Classroom_Desktop/scripts/classroom-dvd

#!/usr/bin/env python3

"""Classroom DVD control.

Discs are never played automatically. Inserting a disc only produces a
notification and changes the dock icon; playback always starts from a
deliberate press of the DVD button.
"""

import argparse
import os
import shutil
import subprocess
import sys

sys.path.insert(0, "/usr/local/lib/ekklesia-classroom")
sys.path.insert(
    0,
    os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "lib"),
)

import classroom_optical as optical  # noqa: E402
from classroom_vlc import PLAYER  # noqa: E402

SESSION_TOOL = "/usr/local/bin/classroom-dvd-session"


def notify(title, message, urgency="normal"):
    try:
        subprocess.Popen(
            [
                "notify-send",
                "--app-name=DVD",
                f"--urgency={urgency}",
                "--",
                title,
                message,
            ],
            start_new_session=True,
        )
    except OSError:
        print(f"{title}: {message}", file=sys.stderr)


def play(device):
    """Hand the disc to DVD mode.

    classroom-dvd-session owns the player from here: it puts a black
    surface up immediately, starts VLC behind it, and provides the
    classroom's own controls.

    Started directly, with nothing arranging windows on the way. A second
    session cannot happen — the session takes an exclusive lock on
    dvd.lock and exits if it cannot get it — and bringing an existing one
    back to the front is the panel's job, not this command's. That is
    what replaced the window helper.
    """
    if shutil.which(PLAYER) is None:
        notify(
            "DVD",
            "The DVD player is not installed on this classroom computer.",
        )
        return 1

    subprocess.Popen([SESSION_TOOL], start_new_session=True)

    return 0


def action_toggle(force_play=False):
    device = optical.default_device()

    if device is None:
        notify("DVD", "No DVD drive is connected to this classroom computer.")
        return 1

    status = optical.drive_status(device)

    if status == optical.CDS_DISC_OK:
        return play(device)

    if status == optical.CDS_DRIVE_NOT_READY:
        notify("DVD", "Reading the disc. Please try again in a moment.")
        return 1

    if status == optical.CDS_TRAY_OPEN:
        notify("DVD", "The disc tray is open. Insert a disc to get started.")
        return 1

    if force_play:
        return play(device)

    notify("DVD", "No disc is in the drive. Insert a disc to get started.")
    return 1


def action_status():
    device = optical.default_device()

    if device is None:
        print("drive: none")
        return 1

    status = optical.drive_status(device)

    print(f"drive: {device}")
    print(f"status: {optical.describe(status)}")
    print(f"player: {shutil.which(PLAYER) or 'not installed'}")

    if status == optical.CDS_DISC_OK:
        print(f"disc: {optical.disc_status(device)}")
        return 0

    return 1


def action_eject():
    device = optical.default_device()

    if device is None:
        notify("DVD", "No DVD drive is connected to this classroom computer.")
        return 1

    if not optical.eject(device):
        notify("DVD", "The disc could not be ejected. It may still be playing.")
        return 1

    return 0


def main():
    parser = argparse.ArgumentParser(description="Classroom DVD control.")
    subparsers = parser.add_subparsers(dest="action", required=True)

    subparsers.add_parser("toggle", help="Dock button behaviour")
    subparsers.add_parser("play", help="Start playback even if the drive is unsure")
    subparsers.add_parser("status", help="Report drive and disc state")
    subparsers.add_parser("eject", help="Open the disc tray")

    arguments = parser.parse_args()

    if arguments.action == "toggle":
        return action_toggle()

    if arguments.action == "play":
        return action_toggle(force_play=True)

    if arguments.action == "status":
        return action_status()

    return action_eject()


if __name__ == "__main__":
    sys.exit(main())