add support for loading privacy policies

so we can link to them in a new tab from server selection

css/main.css

@@ -173,3 +173,17 @@ input[type='text'].large {
     width: 100%;
     box-sizing: border-box;
 }
+
+.LoadServerPolicyView {
+    display: flex;
+}
+
+.LoadServerPolicyView .spinner {
+    width: 32px;
+    height: 32px;
+    margin-right: 12px;
+}
+
+.LoadServerPolicyView h2 {
+    margin-top: 0;
+}

src/RootView.js

@@ -17,12 +17,14 @@ limitations under the License.
 import {TemplateView} from "./utils/TemplateView.js";
 import {OpenLinkView} from "./open/OpenLinkView.js";
 import {CreateLinkView} from "./create/CreateLinkView.js";
+import {LoadServerPolicyView} from "./policy/LoadServerPolicyView.js";
 
 export class RootView extends TemplateView {
 	render(t, vm) {
 		return t.div({className: "RootView"}, [
 			t.mapView(vm => vm.openLinkViewModel, vm => vm ? new OpenLinkView(vm) : null),
 			t.mapView(vm => vm.createLinkViewModel, vm => vm ? new CreateLinkView(vm) : null),
+            t.mapView(vm => vm.loadServerPolicyViewModel, vm => vm ? new LoadServerPolicyView(vm) : null),
 			t.div({className: "footer"}, [
 				t.p(t.img({src: "images/matrix-logo.svg"})),
 				t.p(["This invite uses ", externalLink(t, "https://matrix.org", "Matrix"), ", an open network for secure, decentralized communication."]),

src/RootViewModel.js

@@ -19,6 +19,7 @@ import {ViewModel} from "./utils/ViewModel.js";
 import {OpenLinkViewModel} from "./open/OpenLinkViewModel.js";
 import {createClients} from "./open/clients/index.js";
 import {CreateLinkViewModel} from "./create/CreateLinkViewModel.js";
+import {LoadServerPolicyViewModel} from "./policy/LoadServerPolicyViewModel.js";
 import {Platform} from "./Platform.js";
 
 export class RootViewModel extends ViewModel {
@@ -27,6 +28,7 @@ export class RootViewModel extends ViewModel {
 		this.link = null;
 		this.openLinkViewModel = null;
 		this.createLinkViewModel = null;
+        this.loadServerPolicyViewModel = null;
 	}
 
 	_updateChildVMs(oldLink) {
@@ -48,9 +50,15 @@ export class RootViewModel extends ViewModel {
 	}
 
 	updateHash(hash) {
-		const oldLink = this.link;
-		this.link = Link.parse(hash);
-		this._updateChildVMs(oldLink);
+        if (hash.startsWith("#/policy/")) {
+            const server = hash.substr(9);
+            this.loadServerPolicyViewModel = new LoadServerPolicyViewModel(this.childOptions({server}));
+            this.loadServerPolicyViewModel.load();
+        } else {
+    		const oldLink = this.link;
+    		this.link = Link.parse(hash);
+    		this._updateChildVMs(oldLink);
+        }
 	}
 
 	clearPreferences() {

src/policy/LoadServerPolicyView.js

@@ -0,0 +1,26 @@
+/*
+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 {TemplateView} from "../utils/TemplateView.js";
+
+export class LoadServerPolicyView extends TemplateView {
+	render(t, vm) {
+		return t.div({className: "LoadServerPolicyView card"}, [
+			t.div({className: {spinner: true, hidden: vm => !vm.loading}}),
+            t.h2(vm => vm.message)
+		]);
+	}
+}

src/policy/LoadServerPolicyViewModel.js

@@ -0,0 +1,52 @@
+/*
+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 {ViewModel} from "../utils/ViewModel.js";
+import {resolveServer} from "../preview/HomeServer.js";
+
+export class LoadServerPolicyViewModel extends ViewModel {
+	constructor(options) {
+		super(options);
+		this.server = options.server;
+        this.message = `Looking up ${this.server} privacy policy…`;
+        this.loading = false;
+	}
+
+    async load() {
+        this.loading = true;
+        this.emitChange();
+        try {
+            const homeserver = await resolveServer(this.request, this.server);
+            if (homeserver) {
+                const url = await homeserver.getPrivacyPolicyUrl();
+                if (url) {
+                    this.message = `Loading ${this.server} privacy policy now…`;
+                    this.openLink(url);
+                } else {
+                    this.loading = false;
+                    this.message = `${this.server} does not declare a privacy policy.`;
+                }
+            } else {
+                this.loading = false;
+                this.message = `${this.server} does not look like a matrix homeserver.`;
+            }
+        } catch (err) {
+            this.loading = false;
+            this.message = `Failed to get the privacy policy for ${this.server}`;
+        }
+        this.emitChange();
+    }
+}