// Vulnerability label: external
pragma solidity ^0.4.4;

contract SafeMath {
  function safeMul(uint a, uint b) internal returns (uint) {
    uint c = a * b;
    assert(a == 0 || c / a == b);
    return c;
  }

  function safeDiv(uint a, uint b) internal returns (uint) {
    assert(b > 0);
    uint c = a / b;
    assert(a == b * c + a % b);
    return c;
  }

  function safeSub(uint a, uint b) internal returns (uint) {
    assert(b <= a);
    return a - b;
  }

  function safeAdd(uint a, uint b) internal returns (uint) {
    uint c = a + b;
    assert(c>=a && c>=b);
    return c;
  }

  function max64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a >= b ? a : b;
  }

  function min64(uint64 a, uint64 b) internal constant returns (uint64) {
    return a < b ? a : b;
  }

  function max256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a >= b ? a : b;
  }

  function min256(uint256 a, uint256 b) internal constant returns (uint256) {
    return a < b ? a : b;
  }

  function assert(bool assertion) internal {
    if (!assertion) {
      throw;
    }
  }
}



contract Token is SafeMath {

    function totalSupply() constant returns (uint256 supply) {}

    function balanceOf(address _owner) constant returns (uint256 balance) {}

    function transfer(address _to, uint256 _value) returns (bool success) {}

    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {}

    function approve(address _spender, uint256 _value) returns (bool success) {}

    function allowance(address _owner, address _spender) constant returns (uint256 remaining) {}

    event Transfer(address indexed _from, address indexed _to, uint256 _value);
    event Approval(address indexed _owner, address indexed _spender, uint256 _value);
    
}


//ERC20 Complient
contract StandardToken is Token {

    function transfer(address _to, uint256 _value) returns (bool success) {
        if (balances[msg.sender] >= _value && _value > 0) {
            balances[msg.sender] = safeSub(balances[msg.sender],_value);
            balances[_to] = safeAdd(balances[_to],_value);
            Transfer(msg.sender, _to, _value);
            return true;
        } else { return false; }
    }

    function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {
        if (balances[_from] >= _value && allowed[_from][msg.sender] >= _value && _value > 0) {
            balances[_to] =safeAdd(balances[_to],_value);
            balances[_from] =safeSub(balances[_from],_value);
            allowed[_from][msg.sender] = safeSub(allowed[_from][msg.sender],_value); 
            Transfer(_from, _to, _value);
            return true;
        } else { return false; }
    }

    function balanceOf(address _owner) constant returns (uint256 balance) {
        return balances[_owner];
    }

    function approve(address _spender, uint256 _value) returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);
        return true;
    }

    function allowance(address _owner, address _spender) constant returns (uint256 remaining) {
      return allowed[_owner][_spender];
    }

    mapping (address => uint256) balances;
    mapping (address => mapping (address => uint256)) allowed;
    uint256 public totalSupply=   4500000*10**12;
    uint256 public initialSupply= 2500000*10**12;
}



contract HawalaToken is StandardToken {

    function () {
        //if ether is sent to this address, send it back.
        throw;
    }

    string public name;                  
    uint8 public decimals;               
    string public symbol;
    string public version = 'HAT';       


    function HawalaToken(
        ) {
        //Add initial supply to total supply to make  7M. remaining 4.5M lockedd in escrow until pos impl        
        totalSupply+=initialSupply;
        balances[msg.sender] = initialSupply;               
        name = "HawalaToken";                              
        decimals = 12;                            
        symbol = "HAT";                           
    }

   
    function approveAndCall(address _spender, uint256 _value, bytes _extraData) returns (bool success) {
        allowed[msg.sender][_spender] = _value;
        Approval(msg.sender, _spender, _value);

        if(!_spender.call(bytes4(bytes32(sha3("receiveApproval(address,uint256,address,bytes)"))), msg.sender, _value, this, _extraData)) { throw; }
        return true;
    }
}