Introduce a RiotPermalinkConstructor and fix the setting name

Originally we were planning on using the current location as the permalink prefix, but that doesn't work if the user is a desktop user.

src/utils/permalinks/RiotPermalinkConstructor.js

@@ -0,0 +1,60 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import PermalinkConstructor from "./PermalinkConstructor";
+
+/**
+ * Generates permalinks that self-reference the running webapp
+ */
+export default class RiotPermalinkConstructor extends PermalinkConstructor {
+
+    _riotUrl: string;
+
+    constructor(riotUrl: string) {
+        super();
+        this._riotUrl = riotUrl;
+    }
+
+    forEvent(roomId: string, eventId: string, serverCandidates: string[]): string {
+        // TODO: Fix URL
+        return `${this._riotUrl}/#/${roomId}/${eventId}${this.encodeServerCandidates(serverCandidates)}`;
+    }
+
+    forRoom(roomIdOrAlias: string, serverCandidates: string[]): string {
+        // TODO: Fix URL
+        return `${this._riotUrl}/#/${roomIdOrAlias}${this.encodeServerCandidates(serverCandidates)}`;
+    }
+
+    forUser(userId: string): string {
+        // TODO: Fix URL
+        return `${this._riotUrl}/#/${userId}`;
+    }
+
+    forGroup(groupId: string): string {
+        // TODO: Fix URL
+        return `${this._riotUrl}/#/${groupId}`;
+    }
+
+    isPermalinkHost(testHost: string): boolean {
+        // TODO: Actual check
+        return testHost === this._riotUrl;
+    }
+
+    encodeServerCandidates(candidates: string[]) {
+        if (!candidates || candidates.length === 0) return '';
+        return `?via=${candidates.map(c => encodeURIComponent(c)).join("&via=")}`;
+    }
+}

src/utils/permalinks/RoomPermalinkCreator.js

@@ -17,8 +17,9 @@ limitations under the License.
 import MatrixClientPeg from "../../MatrixClientPeg";
 import isIp from "is-ip";
 import utils from 'matrix-js-sdk/lib/utils';
-import SpecPermalinkConstructor from "./SpecPermalinkConstructor";
+import SpecPermalinkConstructor, {baseUrl as matrixtoBaseUrl} from "./SpecPermalinkConstructor";
 import PermalinkConstructor from "./PermalinkConstructor";
+import RiotPermalinkConstructor from "./RiotPermalinkConstructor";
 
 const SdkConfig = require("../../SdkConfig");
 
@@ -283,8 +284,8 @@ export function isPermalinkHost(host: string): boolean {
 }
 
 function getPermalinkConstructor(): PermalinkConstructor {
-    if (SdkConfig.get()['useRiotToCreatePermalinks']) {
-        // TODO: Return a RiotPermalinkConstructor
+    if (SdkConfig.get()['permalinkPrefix'] && SdkConfig.get()['permalinkPrefix'] !== matrixtoBaseUrl) {
+        return new RiotPermalinkConstructor(SdkConfig.get()['permalinkPrefix']);
     }
 
     return new SpecPermalinkConstructor();