README/keys/model/ui/boxes/core: Add draft message feature.

This adds support for a minimal draft message feature, storing a single
draft message. The draft is stored for each session, and server-side
storage will be added later when the API endpoints are available.

It functions as follows:
* On pressing SAVE_AS_DRAFT(`meta s`), a popup is shown confirming whether
  the message should be saved as a draft. This is not permitted when the
  message is empty, a message is being edited, or the current message is
  the same as a saved draft. The pop-up is bypassed when there is no
  saved draft.
* The saved draft can be opened for editing by using the OPEN_DRAFT(`d`)
  key.

Test amended.

Author: kaustubh-nair

README.md

@@ -119,6 +119,8 @@ source ~/.zshenv
 | ----------------------------------------------------- | --------------------------------------------- |
 | Show/hide help menu                                   | <kbd>?</kbd>                                  |
 | Show/hide about menu                                  | <kbd>Meta</kbd> + <kbd>?</kbd>                |
+| Save current message as a draft                       | <kbd>Meta</kbd> + <kbd>s</kbd>                |
+| Open draft message saved in this session              | <kbd>d</kbd>                                  |
 | Go back                                               | <kbd>esc</kbd>                                |
 | Redraw screen                                         | <kbd>Ctrl</kbd> + <kbd>l</kbd>                |
 | Quit                                                  | <kbd>Ctrl</kbd> + <kbd>C</kbd>                |

tests/ui_tools/test_boxes.py

@@ -430,6 +430,8 @@ def test_keypress_typeahead_mode_autocomplete_key(self, mocker, write_box,
                                                       expect_footer_was_reset,
                                                       key):
         write_box.is_in_typeahead_mode = current_typeahead_mode
+        write_box.msg_write_box = mocker.Mock()
+        write_box.msg_write_box.edit_text = ''
         size = (20,)
 
         write_box.keypress(size, key)

zulipterminal/config/keys.py

@@ -18,6 +18,16 @@
         'excluded_from_random_tips': True,
         'key_category': 'general',
     }),
+    ('SAVE_AS_DRAFT', {
+        'keys': {'meta s'},
+        'help_text': 'Save current message as a draft',
+        'key_category': 'general',
+    }),
+    ('OPEN_DRAFT', {
+        'keys': {'d'},
+        'help_text': 'Open draft message saved in this session',
+        'key_category': 'general',
+    }),
     ('ABOUT', {
         'keys': {'meta ?'},
         'help_text': 'Show/hide about menu',

zulipterminal/core.py

@@ -174,6 +174,12 @@ def search_messages(self, text: str) -> None:
         if 0 <= focus_position < len(w_list):
             self.view.message_view.set_focus(focus_position)
 
+    def save_draft_confirmation_popup(self, message: Message) -> None:
+        question = urwid.Text('Save this message as a draft?'
+                              ' (This will overwrite the existing draft.)')
+        save_draft = partial(self.model.save_draft, message)
+        self.loop.widget = PopUpConfirmationView(self, question, save_draft)
+
     def stream_muting_confirmation_popup(self, button: Any) -> None:
         currently_muted = self.model.is_muted_stream(button.stream_id)
         type_of_action = "unmuting" if currently_muted else "muting"

zulipterminal/model.py

@@ -135,6 +135,7 @@ def __init__(self, controller: Any) -> None:
 
         self.unread_counts = classify_unread_counts(self)
 
+        self.draft = None  # type: Optional[Message]
         self.new_user_input = True
         self._start_presence_updates()
 
@@ -285,6 +286,13 @@ def react_to_message(self,
             response = self.client.add_reaction(reaction_to_toggle_spec)
         display_error_if_present(response, self.controller)
 
+    def session_draft_message(self) -> Optional[Message]:
+        return self.draft
+
+    def save_draft(self, message: Message) -> None:
+        self.draft = message
+        self.controller.view.set_footer_text("Saved message as draft", 3)
+
     @asynch
     def toggle_message_star_status(self, message: Message) -> None:
         base_request = dict(flag='starred', messages=[message['id']])

zulipterminal/ui.py

@@ -217,6 +217,27 @@ def keypress(self, size: Tuple[int, int], key: str) -> Optional[str]:
             search_box.set_edit_text("")
             self.controller.enter_editor_mode_with(search_box)
             return key
+        elif is_command_key('OPEN_DRAFT', key):
+            draft = self.model.session_draft_message()
+            if draft:
+                if draft['type'] == 'stream':
+                    self.write_box.stream_box_view(
+                        caption=draft['display_recipient'],
+                        title=draft['subject'],
+                        stream_id=draft['stream_id'],
+                    )
+                elif draft['type'] == 'private':
+                    self.write_box.private_box_view(
+                        email=draft['display_recipient'],
+                    )
+                content = draft['content']
+                self.write_box.msg_write_box.edit_text = content
+                self.write_box.msg_write_box.edit_pos = len(content)
+                self.middle_column.set_focus('footer')
+            else:
+                self.set_footer_text('No draft message was saved in'
+                                     ' this session.', 3)
+            return key
         elif is_command_key('ABOUT', key):
             self.controller.show_about()
             return key

zulipterminal/ui_tools/boxes.py

@@ -307,6 +307,26 @@ def keypress(self, size: urwid_Size, key: str) -> Optional[str]:
             self.view.controller.exit_editor_mode()
             self.main_view(False)
             self.view.middle_column.set_focus('body')
+        elif is_command_key('SAVE_AS_DRAFT', key):
+            if not self.msg_edit_id:
+                if self.to_write_box:
+                    message = Message(
+                            display_recipient=self.to_write_box.edit_text,
+                            content=self.msg_write_box.edit_text,
+                            type='private',
+                    )
+                elif self.stream_id:
+                    message = Message(
+                        display_recipient=self.stream_write_box.edit_text,
+                        content=self.msg_write_box.edit_text,
+                        subject=self.title_write_box.edit_text,
+                        stream_id=self.stream_id,
+                        type='stream',
+                    )
+                if not self.model.draft:
+                    self.model.save_draft(message)
+                if message != self.model.draft:
+                    self.view.controller.save_draft_confirmation_popup(message)
         elif is_command_key('CYCLE_COMPOSE_FOCUS', key):
             if len(self.contents) == 0:
                 return key