// File: /home/alex/Projects/presale-contracts/contracts/Presale.sol



// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Pausable.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";

contract Presale is Ownable, Pausable, ReentrancyGuard {
  using SafeMath for uint;

  // @dev The denominator component for values specified in basis points.
  uint internal constant BASIS_POINTS_DEN = 100;

  // @dev sale token address
  IERC20 public token;
  // @dev treasury wallet to forward invested eth to
  address payable public treasury;
  // @dev block to start presale after
  uint public startBlock;
  // @dev block to end presale (up to)
  uint public endBlock;
  // @dev block to be able to claim value which was not claimed by investors
  uint public endRefundBlock;
  // @dev total supply of tokens available to be sold
  uint public supply;
  // @dev token to ether rate base on `BASIS_POINTS_DEN` denominator
  // calculus: eth * `rate` / `BASIS_POINTS_DEN`
  // example: 1 eth * 10 / 100 = 0.1 token (rate=10...1 eth= 0.1 token)
  uint public rate;
  // @dev how much a whitelist address is able to invest
  uint public maxInvestment;

  // @dev amount of ether invested
  uint public invested = 0;
  // @dev amount of tokens sold
  uint public tokensSold = 0;
  // @dev presale is public or whitelisted addresses
  bool isPublic;
  // @dev whitelisted investor addresses
  mapping (address => bool) investors;
  // @dev investments in ether done by whitelisted investors
  mapping (address => uint) investments;
  // @dev tokens transfered to a whitelisted investors
  mapping (address => uint) receivedTokens;
  // @dev refunds available to an whitelisted investor
  mapping (address => uint) refunds;

  /**
   * @dev Emitted when the presale details update is triggered by `account`.
   */
  event DetailsUpdated(address account);

  /**
   * @dev Emitted when the `investor` is whitelisted by `account`.
   */
  event Whitelisted(address investor, address account);

  /**
   * @dev Emitted when the `investor` is unwhitelisted by `account`.
   */
  event Unwhitelisted(address investor, address account);

  /**
   * @dev Emitted when the `investor` invests `value` ether and received `tokensReceived` tokens on `wallet`
   * as well as gets back a refund of `valueRefunded` ether
   */
  event Invested(address investor, address wallet, uint value, uint tokensReceived, uint valueRefunded);

  /**
   * @dev Emitted when the `investor` claims the refund of `value` ether
   */
  event Refunded(address investor, uint value);

  /**
   * @dev Modifier to make a function callable only when refunds are available
   */
  modifier whenRefundable() {
    require(endRefundBlock >= block.number, "Value is not refundable anymore");
    require(paused() == false, "Presale is paused");
    _;
  }

  /**
   * @dev Modifier to make a function callable only when refunds are NOT available
   */
  modifier whenNotRefundable() {
    require(endRefundBlock < block.number, "Value is still refundable");
    _;
  }

  /**
   * @dev Modifier to make a function callable only when the presale is running
   */
  modifier whenRunning() {
    require(startBlock <= block.number, "Presale has not started yet");
    require(endBlock >= block.number, "Presale has finalized");
    require(paused() == false, "Presale is paused");
    _;
  }

  /**
    * @dev Modifier to make a function callable only when presale has finalized
    */
  modifier afterEnded() {
    require(endBlock < block.number, "Presale has not finalized yet");
    _;
  }

  /**
    * @dev check if presale is public
    */
  modifier isPublicOrWhitelist() {
    if (!isPublic) {
      require(investors[_msgSender()], "Investor is not whitelisted");
    }
    _;
  }

  constructor(
    address _owner,
    address payable _treasury,
    address _token,
    uint _startBlock,
    uint _endBlock,
    uint _endRefundBlock,
    uint _supply,
    uint _rate,
    uint _maxInvestment,
    bool _isPublic
  ) public {
    require(_treasury != address(0), "Not valid treasury wallet address");
    require(_token != address(0), "Not valid token address");

    treasury = _treasury;
    token = IERC20(_token);
    updateDetails(
      _startBlock,
      _endBlock,
      _endRefundBlock,
      _supply,
      _rate,
      _maxInvestment,
      _isPublic
    );
    transferOwnership(_owner);
  }

  /**
   * @dev Calculate investment details
   */
  function calculateInvestment(address investor, uint value) public view
    returns (uint investment, uint tokensToSend, uint refundValue) {
    uint remainingInvestment = availableInvestment(investor);

    if (value <= remainingInvestment) {
      refundValue = 0;
    } else {
      refundValue = value.sub(remainingInvestment);
    }

    investment = value.sub(refundValue);
    tokensToSend = investment.mul(rate).div(BASIS_POINTS_DEN);

    // if there are too few tokens remaining in supply
    if (tokensToSend > supply) {
      uint extraTokens = tokensToSend.sub(supply);
      tokensToSend = supply;
      refundValue += extraTokens.mul(BASIS_POINTS_DEN).div(rate);
      investment = value.sub(refundValue);
    }
  }

  /**
   * @dev Check if an address is whitelisted investor
   */
  function isInvestor(address investor) public view returns (bool) {
    return investors[investor] == true;
  }

  /**
   * @dev Get amount that was already invested by an investor
   */
  function investedAmount(address investor) public view returns (uint) {
    return investments[investor];
  }

  /**
   * @dev Get amount of tokens received by an investor
   */
  function tokensReceived(address investor) public view returns (uint) {
    return receivedTokens[investor];
  }

  /**
   * @dev Check the value of available investment for an investor
   */
  function availableInvestment(address investor) public view returns (uint) {
    return maxInvestment.sub(investedAmount(investor));
  }

  /**
   * @dev Get value available to being refunded to an investor
   */
  function availableRefund(address investor) public view returns (uint) {
    return refunds[investor];
  }

  function claimRefund(address payable investor) public whenRefundable {
    uint refundValue = availableRefund(investor);
    refunds[investor] = 0;
    investor.transfer(refundValue);

    emit Refunded(investor, refundValue);
  }

  /**
   * @dev Invest into presale
   *
   * `investor` is sending ether and receiving tokens on `wallet` address and partial or full refund back on `invesor` address.
   */
  function invest(address wallet) public payable whenRunning nonReentrant isPublicOrWhitelist {
    address investor = _msgSender();

    require(address(wallet) != address(0), "No wallet to transfer tokens to");
    require(msg.value > 0, "There's no value in transaction");
    require(supply > 0, "No remaining supply");

    (uint investment, uint tokensToSend, uint refundValue) = calculateInvestment(investor, msg.value);
    uint presaleTokenAllocation = token.balanceOf(address(this));

    require(presaleTokenAllocation >= tokensToSend, "Presale contract own less tokens than needed");
    require(investment > 0, "Zero amount for investment");

    supply -= tokensToSend;
    invested += investment;
    tokensSold += tokensToSend;
    investments[investor] += investment;
    receivedTokens[investor] += tokensToSend;
    refunds[investor] += refundValue;

    token.transfer(wallet, tokensToSend);
    treasury.transfer(investment);

    emit Invested(investor, wallet, msg.value, tokensToSend, refundValue);
  }

  /**
   * @dev claim back unsold tokens
   */
  function claimUnsoldTokens(address wallet) public afterEnded onlyOwner {
    supply = 0;
    // in case the contract got more tokens than the supply
    token.transfer(wallet, token.balanceOf(address(this)));
  }

  /**
   * @dev claim back unsold tokens
   */
  function claimUnclaimedRefunds(address payable wallet) public whenNotRefundable onlyOwner {
    wallet.transfer(address(this).balance);
  }

  /**
   * @dev whitelist a list of investors
   */
  function whitelistInvestors(address[] memory _investors) public onlyOwner {
    for (uint i = 0; i < _investors.length; i++) {
      address investor = _investors[i];
      investors[investor] = true;
      emit Whitelisted(investor, _msgSender());
    }
  }

  /**
   * @dev unwhitelist a list of investors
   */
  function unwhitelistInvestors(address[] memory _investors) public onlyOwner {
    for (uint i = 0; i < _investors.length; i++) {
      address investor = _investors[i];
      investors[investor] = false;
      emit Unwhitelisted(investor, _msgSender());
    }
  }

  /**
   * @dev Temporary pause the presale
   */
  function updatePaused(bool paused) public onlyOwner {
    if (paused == true) {
      _pause();
    } else {
      _unpause();
    }
  }

  /**
   * @dev Update presale details
   */
  function updateDetails(
    uint _startBlock,
    uint _endBlock,
    uint _endRefundBlock,
    uint _supply,
    uint _rate,
    uint _maxInvestment,
    bool _isPublic
  ) public onlyOwner {
    require(_endBlock > block.number, "End block must be greater than the current one");
    require(_endBlock > _startBlock, "Start block should be less than the end block");
    require(_endRefundBlock >= _endBlock, "Refund block must be greater than the end block");
    require(_rate > 0, "Rate must be greater than 0");
    require(_maxInvestment > 0, "Noone can invest nothing");

    startBlock = _startBlock;
    endBlock = _endBlock;
    endRefundBlock = _endRefundBlock;
    rate = _rate;
    maxInvestment = _maxInvestment;
    isPublic = _isPublic;

    if (_supply > 0) {
      supply = _supply;
    }

    emit DetailsUpdated(_msgSender());
  }

  /**
   * @dev This function is called for all messages sent to
   * this contract, except plain Ether transfers
   * (there is no other function except the receive function).
   * Any call with non-empty calldata to this contract will execute
   * the fallback function (even if Ether is sent along with the call).
   */
  fallback() external payable {
    invest(_msgSender());
  }

  /**
   * @dev This function is called for plain Ether transfers, i.e.
   * for every call with empty calldata.
   */
  receive() external payable {
    invest(_msgSender());
  }
}

// File: @openzeppelin/contracts/GSN/Context.sol



// 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;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol



// 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;
    }
}

// File: @openzeppelin/contracts/math/SafeMath.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
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;
    }
}

// File: @openzeppelin/contracts/token/ERC20/IERC20.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

/**
 * @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/Pausable.sol



// SPDX-License-Identifier: MIT

pragma solidity ^0.6.0;

import "../GSN/Context.sol";

/**
 * @dev Contract module which allows children to implement an emergency stop
 * mechanism that can be triggered by an authorized account.
 *
 * This module is used through inheritance. It will make available the
 * modifiers `whenNotPaused` and `whenPaused`, which can be applied to
 * the functions of your contract. Note that they will not be pausable by
 * simply including this module, only once the modifiers are put in place.
 */
contract Pausable is Context {
    /**
     * @dev Emitted when the pause is triggered by `account`.
     */
    event Paused(address account);

    /**
     * @dev Emitted when the pause is lifted by `account`.
     */
    event Unpaused(address account);

    bool private _paused;

    /**
     * @dev Initializes the contract in unpaused state.
     */
    constructor () internal {
        _paused = false;
    }

    /**
     * @dev Returns true if the contract is paused, and false otherwise.
     */
    function paused() public view returns (bool) {
        return _paused;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is not paused.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    modifier whenNotPaused() {
        require(!_paused, "Pausable: paused");
        _;
    }

    /**
     * @dev Modifier to make a function callable only when the contract is paused.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    modifier whenPaused() {
        require(_paused, "Pausable: not paused");
        _;
    }

    /**
     * @dev Triggers stopped state.
     *
     * Requirements:
     *
     * - The contract must not be paused.
     */
    function _pause() internal virtual whenNotPaused {
        _paused = true;
        emit Paused(_msgSender());
    }

    /**
     * @dev Returns to normal state.
     *
     * Requirements:
     *
     * - The contract must be paused.
     */
    function _unpause() internal virtual whenPaused {
        _paused = false;
        emit Unpaused(_msgSender());
    }
}

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



// 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;
    }
}