content/public/browser/tts_controller.h

// Copyright (c) 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_PUBLIC_BROWSER_TTS_CONTROLLER_H_
#define CONTENT_PUBLIC_BROWSER_TTS_CONTROLLER_H_

#include <memory>
#include <queue>
#include <set>
#include <string>
#include <vector>

#include "base/memory/singleton.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list_types.h"
#include "content/common/content_export.h"
#include "url/gurl.h"

namespace base {
class Value;
}

namespace content {
class Utterance;
class BrowserContext;
class TtsPlatform;

// Events sent back from the TTS engine indicating the progress.
enum TtsEventType {
  TTS_EVENT_START,
  TTS_EVENT_END,
  TTS_EVENT_WORD,
  TTS_EVENT_SENTENCE,
  TTS_EVENT_MARKER,
  TTS_EVENT_INTERRUPTED,
  TTS_EVENT_CANCELLED,
  TTS_EVENT_ERROR,
  TTS_EVENT_PAUSE,
  TTS_EVENT_RESUME
};

// The continuous parameters that apply to a given utterance.
struct CONTENT_EXPORT UtteranceContinuousParameters {
  UtteranceContinuousParameters();

  double rate;
  double pitch;
  double volume;
};

// Information about one voice.
struct CONTENT_EXPORT VoiceData {
  VoiceData();
  VoiceData(const VoiceData& other);
  ~VoiceData();

  std::string name;
  std::string lang;
  std::string engine_id;
  std::set<TtsEventType> events;

  // If true, the synthesis engine is a remote network resource.
  // It may be higher latency and may incur bandwidth costs.
  bool remote;

  // If true, this is implemented by this platform's subclass of
  // TtsPlatformImpl. If false, this is implemented in a content embedder.
  bool native;
  std::string native_voice_identifier;
};

// Interface that delegates TTS requests to engines in content embedders.
class CONTENT_EXPORT TtsEngineDelegate {
 public:
  virtual ~TtsEngineDelegate() {}

  // Return a list of all available voices registered.
  virtual void GetVoices(BrowserContext* browser_context,
                         std::vector<VoiceData>* out_voices) = 0;

  // Speak the given utterance by sending an event to the given TTS engine.
  virtual void Speak(Utterance* utterance, const VoiceData& voice) = 0;

  // Stop speaking the given utterance by sending an event to the target
  // associated with this utterance.
  virtual void Stop(Utterance* utterance) = 0;

  // Pause in the middle of speaking this utterance.
  virtual void Pause(Utterance* utterance) = 0;

  // Resume speaking this utterance.
  virtual void Resume(Utterance* utterance) = 0;

  // Load the built-in TTS engine.
  virtual bool LoadBuiltInTtsEngine(BrowserContext* browser_context) = 0;
};

// Class that wants to receive events on utterances.
class CONTENT_EXPORT UtteranceEventDelegate {
 public:
  virtual ~UtteranceEventDelegate() {}
  virtual void OnTtsEvent(Utterance* utterance,
                          TtsEventType event_type,
                          int char_index,
                          const std::string& error_message) = 0;
};

// Class that wants to be notified when the set of
// voices has changed.
class CONTENT_EXPORT VoicesChangedDelegate : public base::CheckedObserver {
 public:
  virtual void OnVoicesChanged() = 0;
};

// One speech utterance.
// TODO(katie): Can Utterance be changed into a struct with business logic
// fully in the callers? If not, consider splitting it out into its own file,
// and updating it to meet requirements for content/public interfaces.
class CONTENT_EXPORT Utterance {
 public:
  // Construct an utterance given a profile and a completion task to call
  // when the utterance is done speaking. Before speaking this utterance,
  // its other parameters like text, rate, pitch, etc. should all be set.
  explicit Utterance(BrowserContext* browser_context);
  ~Utterance();

  // Sends an event to the delegate. If the event type is TTS_EVENT_END
  // or TTS_EVENT_ERROR, deletes the utterance. If |char_index| is -1,
  // uses the last good value.
  void OnTtsEvent(TtsEventType event_type,
                  int char_index,
                  const std::string& error_message);

  // Finish an utterance without sending an event to the delegate.
  void Finish();

  // Getters and setters for the text to speak and other speech options.
  void set_text(const std::string& text) { text_ = text; }
  const std::string& text() const { return text_; }

  void set_options(const base::Value* options);
  const base::Value* options() const { return options_.get(); }

  void set_src_id(int src_id) { src_id_ = src_id; }
  int src_id() { return src_id_; }

  void set_src_url(const GURL& src_url) { src_url_ = src_url; }
  const GURL& src_url() { return src_url_; }

  void set_voice_name(const std::string& voice_name) {
    voice_name_ = voice_name;
  }
  const std::string& voice_name() const { return voice_name_; }

  void set_lang(const std::string& lang) { lang_ = lang; }
  const std::string& lang() const { return lang_; }

  void set_continuous_parameters(const double rate,
                                 const double pitch,
                                 const double volume) {
    continuous_parameters_.rate = rate;
    continuous_parameters_.pitch = pitch;
    continuous_parameters_.volume = volume;
  }
  const UtteranceContinuousParameters& continuous_parameters() {
    return continuous_parameters_;
  }

  void set_can_enqueue(bool can_enqueue) { can_enqueue_ = can_enqueue; }
  bool can_enqueue() const { return can_enqueue_; }

  void set_required_event_types(const std::set<TtsEventType>& types) {
    required_event_types_ = types;
  }
  const std::set<TtsEventType>& required_event_types() const {
    return required_event_types_;
  }

  void set_desired_event_types(const std::set<TtsEventType>& types) {
    desired_event_types_ = types;
  }
  const std::set<TtsEventType>& desired_event_types() const {
    return desired_event_types_;
  }

  const std::string& engine_id() const { return engine_id_; }
  void set_engine_id(const std::string& engine_id) { engine_id_ = engine_id; }

  UtteranceEventDelegate* event_delegate() const { return event_delegate_; }
  void set_event_delegate(UtteranceEventDelegate* event_delegate) {
    event_delegate_ = event_delegate;
  }

  // Getters and setters for internal state.
  BrowserContext* browser_context() const { return browser_context_; }
  int id() const { return id_; }
  bool finished() const { return finished_; }

 private:
  // The BrowserContext that initiated this utterance.
  BrowserContext* browser_context_;

  // The content embedder engine ID of the engine providing TTS for this
  // utterance, or empty if native TTS is being used.
  std::string engine_id_;

  // The unique ID of this utterance, used to associate callback functions
  // with utterances.
  int id_;

  // The id of the next utterance, so we can associate requests with
  // responses.
  static int next_utterance_id_;

  // The text to speak.
  std::string text_;

  // The full options arg passed to tts.speak, which may include fields
  // other than the ones we explicitly parse, below.
  std::unique_ptr<base::Value> options_;

  // The source engine's ID of this utterance, so that it can associate
  // events with the appropriate callback.
  int src_id_;

  // The URL of the page where called speak was called.
  GURL src_url_;

  // The delegate to be called when an utterance event is fired.
  UtteranceEventDelegate* event_delegate_;

  // The parsed options.
  std::string voice_name_;
  std::string lang_;
  UtteranceContinuousParameters continuous_parameters_;
  bool can_enqueue_;
  std::set<TtsEventType> required_event_types_;
  std::set<TtsEventType> desired_event_types_;

  // The index of the current char being spoken.
  int char_index_;

  // True if this utterance received an event indicating it's done.
  bool finished_;
};

// Singleton class that manages text-to-speech for all TTS engines and
// APIs, maintaining a queue of pending utterances and keeping
// track of all state.
class CONTENT_EXPORT TtsController {
 public:
  // Get the single instance of this class.
  static TtsController* GetInstance();

  // Returns true if we're currently speaking an utterance.
  virtual bool IsSpeaking() = 0;

  // Speak the given utterance. If the utterance's can_enqueue flag is true
  // and another utterance is in progress, adds it to the end of the queue.
  // Otherwise, interrupts any current utterance and speaks this one
  // immediately.
  virtual void SpeakOrEnqueue(Utterance* utterance) = 0;

  // Stop all utterances and flush the queue. Implies leaving pause mode
  // as well.
  virtual void Stop() = 0;

  // Pause the speech queue. Some engines may support pausing in the middle
  // of an utterance.
  virtual void Pause() = 0;

  // Resume speaking.
  virtual void Resume() = 0;

  // Handle events received from the speech engine. Events are forwarded to
  // the callback function, and in addition, completion and error events
  // trigger finishing the current utterance and starting the next one, if
  // any.
  virtual void OnTtsEvent(int utterance_id,
                          TtsEventType event_type,
                          int char_index,
                          const std::string& error_message) = 0;

  // Return a list of all available voices, including the native voice,
  // if supported, and all voices registered by engines.
  virtual void GetVoices(BrowserContext* browser_context,
                         std::vector<VoiceData>* out_voices) = 0;

  // Called by the content embedder or platform implementation when the
  // list of voices may have changed and should be re-queried.
  virtual void VoicesChanged() = 0;

  // Add a delegate that wants to be notified when the set of voices changes.
  virtual void AddVoicesChangedDelegate(VoicesChangedDelegate* delegate) = 0;

  // Remove delegate that wants to be notified when the set of voices changes.
  virtual void RemoveVoicesChangedDelegate(VoicesChangedDelegate* delegate) = 0;

  // Remove delegate that wants to be notified when an utterance fires an event.
  // Note: this cancels speech from any utterance with this delegate, and
  // removes any utterances with this delegate from the queue.
  virtual void RemoveUtteranceEventDelegate(
      UtteranceEventDelegate* delegate) = 0;

  // Set the delegate that processes TTS requests with engines in a content
  // embedder.
  virtual void SetTtsEngineDelegate(TtsEngineDelegate* delegate) = 0;

  // Get the delegate that processes TTS requests with engines in a content
  // embedder.
  virtual TtsEngineDelegate* GetTtsEngineDelegate() = 0;

  // Visible for testing.
  virtual void SetTtsPlatform(TtsPlatform* tts_platform) = 0;
  virtual int QueueSize() = 0;

 protected:
  virtual ~TtsController() {}
};

}  // namespace content

#endif  // CONTENT_PUBLIC_BROWSER_TTS_CONTROLLER_H_