The Nautilus extension is now working

nautilus/nautilus_mat2.py

 #!/usr/bin/env python3
 
-# TODO:
-# - Test with a large amount of files.
-# - Show a progression bar when the removal takes time.
-# - Improve the MessageDialog list for failed items.
+# pylint: disable=unused-argument,len-as-condition,arguments-differ
+
+"""
+Because writing GUI is non-trivial (cf. https://0xacab.org/jvoisin/mat2/issues/3),
+we decided to write a Nautilus extensions instead
+(cf. https://0xacab.org/jvoisin/mat2/issues/2).
+
+The code is a little bit convoluted because Gtk isn't thread-safe,
+so we're not allowed to call anything Gtk-related outside of the main
+thread, so we'll have to resort to using a `queue` to pass "messages" around.
+"""
 
 import os
+import queue
+import threading
 from urllib.parse import unquote
 
 import gi
 gi.require_version('Nautilus', '3.0')
 gi.require_version('Gtk', '3.0')
-from gi.repository import Nautilus, GObject, Gtk, Gio
+from gi.repository import Nautilus, GObject, Gtk, Gio, GLib
 
 from libmat2 import parser_factory
 
-class Mat2Wrapper():
-    def __init__(self, filepath):
-        self.__filepath = filepath
-
-    def remove_metadata(self):
-        parser, mtype = parser_factory.get_parser(self.__filepath)
-        if parser is None:
-            return False, mtype
-        return parser.remove_all(), mtype
+def _remove_metadata(fpath):
+    """ This is a simple wrapper around libmat2, because it's
+    easier and cleaner this way.
+    """
+    parser, mtype = parser_factory.get_parser(fpath)
+    if parser is None:
+        return False, mtype
+    return parser.remove_all(), mtype
 
 class ColumnExtension(GObject.GObject, Nautilus.MenuProvider, Nautilus.LocationWidgetProvider):
-    def notify(self):
-        self.infobar_msg.set_text("Failed to clean some items")
-        self.infobar.show_all()
+    """ This class adds an item to the right-clic menu in Nautilus. """
+    def __init__(self):
+        super().__init__()
+        self.infobar_hbox = None
+        self.infobar = None
+        self.failed_items = list()
 
-    def get_widget(self, uri, window):
-        self.infobar = Gtk.InfoBar()
-        self.infobar.set_message_type(Gtk.MessageType.ERROR)
+    def __infobar_failure(self):
+        """ Add an hbox to the `infobar` warning about the fact that we didn't
+        manage to remove the metadata from every single file.
+        """
         self.infobar.set_show_close_button(True)
-        self.infobar.connect("response", self.__cb_infobar_response)
-
-        hbox = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL)
-        self.infobar.get_content_area().pack_start(hbox, False, False, 0)
+        self.infobar_hbox = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL)
 
         btn = Gtk.Button("Show")
         btn.connect("clicked", self.__cb_show_failed)
-        self.infobar.get_content_area().pack_end(btn, False, False, 0)
+        self.infobar_hbox.pack_end(btn, False, False, 0)
 
-        self.infobar_msg = Gtk.Label()
-        hbox.pack_start(self.infobar_msg, False, False, 0)
+        infobar_msg = Gtk.Label("Failed to clean some items")
+        self.infobar_hbox.pack_start(infobar_msg, False, False, 0)
+
+        self.infobar.get_content_area().pack_start(self.infobar_hbox, True, True, 0)
+        self.infobar.show_all()
+
+    def get_widget(self, uri, window):
+        """ This is the method that we have to implement (because we're
+        a LocationWidgetProvider) in order to show our infobar.
+        """
+        self.infobar = Gtk.InfoBar()
+        self.infobar.set_message_type(Gtk.MessageType.ERROR)
+        self.infobar.connect("response", self.__cb_infobar_response)
 
         return self.infobar
 
     def __cb_infobar_response(self, infobar, response):
+        """ Callback for the infobar close button.
+        """
         if response == Gtk.ResponseType.CLOSE:
+            self.infobar_hbox.destroy()
             self.infobar.hide()
 
     def __cb_show_failed(self, button):
+        """ Callback to show a popup containing a list of files
+        that we didn't manage to clean.
+        """
+
+        # FIXME this should be done only once the window is destroyed
+        self.infobar_hbox.destroy()
         self.infobar.hide()
 
         window = Gtk.Window()
-        hb = Gtk.HeaderBar()
-        window.set_titlebar(hb)
-        hb.props.title = "Metadata removal failed"
+        headerbar = Gtk.HeaderBar()
+        window.set_titlebar(headerbar)
+        headerbar.props.title = "Metadata removal failed"
 
         exit_buton = Gtk.Button("Exit")
         exit_buton.connect("clicked", lambda _: window.close())
-        hb.pack_end(exit_buton)
+        headerbar.pack_end(exit_buton)
 
         box = Gtk.Box(orientation=Gtk.Orientation.VERTICAL)
         window.add(box)
@@ -71,7 +100,7 @@ class ColumnExtension(GObject.GObject, Nautilus.MenuProvider, Nautilus.LocationW
         listbox.set_selection_mode(Gtk.SelectionMode.NONE)
         box.pack_start(listbox, True, True, 0)
 
-        for i, mtype in self.failed_items:
+        for fname, mtype in self.failed_items:
             row = Gtk.ListBoxRow()
             hbox = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL)
             row.add(hbox)
@@ -80,7 +109,7 @@ class ColumnExtension(GObject.GObject, Nautilus.MenuProvider, Nautilus.LocationW
             select_image = Gtk.Image.new_from_gicon(icon, Gtk.IconSize.BUTTON)
             hbox.pack_start(select_image, False, False, 0)
 
-            label = Gtk.Label(os.path.basename(i))
+            label = Gtk.Label(os.path.basename(fname))
             hbox.pack_start(label, True, False, 0)
 
             listbox.add(row)
@@ -90,37 +119,104 @@ class ColumnExtension(GObject.GObject, Nautilus.MenuProvider, Nautilus.LocationW
 
 
     @staticmethod
-    def __validate(f):
-        if f.get_uri_scheme() != "file" or f.is_directory():
+    def __validate(fileinfo):
+        """ Validate if a given file FileInfo `fileinfo` can be processed."""
+        if fileinfo.get_uri_scheme() != "file" or fileinfo.is_directory():
             return False
-        elif not f.can_write():
+        elif not fileinfo.can_write():
             return False
         return True
 
+    def __create_progressbar(self):
+        """ Create the progressbar used to notify that files are currently
+        being processed.
+        """
+        self.infobar.set_show_close_button(False)
+        self.infobar.set_message_type(Gtk.MessageType.INFO)
+        self.infobar_hbox = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL)
+
+        progressbar = Gtk.ProgressBar()
+        self.infobar_hbox.pack_start(progressbar, True, True, 0)
+        progressbar.set_show_text(True)
+
+        self.infobar.get_content_area().pack_start(self.infobar_hbox, True, True, 0)
+        self.infobar.show_all()
+
+        return progressbar
+
+    def __update_progressbar(self, processing_queue, progressbar):
+        """ This method is run via `Glib.add_idle` to update the progressbar."""
+        try:
+            fname = processing_queue.get(block=False)
+        except queue.Empty:
+            return True
+
+        # `None` is the marker put in the queue to signal that every selected
+        # file was processed.
+        if fname is None:
+            self.infobar_hbox.destroy()
+            self.infobar.hide()
+            if len(self.failed_items):
+                self.__infobar_failure()
+            if not processing_queue.empty():
+                print("Something went wrong, the queue isn't empty :/")
+            return False
+
+        progressbar.pulse()
+        progressbar.set_text("Cleaning %s" % fname)
+        progressbar.show_all()
+        self.infobar_hbox.show_all()
+        self.infobar.show_all()
+        return True
+
+    def __clean_files(self, files, processing_queue):
+        """ This method is threaded in order to avoid blocking the GUI
+        while cleaning up the files.
+        """
+        for fileinfo in files:
+            fname = fileinfo.get_name()
+            processing_queue.put(fname)
+
+            if not self.__validate(fileinfo):
+                self.failed_items.append((fname, None))
+                continue
+
+            fpath = unquote(fileinfo.get_uri()[7:])  # `len('file://') = 7`
+            success, mtype = _remove_metadata(fpath)
+            if not success:
+                self.failed_items.append((fname, mtype))
+        processing_queue.put(None)  # signal that we processed all the files
+        return True
+
+
     def __cb_menu_activate(self, menu, files):
+        """ This method is called when the user clicked the "clean metadata"
+        menu item.
+        """
         self.failed_items = list()
-        for f in files:
-            if not self.__validate(f):
-                self.failed_items.append((f.get_name(), None))
-                continue
+        progressbar = self.__create_progressbar()
+        progressbar.set_pulse_step = 1.0 / len(files)
+        self.infobar.show_all()
+
+        processing_queue = queue.Queue()
+        GLib.idle_add(self.__update_progressbar, processing_queue, progressbar)
 
-            fname = unquote(f.get_uri()[7:])
-            ret, mtype = Mat2Wrapper(fname).remove_metadata()
-            if not ret:
-                self.failed_items.append((f.get_name(), mtype))
+        thread = threading.Thread(target=self.__clean_files, args=(files, processing_queue))
+        thread.daemon = True
+        thread.start()
 
-        if len(self.failed_items):
-            self.notify()
 
     def get_background_items(self, window, file):
         """ https://bugzilla.gnome.org/show_bug.cgi?id=784278 """
         return None
 
     def get_file_items(self, window, files):
+        """ This method is the one allowing us to create a menu item.
+        """
         # Do not show the menu item if not a single file has a chance to be
         # processed by mat2.
         if not any(map(self.__validate, files)):
-            return
+            return None
 
         item = Nautilus.MenuItem(
             name="MAT2::Remove_metadata",
@@ -129,4 +225,4 @@ class ColumnExtension(GObject.GObject, Nautilus.MenuProvider, Nautilus.LocationW
         )
         item.connect('activate', self.__cb_menu_activate, files)
 
-        return [item]
+        return [item, ]