// 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 CHROMECAST_BROWSER_TTS_TTS_CONTROLLER_H_
#define CHROMECAST_BROWSER_TTS_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 "url/gurl.h"

class Utterance;
class TtsPlatformImpl;

namespace base {
class Value;
}  // namespace base

namespace content {
class BrowserContext;
}  // namespace content

// 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
};

enum TtsGenderType { TTS_GENDER_NONE, TTS_GENDER_MALE, TTS_GENDER_FEMALE };

// Returns true if this event type is one that indicates an utterance
// is finished and can be destroyed.
bool IsFinalTtsEventType(TtsEventType event_type);

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

  double rate;
  double pitch;
  double volume;
};

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

  std::string name;
  std::string lang;
  TtsGenderType gender;
  std::string extension_id;  // Not used in cast.
  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 by an extension.
  bool native;
  std::string native_voice_identifier;
};

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

// One speech utterance.
class 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(content::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_gender(TtsGenderType gender) { gender_ = gender; }
  TtsGenderType gender() const { return gender_; }

  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& extension_id() const { return extension_id_; }
  void set_extension_id(const std::string& extension_id) {
    extension_id_ = extension_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.
  content::BrowserContext* browser_context() const { return browser_context_; }
  int id() const { return id_; }
  bool finished() const { return finished_; }

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

  // The extension ID of the extension providing TTS for this utterance, or
  // empty if native TTS is being used.
  std::string extension_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 extension's ID of this utterance, so that it can associate
  // events with the appropriate callback.
  int src_id_;

  // The URL of the page where the source extension called speak.
  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_;
  TtsGenderType gender_;
  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 the TTS extension APIs,
// potentially maintaining a queue of pending utterances and keeping track of
// all state.
class TtsController {
 public:
  virtual ~TtsController() = default;

  // Set the TTS platform implementation to use.
  virtual void SetPlatformImpl(
      std::unique_ptr<TtsPlatformImpl> platform_impl) = 0;

  // 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 extensions.
  virtual void GetVoices(content::BrowserContext* browser_context,
                         std::vector<VoiceData>* out_voices) = 0;

  // For unit testing.
  virtual int QueueSize() = 0;
};

#endif  // CHROMECAST_BROWSER_TTS_TTS_CONTROLLER_H_