pediatric-ai-scribe-v3/public/js/speechRecognition.js

// ============================================================
// WEB SPEECH RECOGNITION — Real-time streaming transcription
// ⚠️  PRIVACY WARNING: Uses browser's built-in ASR which may
// send audio to cloud servers (Chrome/Edge → Google servers)
// Only use if you accept this trade-off for real-time streaming
// ============================================================

(function() {

  var STORAGE_ENABLED = 'ped_web_speech_enabled';

  var SpeechRecognition = window.SpeechRecognition || window.webkitSpeechRecognition;
  var _recognition = null;
  var _transcript = '';
  var _isListening = false;
  var _onPartialCallback = null;
  var _onFinalCallback = null;

  window.WebSpeechRecognition = {

    isSupported: function() {
      return typeof SpeechRecognition !== 'undefined';
    },

    isEnabled: function() {
      try {
        return localStorage.getItem(STORAGE_ENABLED) === '1';
      } catch(e) {
        return false;
      }
    },

    setEnabled: function(val) {
      try {
        localStorage.setItem(STORAGE_ENABLED, val ? '1' : '0');
      } catch(e) {}
    },

    startListening: function(options) {
      if (!this.isSupported()) {
        return Promise.reject(new Error('Web Speech API not supported'));
      }

      if (!this.isEnabled()) {
        return Promise.reject(new Error('Web Speech Recognition not enabled'));
      }

      _transcript = '';
      _isListening = true;

      var opts = options || {};
      _onPartialCallback = opts.onPartial || function() {};
      _onFinalCallback = opts.onFinal || function() {};

      _recognition = new SpeechRecognition();
      _recognition.continuous = true;  // Keep listening
      _recognition.interimResults = true;  // Show partial results
      _recognition.lang = opts.language || 'en-US';
      _recognition.maxAlternatives = 1;

      return new Promise(function(resolve, reject) {
        _recognition.onstart = function() {
          console.log('[WebSpeech] Started listening');
        };

        _recognition.onresult = function(event) {
          var interim = '';
          var final = '';

          for (var i = event.resultIndex; i < event.results.length; i++) {
            var transcript = event.results[i][0].transcript;

            if (event.results[i].isFinal) {
              final += transcript + ' ';
              _transcript += transcript + ' ';
            } else {
              interim += transcript;
            }
          }

          // Callback with partial results (shown in real-time)
          if (interim && _onPartialCallback) {
            _onPartialCallback(interim);
          }

          // Callback with final results (confirmed words)
          if (final && _onFinalCallback) {
            _onFinalCallback(final.trim());
          }
        };

        _recognition.onerror = function(event) {
          console.error('[WebSpeech] Error:', event.error);
          _isListening = false;

          if (event.error === 'no-speech') {
            reject(new Error('No speech detected'));
          } else if (event.error === 'not-allowed') {
            reject(new Error('Microphone permission denied'));
          } else {
            reject(new Error('Speech recognition error: ' + event.error));
          }
        };

        _recognition.onend = function() {
          _isListening = false;
          console.log('[WebSpeech] Stopped listening');
          resolve(_transcript.trim());
        };

        try {
          _recognition.start();
        } catch (e) {
          reject(new Error('Failed to start recognition: ' + e.message));
        }
      });
    },

    stopListening: function() {
      if (_recognition && _isListening) {
        _recognition.stop();
      }
    },

    isListening: function() {
      return _isListening;
    },

    getCurrentTranscript: function() {
      return _transcript.trim();
    },

    // Check if browser likely sends to cloud
    getPrivacyInfo: function() {
      var isChrome = /Chrome/.test(navigator.userAgent) && /Google Inc/.test(navigator.vendor);
      var isEdge = /Edg/.test(navigator.userAgent);

      if (isChrome || isEdge) {
        return {
          provider: 'Google Cloud Speech',
          privacy: 'Audio sent to Google servers',
          warning: 'NOT HIPAA-compliant'
        };
      } else if (/Safari/.test(navigator.userAgent) && !/Chrome/.test(navigator.userAgent)) {
        return {
          provider: 'Apple Speech Recognition',
          privacy: 'May process on-device or Apple servers',
          warning: 'Check Apple privacy policy'
        };
      } else {
        return {
          provider: 'Unknown',
          privacy: 'May send audio to cloud servers',
          warning: 'Privacy unknown'
        };
      }
    }
  };

})();