def rudp_recv(sock):
    tmr = select.select([sock], [], [], 1)
    if tmr[0]:
        data, client = sock.recvfrom(BUFFSIZE)
        packetUnpickle = pickle.loads(data)
        return(packetUnpickle[3], packetUnpickle[1], packetUnpickle[0], client)
    else:
        print("Time out error")
        return(False, -1, -1, -1)

def rudp_send(sock, datatype, data, seq, dest):
    pckt = (datatype, seq, len(data), data)
    packetPickle = pickle.dumps(pckt)
    sock.sendto(packetPickle, dest)
    return pckt

# msgtype 1 = client in state 1, still data left
# msgtype 2 = client in state 1, on last packet
# msgtype 3 = server ack for some data
def rudp_server_bit(host, port, fileObj):
    s = socket(AF_INET, SOCK_DGRAM)
    s.bind(("0.0.0.0", port))
    print ("UDP Bit Server ready")
    bit = 0
    previousBit = 0
    firstRecv = True
    clientaddr = ()
    state = 1 # 1 = receiving, 2 = sending ack
    while 1:
        buff, recv, msgtype, client = rudp_recv(s)
        print(buff)
       # print(client)
        if firstRecv == True:
            if client != -1:
                clientaddr = client
        if bit == recv:
            firstRecv = False
            fileObj.write(buff)
            rudp_send(s, 3, "ack".encode(), bit, clientaddr)
            previousBit = bit
            if bit:
                bit = 0
            else:
                bit = 1
            if msgtype == 2: # received last packet
                break
        else: #if incorrect alternating bit
            if (not firstRecv):
                rudp_send(s, 3, "ack".encode(), previousBit, clientaddr)
                print("Incorrect packet received")
    s.close()

def rudp_client_bit(host, port, fileObj):
    s = socket(AF_INET, SOCK_DGRAM)
    s.setblocking(0)
    addr = ("10.10.2.10", port)
    print("UDP bit client ready")
    buff = fileObj.read(BUFFSIZE)
    bit = 0
    firstSent = True
    state = 1
    pckt = []

    packetnum = 0
    # state 1 = sending packets, state 2 = receiving acks

    #while there is still a message to send:
    while buff:
        if state == 1:
            if firstSent:
                pckt = rudp_send(s, 1, buff, bit, addr)
            else:
        # if remaining buff is less than buffsize, on last packet
                if len(buff) < BUFFSIZE:
                    print("Last packet")
                    pckt = rudp_send(s, 2, buff, bit, addr)
                else:
                    pckt = rudp_send(s, 1, buff, bit, addr)
                    state = 2
        elif state == 2:
            print("Made it to state 2")
            rcved = rudp_recv(s)
            print("Received")
            # if timeout or mismatch or some error
            if rcved[1] != bit:
                pckt = rudp_send(s, pckt[0], pckt[3], bit, addr)
                print("Resend packet: " + str(bit))
            elif rcved[1] == bit:
                firstSent = False
                if bit:
                    bit = 0
                else:
                    bit = 1
                buff = fileObj.read(BUFFSIZE)
                state = 1
    #close after transfer finishes
    s.close()