#!/usr/bin/env python3
"""
This script allows direct interaction with a pmac-Controller over an ethernet connection.
To read the manual, simply run this script without any arguments.

Stefan Mathis, December 2024
"""

import struct
import socket
import curses
import time


def packPmacCommand(command):
    # 0x40 = VR_DOWNLOAD
    # 0xBF = VR_PMAC_GETRESPONSE
    buf = struct.pack('BBHHH', 0x40, 0xBF, 0, 0, socket.htons(len(command)))
    buf = buf + command.encode('utf-8')
    return buf


def readPmacReply(sock):
    msg = bytearray()
    expectAck = True
    sock.settimeout(2.0)
    while True:
        try:
            b = sock.recv(1)
        except socket.timeout:
            print('Timed out')
            return None
        bint = int.from_bytes(b, byteorder='little')
        if bint == 2 or bint == 7:  # STX or BELL
            expectAck = False
            continue
        if expectAck and bint == 6:  # ACK
            return bytes(msg)
        else:
            if bint == 13 and not expectAck:  # CR
                return bytes(msg)
            else:
                msg.append(bint)


if __name__ == "__main__":
    from sys import argv

    try:

        addr = argv[1].split(':')
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect((addr[0], int(addr[1])))

        if len(argv) == 3:
            buf = packPmacCommand(argv[2])
            s.send(buf)
            reply = readPmacReply(s)
            if reply:
                print(reply.decode('utf-8') + '\n')

        else:

            try:

                stdscr = curses.initscr()
                curses.noecho()
                curses.cbreak()
                stdscr.keypad(True)
                stdscr.scrollok(True)

                stdscr.addstr(">> ")
                stdscr.refresh()

                history = [""]
                ptr = len(history) - 1

                while True:
                    c = stdscr.getch()
                    if c == curses.KEY_RIGHT:
                        (y, x) = stdscr.getyx()
                        if x < len(history[ptr]) + 3:
                            stdscr.move(y, x+1)
                            stdscr.refresh()
                    elif c == curses.KEY_LEFT:
                        (y, x) = stdscr.getyx()
                        if x > 3:
                            stdscr.move(y, x-1)
                            stdscr.refresh()
                    elif c == curses.KEY_UP:
                        if ptr > 0:
                            ptr -= 1
                            stdscr.addch("\r")
                            stdscr.clrtoeol()
                            stdscr.addstr(">> " + history[ptr])
                    elif c == curses.KEY_DOWN:
                        if ptr < len(history) - 1:
                            ptr += 1
                            stdscr.addch("\r")
                            stdscr.clrtoeol()
                            stdscr.addstr(">> " + history[ptr])
                    elif c == curses.KEY_ENTER or c == ord('\n') or c == ord('\r'):
                        if history[ptr] == 'quit':
                            break

                        # because of arrow keys move back to the end of the line
                        (y, x) = stdscr.getyx()
                        stdscr.move(y, 3+len(history[ptr]))

                        if history[ptr]:
                            buf = packPmacCommand(history[ptr])
                            s.send(buf)
                            reply = readPmacReply(s)
                            stdscr.addstr("\n" + reply.decode('utf-8')[0:-1])

                        if ptr == len(history) - 1 and history[ptr] != "":
                            history += [""]
                        else:
                            history[-1] = ""
                        ptr = len(history) - 1

                        stdscr.addstr("\n>> ")
                        stdscr.refresh()

                    else:
                        if ptr < len(history) - 1:  # Modifying previous input
                            if len(history[-1]) == 0:
                                history[-1] = history[ptr]
                                ptr = len(history) - 1

                            else:
                                history += [history[ptr]]
                                ptr = len(history) - 1

                        if c == curses.KEY_BACKSPACE:
                            if len(history[ptr]) == 0:
                                continue
                            (y, x) = stdscr.getyx()
                            history[ptr] = history[ptr][0:x-4] + \
                                history[ptr][x-3:]
                            stdscr.addch("\r")
                            stdscr.clrtoeol()
                            stdscr.addstr(">> " + history[ptr])
                            stdscr.move(y, x-1)
                            stdscr.refresh()

                        else:
                            (y, x) = stdscr.getyx()
                            history[ptr] = history[ptr][0:x-3] + \
                                chr(c) + history[ptr][x-3:]
                            stdscr.addch("\r")
                            stdscr.clrtoeol()
                            stdscr.addstr(">> " + history[ptr])
                            stdscr.move(y, x+1)
                            stdscr.refresh()

            finally:

                # to quit
                curses.nocbreak()
                stdscr.keypad(False)
                curses.echo()
                curses.endwin()

    except:
        print("""
        Invalid Arguments

        Option 1: Single Command
        ------------------------

        Usage: writeRead.py pmachost:port command
        This then returns the response for command. 

        Option 2: CLI Mode
        ------------------

        Usage: writeRead.py pmachost:port

        You can then type in a command, hit enter, and the response will see
        the reponse, before being prompted to again enter a command. Type
        'quit' to close prompt.
        """)