macOS: Add a way to set kitty as the default handler for the URL schemes

docs/open_actions.rst

@@ -120,6 +120,16 @@ These actions can also be executed from the command line by running::
     or
     kitty +open file_or_url ...
 
+Since macOS lacks an official interface to set default URL scheme handler, you
+can set it with the following command. The first argument for
+``cocoa_set_url_handler`` is the URL scheme, and the second optional argument is
+the bundle id of the app, which defaults to kitty's. (Restores when the second
+argument is an empty string.)
+
+.. code-block:: sh
+
+    kitty +runpy 'from kitty.fast_data_types import cocoa_set_url_handler; print(cocoa_set_url_handler("ssh", "net.kovidgoyal.kitty"));'
+
 You can customize these actions by creating a :file:`launch-actions.conf` file
 in the kitty config directory, just like
 the :file:`open-actions.conf` file above. For example:

kitty/cocoa_window.m

@@ -829,6 +829,31 @@ cocoa_set_titlebar_color(void *w, color_type titlebar_color)
     } // autoreleasepool
 }
 
+static PyObject*
+cocoa_set_url_handler(PyObject UNUSED *self, PyObject *args) {
+    @autoreleasepool {
+
+    const char *url_scheme = NULL, *bundle_id = NULL;
+    if (!PyArg_ParseTuple(args, "s|z", &url_scheme, &bundle_id)) return NULL;
+    if (!url_scheme || url_scheme[0] == '\0') Py_RETURN_FALSE;
+
+    NSString *scheme = [NSString stringWithUTF8String:url_scheme];
+    NSString *identifier = @"";
+    if (!bundle_id) {
+        identifier = [[NSBundle mainBundle] bundleIdentifier];
+        if (!identifier || identifier.length == 0) identifier = @"net.kovidgoyal.kitty";
+    } else if (bundle_id[0] != '\0') {
+        identifier = [NSString stringWithUTF8String:bundle_id];
+    }
+    // This API has been marked as deprecated. It will need to be replaced when a new approach is available.
+    if (LSSetDefaultHandlerForURLScheme((CFStringRef)scheme, (CFStringRef)identifier) == noErr) {
+        Py_RETURN_TRUE;
+    }
+    Py_RETURN_FALSE;
+
+    } // autoreleasepool
+}
+
 static NSSound *beep_sound = nil;
 
 static void
@@ -878,6 +903,7 @@ static PyMethodDef module_methods[] = {
     {"cocoa_set_global_shortcut", (PyCFunction)cocoa_set_global_shortcut, METH_VARARGS, ""},
     {"cocoa_send_notification", (PyCFunction)cocoa_send_notification, METH_VARARGS, ""},
     {"cocoa_set_notification_activated_callback", (PyCFunction)set_notification_activated_callback, METH_O, ""},
+    {"cocoa_set_url_handler", (PyCFunction)cocoa_set_url_handler, METH_VARARGS, ""},
     {NULL, NULL, 0, NULL}        /* Sentinel */
 };
 

kitty/fast_data_types.pyi

@@ -737,6 +737,8 @@ def cocoa_set_global_shortcut(name: str, mods: int, key: int) -> bool:
 def cocoa_get_lang() -> Optional[str]:
     pass
 
+def cocoa_set_url_handler(url_scheme: str, bundle_id: Optional[str]) -> bool:
+    pass
 
 def locale_is_valid(name: str) -> bool:
     pass