From 417ce19143b021e07d32740e5eca5a629a3d82be Mon Sep 17 00:00:00 2001
From: William Wong <compulim@hotmail.com>
Date: Wed, 30 Oct 2019 00:13:16 -0700
Subject: [PATCH] Stop dictate if microphone is not available

---
 CHANGELOG.md                        |  1 +
 packages/component/src/Dictation.js | 42 +++++++++++++++++++++++++++--
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d1f0f198b..3c156d7786 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -97,6 +97,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 -  Fixes [#2473](https://github.com/microsoft/BotFramework-WebChat/issues/2473). Fix samples 13 using wrong region for Speech Services credentials, by [@compulim](https://github.com/compulim) in PR [#2482](https://github.com/microsoft/BotFramework-WebChat/pull/2482)
 -  Fixes [#2420](https://github.com/microsoft/BotFramework-WebChat/issues/2420). Fix saga error should not result in an unhandled exception, by [@compulim](https://github.com/compulim) in PR [#2421](https://github.com/microsoft/BotFramework-WebChat/pull/2421)
 -  Fixes [#2513](https://github.com/microsoft/BotFramework-WebChat/issues/2513). Fix `core-js` not loading properly, by [@compulim](https://github.com/compulim) in PR [#2514](https://github.com/microsoft/BotFramework-WebChat/pull/2514)
+-  Fixes [#2516](https://github.com/microsoft/BotFramework-WebChat/issues/2516). Disable microphone input for `expecting` input hint on Safari, by [@compulim](https://github.com/compulim) in PR [#2517](https://github.com/microsoft/BotFramework-WebChat/pull/2517)
 
 ### Added
 
diff --git a/packages/component/src/Dictation.js b/packages/component/src/Dictation.js
index ac0dda946b..32ba29c46a 100644
--- a/packages/component/src/Dictation.js
+++ b/packages/component/src/Dictation.js
@@ -1,7 +1,7 @@
 import { Composer as DictateComposer } from 'react-dictate-button';
 import { Constants } from 'botframework-webchat-core';
 import PropTypes from 'prop-types';
-import React, { useCallback } from 'react';
+import React, { useCallback, useMemo } from 'react';
 
 import connectToWebChat from './connectToWebChat';
 
@@ -9,6 +9,26 @@ const {
   DictateState: { DICTATING, IDLE, STARTING }
 } = Constants;
 
+const PrefixedAudioContext = window.AudioContext || window.webkitAudioContext;
+
+// The result of this check is asynchronous and it will fail on user interaction requirement.
+async function canOpenMicrophone() {
+  const audioContext = new PrefixedAudioContext();
+
+  try {
+    if (audioContext.state === 'suspended') {
+      return await Promise.race([
+        audioContext.resume().then(() => true),
+        new Promise(resolve => setImmediate(resolve)).then(() => false)
+      ]);
+    }
+
+    return true;
+  } finally {
+    await audioContext.close();
+  }
+}
+
 const Dictation = ({
   dictateState,
   disabled,
@@ -62,6 +82,24 @@ const Dictation = ({
     onError && onError(event);
   }, [dictateState, onError, setDictateState, stopDictate]);
 
+  const shouldStart = !disabled && (dictateState === STARTING || dictateState === DICTATING) && !numSpeakingActivities;
+
+  // We need to check if the browser allow us to do open microphone.
+  // In Safari, it block microphone access if the code was not executed based on user interaction.
+
+  // Since the check call is asynchronous, the result will always fail the user interaction requirement.
+  // Thus, we can never open microphone after we receive the check result.
+  // Instead, we will both open microphone and check the result. If the result is negative, we will close the microphone.
+
+  // TODO: [P3] Investigate if a resumed AudioContext instance is kept across multiple session, can we workaround Safari's restrictions.
+  useMemo(async () => {
+    if (shouldStart) {
+      const canStart = await canOpenMicrophone();
+
+      !canStart && stopDictate();
+    }
+  }, [shouldStart, stopDictate]);
+
   return (
     <DictateComposer
       lang={language}
@@ -70,7 +108,7 @@ const Dictation = ({
       onProgress={handleDictating}
       speechGrammarList={SpeechGrammarList}
       speechRecognition={SpeechRecognition}
-      started={!disabled && (dictateState === STARTING || dictateState === DICTATING) && !numSpeakingActivities}
+      started={shouldStart}
     />
   );
 };