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 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.
   */
  function Ownable() 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;
  }

  /**
   * @dev Allows the current owner to relinquish control of the contract.
   */
  function renounceOwnership() public onlyOwner {
    emit OwnershipRenounced(owner);
    owner = address(0);
  }
}

/**
 * @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();
  }
}

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);
}

contract BasicToken is ERC20Basic {
  using SafeMath for uint256;
    
  mapping (address => uint256) balances;
  uint256 totalSupply_;
  
  function totalSupply() public view returns (uint256) {
    return totalSupply_;
  }
  
    /**
  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  */
  
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
    return true;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of. 
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];
  }
}

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);
}

contract BurnableToken is BasicToken {

  event Burn(address indexed burner, uint256 value);

  /**
   * @dev Burns a specific amount of tokens.
   * @param _value The amount of token to be burned.
   */
  function burn(uint256 _value) public {
    require(_value <= balances[msg.sender]);
    // no need to require value <= totalSupply, since that would imply the
    // sender's balance is greater than the totalSupply, which *should* be an assertion failure

    address burner = msg.sender;
    balances[burner] = balances[burner].sub(_value);
    totalSupply_ = totalSupply_.sub(_value);
    emit Burn(burner, _value);
    emit Transfer(burner, address(0), _value);
  }
}

contract StandardToken is ERC20, BurnableToken {

  mapping (address => mapping (address => uint256)) allowed;

  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_to] = balances[_to].add(_value);
    balances[_from] = balances[_from].sub(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);

    emit Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Aprove the passed address to spend the specified amount of tokens on behalf of msg.sender.
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
   */
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    return true;
  }

  /**
   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifing the amount of tokens still avaible for the spender.
   */
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }
  
}

contract BittechToken is StandardToken {

  string constant public name = "Bittech Token";
  string constant public symbol = "BTECH";
  uint256 constant public decimals = 18;

  address constant public bountyWallet = 0x8E8d4cdADbc027b192DfF91c77382521B419E5A2;
  uint256 public bountyPart = uint256(5000000).mul(10 ** decimals); 
  address constant public adviserWallet = 0x1B9D19Af310E8cB35D0d3B8977b65bD79C5bB299;
  uint256 public adviserPart = uint256(1000000).mul(10 ** decimals);
  address constant public reserveWallet = 0xa323DA182fDfC10861609C2c98894D9745ABAB91;
  uint256 public reservePart = uint256(20000000).mul(10 ** decimals);
  address constant public ICOWallet = 0x1ba99f4F5Aa56684423a122D72990A7851AaFD9e;
  uint256 public ICOPart = uint256(60000000).mul(10 ** decimals);
  uint256 public PreICOPart = uint256(5000000).mul(10 ** decimals);
  address constant public teamWallet = 0x69548B7740EAf1200312d803f8bDd04F77523e09;
  uint256 public teamPart = uint256(9000000).mul(10 ** decimals);

  uint256 constant public yearSeconds = 31536000; // 60*60*24*365 = 31536000
  uint256 constant public secsPerBlock = 15; // 1 block per 15 seconds
  uint256 public INITIAL_SUPPLY = uint256(100000000).mul(10 ** decimals); // 100 000 000 tokens

  uint256 public withdrawTokens = 0;
  uint256 public startTime;

  function BittechToken() public {
    totalSupply_ = INITIAL_SUPPLY;

    balances[bountyWallet] = bountyPart;
    emit Transfer(this, bountyWallet, bountyPart);

    balances[adviserWallet] = adviserPart;
    emit Transfer(this, adviserWallet, adviserPart);

    balances[reserveWallet] = reservePart;
    emit Transfer(this, reserveWallet, reservePart);

    balances[ICOWallet] = ICOPart;
    emit Transfer(this, ICOWallet, ICOPart);

    balances[msg.sender] = PreICOPart;
    emit Transfer(this, msg.sender, PreICOPart);

    balances[this] = teamPart;
    emit Transfer(this, this, teamPart); 

    startTime = block.number;
  }

  modifier onlyTeam() {
    require(msg.sender == teamWallet);
    _;
  }

  function viewTeamTokens() public view returns (uint256) {

    if (block.number >= startTime.add(yearSeconds.div(secsPerBlock))) {
      return 3000000;
    }

    if (block.number >= startTime.add(yearSeconds.div(secsPerBlock).mul(2))) {
      return 6000000;
    }

    if (block.number >= startTime.add(yearSeconds.div(secsPerBlock).mul(3))) {
      return 9000000;
    }

  }

  function getTeamTokens(uint256 _tokens) public onlyTeam {
    uint256 tokens = _tokens.mul(10 ** decimals);
    require(withdrawTokens.add(tokens) <= viewTeamTokens().mul(10 ** decimals));
    transfer(teamWallet, tokens);
    emit Transfer(this, teamWallet, tokens);
    withdrawTokens = withdrawTokens.add(tokens);
  }
  
}