Don't lose the focus when refreshing a thread

This commit allows keeping the currently focused message selected
across thread refreshes.

Since this operation can take a long time in large threads, a
`search_threads_rebuild_limit` option is introduced. When defined,
it sets the maximum amount of messages that will be iterated upon
when trying to find the previously focused message.

alot/buffers/search.py

@@ -25,7 +25,10 @@ def __init__(self, ui, initialquery='', sort_order=None):
         default_order = settings.get('search_threads_sort_order')
         self.sort_order = sort_order or default_order
         self.result_count = 0
+        self.search_threads_rebuild_limit = \
+            settings.get('search_threads_rebuild_limit')
         self.isinitialized = False
+        self.threadlist = None
         self.rebuild()
         Buffer.__init__(self, ui, self.body)
 
@@ -44,12 +47,16 @@ def get_info(self):
     def rebuild(self, reverse=False):
         self.isinitialized = True
         self.reversed = reverse
+        selected_thread = None
 
         if reverse:
             order = self._REVERSE[self.sort_order]
         else:
             order = self.sort_order
 
+        if self.threadlist:
+            selected_thread = self.get_selected_thread()
+
         exclude_tags = settings.get_notmuch_setting('search', 'exclude_tags')
         if exclude_tags:
             exclude_tags = [t for t in exclude_tags.split(';') if t]
@@ -72,6 +79,9 @@ def rebuild(self, reverse=False):
         self.listbox = urwid.ListBox(self.threadlist)
         self.body = self.listbox
 
+        if selected_thread:
+            self.focus_thread(selected_thread)
+
     def get_selected_threadline(self):
         """
         returns curently focussed :class:`alot.widgets.ThreadlineWidget`
@@ -92,6 +102,14 @@ def consume_pipe(self):
         while not self.threadlist.empty:
             self.threadlist._get_next_item()
 
+    def consume_pipe_until(self, predicate, limit=0):
+        n = limit
+        while not limit or n > 0:
+            if self.threadlist.empty \
+               or predicate(self.threadlist._get_next_item()):
+                break
+            n -= 1
+
     def focus_first(self):
         if not self.reversed:
             self.body.set_focus(0)
@@ -108,3 +126,13 @@ def focus_last(self):
         else:
             self.rebuild(reverse=True)
 
+    def focus_thread(self, thread):
+        tid = thread.get_thread_id()
+        self.consume_pipe_until(lambda w:
+                                w and w.get_thread().get_thread_id() == tid,
+                                self.search_threads_rebuild_limit)
+
+        for pos, threadlinewidget in enumerate(self.threadlist.get_lines()):
+            if threadlinewidget.get_thread().get_thread_id() == tid:
+                self.body.set_focus(pos)
+                break

alot/defaults/alot.rc.spec

@@ -189,6 +189,10 @@ initial_command = string(default='search tag:inbox AND NOT tag:killed')
 # default sort order of results in a search
 search_threads_sort_order = option('oldest_first', 'newest_first', 'message_id', 'unsorted', default='newest_first')
 
+# maximum amount of threads that will be consumed to try to restore the focus, upon triggering a search buffer rebuild
+# when set to 0, no limit is set (can be very slow in searches that yield thousands of results)
+search_threads_rebuild_limit = integer(default=0)
+
 # in case more than one account has an address book:
 # Set this to True to make tab completion for recipients during compose only
 # look in the abook of the account matching the sender address

docs/source/configuration/alotrc_table

@@ -588,6 +588,17 @@
     :default: [{buffer_no}: search] for "{querystring}", {input_queue} {result_count} of {total_messages} messages
 
 
+.. _search-threads-rebuild-limit:
+
+.. describe:: search_threads_rebuild_limit
+
+     maximum amount of threads that will be consumed to try to restore the focus, upon triggering a search buffer rebuild
+     when set to 0, no limit is set (can be very slow in searches that yield thousands of results)
+
+    :type: integer
+    :default: 0
+
+
 .. _search-threads-sort-order:
 
 .. describe:: search_threads_sort_order