av_control.py

#!/usr/bin/env python

"""
Manage I/O between a collection of A/V devices.

The A/V devices (and some not-so-A/V devices) are each represented by a class
instance derived from the AV_Device API.

The A/V devices are controlled by an AV_Loop instance, which mediates
communication and runtime between the instantiated devices.

Devices may submit commands (strings) to the AV_Loop, which then dispatches the
command to the command handler registered for that command (or falls back to
the empty ('') catch-all command handler if no handler is registered for the
given command).

Additionally, AV_Devices may register I/O handlers with the AV_Loop, which will
then listen for I/O events on the given file descriptors.
"""

import sys
import argparse
from tornado.ioloop import IOLoop

from hdmi_switch import HDMI_Switch
from avr_device import AVR_Device
from http_server import AV_HTTPServer
from av_loop import AV_Loop


Devices = (
    ("hdmi", HDMI_Switch),
    ("avr",  AVR_Device),
    ("http", AV_HTTPServer),
)

AVR_Device.DefaultTTY = "/dev/ttyUSB1"


def main(args):
    parser = argparse.ArgumentParser(
        description="Controller daemon for A/V devices")
    for name, cls in Devices:
        cls.register_args(name, parser)

    IOLoop.configure(AV_Loop, parsed_args=vars(parser.parse_args(args)))
    mainloop = IOLoop.instance()

    for name, cls in Devices:
        try:
            print("*** Initializing %s..." % (cls.Description), end=' ')
            mainloop.add_device(name, cls(mainloop, name))
            print("done")
        except Exception as e:
            print(e)

    if not mainloop.cmd_handlers:
        print("No A/V commands registered. Aborting...")
        return 1

    def cmd_catch_all(empty, cmd):
        """Handle commands that are not handled elsewhere."""
        assert empty == ""
        print("*** Unknown A/V command: '%s'" % (cmd))
    mainloop.add_cmd_handler("", cmd_catch_all)

    print("Starting A/V controller main loop.")
    return mainloop.run()


if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))