Add support for OSC 777 based desktop notifications

Might as well, since we also support OSC 9, so why not yet another
poorly designed legacy scheme.

docs/changelog.rst

@@ -112,6 +112,8 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
 - All tab bar margins are now drawn using the general background color, instead
   of drawing only the left and right margins with the tab bar background color
 
+- Add support for OSC 777 based desktop notifications
+
 
 0.23.1 [2021-08-17]
 ----------------------

kitty/notify.py

@@ -67,6 +67,9 @@ class NotificationCommand:
     body: str = ''
     actions: str = ''
 
+    def __repr__(self) -> str:
+        return f'NotificationCommand(identifier={self.identifier!r}, title={self.title!r}, body={self.body!r}, actions={self.actions!r}, done={self.done!r})'
+
 
 def parse_osc_9(raw: str) -> NotificationCommand:
     ans = NotificationCommand()
@@ -74,6 +77,15 @@ def parse_osc_9(raw: str) -> NotificationCommand:
     return ans
 
 
+def parse_osc_777(raw: str) -> NotificationCommand:
+    parts = raw.split(';', 1)
+    ans = NotificationCommand()
+    ans.title = parts[0]
+    if len(parts) > 1:
+        ans.body = parts[1]
+    return ans
+
+
 def parse_osc_99(raw: str) -> NotificationCommand:
     cmd = NotificationCommand()
     metadata, payload = raw.partition(';')[::2]
@@ -201,3 +213,8 @@ def handle_notification_cmd(
     if osc_code == 9:
         cmd = parse_osc_9(raw_data)
         notify_with_command(cmd, window_id, notify_implementation)
+        return cmd
+    if osc_code == 777:
+        cmd = parse_osc_777(raw_data)
+        notify_with_command(cmd, window_id, notify_implementation)
+        return cmd

kitty/parser.c

@@ -420,6 +420,7 @@ dispatch_osc(Screen *screen, PyObject DUMP_UNUSED *dump_callback) {
             break;
         case 9:
         case 99:
+        case 777:
             START_DISPATCH
             DISPATCH_OSC_WITH_CODE(desktop_notify)
             END_DISPATCH

kitty/window.py

@@ -620,6 +620,11 @@ def set_title(self, title: Optional[str]) -> None:
         self.title_updated()
 
     def desktop_notify(self, osc_code: int, raw_data: str) -> None:
+        if osc_code == 777:
+            if not raw_data.startswith('notify;'):
+                log_error(f'Ignoring unknown OSC 777: {raw_data}')
+                return  # unknown OSC 777
+            raw_data = raw_data[len('notify;'):]
         cmd = handle_notification_cmd(osc_code, raw_data, self.id, self.prev_osc99_cmd)
         if cmd is not None and osc_code == 99:
             self.prev_osc99_cmd = cmd