Loading threads with server-side assistance (#2735)

* Fix bug where undefined vs null in pagination tokens wasn't correctly handled
* Fix bug where thread list results were sorted incorrectly
* Allow removing the relationship of an event to a thread
* Implement feature detection for new threads MSCs and specs
* Prefix dir parameter for threads pagination if necessary
* Make threads conform to the same timeline APIs as any other timeline
* Extract thread timeline loading out of thread class
* fix thread roots not being updated correctly
* fix jumping to events by link
* implement new thread timeline loading
* Fix fetchRoomEvent incorrect return type

Co-authored-by: Germain <germains@element.io>
Co-authored-by: Germain <germain@souquet.com>

src/utils.ts

@@ -22,6 +22,7 @@ limitations under the License.
 
 import unhomoglyph from "unhomoglyph";
 import promiseRetry from "p-retry";
+import { Optional } from "matrix-events-sdk";
 
 import { MatrixEvent } from "./models/event";
 import { M_TIMESTAMP } from "./@types/location";
@@ -76,6 +77,25 @@ export function encodeParams(params: QueryDict, urlSearchParams?: URLSearchParam
 
 export type QueryDict = Record<string, string[] | string | number | boolean | undefined>;
 
+/**
+ * Replace a stable parameter with the unstable naming for params
+ * @param stable
+ * @param unstable
+ * @param dict
+ */
+export function replaceParam(
+    stable: string,
+    unstable: string,
+    dict: QueryDict,
+): QueryDict {
+    const result = {
+        ...dict,
+        [unstable]: dict[stable],
+    };
+    delete result[stable];
+    return result;
+}
+
 /**
  * Decode a query string in `application/x-www-form-urlencoded` format.
  * @param {string} query A query string to decode e.g.
@@ -103,13 +123,17 @@ export function decodeParams(query: string): Record<string, string | string[]> {
  * variables with. E.g. { "$bar": "baz" }.
  * @return {string} The result of replacing all template variables e.g. '/foo/baz'.
  */
-export function encodeUri(pathTemplate: string, variables: Record<string, string>): string {
+export function encodeUri(pathTemplate: string, variables: Record<string, Optional<string>>): string {
     for (const key in variables) {
         if (!variables.hasOwnProperty(key)) {
             continue;
         }
+        const value = variables[key];
+        if (value === undefined || value === null) {
+            continue;
+        }
         pathTemplate = pathTemplate.replace(
-            key, encodeURIComponent(variables[key]),
+            key, encodeURIComponent(value),
         );
     }
     return pathTemplate;