pragma solidity ^0.4.9;

// import "./receiver_interface.sol";
// import "./erc223_interface.sol";

 contract ContractReceiver {
     
    struct TKN {
        address sender;
        uint value;
        bytes data;
        bytes4 sig;
    }
    
    
    function tokenFallback(address _from, uint _value, bytes _data){
      TKN memory tkn;
      tkn.sender = _from;
      tkn.value = _value;
      tkn.data = _data;
      uint32 u = uint32(_data[3]) + (uint32(_data[2]) << 8) + (uint32(_data[1]) << 16) + (uint32(_data[0]) << 24);
      tkn.sig = bytes4(u);
      
      /* tkn variable is analogue of msg variable of Ether transaction
      *  tkn.sender is person who initiated this token transaction   (analogue of msg.sender)
      *  tkn.value the number of tokens that were sent   (analogue of msg.value)
      *  tkn.data is data of token transaction   (analogue of msg.data)
      *  tkn.sig is 4 bytes signature of function
      *  if data of token transaction is a function execution
      */
    }
}


contract ERC223 {
  uint public totalSupply;
  function balanceOf(address who) constant returns (uint);
  
  function name() constant returns (string _name);
  function symbol() constant returns (string _symbol);
  function decimals() constant returns (uint8 _decimals);
  function totalSupply() constant returns (uint256 _supply);

  function transfer(address to, uint value) returns (bool ok);
  function transfer(address to, uint value, bytes data) returns (bool ok);
  event Transfer(address indexed from, address indexed to, uint value, bytes indexed data);
}


contract SafeMath {
    uint256 constant public MAX_UINT256 =
    0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF;

    function safeAdd(uint256 x, uint256 y) constant internal returns (uint256 z) {
        if (x > MAX_UINT256 - y) throw;
        return x + y;
    }

    function safeSub(uint256 x, uint256 y) constant internal returns (uint256 z) {
        if (x < y) throw;
        return x - y;
    }

    function safeMul(uint256 x, uint256 y) constant internal returns (uint256 z) {
        if (y == 0) return 0;
        if (x > MAX_UINT256 / y) throw;
        return x * y;
    }
}
 
contract StellarToken is ERC223, SafeMath {

  mapping(address => uint) balances;
  
  string public name;
  string public symbol;
  uint8 public decimals;
  uint256 public totalSupply;


  // Constructor
  function StellarToken(uint256 initialSupply, string tokenName, uint8 decimalUnits, string tokenSymbol) {
    balances[msg.sender] = initialSupply;
    name = tokenName;                                   // Set the name for display purposes
    symbol = tokenSymbol;                               // Set the symbol for display purposes
    decimals = decimalUnits;                            // Amount of decimals for display purposes
    totalSupply = initialSupply;
  }


  // Function to access name of token .
  function name() constant returns (string _name) {
      return name;
  }
  // Function to access symbol of token .
  function symbol() constant returns (string _symbol) {
      return symbol;
  }
  // Function to access decimals of token .
  function decimals() constant returns (uint8 _decimals) {
      return decimals;
  }
  // Function to access total supply of tokens .
  function totalSupply() constant returns (uint256 _totalSupply) {
      return totalSupply;
  }
  
  

  // Function that is called when a user or another contract wants to transfer funds .
  function transfer(address _to, uint _value, bytes _data) returns (bool success) {
      
    if(isContract(_to)) {
        return transferToContract(_to, _value, _data);
    }
    else {
        return transferToAddress(_to, _value, _data);
    }
}
  
  // Standard function transfer similar to ERC20 transfer with no _data .
  // Added due to backwards compatibility reasons .
  function transfer(address _to, uint _value) returns (bool success) {
      
    //standard function transfer similar to ERC20 transfer with no _data
    //added due to backwards compatibility reasons
    bytes memory empty;
    if(isContract(_to)) {
        return transferToContract(_to, _value, empty);
    }
    else {
        return transferToAddress(_to, _value, empty);
    }
}

//assemble the given address bytecode. If bytecode exists then the _addr is a contract.
  function isContract(address _addr) private returns (bool is_contract) {
      uint length; 
      assembly {
            //retrieve the size of the code on target address, this needs assembly
            length := extcodesize(_addr)
        }
        if(length>0) {
            return true;
        }
        else {
            return false;
        }
    }

  //function that is called when transaction target is an address
  function transferToAddress(address _to, uint _value, bytes _data) private returns (bool success) {
    if (balanceOf(msg.sender) < _value) throw;
    balances[msg.sender] = safeSub(balanceOf(msg.sender), _value);
    balances[_to] = safeAdd(balanceOf(_to), _value);
    Transfer(msg.sender, _to, _value, _data);
    return true;
  }
  
  //function that is called when transaction target is a contract
  function transferToContract(address _to, uint _value, bytes _data) private returns (bool success) {
    if (balanceOf(msg.sender) < _value) throw;
    balances[msg.sender] = safeSub(balanceOf(msg.sender), _value);
    balances[_to] = safeAdd(balanceOf(_to), _value);
    ContractReceiver reciever = ContractReceiver(_to);
    reciever.tokenFallback(msg.sender, _value, _data);
    Transfer(msg.sender, _to, _value, _data);
    return true;
}


  function balanceOf(address _owner) constant returns (uint balance) {
    return balances[_owner];
  }
}