creation_sourcecode: /**
   *Submitted for verification at BscScan.com on 2023-08-19
  */
  
  pragma solidity ^0.8.0;
  
  // 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;
          }
      }
  }
  
  
  // File @openzeppelin/contracts/token/ERC20/IERC20.sol@v4.4.2
  
  // 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/Context.sol@v4.4.2
  
  // 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/access/Ownable.sol@v4.4.2
  
  // OpenZeppelin Contracts v4.4.1 (access/Ownable.sol)
  
  pragma solidity ^0.8.0;
  
  /**
   * @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 contracts/OwnerWithdrawable.sol
  
  pragma solidity ^0.8.0;
  
  
  
  contract OwnerWithdrawable is Ownable {
      using SafeMath for uint256;
      using SafeERC20 for IERC20;
  
      receive() external payable {}
  
      fallback() external payable {}
  
      function withdraw(address token, uint256 amt) public onlyOwner {
          IERC20(token).safeTransfer(msg.sender, amt);
      }
  
      function withdrawAll(address token) public onlyOwner {
          uint256 amt = IERC20(token).balanceOf(address(this));
          withdraw(token, amt);
      }
  
      function withdrawCurrency(uint256 amt) public onlyOwner {
          payable(msg.sender).transfer(amt);
      }
  
      // function deposit(address token, uint256 amt) public onlyOwner {
      //     uint256 allowance = IERC20(token).allowance(msg.sender, address(this));
      //     require(allowance >= amt, "Check the token allowance");
      //     IERC20(token).transferFrom(owner(), address(this), amt);
      // }
  }
  
  // File @openzeppelin/contracts/utils/Address.sol@v4.4.2
  
  // 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);
              }
          }
      }
  }
  
  
  // File @openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol@v4.4.2
  
  // OpenZeppelin Contracts v4.4.1 (token/ERC20/utils/SafeERC20.sol)
  
  pragma solidity ^0.8.0;
  
  
  /**
   * @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/token/ERC20/extensions/IERC20Metadata.sol@v4.4.2
  
  // OpenZeppelin Contracts v4.4.1 (token/ERC20/extensions/IERC20Metadata.sol)
  
  pragma solidity ^0.8.0;
  
  /**
   * @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
  // import "hardhat/console.sol";
  pragma solidity ^0.8.0;
  
  contract ApexarPresale is OwnerWithdrawable {
      using SafeMath for uint256;
      using SafeERC20 for IERC20;
      using SafeERC20 for IERC20Metadata;
  
      uint256 public rate;
      address public saleToken;
      uint public saleTokenDec;
      uint256 public totalTokensforSale;
      uint256 public maxBuyLimit;
      uint256 public minBuyLimit;
  
      // Whitelist of tokens to buy from
      mapping(address => bool) public tokenWL;
  
      // 1 Token price in terms of WL tokens
      mapping(address => uint256) public tokenPrices;
  
      address[] public buyers;
  
      bool public isUnlockingStarted;
      bool public isPresaleStarted;
      uint public presalePhase;
      
      mapping(address => BuyerTokenDetails) public buyersAmount;
      mapping(address => uint256) public presaleData;
  
      uint256 public totalTokensSold;
  
      struct BuyerTokenDetails {
          uint amount;
          bool isClaimed;
      }
  
      constructor() { }
  
      modifier saleStarted(){
          require (!isPresaleStarted, "PreSale: Sale has already started");
          _;
      }
  
      //function to set information of Token sold in Pre-Sale and its rate in Native currency
      function setSaleTokenParams(
          address _saleToken,
          uint256 _totalTokensforSale
      ) external onlyOwner saleStarted{
          saleToken = _saleToken;
          saleTokenDec = IERC20Metadata(saleToken).decimals();
          totalTokensforSale = _totalTokensforSale;
          IERC20(saleToken).safeTransferFrom(msg.sender, address(this), totalTokensforSale);
      }
  
      // Add a token to buy presale token from, with price
      function addWhiteListedToken(
          address _token,
          uint256 _price
      ) external onlyOwner {
          require(_price != 0, "Presale: Cannot set price to 0");
          tokenWL[_token] = true;
          tokenPrices[_token] = _price;
      }
  
      function updateEthRate(uint256 _rate) external  onlyOwner {
          rate = _rate;
      }
  
      function updateTokenRate(
          address _token,
          uint256 _price
      )external onlyOwner{
          require(tokenWL[_token], "Presale: Token not whitelisted");
          require(_price != 0, "Presale: Cannot set price to 0");
          tokenPrices[_token] = _price;
      }
  
      function startPresale() external onlyOwner {
          require(!isPresaleStarted, "PreSale: Sale has already started");
          isPresaleStarted = true;
      }
  
      function stopPresale() external onlyOwner {
          require(isPresaleStarted, "PreSale: Sale hasn't started yet!");
          isPresaleStarted = false;
      }
  
      function startUnlocking() external onlyOwner {
          require(!isUnlockingStarted, "PreSale: Unlocking has already started");
          isUnlockingStarted = true;
      }
  
      function stopUnlocking() external onlyOwner {
          require(isUnlockingStarted, "PreSale: Unlocking hasn't started yet!");
          isUnlockingStarted = false;
      }
  
      // Public view function to calculate amount of sale tokens returned if you buy using "amount" of "token"
      function getTokenAmount(address token, uint256 amount)
          public
          view
          returns (uint256)
      {
          if(!isPresaleStarted) {
              return 0;
          }
          uint256 amtOut;
          if(token != address(0)){
              require(tokenWL[token] == true, "Presale: Token not whitelisted");
              uint256 price = tokenPrices[token];
              amtOut = amount.mul(10**saleTokenDec).div(price);
          }
          else{
              amtOut = amount.mul(10**saleTokenDec).div(rate);
          }
          return amtOut;
      }
  
      // Public Function to buy tokens. APPROVAL needs to be done first
      function buyToken(address _token, uint256 _amount) external payable{
          require(isPresaleStarted, "PreSale: Sale stopped!");
  
          uint256 saleTokenAmt;
          if(_token != address(0)){
              require(_amount > 0, "Presale: Cannot buy with zero amount");
              require(tokenWL[_token] == true, "Presale: Token not whitelisted");
  
              saleTokenAmt = getTokenAmount(_token, _amount);
  
              // check if saleTokenAmt is greater than minBuyLimit
              require(saleTokenAmt >= minBuyLimit, "Presale: Min buy limit not reached");
              require(presaleData[msg.sender] + saleTokenAmt <= maxBuyLimit, "Presale: Max buy limit reached for this phase");
              require((totalTokensSold + saleTokenAmt) <= totalTokensforSale, "PreSale: Total Token Sale Reached!");
  
              IERC20(_token).safeTransferFrom(msg.sender, address(this), _amount);
          }
          else{
              saleTokenAmt = getTokenAmount(address(0), msg.value);
  
              // check if saleTokenAmt is greater than minBuyLimit
              require(saleTokenAmt >= minBuyLimit, "Presale: Min buy limit not reached");
              require(presaleData[msg.sender] + saleTokenAmt <= maxBuyLimit, "Presale: Max buy limit reached for this phase");
              require((totalTokensSold + saleTokenAmt) <= totalTokensforSale, "PreSale: Total Token Sale Reached!");
  
          }
   
          totalTokensSold += saleTokenAmt;
          buyersAmount[msg.sender].amount += saleTokenAmt;
          presaleData[msg.sender] += saleTokenAmt; 
      }
  
      function withdrawToken() external {
          uint256 tokensforWithdraw;
          require(buyersAmount[msg.sender].isClaimed == false, "Presale: Already claimed");
          require(isUnlockingStarted, "Presale: Locking period not over yet");
          tokensforWithdraw = buyersAmount[msg.sender].amount;
          buyersAmount[msg.sender].isClaimed = true;
          IERC20(saleToken).safeTransfer(msg.sender, tokensforWithdraw);
      }
  
      function setMinBuyLimit(uint _minBuyLimit) external onlyOwner {
          minBuyLimit = _minBuyLimit;
      }
  
      function setMaxBuyLimit(uint _maxBuyLimit) external onlyOwner {
          maxBuyLimit = _maxBuyLimit;
      }
  }