pragma solidity ^0.4.11;

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
contract ERC20 {

  uint256 public totalSupply;

  function balanceOf(address _owner) constant returns (uint256);
  function transfer(address _to, uint256 _value) returns (bool);
  function transferFrom(address _from, address _to, uint256 _value) returns (bool);
  function approve(address _spender, uint256 _value) returns (bool);
  function allowance(address _owner, address _spender) constant returns (uint256);
  
  event Transfer(address indexed _from, address indexed _to, uint256 _value);
  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 mul(uint256 a, uint256 b) internal constant returns (uint256) {
    uint256 c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function div(uint256 a, uint256 b) internal constant 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;
  }

  function sub(uint256 a, uint256 b) internal constant returns (uint256) {
    assert(b <= a);
    return a - b;
  }

  function add(uint256 a, uint256 b) internal constant returns (uint256) {
    uint256 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;


  /**
   * @dev The Ownable constructor sets the original `owner` of the contract to the sender
   * account.
   */
  function Ownable() {
    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) onlyOwner {
    if (newOwner != address(0)) {
      owner = newOwner;
    }
  }

}


/**
 * Standard ERC20 token
 *
 * https://github.com/ethereum/EIPs/issues/20
 * Based on code by FirstBlood:
 * https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */

/// @title Proof Presale Token (PROOFP)

contract ProofPresaleToken is ERC20, Ownable {

  using SafeMath for uint256;

  mapping(address => uint) balances;
  mapping (address => mapping (address => uint)) allowed;

  string public constant name = "Proof Presale Token";
  string public constant symbol = "PPT";
  uint8 public constant decimals = 18;
  bool public mintingFinished = false;

  event Mint(address indexed to, uint256 amount);
  event MintFinished();

  function ProofPresaleToken() {}


  // TODO : need to replace throw by 0.4.11 solidity compiler syntax
  function() payable {
    revert();
  }

  function balanceOf(address _owner) constant returns (uint balance) {
    return balances[_owner];
  }
    
  function transfer(address _to, uint _value) returns (bool success) {

    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);

    Transfer(msg.sender, _to, _value);
    return true;
  }

  function transferFrom(address _from, address _to, uint _value) returns (bool success) {
    var _allowance = allowed[_from][msg.sender];

    balances[_to] = balances[_to].add(_value);
    balances[_from] = balances[_from].sub(_value);
    allowed[_from][msg.sender] = _allowance.sub(_value);

    Transfer(_from, _to, _value);
    return true;
  }

  function approve(address _spender, uint _value) returns (bool success) {
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;
  }

  function allowance(address _owner, address _spender) constant returns (uint remaining) {
    return allowed[_owner][_spender];
  }
    
    
  modifier canMint() {
    require(!mintingFinished);
    _;
  }

  /**
   * Function to mint tokens
   * @param _to The address that will recieve the minted tokens.
   * @param _amount The amount of tokens to mint.
   * @return A boolean that indicates if the operation was successful.
   */

  function mint(address _to, uint256 _amount) onlyOwner canMint returns (bool) {
    totalSupply = totalSupply.add(_amount);
    balances[_to] = balances[_to].add(_amount);
    Mint(_to, _amount);
    return true;
  }

  /**
   * @dev Function to stop minting new tokens.
   * @return True if the operation was successful.
   */
  function finishMinting() onlyOwner returns (bool) {
    mintingFinished = true;
    MintFinished();
    return true;
  }

  
  
}