Extensions: detect dropping URL's from disabled repositories

Report an error when dropping a URL into a repository which has been
disabled.

scripts/addons_core/bl_pkg/bl_extension_ops.py

@@ -140,6 +140,16 @@ class CheckSIGINT_Context:
 # Internal Utilities
 #
 
+def _preferences_repo_find_by_remote_url(context, remote_url):
+    remote_url = remote_url.rstrip("/")
+    prefs = context.preferences
+    extension_repos = prefs.extensions.repos
+    for repo in extension_repos:
+        if repo.use_remote_url and repo.remote_url.rstrip("/") == remote_url:
+            return repo
+    return None
+
+
 def extension_url_find_repo_index_and_pkg_id(url):
     from .bl_extension_utils import (
         pkg_manifest_archive_url_abs_from_remote_url,
@@ -1922,9 +1932,19 @@ class BlPkgPkgInstall(Operator, _BlPkgCmdMixIn):
         return self.execute(context)
 
     def _invoke_for_drop(self, context, event):
+        from .bl_extension_utils import url_params_extract_repo_url
+
         url = self.url
         print("DROP URL:", url)
 
+        # First check if this is part of a disabled repository.
+        remote_url = url_params_extract_repo_url(url)
+        repo_from_url = None if remote_url is None else _preferences_repo_find_by_remote_url(context, remote_url)
+
+        if repo_from_url and not repo_from_url.enabled:
+            self.report({'ERROR'}, "Extension: repository \"{:s}\" exists but is disabled".format(repo_from_url.name))
+            return {'CANCELLED'}
+
         _preferences_ensure_sync()
 
         repo_index, repo_name, pkg_id, item_remote, item_local = extension_url_find_repo_index_and_pkg_id(url)

scripts/addons_core/bl_pkg/bl_extension_utils.py

@@ -27,6 +27,7 @@ __all__ = (
     "pkg_theme_file_list",
     "platform_from_this_system",
     "url_params_append_for_blender",
+    "url_params_extract_repo_url",
     "file_mtime_or_none",
 
     # Public API.
@@ -356,6 +357,35 @@ def url_params_append_for_blender(url: str, blender_version: Tuple[int, int, int
     return _url_params_append(url, params)
 
 
+def url_params_extract_repo_url(url: str) -> Optional[str]:
+    # Extract `?repository=...` value from the URL and return it.
+    # Concatenating it where appropriate.
+    import urllib
+    import urllib.parse
+
+    # Parse the URL to get its scheme, domain, and query parameters.
+    parsed_url = urllib.parse.urlparse(url)
+
+    # Combine existing query parameters with new parameters
+    params = urllib.parse.parse_qsl(parsed_url.query)
+
+    if repo_path := next((value for key, value in params if key == "repository"), None):
+        if repo_path.startswith("/"):
+            repo_url = urllib.parse.urlunparse((
+                parsed_url.scheme,
+                parsed_url.netloc,
+                repo_path[1:],
+                None,  # `parsed_url.params,`
+                None,  # `parsed_url.query,`
+                None,  # `parsed_url.fragment,`
+            ))
+        else:
+            repo_url = repo_path
+        return repo_url
+
+    return None
+
+
 # -----------------------------------------------------------------------------
 # Public Repository Actions
 #