pragma solidity ^0.4.24;

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, throws on overflow.
  */
  function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
    if (a == 0) {
      return 0;
    }
    c = a * b;
    assert(c / a == b);
    return c;
  }

  /**
  * @dev Integer division of two numbers, truncating the quotient.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    // uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return a / b;
  }

  /**
  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  /**
  * @dev Adds two numbers, throws on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
    c = a + b;
    assert(c >= a);
    return c;
  }
}


/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
  function totalSupply() public view returns (uint256);
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);
}

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender)
    public view returns (uint256);

  function transferFrom(address from, address to, uint256 value)
    public returns (bool);

  function approve(address spender, uint256 value) public returns (bool);
  event Approval(
    address indexed owner,
    address indexed spender,
    uint256 value
  );
}

/**
 * @title Ownable
 * @dev The Ownable contract has an owner address, and provides basic authorization control
 * functions, this simplifies the implementation of "user permissions".
 */
contract Ownable {
  address public owner;


  event OwnershipRenounced(address indexed previousOwner);
  event OwnershipTransferred(
    address indexed previousOwner,
    address indexed newOwner
  );


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  constructor() public {
    owner = msg.sender;
  }

  /**
   * @dev Throws if called by any account other than the owner.
   */
  modifier onlyOwner() {
    require(msg.sender == owner);
    _;
  }

  /**
   * @dev Allows the current owner to transfer control of the contract to a newOwner.
   * @param newOwner The address to transfer ownership to.
   */
  function transferOwnership(address newOwner) public onlyOwner {
    require(newOwner != address(0));
    emit OwnershipTransferred(owner, newOwner);
    owner = newOwner;
  }

}

/**
 * @title Pausable
 * @dev Base contract which allows children to implement an emergency stop mechanism.
 */
contract Pausable is Ownable {
  event Pause();
  event Unpause();

  bool public paused = false;


  /**
   * @dev Modifier to make a function callable only when the contract is not paused.
   */
  modifier whenNotPaused() {
    require(!paused);
    _;
  }

  /**
   * @dev Modifier to make a function callable only when the contract is paused.
   */
  modifier whenPaused() {
    require(paused);
    _;
  }

  /**
   * @dev called by the owner to pause, triggers stopped state
   */
  function pause() onlyOwner whenNotPaused public {
    paused = true;
    emit Pause();
  }

  /**
   * @dev called by the owner to unpause, returns to normal state
   */
  function unpause() onlyOwner whenPaused public {
    paused = false;
    emit Unpause();
  }
}

/**
 * @title ERC20 Private Token Generation Program
 */
contract ChainBowPrivateSale is Pausable {

    using SafeMath for uint256;

    ERC20 public tokenContract;
    address public teamWallet;
    string public leader;
    uint256 public rate = 5000;

    uint256 public totalSupply = 0;

    event Buy(address indexed sender, address indexed recipient, uint256 value, uint256 tokens);

    mapping(address => uint256) public records;

    constructor(address _tokenContract, address _teamWallet, string _leader, uint _rate) public {
        require(_tokenContract != address(0));
        require(_teamWallet != address(0));
        tokenContract = ERC20(_tokenContract);
        teamWallet = _teamWallet;
        leader = _leader;
        rate = _rate;
    }


    function () payable public {
        buy(msg.sender);
    }

    function buy(address recipient) payable public whenNotPaused {
        require(msg.value >= 0.1 ether);

        uint256 tokens =  rate.mul(msg.value);

        tokenContract.transferFrom(teamWallet, msg.sender, tokens);

        records[recipient] = records[recipient].add(tokens);
        totalSupply = totalSupply.add(tokens);

        emit Buy(msg.sender, recipient, msg.value, tokens);

    }


    /**
     * change rate
     */
    function changeRate(uint256 _rate) public onlyOwner {
        rate = _rate;
    }

    /**
     * change team wallet
     */
    function changeTeamWallet(address _teamWallet) public onlyOwner {
        teamWallet = _teamWallet;
    }

    /**
     * withdraw ether
     */
    function withdrawEth() public onlyOwner {
        teamWallet.transfer(address(this).balance);
    }


    /**
     * withdraw foreign tokens
     */
    function withdrawForeignTokens(address _tokenContract) onlyOwner public returns (bool) {
        ERC20Basic token = ERC20Basic(_tokenContract);
        uint256 amount = token.balanceOf(address(this));
        return token.transfer(owner, amount);
    }

}