;
interface IERC20 {
    function totalSupply() external view returns (uint256);
    function balanceOf(address account) external view returns (uint256);
    function allowance(address owner, address spender) external view returns (uint256);
    function approve(address spender, uint256 amount) external returns (bool);
    event Transfer(address indexed from, address indexed to, uint256 value);
    event Approval(address indexed owner, address indexed spender, uint256 value);
    /// @notice EIP 2612
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;
}// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/**
 * @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].
 */
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 () internal {
        _status = _NOT_ENTERED;
    }
    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");
        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;
        _;
        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
import "../GSN/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.
 */
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 () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }
    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view 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 {
        emit OwnershipTransferred(_owner, address(0));
        _owner = 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");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.6.0;
/*
 * @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 GSN 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 payable) {
        return msg.sender;
    }
    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity 0.8.9;
import "@openzeppelin/contracts/token/ERC20/extensions/ERC20Burnable.sol";
/**
 * @dev {ERC20} token, including:
 *
 *  - ability for holders to burn (destroy) their tokens
 *
 * The account that deploys the contract will get the allocation of all the tokens.
 */
contract SophiaVerseToken is ERC20Burnable {
    uint256 public constant MAX_SUPPLY = 1000000000 * 10**uint256(18);
    /**
     * @dev Contructor will mint all the tokens and allocates to the deployer.
     *
     */
    constructor(string memory name, string memory symbol) ERC20(name, symbol) {
        // to mint the whole tokens
        _mint(msg.sender, MAX_SUPPLY);
    }
}
// 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;
    }
}
// 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);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.5.0) (token/ERC20/extensions/ERC20Burnable.sol)
pragma solidity ^0.8.0;
import "../ERC20.sol";
import "../../../utils/Context.sol";
/**
 * @dev Extension of {ERC20} that allows token holders to destroy both their own
 * tokens and those that they have an allowance for, in a way that can be
 * recognized off-chain (via event analysis).
 */
abstract contract ERC20Burnable is Context, ERC20 {
    /**
     * @dev Destroys `amount` tokens from the caller.
     *
     * See {ERC20-_burn}.
     */
    function burn(uint256 amount) public virtual {
        _burn(_msgSender(), amount);
    }
    /**
     * @dev Destroys `amount` tokens from `account`, deducting from the caller's
     * allowance.
     *
     * See {ERC20-_burn} and {ERC20-allowance}.
     *
     * Requirements:
     *
     * - the caller must have allowance for ``accounts``'s tokens of at least
     * `amount`.
     */
    function burnFrom(address account, uint256 amount) public virtual {
        _spendAllowance(account, _msgSender(), amount);
        _burn(account, amount);
    }
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
pragma solidity ^0.8.0;
/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    /**
     * @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);
    /**
     * @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 `to`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address to, 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 `from` to `to` 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 from,
        address to,
        uint256 amount
    ) external returns (bool);
}
// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/ERC20.sol)
pragma solidity ^0.8.0;
import "./IERC20.sol";
import "./extensions/IERC20Metadata.sol";
import "../../utils/Context.sol";
/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, IERC20, IERC20Metadata {
    mapping(address => uint256) private _balances;
    mapping(address => mapping(address => uint256)) private _allowances;
    uint256 private _totalSupply;
    string private _name;
    string private _symbol;
    /**
     * @dev Sets the values for {name} and {symbol}.
     *
     * The default value of {decimals} is 18. To select a different value for
     * {decimals} you should overload it.
     *
     * All two of these values are immutable: they can only be set once during
     * construction.
     */
    constructor(string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
    }
    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual override returns (string memory) {
        return _name;
    }
    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual override returns (string memory) {
        return _symbol;
    }
    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5.05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless this function is
     * overridden;
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual override returns (uint8) {
        return 18;
    }
    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }
    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }
    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address to, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _transfer(owner, to, amount);
        return true;
    }
    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }
    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, amount);
        return true;
    }
    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * NOTE: Does not update the allowance if the current allowance
     * is the maximum `uint256`.
     *
     * Requirements:
     *
     * - `from` and `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     * - the caller must have allowance for ``from``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }
    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
        address owner = _msgSender();
        _approve(owner, spender, allowance(owner, spender) + addedValue);
        return true;
    }
    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
        address owner = _msgSender();
        uint256 currentAllowance = allowance(owner, spender);
        require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
        unchecked {
            _approve(owner, spender, currentAllowance - subtractedValue);
        }
        return true;
    }
    /**
     * @dev Moves `amount` of tokens from `from` to `to`.
     *
     * This internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `from` cannot be the zero address.
     * - `to` cannot be the zero address.
     * - `from` must have a balance of at least `amount`.
     */
    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");
        _beforeTokenTransfer(from, to, amount);
        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
            // Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
            // decrementing then incrementing.
            _balances[to] += amount;
        }
        emit Transfer(from, to, amount);
        _afterTokenTransfer(from, to, amount);
    }
    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: mint to the zero address");
        _beforeTokenTransfer(address(0), account, amount);
        _totalSupply += amount;
        unchecked {
            // Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
            _balances[account] += amount;
        }
        emit Transfer(address(0), account, amount);
        _afterTokenTransfer(address(0), account, amount);
    }
    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        require(account != address(0), "ERC20: burn from the zero address");
        _beforeTokenTransfer(account, address(0), amount);
        uint256 accountBalance = _balances[account];
        require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
        unchecked {
            _balances[account] = accountBalance - amount;
            // Overflow not possible: amount <= accountBalance <= totalSupply.
            _totalSupply -= amount;
        }
        emit Transfer(account, address(0), amount);
        _afterTokenTransfer(account, address(0), amount);
    }
    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");
        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
    /**
     * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
     *
     * Does not update the allowance amount in case of infinite allowance.
     * Revert if not enough allowance is available.
     *
     * Might emit an {Approval} event.
     */
    function _spendAllowance(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        uint256 currentAllowance = allowance(owner, spender);
        if (currentAllowance != type(uint256).max) {
            require(currentAllowance >= amount, "ERC20: insufficient allowance");
            unchecked {
                _approve(owner, spender, currentAllowance - amount);
            }
        }
    }
    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
    /**
     * @dev Hook that is called after any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * has been transferred to `to`.
     * - when `from` is zero, `amount` tokens have been minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _afterTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual {}
}