# vim:et sts=4 sw=4
#
# ibus-typing-booster - A completion input method for IBus
#
# Copyright (c) 2013-2018 Mike FABIAN <mfabian@redhat.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>
'''
This helper uses GTK 4 to access the primary selection (mouse selection).
On Wayland, GTK 3 cannot access the primary selection at all, but GTK 4 can,
if built with support for the zwp_primary_selection_v1 protocol.

ibus-typing-booster uses GTK 3 and cannot safely mix GTK 3 and GTK 4 in the
same process. Therefore, this helper runs as a separate subprocess to
retrieve the primary selection text using GTK 4, even when the main program
is using GTK 3.
'''
from typing import Optional
import sys
import os
from gi import require_version
# pylint: disable=wrong-import-position
require_version('GLib', '2.0')
require_version('Gio', '2.0')
from gi.repository import Gio, GLib # type: ignore
os.environ['ITB_GTK_VERSION'] = '4'
from itb_gtk import Gdk, Gtk
# pylint: enable=wrong-import-position

class ClipboardApp(Gtk.Application): # type: ignore[misc]
    '''Class used to read the clipboard'''
    def __init__(self) -> None:
        super().__init__(application_id="org.freedesktop.ibus.engine.typing_booster.GetSelection")
        self.window: Optional[Gtk.ApplicationWindow] = None
        self.display: Gdk.Display = Gdk.Display.get_default() # pylint: disable=no-value-for-parameter

    def do_activate(self) -> None: # pylint: disable=arguments-differ
        if 'wayland' in self.display.get_name().lower():
            # A window is needed so that zwp_primary_selection_v1
            # (mouse selection) works on Wayland. When there is no
            # visible window, GTK might delay registration of the
            # app’s data device manager or primary selection device,
            # especially if nothing is mapped on screen.
            self.window = Gtk.ApplicationWindow(application=self)
            self.window.set_default_size(1, 1)
            self.window.set_decorated(False)
            self.window.present() # Must be presented on Wayland
            # Delay clipboard read to allow Wayland registration
            GLib.timeout_add(200, self.try_read_clipboard)
        else:
            self.try_read_clipboard()

    def try_read_clipboard(self) -> bool:
        '''Method to read the clipboard and print the result'''
        clipboard: Gdk.Clipboard = self.display.get_primary_clipboard() # pylint: disable=c-extension-no-member

        def on_text_received(
                clipboard: 'Gdk.Clipboard', result: Gio.AsyncResult) -> None:
            try:
                text: Optional[str] = clipboard.read_text_finish(result)
                if text is not None:
                    print(text)
            except GLib.Error as error:
                print(f'Error reading primary selection: {error}',
                      file=sys.stderr)
            app.quit() # pylint: disable=possibly-used-before-assignment

        clipboard.read_text_async(None, on_text_received)
        return False # Do not repeat timeout

if __name__ == "__main__":
    app = ClipboardApp()
    app.run()