pragma solidity 0.4.25;

/**
 * @title ERC20Basic
 * @dev Simpler version of ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/179
 */
contract ERC20Basic {
  uint256 public totalSupply;
  function balanceOf(address who) public constant 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 constant 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 SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a); 
    return a - b; 
  } 
  
  function add(uint256 a, uint256 b) internal pure returns (uint256) { 
    uint256 c = a + b; assert(c >= a);
    return c;
  }

}

/**
 * @title Basic token
 * @dev Basic version of StandardToken, with no allowances.
 */
contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  /**
  * @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); 
    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 constant returns (uint256 balance) { 
    return balances[_owner]; 
  }
} 

/** 
 * @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); 
    emit 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; 
    emit 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 constant returns (uint256 remaining) { 
    return allowed[_owner][_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 
  */ 
  function increaseApproval (address _spender, uint _addedValue) public returns (bool success) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]); 
    return true; 
  }

  function decreaseApproval (address _spender, uint _subtractedValue) public returns (bool success) {
    uint oldValue = allowed[msg.sender][_spender]; 
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    }
    emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;
  }

  function () public payable {
    ///revert();
  }

}

/**
 * @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;

  /**
   * @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);
    _;
  }
  
}


contract GoodPriceToken is StandardToken, Ownable {
    
    string public constant name = "GoodPrice";
    string public constant symbol = "GPS";
    uint32 public constant decimals = 18;
    
    uint256 public constant totalSupply = 300000000 * (10 ** 18);
    
    constructor(address [] _holders, uint256 [] _tokens) public {
        uint256 total = 0;
        for(uint i=0; i<_holders.length; ++i) {
            balances[_holders[i]] = _tokens[i];
            total += _tokens[i];
            emit Transfer(address(this), _holders[i], _tokens[i]);
        }
        require(total == totalSupply);
    }
    
    function transferSale(address addr, uint256 tokens) public onlyOwner {
        require(addr != address(0));
        require(balances[address(this)] >= tokens);
        
        balances[addr] = balances[addr].add(tokens);
        balances[address(this)] = balances[address(this)].sub(tokens);
        emit Transfer(address(this), addr, tokens);
    }    
}