// File: @openzeppelin/contracts/utils/Context.sol

// 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;
    }
}

// File: @openzeppelin/contracts/access/Ownable.sol


// OpenZeppelin Contracts (last updated v4.9.0) (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 Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling 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: @openzeppelin/contracts/token/ERC20/IERC20.sol


// OpenZeppelin Contracts (last updated v4.9.0) (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);
}

// File: @chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol


pragma solidity ^0.8.0;

interface AggregatorV3Interface {
  function decimals() external view returns (uint8);

  function description() external view returns (string memory);

  function version() external view returns (uint256);

  function getRoundData(
    uint80 _roundId
  ) external view returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound);

  function latestRoundData()
    external
    view
    returns (uint80 roundId, int256 answer, uint256 startedAt, uint256 updatedAt, uint80 answeredInRound);
}

// File: contracts/Itoken.sol


pragma solidity ^0.8.4;

interface iTokenContract{

    event tokenStake(uint indexed id, address indexed staker, uint indexed tokenAmount);
    event releaseStake(uint indexed id, address indexed staker, uint indexed tokenAmount); 

    function stake(address _staker, uint256 _amount)external returns(bool);

    


}

// File: contracts/vendor.sol


pragma solidity ^0.8.4;
contract DCC_Vendor is Ownable {


  // token price for ETH
  uint256 public tokenPrice =10000000;
  uint maxBuy = 100000000;
  uint public roundAmount = 200000000;
  
  address tokenAddress;
  address priceAddress;

  bool isSaleOpen = false;

  mapping(address => bool)private senders;

  // Event that log buy operation
  event BuyTokens(address buyer, uint256 amountOfETH, uint256 amountOfTokens);
  event SellTokens(address seller, uint256 amountOfTokens, uint256 amountOfETH);

    AggregatorV3Interface internal dataFeed;
    IERC20 internal tokenInterface;
    iTokenContract internal iTokenInterface;

    constructor(address _tokenAddress, address _priceAddress) {
        tokenAddress = _tokenAddress;
        priceAddress = _priceAddress;

        senders[msg.sender] = true; // add owner

        dataFeed = AggregatorV3Interface(
                priceAddress);

        tokenInterface = IERC20(_tokenAddress);
        iTokenInterface = iTokenContract(_tokenAddress);
    
    }

        function addSender(address _address) public onlyOwner  {
        
        require(_address != address(0));
        senders[_address] = true;
       
    }
    
    function removeSender(address _address) public onlyOwner {
        require(_address != address(0));
        senders[_address] = false;
        
    }

    function flipSaleStatus()public  {
        require(senders[_msgSender()]);
        isSaleOpen = !isSaleOpen;
    }
  


    function changeTokenAddress(address _address)public  returns(bool) {
        require(senders[_msgSender()]);
        tokenInterface = IERC20(_address);
        iTokenInterface = iTokenContract(_address);

        return true;

    }



  /**
  * @notice Allow users to buy tokens for ETH
  */
  function getLatestData() public view returns (bool,int) {
 
        (
            /* uint80 roundID */,
            int answer,
            /*uint startedAt*/,
            uint timeStamp,
            /*uint80 answeredInRound*/
        ) = dataFeed.latestRoundData();
       


  
        require(block.timestamp - timeStamp < 7200,"not updated");
        require(answer > 0,"no rate");

        return (true,answer);
        
    }


    function updateRound(uint _amount)public  {
      require(senders[_msgSender()]);
       roundAmount = _amount;
    }

  function confirmBuy(uint _amount)private view returns(bool){

    require(isSaleOpen,"sale");
    require(_amount > 0 && _amount <= roundAmount,"round");
    require(_amount <=maxBuy, "amount");

    return true;

  }

  function getWeiPrice(uint _amount)public view returns(uint){
       (bool isRate,int EthUsd) = getLatestData();
       require(isRate && EthUsd>0,"rate");
      
       uint weiTokenVal = (((_amount*1e18) * tokenPrice )/uint(EthUsd));
       
       return weiTokenVal;

  }


  function buyTokens(uint _amount) public payable returns (bool ) {

    require(confirmBuy(_amount));
    
    uint weiTokenVal = getWeiPrice(_amount);

    require(msg.value >= weiTokenVal, "ETH");

    roundAmount -= _amount;

 
    // check if the Vendor Contract has enough amount of tokens for the transaction
    uint256 vendorBalance = tokenInterface.balanceOf(address(this));
    require(vendorBalance >= _amount, "Vendor contract has not enough tokens in its balance");

    // Transfer token to the msg.sender
    (bool sent) = tokenInterface.transfer(msg.sender, _amount);
    require(sent, "Failed to transfer token to user");

    // emit the event
    emit BuyTokens(msg.sender, msg.value, _amount);

    return true;
    
  }

  function buyPreSale(uint _amount)public payable returns(bool){

      bool buyToken = buyTokens(_amount);
      require(buyToken,"purchase failed");

      bool staked = iTokenInterface.stake(_msgSender(),_amount);

      require(staked,"stake failed");

      return true;



  }

  function withdraw() public onlyOwner {
    uint256 ownerBalance = address(this).balance;
    require(ownerBalance > 0, "Owner has not balance to withdraw");

    (bool sent,) = msg.sender.call{value: address(this).balance}("");
    require(sent, "Failed to send user balance back to the owner");
  }
}