Refac.

setsysmode

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+#! /usr/bin/env python3
+"""Sets the system mode."""
+
+from argparse import ArgumentParser
+from subprocess import DEVNULL, CalledProcessError, check_call, run
+from sys import stderr
+
+
+DESCRIPTION = 'Sets or toggles the system mode.'
+LAPTOP_MODE_SERVICE = 'laptop-mode.service'
+TABLET_MODE_SERVICE = 'tablet-mode.service'
+
+
+def get_arguments():
+    """Returns the CLI arguments."""
+
+    parser = ArgumentParser(description=DESCRIPTION)
+    parser.add_argument(
+        '-n', '--notify', action='store_true',
+        help='display an on-screen notification')
+    subparsers = parser.add_subparsers(dest='mode')
+    subparsers.add_parser('toggle', help='toggles the system mode')
+    subparsers.add_parser('laptop', help='switch to laptop mode')
+    subparsers.add_parser('tablet', help='switch to tablet mode')
+    subparsers.add_parser('default', help='do not disable any input devices')
+    return parser.parse_args()
+
+
+def systemctl(action, unit, *, root=False):
+    """Runs systemctl."""
+
+    command = ['/usr/bin/sudo'] if root else []
+    command.append('systemctl')
+    command.append(action)
+    command.append(unit)
+
+    try:
+        check_call(command, stdout=DEVNULL)     # Return 0 on success.
+    except CalledProcessError:
+        return False
+
+    return True
+
+
+def notify_send(summary, body=None):
+    """Sends the respective message."""
+
+    command = ['/usr/bin/notify-send', summary]
+
+    if body is not None:
+        command.append(body)
+
+    return run(command, stdout=DEVNULL)
+
+
+def notify_laptop_mode():
+    """Notifies about laptop mode."""
+
+    return notify_send('Laptop mode.', 'The system is now in laptop mode.')
+
+
+def notify_tablet_mode():
+    """Notifies about tablet mode."""
+
+    return notify_send('Tablet mode.', 'The system is now in tablet mode.')
+
+
+def toggle_mode(notify):
+    """Toggles between laptop and tablet mode."""
+
+    if systemctl('status', LAPTOP_MODE_SERVICE):
+        systemctl('stop', LAPTOP_MODE_SERVICE, root=True)
+        systemctl('start', TABLET_MODE_SERVICE, root=True)
+
+        if notify:
+            notify_tablet_mode()
+    else:
+        systemctl('stop', TABLET_MODE_SERVICE, root=True)
+        systemctl('start', LAPTOP_MODE_SERVICE, root=True)
+
+        if notify:
+            notify_laptop_mode()
+
+
+def default_mode(notify):
+    """Restores all blocked input devices."""
+
+    systemctl('stop', LAPTOP_MODE_SERVICE, root=True)
+    systemctl('stop', TABLET_MODE_SERVICE, root=True)
+
+    if notify:
+        notify_send('Default mode.', 'The system is now in default mode.')
+
+
+def laptop_mode(notify):
+    """Starts the laptop mode."""
+
+    systemctl('stop', TABLET_MODE_SERVICE, root=True)
+    systemctl('start', LAPTOP_MODE_SERVICE, root=True)
+
+    if notify:
+        notify_laptop_mode()
+
+
+def tablet_mode(notify):
+    """Starts the tablet mode."""
+
+    systemctl('stop', LAPTOP_MODE_SERVICE, root=True)
+    systemctl('start', TABLET_MODE_SERVICE, root=True)
+
+    if notify:
+        notify_tablet_mode()
+
+
+def main():
+    """Runs the main program."""
+
+    arguments = get_arguments()
+
+    if arguments.mode == 'toggle':
+        toggle_mode(arguments.notify)
+    elif arguments.mode == 'default':
+        default_mode(arguments.notify)
+    elif arguments.mode == 'laptop':
+        laptop_mode(arguments.notify)
+    elif arguments.mode == 'tablet':
+        tablet_mode(arguments.notify)
+    else:
+        print('Must specify a mode.', file=stderr, flush=True)