feat(themes): Implement categorized theme menus and debug tools

[kacperpaczos]

• Organizes themes into distinct categories (Mint-X, Mint-Y, etc.) with labeled separators
• Groups theme variants (Light/Dark/Darker) within each category
• Improves menu readability by fixing gray separator background issues
• Enhances theme selection UX with logical grouping and clear visual hierarchy

[kacperpaczos]

Before:

After:

[kacperpaczos]

Before:

After:

[fredcw]

I like it, but you can also end up with lots of themes on separate lines:

Maybe themes in categories that contain only 1 theme can all be grouped together at the top without a category title.

[kacperpaczos]

I believe I have fixed that. @fredcw

[mtwebster]

Hi, the single themes being bunched together is good, but since they're listed first, I don't think we need an actual label for them.

Just:

theme_a theme_b theme_c
theme_d theme_e ...
...
Mint-Y
...
Mint-X
...

[fredcw]

@kacperpaczos

I would write the icons bit like this as it avoids the duplication of code and simplifies it a bit. You could probably do something similar to the gtk/cinnamon section though that's not as long:

if path_suffix == 'icons':
            cache_folder = GLib.get_user_cache_dir() + '/cs_themes/'
            icon_cache_path = os.path.join(cache_folder, 'icons')

            # Retrieve list of known themes/locations for faster loading (icon theme loading and lookup are very slow)
            if os.path.exists(icon_cache_path):
                read_path = icon_cache_path
            else:
                read_path = '/usr/share/cinnamon/cinnamon-settings/icons'
            icon_paths = {}
            with open(read_path, 'r') as cache_file:
                for line in cache_file:
                    theme_name, icon_path = line.strip().split(':')
                    icon_paths[theme_name] = icon_path

            # Collect all themes with their categories and variants
            categorized_themes = []
            for theme in themes:
                category, variant = self.get_theme_category(theme, 'icon')
                categorized_themes.append({'name': theme, 'category': category, 'variant': variant})

            categorized_themes.sort(key=lambda x: (x['category'], variant_sort_order.get(x['variant'], 3), x['name']))

            grouped_themes = {"ungrouped": []}
            for theme_info in categorized_themes:
                if theme_info['category'] not in grouped_themes:
                    grouped_themes[theme_info['category']] = []
                grouped_themes[theme_info['category']].append(theme_info)
            
            for key, group in grouped_themes.items():
                if len(group) == 1:
                    grouped_themes['ungrouped'].append(group[0])
                    grouped_themes[key] = None

            # Reset column position at the start
            chooser.col = 0
            chooser.row = 0
            dump = False

            for key, group in grouped_themes.items():
                if group is None:
                    continue
                if key != 'ungrouped':
                    chooser.add_separator()
                    chooser.add_separator(key)
                    chooser.add_separator()

                for theme_info in group:
                    theme = theme_info['name']

                    theme_path = None
                    if theme in icon_paths:
                        # loop through all possible locations until we find a match
                        # (user folders should override system ones)
                        for theme_folder in ICON_FOLDERS:
                            possible_path = os.path.join(theme_folder, icon_paths[theme])
                            if os.path.exists(possible_path):
                                theme_path = possible_path
                                break
                    if theme_path is None:
                        icon_theme = Gtk.IconTheme()
                        icon_theme.set_custom_theme(theme)
                        folder = icon_theme.lookup_icon('folder', ICON_SIZE, Gtk.IconLookupFlags.FORCE_SVG)
                        if folder:
                            theme_path = folder.get_filename()
                            # we need to get the relative path for storage
                            for theme_folder in ICON_FOLDERS:
                                if os.path.commonpath([theme_folder, theme_path]) == theme_folder:
                                    icon_paths[theme] = os.path.relpath(theme_path, start=theme_folder)
                                    break
                            dump = True

                    if theme_path is None:
                        continue
                    if os.path.exists(theme_path):
                        chooser.add_picture(theme_path, callback, title=theme, id=theme)
                    GLib.timeout_add(5, self.increment_progress, (chooser, inc))
            if dump:
                if not os.path.exists(cache_folder):
                    os.mkdir(cache_folder)

                with open(icon_cache_path, 'w') as cache_file:
                    for theme_name, icon_path_val in icon_paths.items(): # Renamed icon_path to avoid conflict
                        cache_file.write('%s:%s\\n' % (theme_name, icon_path_val))