initial changes for major tts revamp

lib/session/call-session.js

@@ -1,4 +1,5 @@
 const Emitter = require('events');
+const fs = require('fs');
 const {CallDirection, TaskPreconditions, CallStatus, TaskName} = require('../utils/constants');
 const moment = require('moment');
 const assert = require('assert');
@@ -40,6 +41,8 @@ class CallSession extends Emitter {
     this.stackIdx = 0;
     this.callGone = false;
 
+    this.tmpFiles = new Set();
+
     sessionTracker.add(this.callSid, this);
   }
 
@@ -99,6 +102,12 @@ class CallSession extends Emitter {
   get speechSynthesisVoice() {
     return this.application.speech_synthesis_voice;
   }
+  /**
+   * default language to use for speech synthesis if not provided in the app
+   */
+  get speechSynthesisLanguage() {
+    return this.application.speech_synthesis_language;
+  }
 
   /**
    * default vendor to use for speech recognition if not provided in the app
@@ -172,6 +181,10 @@ class CallSession extends Emitter {
     sessionTracker.remove(this.callSid);
   }
 
+  trackTmpFile(path) {
+    this.tmpFiles.add(path);
+  }
+
   normalizeUrl(url, method, auth) {
     const hook = {
       url,
@@ -492,6 +505,17 @@ class CallSession extends Emitter {
         this.logger.error(err, 'CallSession:_clearResources error');
       }
     }
+
+    // remove any temporary tts files that were created (audio is still cached in redis)
+    for (const path of this.tmpFiles) {
+      fs.unlink(path, (err) => {
+        if (err) {
+          return this.logger.error(err, `CallSession:_clearResources Error deleting tmp file ${path}`);
+        }
+        this.logger.debug(`CallSession:_clearResources successfully deleted ${path}`);
+      });
+    }
+    this.tmpFiles.clear();
   }
 
   /**