#!/usr/bin/env python3
"""
  Usage: macmaster.py  macmasterhost port
    Listen for commands to send and returns reponse
    until exit has been typed

    Mark Koennecke, March 2023
"""

import socket
import struct


class MasterMACS():
    def __init__(self, host, port):
        self._socke = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self._socke.connect((host, int(port)))

    def send(self, command):
        buf = struct.pack('BBBB', 0x05, len(command) + 4, 0,  0x19)
        buf += bytes(command, 'utf-8')
        buf += struct.pack('BB', 0x0D, 0x03)
        self._socke.send(buf)

    def receive(self):
        buf = self._socke.recv(35, socket.MSG_WAITALL)
        if len(buf) < 35:
            raise  EOFException('Master MACS returned only %d bytes, 35 expected' % len(buf))
        idx = buf.find(0x0D)
        ackbyte = buf[idx-1]
        if ackbyte == 0x06:
            ack = 'ACK'
        elif ackbyte == 0x15:
            ack = 'NAK',
        else:
            ack = 'NO'
        reply = buf[4:idx-1].decode('utf-8')
        return ack, reply

if __name__ == "__main__":
    from sys import argv, exit, stdin
    if len(argv) < 3:
        print('Usage:\n\tmacmaster.py machost macport')
        exit(1)
    mac = MasterMACS(argv[1], argv[2])
    while(True):
        # import pdb; pdb.set_trace()
        line = stdin.readline()
        if line.find('exit') >= 0:
            exit(0)
        mac.send(line.strip())
        ack, reply = mac.receive()
        print('%s, %s' %(ack, reply))