# nix-env-apps: Manage declarative nix-env with a GUI
#
# 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, version 3.

import os
import subprocess
from typing import Any, Callable

import gi
gi.require_version("Gtk", "4.0")
from gi.repository import Gtk  # nopep8 pylint: disable=wrong-import-position


def on_edit(_: Any) -> None:
    config_dir = os.path.join(
        os.environ.get('XDG_CONFIG_HOME', os.path.expanduser('~/.config')),
        'nixpkgs',
        'overlays')
    os.makedirs(config_dir, exist_ok=True)
    config_file = os.path.join(config_dir, 'userPackages.nix')
    try:
        with open(config_file, mode="x", encoding='utf-8') as f:
            f.write('''final: prev: {
  userPackages = final.buildEnv {
    name = "userPackages";
    paths = (with final; [



    ];
  };
}
''')
    except FileExistsError:
        pass
    subprocess.run(['xdg-open', config_file], check=True)


def try_exec_terminal(terminal: str, args: list[str]) -> None:
    try:
        os.execvp(terminal, [terminal] + args)
    except FileNotFoundError:
        pass


def on_apply(_: Any) -> None:
    command = ['nix-env', '-riA', 'nixos.userPackages']
    command_string = ' '.join(command)
    close_string = (
        ''' && read -p "SUCCESS: Press ENTER to close this window"''' +
        ''' || read -p "FAILURE: Press ENTER to close this window"''')
    # This should be a simple `xdg-terminal` invocation, but as of 2025,
    # xdg-terminal is extremely broken in Gnome:
    #   * It doesn't cause a terminal window to appear
    #   * It doesn't run the given command
    #   * It exits with status 0, so you can't even tell that it failed
    #   * There's no way for the user to configure their preferred terminal?
    # So we just try launching a whole bunch of terminals until we find one
    # that works
    if os.fork() == 0:
        try_exec_terminal('kitty', ['sh', '-c', command_string + close_string])
        try_exec_terminal(
            'alactritty', [
                '-e', 'sh', '-c', command_string + close_string])
        try_exec_terminal('kgx', ['--'] + command)
        try_exec_terminal(
            'konsole', [
                '-e', 'sh', '-c', command_string + close_string])
        try_exec_terminal('xfce4-terminal', ['--hold', '-e', command_string])
        try_exec_terminal('st', ['sh', '-c', command_string + close_string])
        try_exec_terminal(
            'urxvt', [
                '-e', 'sh', '-c', command_string + close_string])
        try_exec_terminal(
            'xterm', [
                '-e', 'sh', '-c', command_string + close_string])

        # Don't even try gnome-terminal.  Sometimes it will start, but not run the command,
        # and exit with status 0 so we wouldn't even be able to tell that there was a problem.
        # try_exec_terminal('gnome-terminal', ['--', 'sh', '-c', command_string + close_string])

        # As a last resort, run the command directly, without a terminal, where
        # the user probably can't see it.  :(
        os.execvp(command[0], command)


def make_button(label: str, action: Callable[[Any], None]) -> Gtk.Button:
    button = Gtk.Button(label=label)
    button.connect('clicked', action)
    button.set_margin_top(10)
    button.set_margin_start(10)
    button.set_margin_end(10)
    button.set_margin_bottom(10)
    return button


def on_activate(app: Gtk.Application) -> None:
    win = Gtk.ApplicationWindow(application=app)
    win.set_title('Apps')
    box = Gtk.Box()
    box.set_orientation(Gtk.Orientation.VERTICAL)
    edit = make_button("Edit Configuration", on_edit)
    apply = make_button("Apply Configuration", on_apply)
    box.append(edit)
    box.append(apply)
    win.set_child(box)
    win.present()


def main() -> None:
    app = Gtk.Application(application_id='net.chkno.nix-env-apps')
    app.connect('activate', on_activate)
    app.run(None)


if __name__ == '__main__':
    main()