Simplify route navigation

I see it as the first step in simplifying the route navigate of the
JavaScript app by removing BlankWelcomePage from _getRouteToRender. From
a faraway point of view, the app is at the route at which it is not in a
conference. Historically, the route was known as the Welcome page. But
mobile complicated the route by saying that actually it may not want to
see the room name input and join button.

Additionally, I renamed BlankWelcomePage to BlankPage because I don't
think of it as a WelcomePage alternative but rather as a more generic
BlankPage which may be utilized elsewhere in the future.

I plan for the next steps to:
* Merge Entryway, _interceptComponent, and _getRouteToRender in one
React Component rendered by AbstractApp so that the whole logic is in
one file;
* Get rid of RouteRegistry and routes.

react/features/app/functions.native.js

@@ -1,7 +1,9 @@
+/* @flow */
+
 import { isRoomValid } from '../base/conference';
 import { RouteRegistry } from '../base/react';
 import { Conference } from '../conference';
-import { BlankWelcomePage, WelcomePage } from '../welcome';
+import { Entryway } from '../welcome';
 
 /**
  * Determines which route is to be rendered in order to depict a specific Redux
@@ -11,28 +13,13 @@ import { BlankWelcomePage, WelcomePage } from '../welcome';
  * method.
  * @returns {Route}
  */
-export function _getRouteToRender(stateOrGetState) {
+export function _getRouteToRender(stateOrGetState: Object | Function) {
     const state
         = typeof stateOrGetState === 'function'
             ? stateOrGetState()
             : stateOrGetState;
     const { room } = state['features/base/conference'];
-    let component;
-
-    if (isRoomValid(room)) {
-        component = Conference;
-    } else {
-        // The value of the App prop welcomePageEnabled was stored in redux in
-        // saghul's PR. But I removed the redux state, action, action type, etc.
-        // because I didn't like the name. We are not using the prop is a
-        // React-ive way anyway so it's all the same difference.
-        const { app } = state['features/app'];
-
-        component
-            = app && app.props.welcomePageEnabled
-                ? WelcomePage
-                : BlankWelcomePage;
-    }
+    const component = isRoomValid(room) ? Conference : Entryway;
 
     return RouteRegistry.getRouteByComponent(component);
 }

react/features/app/functions.web.js

@@ -1,15 +1,17 @@
 /* @flow */
 
-import { isRoomValid } from '../base/conference';
-import { Platform, RouteRegistry } from '../base/react';
-import { Conference } from '../conference';
+import { Platform } from '../base/react';
 import {
     NoMobileApp,
     PluginRequiredBrowser,
     UnsupportedDesktopBrowser,
     UnsupportedMobileBrowser
 } from '../unsupported-browser';
-import { WelcomePage } from '../welcome';
+
+import {
+    // eslint-disable-next-line camelcase
+    _getRouteToRender as _super_getRouteToRender
+} from './functions.native';
 
 declare var APP: Object;
 declare var interfaceConfig: Object;
@@ -61,8 +63,7 @@ const _INTERCEPT_COMPONENT_RULES = [
             break;
 
         case 'undefined':
-            // If webRTCReady is not set, then we cannot use it to take a
-            // decision.
+            // If webRTCReady is not set, then we cannot base a decision on it.
             break;
 
         default:
@@ -80,19 +81,11 @@ const _INTERCEPT_COMPONENT_RULES = [
  * @returns {Route}
  */
 export function _getRouteToRender(stateOrGetState: Object | Function) {
-    const state
-        = typeof stateOrGetState === 'function'
-            ? stateOrGetState()
-            : stateOrGetState;
-
-    // If mobile browser page was shown, there is no need to show it again.
-    const { room } = state['features/base/conference'];
-    const component = isRoomValid(room) ? Conference : WelcomePage;
-    const route = RouteRegistry.getRouteByComponent(component);
+    const route = _super_getRouteToRender(stateOrGetState);
 
-    // Intercepts route components if any of component interceptor rules
-    // is satisfied.
-    route.component = _interceptComponent(state, component);
+    // Intercepts route components if any of component interceptor rules is
+    // satisfied.
+    route.component = _interceptComponent(stateOrGetState, route.component);
 
     return route;
 }

react/features/welcome/components/BlankWelcomePage.js → react/features/welcome/components/BlankPage.js

@@ -5,16 +5,16 @@ import { connect } from 'react-redux';
 import { destroyLocalTracks } from '../../base/tracks';
 
 /**
- * Component for rendering a blank welcome page. It renders absolutely nothing
- * and destroys local tracks upon being mounted, since no media is desired when
+ * A React <tt>Component<tt> which represents a blank page. It renders nothing
+ * and destroys local tracks upon being mounted since no media is desired when
  * this component is rendered.
  *
- * The use case is mainly mobile, where SDK users probably disable the welcome
- * page, but using it on the web in the future is not out of the question.
+ * The use case which prompted the introduction of this component is mobile
+ * where SDK users probably disable the Welcome page.
  */
-class BlankWelcomePage extends Component {
+class BlankPage extends Component {
     /**
-     * {@code BlankWelcomePage} component's property types.
+     * {@code BlankPage} component's property types.
      *
      * @static
      */
@@ -46,4 +46,4 @@ class BlankWelcomePage extends Component {
     }
 }
 
-export default connect()(BlankWelcomePage);
+export default connect()(BlankPage);

react/features/welcome/components/Entryway.js

@@ -0,0 +1,74 @@
+import PropTypes from 'prop-types';
+import React, { Component } from 'react';
+import { connect } from 'react-redux';
+
+import BlankPage from './BlankPage';
+import WelcomePage from './WelcomePage';
+
+/**
+ * A React <tt>Component</tt> which is rendered when there is no (valid) room
+ * (name) i.e. it is the opposite of <tt>Conference</tt>. Generally and
+ * historically, it is <tt>WelcomePage</tt>. However, Jitsi Meet SDK for Android
+ * and iOS allows the use of the (JavaScript) app without <tt>WelcomePage</tt>
+ * and it needs to display something between conferences.
+ */
+class Entryway extends Component {
+    /**
+     * <tt>Entryway</tt>'s React <tt>Component</tt> prop types.
+     */
+    static propTypes = {
+        /**
+         * The indicator which determines whether <tt>WelcomePage</tt> is (to
+         * be) rendered.
+         *
+         * @private
+         */
+        _welcomePageEnabled: PropTypes.bool
+    };
+
+    /**
+     * Implements React's {@link Component#render()}.
+     *
+     * @inheritdoc
+     * @returns {ReactElement}
+     */
+    render() {
+        return (
+            this.props._welcomePageEnabled ? <WelcomePage /> : <BlankPage />
+        );
+    }
+}
+
+/**
+ * Maps (parts of) the redux state to the associated Entryway's props.
+ *
+ * @param {Object} state - The redux state.
+ * @private
+ * @returns {{
+ *     _welcomePageEnabled: boolean
+ * }}
+ */
+function _mapStateToProps(state) {
+    let welcomePageEnabled;
+
+    if (navigator.product === 'ReactNative') {
+        // We introduced the welcomePageEnabled prop on App in Jitsi Meet SDK
+        // for Android and iOS. There isn't a strong reason not to introduce it
+        // on Web but there're a few considerations to be taken before I go
+        // there among which:
+        // - Enabling/disabling the Welcome page on Web historically
+        // automatically redirects to a random room and that does not make sense
+        // on mobile (right now).
+        const { app } = state['features/app'];
+
+        welcomePageEnabled = Boolean(app && app.props.welcomePageEnabled);
+    } else {
+        welcomePageEnabled = true;
+    }
+
+    return {
+        _welcomePageEnabled: welcomePageEnabled
+    };
+}
+
+export default connect(_mapStateToProps)(Entryway);

react/features/welcome/components/index.js

@@ -1,2 +1,3 @@
-export { default as BlankWelcomePage } from './BlankWelcomePage';
+export { default as BlankPage } from './BlankPage';
+export { default as Entryway } from './Entryway';
 export { default as WelcomePage } from './WelcomePage';

react/features/welcome/route.js

@@ -2,26 +2,17 @@
 
 import { RouteRegistry } from '../base/react';
 
-import { BlankWelcomePage, WelcomePage } from './components';
+import { Entryway } from './components';
 import { generateRoomWithoutSeparator } from './roomnameGenerator';
 
 declare var APP: Object;
 declare var config: Object;
 
 /**
- * Register route for BlankWelcomePage.
+ * Register route for Entryway.
  */
 RouteRegistry.register({
-    component: BlankWelcomePage,
-    undefined,
-    path: '/#blank'
-});
-
-/**
- * Register route for WelcomePage.
- */
-RouteRegistry.register({
-    component: WelcomePage,
+    component: Entryway,
     onEnter,
     path: '/'
 });