pragma solidity ^0.4.19;


contract OwnableToken {
    mapping (address => bool) owners;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
    event OwnershipExtended(address indexed host, address indexed guest);

    modifier onlyOwner() {
        require(owners[msg.sender]);
        _;
    }

    function OwnableToken() public {
        owners[msg.sender] = true;
    }

    function addOwner(address guest) public onlyOwner {
        require(guest != address(0));
        owners[guest] = true;
        emit OwnershipExtended(msg.sender, guest);
    }

    function transferOwnership(address newOwner) public onlyOwner {
        require(newOwner != address(0));
        owners[newOwner] = true;
        delete owners[msg.sender];
        emit OwnershipTransferred(msg.sender, newOwner);
    }
}


/**
 * @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) {
    if (a == 0) {
      return 0;
    }
    uint256 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 c;
  }

  /**
  * @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) {
    uint256 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 Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  uint256 totalSupply_;

  /**
  * @dev total number of tokens in existence
  */
  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]);

    // SafeMath.sub will throw if there is not enough balance.
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    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];
  }

}


/**
 * @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 Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * @dev https://github.com/ethereum/EIPs/issues/20
 * @dev Based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) internal allowed;


  /**
   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
   */
  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[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    Transfer(_from, _to, _value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   *
   * 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
   * @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;
    Approval(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 specifying the amount of tokens still available for the spender.
   */
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _addedValue The amount of tokens to increase the allowance by.
   */
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   *
   * approve should be called when allowed[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param _spender The address which will spend the funds.
   * @param _subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

}


contract ABL is StandardToken, OwnableToken {
    using SafeMath for uint256;

    // Token Distribution Rate
    uint256 public constant SUM = 400000000;   // totalSupply
    uint256 public constant DISTRIBUTION = 221450000; // distribution
    uint256 public constant DEVELOPERS = 178550000;   // developer

    // Token Information
    string public constant name = "Airbloc";
    string public constant symbol = "ABL";
    uint256 public constant decimals = 18;
    uint256 public totalSupply = SUM.mul(10 ** uint256(decimals));

    // token is non-transferable until owner calls unlock()
    // (to prevent OTC before the token to be listed on exchanges)
    bool isTransferable = false;

    function ABL(
        address _dtb,
        address _dev
        ) public {
        require(_dtb != address(0));
        require(_dev != address(0));
        require(DISTRIBUTION + DEVELOPERS == SUM);

        balances[_dtb] = DISTRIBUTION.mul(10 ** uint256(decimals));
        emit Transfer(address(0), _dtb, balances[_dtb]);

        balances[_dev] = DEVELOPERS.mul(10 ** uint256(decimals));
        emit Transfer(address(0), _dev, balances[_dev]);
    }

    function unlock() external onlyOwner {
        isTransferable = true;
    }

    function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
        require(isTransferable || owners[msg.sender]);
        return super.transferFrom(_from, _to, _value);
    }

    function transfer(address _to, uint256 _value) public returns (bool) {
        require(isTransferable || owners[msg.sender]);
        return super.transfer(_to, _value);
    }

//////////////////////
//  mint and burn   //
//////////////////////
    function mint(
        address _to,
        uint256 _amount
        ) onlyOwner public returns (bool) {
        require(_to != address(0));
        require(_amount >= 0);

        uint256 amount = _amount.mul(10 ** uint256(decimals));

        totalSupply = totalSupply.add(amount);
        balances[_to] = balances[_to].add(amount);

        emit Mint(_to, amount);
        emit Transfer(address(0), _to, amount);

        return true;
    }

    function burn(
        uint256 _amount
        ) onlyOwner public {
        require(_amount >= 0);
        require(_amount <= balances[msg.sender]);

        totalSupply = totalSupply.sub(_amount.mul(10 ** uint256(decimals)));
        balances[msg.sender] = balances[msg.sender].sub(_amount.mul(10 ** uint256(decimals)));

        emit Burn(msg.sender, _amount.mul(10 ** uint256(decimals)));
        emit Transfer(msg.sender, address(0), _amount.mul(10 ** uint256(decimals)));
    }

    event Mint(address indexed _to, uint256 _amount);
    event Burn(address indexed _from, uint256 _amount);
}