From b8dcb249ffce44784051450923a5b9a2e9173a76 Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Tue, 6 Oct 2020 18:03:12 +0200
Subject: [PATCH] implement url router

---
 src/domain/navigation/URLRouter.js | 74 ++++++++++++++++++++++++++++++
 src/ui/web/dom/HashObservable.js   | 59 ++++++++++++++++++++++++
 2 files changed, 133 insertions(+)
 create mode 100644 src/domain/navigation/URLRouter.js
 create mode 100644 src/ui/web/dom/HashObservable.js

diff --git a/src/domain/navigation/URLRouter.js b/src/domain/navigation/URLRouter.js
new file mode 100644
index 00000000..5dcd9944
--- /dev/null
+++ b/src/domain/navigation/URLRouter.js
@@ -0,0 +1,74 @@
+/*
+Copyright 2020 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 {Segment} from "./Navigation.js";
+
+export class URLRouter {
+    constructor(pathObservable, navigation) {
+        this._subscription = null;
+        this._pathObservable = pathObservable;
+        this._navigation = navigation;
+    }
+
+    start() {
+        this._subscription = this._pathObservable.subscribe(url => {
+            const segments = this._segmentsFromUrl(url);
+            const path = this._navigation.pathFrom(segments);
+            this._navigation.applyPath(path);
+        });
+    }
+
+    stop() {
+        this._subscription = this._subscription();
+    }
+
+    _segmentsFromUrl(path) {
+        const parts = path.split("/");
+        let index = 0;
+        const segments = [];
+        while (index < parts.length) {
+            const type = parts[index];
+            if ((index + 1) < parts.length) {
+                index += 1;
+                const value = parts[index];
+                segments.push(new Segment(type, value));
+            } else {
+                segments.push(new Segment(type));
+            }
+            index += 1;
+        }
+        return segments;
+    }
+
+    urlForSegment(type, value) {
+        const path = this._navigation.path.with(new Segment(type, value));
+        if (path) {
+            return this.urlForPath(path);
+        }
+    }
+
+    urlForPath(path) {
+        let url = "#";
+        for (const {type, value} of path.segments) {
+            if (typeof value === "boolean") {
+                url += `/${type}`;
+            } else {
+                url += `/${type}/${value}`;
+            }
+        }
+        return url;
+    }
+}
diff --git a/src/ui/web/dom/HashObservable.js b/src/ui/web/dom/HashObservable.js
new file mode 100644
index 00000000..4239f6ac
--- /dev/null
+++ b/src/ui/web/dom/HashObservable.js
@@ -0,0 +1,59 @@
+/*
+Copyright 2020 Bruno Windels <bruno@windels.cloud>
+
+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 {BaseObservableValue} from "../../../observable/ObservableValue.js";
+
+export class HashObservable extends BaseObservableValue {
+    constructor() {
+        super();
+        this._boundOnHashChange = null;
+        this._expectSetEcho = false;
+    }
+
+    _onHashChange() {
+        if (this._expectSetEcho) {
+            this._expectSetEcho = false;
+            return;
+        }
+        this.emit(this.get());
+    }
+
+    get() {
+        const hash = document.location.hash;
+        if (hash.length) {
+            // trim '#'
+            return hash.substr(1);
+        }
+        return hash;
+    }
+
+    set(hash) {
+        if (this._boundOnHashChange) {
+            this._expectSetEcho = true;
+        }
+        document.location.hash = hash;
+    }
+
+    onSubscribeFirst() {
+        this._boundOnHashChange = this._onHashChange.bind(this);
+        window.addEventListener('hashchange', this._boundOnHashChange);
+    }
+
+    onUnsubscribeLast() {
+        window.removeEventListener('hashchange', this._boundOnHashChange);
+        this._boundOnHashChange = null;
+    }
+}