Add single room application

This application lets the user pick a single room and join it. It also
displays error messages when a room could not be joined.

cheuph/euphoria/single_room_application.py

@@ -0,0 +1,118 @@
+from typing import Any, Optional
+
+import urwid
+
+from ..attributed_text_widget import ATWidget
+from ..markup import Attributes
+from .edit_widgets import EditWidget
+from .room_widget import RoomWidget
+
+__all__ = ["SingleRoomApplication"]
+
+class ChooseRoomWidget(urwid.WidgetWrap):
+
+    def __init__(self,
+            room_style: Optional[str] = None,
+            error_attrs: Attributes = {},
+            error_room_attrs: Attributes = {},
+            ) -> None:
+
+        self._room_style = room_style
+        self._error_attrs = error_attrs
+        self._error_room_attrs = error_room_attrs
+
+        self.error = None
+        self.edit = EditWidget("Choose a room:", caption="&", style=room_style)
+        self.filler = urwid.Filler(self.edit)
+        super().__init__(self.filler)
+
+    def render(self, size: Any, focus: Any) -> Any:
+        if self.error:
+            width, _ = size
+            rows = self.error.rows((width,), focus)
+            self.filler.bottom = rows
+
+        return super().render(size, focus)
+
+    def set_error(self, text: Any) -> None:
+        self.error = text
+        self.pile = urwid.Pile([
+            self.error,
+            self.edit,
+        ])
+        self.filler = urwid.Filler(self.pile)
+        self._w = self.filler
+
+    def unset_error(self) -> None:
+        self.error = None
+        self.filler = urwid.Filler(self.edit)
+        self._w = self.filler
+
+    def could_not_connect(self, roomname: str) -> None:
+        text = AT("Could not connect to ", attributes=self._error_attrs)
+        text += AT("&" + roomname, attributes=self._error_room_attrs)
+        text += AT(".", attributes=self._error_attrs)
+
+        self.set_error(ATWidget(text, align=urwid.CENTER))
+
+    def invalid_room_name(self, reason: str) -> None:
+        text = AT(f"Invalid room name: {reason}", attributes=self._error_attrs)
+        self.set_error(ATWidget(text, align=urwid.CENTER))
+
+class SingleRoomApplication(urwid.WidgetWrap):
+    #
+    # The characters in the ALPHABET make up the characters that are allowed in
+    # room names.
+    ALPHABET = "abcdefghijklmnopqrstuvwxyz0123456789"
+
+    # These are other characters or character combinations necessary for the
+    # editor to function well.
+    ALLOWED_EDITOR_KEYS = {
+            "backspace", "delete",
+            "left", "right",
+            "home", "end",
+    }
+
+    def __init__(self) -> None:
+        self.choose_room = ChooseRoomWidget()
+        super().__init__(self.choose_room)
+
+    def selectable(self) -> bool:
+        return True
+
+    def switch_to_choose(self) -> None:
+        self.choose_room.could_not_connect(self.choose_room.edit.edit_text)
+        self._w = self.choose_room
+
+    def keypress(self, size: Any, key: str) -> Optional[str]:
+        if self._w is self.choose_room:
+            if key == "esc":
+                raise urwid.ExitMainLoop()
+
+            self.choose_room.unset_error()
+
+            if key == "enter":
+                roomname = self.choose_room.edit.text
+
+                if roomname:
+                    room = RoomWidget(roomname)
+                    urwid.connect_signal(room, "close", self.switch_to_choose)
+                    room.connect()
+                    self._w = room
+                else:
+                    self.choose_room.invalid_room_name("too short")
+
+            elif not super().selectable():
+                return key
+            # Make sure we only enter valid room names
+            elif key.lower() in self.ALPHABET:
+                return super().keypress(size, key.lower())
+            elif key in self.ALLOWED_EDITOR_KEYS:
+                return super().keypress(size, key)
+
+            return None
+
+        elif super().selectable():
+            return super().keypress(size, key)
+
+        return key