import json, socket, threading, time

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_socket.bind(("0.0.0.0", 9876))
server_socket.listen(128)

def handler(socket, address):
    """
    Description:
        Handle a WebSocket request.  Parse the incoming request header and return a
    """
    print "Received connection from %s:%d" % (address[0], address[1])

    try:
        # Build HTTP Response Header and Send It
        data = read_until(socket, "\r\n\r\n")
        response = parse_request(data)
        socket.send(response)

        # Loop and keep socket open
        while True:
            data = read_until(socket, "\xFF").strip("\x00\xFF")
            try:
                req = json.loads(data)
            except:
                socket.send("\x00%s\xFF" % json.dumps({"error_msg": "Invalid JSON syntax sent"}))

            if req['task'] == "GetDateTime":
                socket.send("\x00%s\xFF" % json.dumps({"date_time": time.strftime('%X %x %Z')}))
            else:
                socket.send("\x00%s\xFF" % json.dumps({"error_msg": "Unknown task request"}))

    except Exception,e:
        # The dishes are done!
        print e
        socket.close()

def time_update(socket, address):
    try:
        # Loop and keep socket open
        while True:
            socket.send("\x00%s\xFF" % json.dumps({"date_time": time.strftime('%X %x %Z')}))
            time.sleep(5)

        # The dishes are done!
        socket.close()

    except Exception,e:
        # The dishes are done!
        socket.close()

def parse_request (request):
    """
    Description:
        Parse the incoming request header and return a response header.

    Param:
        (String) request:   The request header from the client.

    Return:
        (String) Response header.
    """

    request_details = {}

    # Parse incoming request
    for line in request.split("\r\n"):
        try:
            field, value = line.split(": ",1)
            if field in ["Host","Origin"] and value:
                request_details[field] = value
        except:
            pass

    # Build response header
    response_header = "HTTP/1.1 101 Web Socket Protocol Handshake\r\n" +\
                      "Upgrade: WebSocket\r\n" +\
                      "Connection: Upgrade\r\n" +\
                      "WebSocket-Origin: %s\r\n" % request_details['Origin'] +\
                      "WebSocket-Location: ws://%s/\r\n" % request_details['Host'] +\
                      "WebSocket-Protocol: sample"
    response_header = response_header.strip() + '\r\n\r\n'
    return response_header

def read_until (socket, delimiter):
    """
    Description:
        Read from socket until a delimter is met.

    Params:
        (Socket) socket
        (String) delimter

    Return:
        (String)
    """

    data = ""

    while True:
        byte = socket.recv(4096)

        if len(byte) == 0:
            # client left us :<
            raise Exception("Client closed connection")

        data += byte

        if data.find(delimiter) > -1:
            # found what we were lookin' for, yo!
            return data.rstrip()

# Start Taking Connections
while True:
    client_socket, address = server_socket.accept()
    threading.Thread(target = handler, args = (client_socket, address)).start()
    time.sleep(3)
    # This is just for testing sending data to the client even when it is not requesting data
    threading.Thread(target = time_update, args = (client_socket, address)).start()