taglist: implement untag command

The usual untag command requires an argument. In the taglist, we have a
a shortcut available since a tag is selected. Use that for quickly
removing tags.

alot/buffers/taglist.py

@@ -104,8 +104,16 @@ def focus_last(self):
             lastpos = allpos[0]
             self.body.set_focus(lastpos)
 
+    def get_selected_tagline(self):
+        """
+        returns curently focussed :class:`urwid.AttrMap` tagline widget
+        from the result list.
+        """
+        cols, _ = self.taglist.get_focus()
+        return cols
+
     def get_selected_tag(self):
         """returns selected tagstring or throws AttributeError if none"""
-        cols, _ = self.taglist.get_focus()
+        cols = self.get_selected_tagline()
         tagwidget = cols.original_widget.get_focus()
         return tagwidget.tag

alot/commands/taglist.py

@@ -6,6 +6,7 @@
 
 from . import Command, registerCommand
 from .globals import SearchCommand
+from .. import commands
 
 MODE = 'taglist'
 
@@ -45,3 +46,39 @@ async def apply(self, ui):
             tagstring = '"%s"' % tagstring
         cmd = SearchCommand(query=['tag:%s' % tagstring])
         await ui.apply_command(cmd)
+
+
+@registerCommand(MODE, 'untag')
+class UntagCommand(Command):
+
+    """remove selected tag from all messages within original buffer"""
+    async def apply(self, ui):
+        taglistbuffer = ui.current_buffer
+        taglinewidget = taglistbuffer.get_selected_tagline()
+        try:
+            tag = taglistbuffer.get_selected_tag()
+        except AttributeError:
+            logging.debug("taglist untag without tag selection")
+            return
+        tagstring = 'tag:"%s"' % tag
+        querystring = taglistbuffer.querystring
+        if querystring:
+            fullquerystring = '(%s) AND %s' % (querystring, tagstring)
+        else:
+            fullquerystring = tagstring
+
+        def refresh():
+            if taglinewidget in taglistbuffer.taglist:
+                taglistbuffer.taglist.remove(taglinewidget)
+            if tag in taglistbuffer.tags:
+                taglistbuffer.tags.remove(tag)
+            taglistbuffer.rebuild()
+            ui.update()
+
+        try:
+            ui.dbman.untag(fullquerystring, [tag])
+        except DatabaseROError:
+            ui.notify('index in read-only mode', priority='error')
+            return
+
+        await ui.apply_command(commands.globals.FlushCommand(callback=refresh))

docs/source/usage/modes/taglist.rst

@@ -19,3 +19,10 @@ The following commands are available in taglist mode:
     search for messages with selected tag within original buffer
 
 
+.. _cmd.taglist.untag:
+
+.. describe:: untag
+
+    remove selected tag from all messages within original buffer
+
+