Allow installing new metadata sources from the configure metadata download window

src/calibre/gui2/dialogs/plugin_updater.py

@@ -538,6 +538,7 @@ class PluginUpdaterDialog(SizePersistedDialog):
 
     initial_extra_size = QSize(350, 100)
     forum_label_text = _('Plugin homepage')
+    warn_about_neededing_restart = True
 
     @property
     def gui(self):
@@ -546,6 +547,7 @@ class PluginUpdaterDialog(SizePersistedDialog):
 
     def __init__(self, parent, initial_filter=FILTER_UPDATE_AVAILABLE, initial_category: Category | None = None):
         SizePersistedDialog.__init__(self, parent, 'Plugin Updater plugin:plugin updater dialog')
+        self.number_installed = 0
         self.forum_link = None
         self.zip_url = None
         self.model = None
@@ -855,7 +857,11 @@ class PluginUpdaterDialog(SizePersistedDialog):
             widget.gui = self.gui
             widget.check_for_add_to_toolbars(plugin, previously_installed=plugin.name in installed_plugins)
             self.gui.status_bar.showMessage(_('Plugin installed: %s') % display_plugin.name)
+            if self.warn_about_neededing_restart:
                 do_restart = notify_on_successful_install(self.gui, plugin)
+            else:
+                info_dialog(self, _('Plugin installed'), _('The plugin {} was successfully installed.').format(display_plugin.name), show=True)
+            self.number_installed += 1
             display_plugin.plugin = plugin
             # We cannot read the 'actual' version information as the plugin will not be loaded yet
             display_plugin.installed_version = display_plugin.available_version

src/calibre/gui2/metadata/single.py

@@ -322,7 +322,11 @@ class MetadataSingleDialogBase(QDialog):
 
         self.fetch_metadata_button = b = CenteredToolButton(QIcon.ic('download-metadata.png'), _('&Download metadata'), self)
         b.setPopupMode(QToolButton.ToolButtonPopupMode.DelayedPopup)
-        b.setToolTip(_('Download metadata for this book [%s]') % self.download_shortcut.key().toString(QKeySequence.SequenceFormat.NativeText))
+        b.setToolTip(_(
+            'Download metadata for this book [{}]\n\nMetadata includes title, authors, series, covers, etc.\n'
+            'For improved results, you can install more metadata sources,\n'
+            'by clicking the configure button to the right.').format(
+                self.download_shortcut.key().toString(QKeySequence.SequenceFormat.NativeText)))
         self.fetch_metadata_button.clicked.connect(self.fetch_metadata)
         self.fetch_metadata_menu = m = QMenu(self.fetch_metadata_button)
         m.addAction(QIcon.ic('edit-undo.png'), _('Undo last metadata download'), self.undo_fetch_metadata)

src/calibre/gui2/preferences/metadata_sources.py

@@ -5,8 +5,6 @@ __license__   = 'GPL v3'
 __copyright__ = '2011, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-from operator import attrgetter
-
 from qt.core import (
     QAbstractListModel,
     QAbstractTableModel,
@@ -29,6 +27,7 @@ from calibre.ebooks.metadata.sources.prefs import msprefs
 from calibre.gui2 import error_dialog, question_dialog
 from calibre.gui2.preferences import ConfigWidgetBase, test_widget
 from calibre.gui2.preferences.metadata_sources_ui import Ui_Form
+from calibre.utils.icu import primary_sort_key
 from calibre.utils.localization import ngettext
 from polyglot.builtins import iteritems
 
@@ -43,10 +42,16 @@ class SourcesModel(QAbstractTableModel):  # {{{
         self.enabled_overrides = {}
         self.cover_overrides = {}
 
+    def reload_plugins(self):
+        self.beginResetModel()
+        self.plugins = list(all_metadata_plugins())
+        self.plugins.sort(key=lambda p: primary_sort_key(p.name))
+        self.endResetModel()
+
     def initialize(self):
         self.beginResetModel()
         self.plugins = list(all_metadata_plugins())
-        self.plugins.sort(key=attrgetter('name'))
+        self.plugins.sort(key=lambda p: primary_sort_key(p.name))
         self.enabled_overrides = {}
         self.cover_overrides = {}
         self.endResetModel()
@@ -352,6 +357,16 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         l = self.page.layout()
         l.setStretch(0, 1)
         l.setStretch(1, 1)
+        self.add_new_source_button.clicked.connect(self.add_new_source)
+
+    def add_new_source(self):
+        from calibre.gui2.dialogs.plugin_updater import FILTER_NOT_INSTALLED, Category, PluginUpdaterDialog
+        d = PluginUpdaterDialog(self, initial_filter=FILTER_NOT_INSTALLED, initial_category=Category.MetadataSource)
+        d.warn_about_neededing_restart = False
+        d.exec()
+        if d.number_installed:
+            self.sources_model.reload_plugins()
+            self.fields_model.initialize()
 
     def context_menu(self, pos):
         m = QMenu(self)

src/calibre/gui2/preferences/metadata_sources.ui

@@ -77,6 +77,17 @@
             </property>
            </widget>
           </item>
+          <item>
+           <widget class="QPushButton" name="add_new_source_button">
+            <property name="text">
+             <string>&amp;Add new source</string>
+            </property>
+            <property name="icon">
+             <iconset resource="../../../../resources/images.qrc">
+              <normaloff>:/images/plus.png</normaloff>:/images/plus.png</iconset>
+            </property>
+           </widget>
+          </item>
          </layout>
         </widget>
        </item>
@@ -164,7 +175,7 @@
               <x>0</x>
               <y>0</y>
               <width>350</width>
-              <height>441</height>
+              <height>455</height>
              </rect>
             </property>
             <property name="sizePolicy">