web ui: New setting for browser-based login

This is useful in cases where OIDC login is active
which would then redirect the user to a central
login page.

See https://github.com/Kozea/Radicale/issues/2143

radicale/web/internal.py

@@ -34,7 +34,27 @@ FALLBACK_MIMETYPE = httputils.FALLBACK_MIMETYPE  # deprecated
 
 class Web(web.BaseWeb):
 
-    def get(self, environ: types.WSGIEnviron, base_prefix: str, path: str,
-            user: str, request_info: dict) -> types.WSGIResponse:
-        return httputils.serve_resource("radicale.web", "internal_data",
-                                        base_prefix, path)
+    def get(
+        self,
+        environ: types.WSGIEnviron,
+        base_prefix: str,
+        path: str,
+        user: str,
+        request_info: dict,
+    ) -> types.WSGIResponse:
+        if path == "/.web/js/config.js":
+            prefer_browser_login = (
+                "true"
+                if self.configuration.get("web", "prefer_browser_login")
+                else "false"
+            )
+            content = (
+                f"export const PREFER_BROWSER_LOGIN = {prefer_browser_login};\n".encode(
+                    "utf-8"
+                )
+            )
+            headers = {"Content-Type": "application/javascript"}
+            return 200, headers, content, None
+        return httputils.serve_resource(
+            "radicale.web", "internal_data", base_prefix, path
+        )

radicale/web/internal_data/js/config.js

@@ -0,0 +1,3 @@
+// This file is dynamically overwritten during serving. The contents here are just to enable development an testing.
+
+export const PREFER_BROWSER_LOGIN = false;

radicale/web/internal_data/js/scenes/LoginScene.js

@@ -20,6 +20,7 @@
  */
 
 import { get_principal } from "../api/api.js";
+import { PREFER_BROWSER_LOGIN } from "../config.js";
 import { ROOT_PATH, SERVER } from "../constants.js";
 import { Collection } from "../models/collection.js";
 import { extract_title, extractUsernameFromPrincipalCollection } from "../utils/collection_utils.js";
@@ -167,7 +168,7 @@ export class LoginScene {
         fetch(SERVER + ROOT_PATH, {
             method: 'PROPFIND',
             headers: { 'Depth': '0' },
-            credentials: 'omit'
+            credentials: PREFER_BROWSER_LOGIN ? 'include' : 'omit'
         }).then((response) => {
             if (response.ok) {
                 // Authenticated! Now it's safe to call get_principal