feat(prejoin_page): Add prejoin page

react/features/toolbox/functions.web.js

@@ -1,5 +1,12 @@
 // @flow
 
+import {
+    isAudioDisabled,
+    isPrejoinPageVisible,
+    isPrejoinVideoDisabled
+} from '../prejoin';
+import { hasAvailableDevices } from '../base/devices';
+
 declare var interfaceConfig: Object;
 
 /**
@@ -45,3 +52,32 @@ export function isToolboxVisible(state: Object) {
     return Boolean(!iAmSipGateway && (timeoutID || visible || alwaysVisible
                                       || audioSettingsVisible || videoSettingsVisible));
 }
+
+/**
+ * Indicates if the audio settings button is disabled or not.
+ *
+ * @param {string} state - The state from the Redux store.
+ * @returns {boolean}
+ */
+export function isAudioSettingsButtonDisabled(state: Object) {
+    const devicesMissing = !hasAvailableDevices(state, 'audioInput')
+          && !hasAvailableDevices(state, 'audioOutput');
+
+    return isPrejoinPageVisible(state)
+        ? devicesMissing || isAudioDisabled(state)
+        : devicesMissing;
+}
+
+/**
+ * Indicates if the video settings button is disabled or not.
+ *
+ * @param {string} state - The state from the Redux store.
+ * @returns {boolean}
+ */
+export function isVideoSettingsButtonDisabled(state: Object) {
+    const devicesMissing = !hasAvailableDevices(state, 'videoInput');
+
+    return isPrejoinPageVisible(state)
+        ? devicesMissing || isPrejoinVideoDisabled(state)
+        : devicesMissing;
+}