pragma solidity ^0.4.24;

contract owned {
    address public owner;

    constructor() public {
        owner = msg.sender;
    }

    modifier onlyOwner {
        require(msg.sender == owner);
        _;
    }

    function transferOwnership(address newOwner) onlyOwner public {
        owner = newOwner;
    }
}

contract ERC223ReceivingContract { 
  function tokenFallback(address _from, uint _value, bytes _data) public;
}

contract ERC20CompatibleToken is owned {
  using SafeMath for uint;

  // Public variables of the token
  string public name;
  string public symbol;
  uint8 public decimals = 18;
  uint256 public totalSupply;

  mapping(address => uint) balances; // List of user balances.

  event Transfer(address indexed from, address indexed to, uint value);
  event Approval(address indexed owner, address indexed spender, uint256 value);
  mapping (address => mapping (address => uint256)) internal allowed;
  mapping (address => bool) public frozenAccount;

  /**
   * Constrctor function
   *
   * Initializes contract with initial supply tokens to the creator of the contract
   */
  constructor(
      uint256 initialSupply,
      string memory tokenName,
      string memory tokenSymbol, 
      address owner
  ) public {
      totalSupply = initialSupply * 10 ** uint256(decimals);  // Update total supply with the decimal amount
      balances[owner] = totalSupply;                    // Give the creator all initial tokens
      name = tokenName;                                       // Set the name for display purposes
      symbol = tokenSymbol;                                   // Set the symbol for display purposes
  }

  /**
  * @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) {
    uint codeLength;
    bytes memory empty;

    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    require(!frozenAccount[_from]);                         // Check if sender is frozen
    require(!frozenAccount[_to]);                           // Check if recipient is frozen

    assembly {
      // Retrieve the size of the code on target address, this needs assembly .
      codeLength := extcodesize(_to)
    }
    if(codeLength>0) {
      ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
      receiver.tokenFallback(_from, _value, empty);
    }

    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.
   *
   * @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 view returns (uint256) {
    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) {
    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) {
    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;
  }

  /* This generates a public event on the blockchain that will notify clients */
  event FrozenFunds(address target, bool frozen);

  /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
  /// @param target Address to be frozen
  /// @param freeze either to freeze it or not
  function freezeAccount(address target, bool freeze) onlyOwner public {
      frozenAccount[target] = freeze;
      emit FrozenFunds(target, freeze);
  }

}

contract ERC223Interface {
    function balanceOf(address who) public constant returns (uint);
    function transfer(address to, uint value) public;
    function transfer(address to, uint value, bytes data) public;
    event Transfer(address indexed from, address indexed to, uint value, bytes data);
}

/**
 * @title SafeMath
 * @dev Math operations with safety checks that throw on error
 */
library SafeMath {
  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;
  }

  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;
  }

  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 Mango Coin Main Contract
 * @dev Reference implementation of the ERC223 standard token.
 */
contract MangoCoin is owned, ERC223Interface, ERC20CompatibleToken {
    using SafeMath for uint;

    mapping (address => bool) public frozenAccount;

    /* Initializes contract with initial supply tokens to the creator of the contract */
    constructor(
        uint256 initialSupply,
        string memory tokenName,
        string memory tokenSymbol, 
        address owner
    ) ERC20CompatibleToken(initialSupply, tokenName, tokenSymbol, owner) public {}

    /**
     * @dev Transfer the specified amount of tokens to the specified address.
     *      Invokes the `tokenFallback` function if the recipient is a contract.
     *      The token transfer fails if the recipient is a contract
     *      but does not implement the `tokenFallback` function
     *      or the fallback function to receive funds.
     *
     * @param _to    Receiver address.
     * @param _value Amount of tokens that will be transferred.
     * @param _data  Transaction metadata.
     */
    function transfer(address _to, uint _value, bytes _data) public {
        // Standard function transfer similar to ERC20 transfer with no _data .
        // Added due to backwards compatibility reasons .
        uint codeLength;

        require(!frozenAccount[msg.sender]);                    // Check if sender is frozen
        require(!frozenAccount[_to]);                           // Check if recipient is frozen

        assembly {
            // Retrieve the size of the code on target address, this needs assembly .
            codeLength := extcodesize(_to)
        }

        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        if(codeLength>0) {
            ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
            receiver.tokenFallback(msg.sender, _value, _data);
        }
        emit Transfer(msg.sender, _to, _value);
        return ;
    }

    /**
     * @dev Transfer the specified amount of tokens to the specified address.
     *      This function works the same with the previous one
     *      but doesn't contain `_data` param.
     *      Added due to backwards compatibility reasons.
     *
     * @param _to    Receiver address.
     * @param _value Amount of tokens that will be transferred.
     */
    function transfer(address _to, uint _value) public {
        uint codeLength;
        bytes memory empty;

        require(!frozenAccount[msg.sender]);                    // Check if sender is frozen
        require(!frozenAccount[_to]);                           // Check if recipient is frozen

        assembly {
            // Retrieve the size of the code on target address, this needs assembly .
            codeLength := extcodesize(_to)
        }

        balances[msg.sender] = balances[msg.sender].sub(_value);
        balances[_to] = balances[_to].add(_value);
        if(codeLength>0) {
            ERC223ReceivingContract receiver = ERC223ReceivingContract(_to);
            receiver.tokenFallback(msg.sender, _value, empty);
        }
        emit Transfer(msg.sender, _to, _value);
        return ;
    }


    /**
     * @dev Returns balance of the `_owner`.
     *
     * @param _owner   The address whose balance will be returned.
     * @return balance Balance of the `_owner`.
     */
    function balanceOf(address _owner) public constant returns (uint balance) {
        return balances[_owner];
    }

    /* This generates a public event on the blockchain that will notify clients */
    event FrozenFunds(address target, bool frozen);

    /// @notice `freeze? Prevent | Allow` `target` from sending & receiving tokens
    /// @param target Address to be frozen
    /// @param freeze either to freeze it or not
    function freezeAccount(address target, bool freeze) onlyOwner public {
        frozenAccount[target] = freeze;
        emit FrozenFunds(target, freeze);
        return ;
    }

}