components/live_caption/views/caption_bubble_model.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_LIVE_CAPTION_VIEWS_CAPTION_BUBBLE_MODEL_H_
#define COMPONENTS_LIVE_CAPTION_VIEWS_CAPTION_BUBBLE_MODEL_H_

#include <string>

#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/types/id_type.h"

namespace captions {

class CaptionBubble;
class CaptionBubbleContext;

// These values are persisted to logs. Entries should not be renumbered and
// numeric values should never be reused.
// LINT.IfChange(CaptionBubbleErrorType)
enum CaptionBubbleErrorType {
  kGeneric = 0,
  kMediaFoundationRendererUnsupported = 1,
  kMaxValue = kMediaFoundationRendererUnsupported
};
// LINT.ThenChange(/tools/metrics/histograms/metadata/accessibility/enums.xml:CaptionBubbleErrorType)

using OnErrorClickedCallback = base::RepeatingCallback<void()>;
using OnDoNotShowAgainClickedCallback =
    base::RepeatingCallback<void(CaptionBubbleErrorType, bool)>;
using OnCaptionBubbleClosedCallback =
    base::RepeatingCallback<void(const std::string&)>;

///////////////////////////////////////////////////////////////////////////////
// Caption Bubble Model
//
//  A representation of the data a caption bubble needs for a particular media
//  stream. The caption bubble controller sets the value of the text. The
//  caption bubble observes the model, and when the values change, the observer
//  is alerted.
//
//  There exists one CaptionBubble and one CaptionBubbleControllerViews per
//  profile, but one CaptionBubbleModel per media stream. The CaptionBubbleModel
//  is owned by the CaptionBubbleControllerViews. It is created when
//  transcriptions from a new media stream are received and exists until the
//  audio stream ends for that stream.
//
//  Partial text is a speech result that is subject to change. Incoming partial
//  texts overlap with the previous partial text.
//  Final text is the final transcription from the speech service that no
//  longer changes. Incoming partial texts do not overlap with final text.
//  When a final result is received from the speech service, the partial text is
//  appended to the end of the final text. The caption bubble displays the full
//  final + partial text.
//
class CaptionBubbleModel {
 public:
  using Id = base::IdTypeU64<CaptionBubbleModel>;

  CaptionBubbleModel(CaptionBubbleContext* context,
                     OnCaptionBubbleClosedCallback callback);
  ~CaptionBubbleModel();
  CaptionBubbleModel(const CaptionBubbleModel&) = delete;
  CaptionBubbleModel& operator=(const CaptionBubbleModel&) = delete;

  void SetObserver(CaptionBubble* observer);
  void RemoveObserver();

  // Set the partial text and alert the observer.
  void SetPartialText(const std::string& partial_text);

  // Set the download progress label and alert the observer.
  void SetDownloadProgressText(const std::u16string& download_progress_text);

  // Notify the observer that a language pack was installed.
  void OnLanguagePackInstalled();

  // Commits the partial text as final text.
  void CommitPartialText();

  // Set that the bubble has an error and alert the observer.
  void OnError(CaptionBubbleErrorType error_type,
               OnErrorClickedCallback error_clicked_callback,
               OnDoNotShowAgainClickedCallback error_silenced_callback);

  // Mark the bubble as closed.
  void CloseButtonPressed();

  // Clear the partial and final text, and alert the
  // observer.
  void Close();

  // Clears the partial and final text and alerts the observer.
  void ClearText();

  bool IsClosed() const { return is_closed_; }
  bool HasError() const { return has_error_; }
  CaptionBubbleErrorType ErrorType() const { return error_type_; }
  std::string GetFullText() const;
  CaptionBubbleContext* GetContext() { return context_; }
  std::u16string GetDownloadProgressText() const {
    return download_progress_text_;
  }

  // Returns the auto-detected language code or an empty string if the language
  // was not automatically switched.
  std::string GetAutoDetectedLanguageCode() const {
    return auto_detected_language_code_;
  }

  Id unique_id() const { return unique_id_; }

  void SetLanguage(const std::string& language_code);

 private:
  // Generates the next unique id.
  static Id GetNextId();

  // Alert the observer that a change has occurred to the model text.
  void OnTextChanged();

  // Alert the observer that the auto-detected language of the model has
  // changed.
  void OnAutoDetectedLanguageChanged();

  const Id unique_id_;

  std::string final_text_;
  std::string partial_text_;
  std::u16string download_progress_text_;

  std::string auto_detected_language_code_ = std::string();

  // Whether the bubble has been closed by the user.
  bool is_closed_ = false;

  // Whether an error should be displayed in the bubble.
  bool has_error_ = false;

  // The most recent error type encountered.
  CaptionBubbleErrorType error_type_ = CaptionBubbleErrorType::kGeneric;

  // The CaptionBubble observing changes to this model.
  raw_ptr<CaptionBubble, DanglingUntriaged> observer_ = nullptr;

  OnCaptionBubbleClosedCallback caption_bubble_closed_callback_;

  // Used to calculate and log the amount of flickering between partial results.
  int erasure_count_ = 0;
  int partial_result_count_ = 0;

  const raw_ptr<CaptionBubbleContext, DanglingUntriaged> context_;
};

}  // namespace captions

#endif  // COMPONENTS_LIVE_CAPTION_VIEWS_CAPTION_BUBBLE_MODEL_H_