Switch OIDC to response_mode=fragment (#33100)

* Refactor: kill off `parseQs` in favour of URLSearchParams

* Consolidate app-load url parameter handling

* Switch to responseMode=fragment

apps/web/test/unit-tests/vector/url_utils-test.ts

@@ -5,37 +5,54 @@ SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Com
 Please see LICENSE files in the repository root for full details.
 */
 
-import { parseQsFromFragment, parseQs } from "../../../src/vector/url_utils";
+import { parseAppUrl, parseQsFromFragment, searchParamsToQueryDict } from "../../../src/vector/url_utils";
 
-describe("url_utils.ts", function () {
-    // @ts-ignore
-    const location: Location = {
-        hash: "",
-        search: "",
-    };
+// @ts-ignore
+const location: Location = {
+    hash: "",
+    search: "",
+};
 
-    it("parseQsFromFragment", function () {
-        location.hash = "/home?foo=bar";
+describe("parseQsFromFragment", () => {
+    it("should parse correctly", () => {
+        location.hash = "#/home?foo=bar";
         expect(parseQsFromFragment(location)).toEqual({
-            location: "home",
-            params: {
+            location: "/home",
+            params: new URLSearchParams({
                 foo: "bar",
-            },
-        });
-    });
-
-    it("parseQs", function () {
-        location.search = "?foo=bar";
-        expect(parseQs(location)).toEqual({
-            foo: "bar",
-        });
-    });
-
-    it("parseQs with arrays", function () {
-        location.search = "?via=s1&via=s2&via=s2&foo=bar";
-        expect(parseQs(location)).toEqual({
-            via: ["s1", "s2", "s2"],
-            foo: "bar",
+            }),
         });
     });
 });
+
+describe("searchParamsToQueryDict", () => {
+    it("should handle arrays correctly", () => {
+        const u = new URLSearchParams("a=b&b=c&c=d&a=e&a=f");
+        expect(searchParamsToQueryDict(u)).toEqual({
+            a: ["b", "e", "f"],
+            b: "c",
+            c: "d",
+        });
+    });
+});
+
+describe("parseUrlParameters", () => {
+    it("should parse legacy sso parameters from query", () => {
+        const u = new URL("https://app.element.io?loginToken=foobar");
+        const parsed = parseAppUrl(u);
+        expect(parsed.params.legacy_sso?.loginToken).toEqual("foobar");
+    });
+
+    it("should parse oidc parameters from oauth-fragment", () => {
+        const u = new URL("https://app.element.io/#code=foobar&state=barfoo");
+        const parsed = parseAppUrl(u);
+        expect(parsed.params.oidc?.code).toEqual("foobar");
+        expect(parsed.params.oidc?.state).toEqual("barfoo");
+    });
+
+    it("should parse guest parameters", () => {
+        const u = new URL("https://app.element.io?foo=bar#/room/!roomId:server?guest_access_token=foobar");
+        const parsed = parseAppUrl(u);
+        expect(parsed.params.guest?.guest_access_token).toEqual("foobar");
+    });
+});