elevators-sockets.py

import socket

# TODO handle exceptions everywhere

# XXX describe/document usage
# XXX create github repo

# XXX send project to github
# jakub.vojvoda@gmail.com
# lukbej@gmail.com
# enum@tutanota.com
# kremes18@gmail.com

class SocketElevatorController:
    def __init__(self):
        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        # XXX except ConnectionRefusedError - tell user to launch server first
        self.sock.connect(("127.0.0.1", 4242))
        self.recvbuf = b""

    def shutdown(self):
        print( "Shutting down" )
        self.sock.close()

    def request_beep(self, time_step, current_floor, target_floor ):
        # in:  type==beep, time step, current floor, target floor,
        # out: type==beep, time step, elevator number
        self.send_msg( str.encode("beep {} {} {}\n".format( time_step, current_floor, target_floor ) ) )
        reply = self.recv_msg_blocking()
        parts = reply.split()
        print( parts )
        print( parts[0] )
        if parts[0] != b"beep":
            print("Unexpected reply (incorrect message type)!")
            return None
        if len(parts) < 3:
            print("Unexpected reply (too few fields)!")
            return None
        try:
            return (int(parts[1]), int(parts[2]))
        except ValueError:
            print("Unexpected reply (unexpected data type)!")
            return None

    def request_update(self, time_step, elevator_states):
        # in:  type==update, time step, [(elev_1_position,elev_1_state), ..., (elev_n_position, elev_n_state)]
        # out: type==update, time step, [(elev_1_position,elev_1_command), ..., (elev_n_position, elev_n_command)]
        states_str = " ".join([ "{} {}".format(pos, state) for (pos, state) in elevator_states])
        msg = str.encode("update {} {} {}\n".format(time_step, len(elevator_states), states_str) )
        self.send_msg( msg )
        reply = self.recv_msg_blocking()
        parts = reply.split()
        if parts[0] != b"update":
            print("Unexpected reply (incorrect message type)!")
            return None
        if len(parts) < 3:
            print("Unexpected reply (too few fields)!")
            return None
        try:
            time_step  = int(parts[1])
            elev_count = int(parts[2])
            elev_commands = []
            if len(parts) < 3 + 2 * elev_count:
                print("Unexpected reply (too few fields)!")
                return None
            for i in range(elev_count):
                position = int(3 + i * 2)
                command  = str(3 + i * 2 + 1)
                elev_commands.append( (position, command) )
            return (time_step, elev_commands)
        except ValueError:
            print("Unexpected reply (unexpected data type)!")
            return None

    def request_end(self):
        self.sock.sendall(b"Stop\n")

    def send_msg(self, msg):
        # TODO check that the msg ends with newline
        print( "Sending message: '{}'".format(msg) )
        self.sock.sendall( msg )

    def recv_msg_blocking(self):
        # TODO timeout
        while True:
            self.recvbuf += self.sock.recv(128)
            if b"\n" in self.recvbuf:
                (msg, newline, self.recvbuf) = self.recvbuf.partition(b"\n")
                print("Received message: '{}'".format(msg))
                return msg

if __name__ == "__main__":
    api = SocketElevatorController()
    # going from 4 to 8 at time 1
    (time, assigned_elevator) = api.request_beep( 1, 4, 8 )
    # state of 4 elevators at time 1
    (time, elevator_commands) = api.request_update( 1, [(1, "is_closed"), (1, "moving_up"), (5, "moving_down"), (7, "is_open")] )

    api.request_end()
    api.shutdown()