import socket
import select
import json
import struct

HEADER_LENGTH = 2

class Connection:
    buf = ''

    def __init__(self, address='127.0.0.1', port=4000):
        self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self._read_buffer = ''
        self._packets = []
        self.address = address
        self.port = port
        self.connected = False
        self.read_delimiter = HEADER_LENGTH
        self.handle_read = self.handle_packet_header


    def handle_packet_header(self, data):
        #print 'handle_packet_header: ', data
        format = "!H"
        raw_packet = struct.unpack(format, data)
        #print raw_packet
        packet_length = int(raw_packet[0])

        self.read_delimiter = packet_length
        self.handle_read = self.handle_packet_content

    def handle_packet_content(self, data):
        #print 'handle_packet_content: ', data
        format = "!%ds" % self.read_delimiter
        raw_packet = struct.unpack(format, data)
        #print raw_packet
        self._packets.append(json.loads(raw_packet[0]))
        self.read_delimiter = HEADER_LENGTH
        self.handle_read = self.handle_packet_header

    def connect(self):
        self._sock.connect((self.address, self.port))
        self._sock.setblocking(0)
        self.connected = True

    def _recv(self):
        if self.connected:
            delimiter = self.read_delimiter
            if len(self._read_buffer) < delimiter:
                l = select.select([self._sock], [self._sock], [])
                for s in l[0]:
                    data = s.recv(1024)
                    self._read_buffer += data
            else:
                data = self._read_buffer[:delimiter]
                self._read_buffer = self._read_buffer[delimiter:]
                self.handle_read(data)

    def read(self):
        if self.connected:
            self._recv()
            if self._packets:
                return True
            else:
                return False

    def get_packet(self):
        return self._packets.pop()

    def send(self, msg):
        self._sock.send(msg.rstrip())

    def close(self):
        if self.connected:
            self._sock.close()
            self.connected = False