feat(permalinks): point Share links/QR at to.healthchat.ch

Add a config-driven matrix_to_url option so Share dialog links and QR
codes resolve against a matrix.to-compatible resolver instead of the
hardcoded public matrix.to. MatrixToPermalinkConstructor now reads the
base URL lazily from config (default https://matrix.to), keeping the
matrix.to URL format. HealthChat configs point it at the in-house fork
https://to.healthchat.ch and drop the conflicting permalink_prefix
(which routes to the Element-format constructor a matrix.to fork can't
parse).

apps/desktop/element.io/healthchat/config.json

@@ -33,7 +33,7 @@
         "preferred_domain": "jitsi.healthchat.ch"
     },
     "logout_redirect_url": "",
-    "permalink_prefix": "https://matrix.to",
+    "matrix_to_url": "https://to.healthchat.ch",
     "room_directory": {
         "servers": ["matrix.org"]
     },

apps/web/config.json

@@ -35,7 +35,7 @@
         "preferred_domain": "jitsi.healthchat.ch"
     },
     "logout_redirect_url": "",
-    "permalink_prefix": "https://matrix.to",
+    "matrix_to_url": "https://to.healthchat.ch",
     "room_directory": {
         "servers": [
             "matrix.org"

apps/web/src/IConfigOptions.ts

@@ -70,6 +70,12 @@ export interface IConfigOptions {
     };
 
     permalink_prefix?: string;
+    /**
+     * Base URL of a matrix.to-compatible resolver to use for Share links and QR codes,
+     * instead of the public `https://matrix.to`. Must use the matrix.to URL format
+     * (`/#/<entity>`), e.g. a self-hosted matrix.to fork.
+     */
+    matrix_to_url?: string;
 
     update_base_url?: string;
     desktop_builds: {

apps/web/src/utils/permalinks/MatrixToPermalinkConstructor.ts

@@ -7,10 +7,27 @@ Please see LICENSE files in the repository root for full details.
 */
 
 import PermalinkConstructor, { PermalinkParts } from "./PermalinkConstructor";
+import SdkConfig from "../../SdkConfig";
 
-export const host = "matrix.to";
+const DEFAULT_BASE_URL = "https://matrix.to";
-export const baseUrl = `https://${host}`;
+
-export const baseUrlPattern = `^(?:https?://)?${host.replace(".", "\\.")}/#/(.*)`;
+/**
+ * The base URL of the matrix.to-compatible resolver to generate permalinks against.
+ * Defaults to the public `https://matrix.to`, but can be pointed at a self-hosted
+ * matrix.to fork via the `matrix_to_url` config option. Read lazily so the value
+ * reflects the runtime config rather than module-load time.
+ */
+export function baseUrl(): string {
+    return SdkConfig.get("matrix_to_url") ?? DEFAULT_BASE_URL;
+}
+
+export function host(): string {
+    return new URL(baseUrl()).host;
+}
+
+export function baseUrlPattern(): string {
+    return `^(?:https?://)?${host().replaceAll(".", "\\.")}/#/(.*)`;
+}
 
 /**
  * Generates matrix.to permalinks
@@ -21,23 +38,23 @@ export default class MatrixToPermalinkConstructor extends PermalinkConstructor {
     }
 
     public forEvent(roomId: string, eventId: string, serverCandidates: string[]): string {
-        return `${baseUrl}/#/${roomId}/${eventId}${this.encodeServerCandidates(serverCandidates)}`;
+        return `${baseUrl()}/#/${roomId}/${eventId}${this.encodeServerCandidates(serverCandidates)}`;
     }
 
     public forRoom(roomIdOrAlias: string, serverCandidates: string[]): string {
-        return `${baseUrl}/#/${roomIdOrAlias}${this.encodeServerCandidates(serverCandidates)}`;
+        return `${baseUrl()}/#/${roomIdOrAlias}${this.encodeServerCandidates(serverCandidates)}`;
     }
 
     public forUser(userId: string): string {
-        return `${baseUrl}/#/${userId}`;
+        return `${baseUrl()}/#/${userId}`;
     }
 
     public forEntity(entityId: string): string {
-        return `${baseUrl}/#/${entityId}`;
+        return `${baseUrl()}/#/${entityId}`;
     }
 
     public isPermalinkHost(testHost: string): boolean {
-        return testHost === host;
+        return testHost === host();
     }
 
     public encodeServerCandidates(candidates: string[]): string {
@@ -52,7 +69,7 @@ export default class MatrixToPermalinkConstructor extends PermalinkConstructor {
             throw new Error("Does not appear to be a permalink");
         }
 
-        const matches = [...fullUrl.matchAll(new RegExp(baseUrlPattern, "gi"))][0];
+        const matches = [...fullUrl.matchAll(new RegExp(baseUrlPattern(), "gi"))][0];
 
         if (!matches || matches.length < 2) {
             throw new Error("Does not appear to be a permalink");

apps/web/src/utils/permalinks/Permalinks.ts

@@ -16,6 +16,7 @@ import MatrixToPermalinkConstructor, {
     baseUrl as matrixtoBaseUrl,
     baseUrlPattern as matrixToBaseUrlPattern,
 } from "./MatrixToPermalinkConstructor";
+// `matrixtoBaseUrl` and `matrixToBaseUrlPattern` are functions (config-driven); call them at use sites.
 import { type PermalinkParts } from "./PermalinkConstructor";
 import type PermalinkConstructor from "./PermalinkConstructor";
 import ElementPermalinkConstructor from "./ElementPermalinkConstructor";
@@ -342,13 +343,13 @@ export function tryTransformEntityToPermalink(matrixClient: MatrixClient, entity
             if (permalinkParts) {
                 if (permalinkParts.roomIdOrAlias) {
                     const eventIdPart = permalinkParts.eventId ? `/${permalinkParts.eventId}` : "";
-                    let pl = matrixtoBaseUrl + `/#/${permalinkParts.roomIdOrAlias}${eventIdPart}`;
+                    let pl = matrixtoBaseUrl() + `/#/${permalinkParts.roomIdOrAlias}${eventIdPart}`;
                     if (permalinkParts.viaServers?.length) {
                         pl += new MatrixToPermalinkConstructor().encodeServerCandidates(permalinkParts.viaServers);
                     }
                     return pl;
                 } else if (permalinkParts.userId) {
-                    return matrixtoBaseUrl + `/#/${permalinkParts.userId}`;
+                    return matrixtoBaseUrl() + `/#/${permalinkParts.userId}`;
                 }
             }
         } catch {}
@@ -437,7 +438,7 @@ export function getPrimaryPermalinkEntity(permalink: string): string | null {
  */
 function getPermalinkConstructor(isPill = false): PermalinkConstructor {
     const elementPrefix = SdkConfig.get("permalink_prefix");
-    if (elementPrefix && elementPrefix !== matrixtoBaseUrl && !isPill) {
+    if (elementPrefix && elementPrefix !== matrixtoBaseUrl() && !isPill) {
         return new ElementPermalinkConstructor(elementPrefix);
     }
 
@@ -448,7 +449,7 @@ export function parsePermalink(fullUrl: string): PermalinkParts | null {
     try {
         const elementPrefix = SdkConfig.get("permalink_prefix");
         const decodedUrl = decodeURIComponent(fullUrl);
-        if (new RegExp(matrixToBaseUrlPattern, "i").test(decodedUrl)) {
+        if (new RegExp(matrixToBaseUrlPattern(), "i").test(decodedUrl)) {
             return new MatrixToPermalinkConstructor().parsePermalink(decodedUrl);
         } else if (fullUrl.startsWith("matrix:")) {
             return new MatrixSchemePermalinkConstructor().parsePermalink(fullUrl);

apps/web/test/unit-tests/utils/permalinks/MatrixToPermalinkConstructor-test.ts

@@ -8,6 +8,7 @@ Please see LICENSE files in the repository root for full details.
 
 import MatrixToPermalinkConstructor from "../../../../src/utils/permalinks/MatrixToPermalinkConstructor";
 import { PermalinkParts } from "../../../../src/utils/permalinks/PermalinkConstructor";
+import SdkConfig from "../../../../src/SdkConfig";
 
 describe("MatrixToPermalinkConstructor", () => {
     const peramlinkConstructor = new MatrixToPermalinkConstructor();
@@ -49,4 +50,32 @@ describe("MatrixToPermalinkConstructor", () => {
             ).toEqual("https://matrix.to/#/!myroom:example.com/$event4?via=one.example.com&via=two.example.com");
         });
     });
+
+    describe("with a custom matrix_to_url config", () => {
+        beforeEach(() => {
+            SdkConfig.add({ matrix_to_url: "https://to.healthchat.ch" });
+        });
+
+        afterEach(() => {
+            SdkConfig.reset();
+        });
+
+        it("generates links against the configured host", () => {
+            const constructor = new MatrixToPermalinkConstructor();
+            expect(constructor.forUser("@user:example.com")).toEqual("https://to.healthchat.ch/#/@user:example.com");
+            expect(constructor.forRoom("!myroom:example.com", [])).toEqual(
+                "https://to.healthchat.ch/#/!myroom:example.com",
+            );
+        });
+
+        it("parses links from the configured host and rejects matrix.to links", () => {
+            const constructor = new MatrixToPermalinkConstructor();
+            expect(constructor.parsePermalink("https://to.healthchat.ch/#/@user:example.com")).toEqual(
+                new PermalinkParts(null, null, "@user:example.com", null),
+            );
+            expect(() => constructor.parsePermalink("https://matrix.to/#/@user:example.com")).toThrow(
+                new Error("Does not appear to be a permalink"),
+            );
+        });
+    });
 });

docs/config.md

@@ -125,6 +125,10 @@ complete re-branding/private labeling, a more personalised experience can be ach
 3. `brand`: Optional name for the app. Defaults to `Element`. This is used throughout the application in various strings/locations.
 4. `permalink_prefix`: An optional URL pointing to an Element Web deployment. For example, `https://app.element.io`. This will
    change all permalinks (via the "Share" menus) to point at the Element Web deployment rather than `matrix.to`.
+   4a. `matrix_to_url`: An optional base URL of a matrix.to-compatible resolver to use for Share links and QR codes instead of
+   the public `https://matrix.to`. Unlike `permalink_prefix` (which points at an Element Web deployment and uses Element's
+   `/#/room/…` URL format), this keeps the matrix.to URL format (`/#/<entity>`), so it must point at a matrix.to deployment or
+   fork. For example, `https://to.example.com`.
 5. `desktop_builds`: Optional. Where the desktop builds for the application are, if available. This is explained in more detail
    down below.
 6. `mobile_builds`: Optional. Like `desktop_builds`, except for the mobile apps. Also described in more detail down below.