// Copyright (c) 2011 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 CHROME_BROWSER_TAB_CONTENTS_LANGUAGE_STATE_H_
#define CHROME_BROWSER_TAB_CONTENTS_LANGUAGE_STATE_H_

#include <string>

#include "base/basictypes.h"

class LanguageStateObserver;

namespace content {
struct LoadCommittedDetails;
class NavigationController;
class WebContents;
}

// This class holds the language state of the current page.
// There is one LanguageState instance per WebContents.
// It is used to determine when navigating to a new page whether it should
// automatically be translated.
// This auto-translate behavior is the expected behavior when:
// - user is on page in language A that they had translated to language B.
// - user clicks a link in that page that takes them to a page also in language
//   A.

class LanguageState {
 public:
  explicit LanguageState(content::NavigationController* nav_controller);
  ~LanguageState();

  // Should be called when the page did a new navigation (whether it is a main
  // frame or sub-frame navigation).
  void DidNavigate(const content::LoadCommittedDetails& details);

  // Should be called when the language of the page has been determined.
  // |page_needs_translation| when false indicates that the browser should not
  // offer to translate the page.
  void LanguageDetermined(const std::string& page_language,
                          bool page_needs_translation);

  // Returns the language the current page should be translated to, based on the
  // previous page languages and the transition.  This should be called after
  // the language page has been determined.
  // Returns an empty string if the page should not be auto-translated.
  std::string AutoTranslateTo() const;

  // Returns true if the user is navigating through translated links.
  bool InTranslateNavigation() const;

  // Returns true if the current page in the associated tab has been translated.
  bool IsPageTranslated() const { return original_lang_ != current_lang_; }

  const std::string& original_language() const { return original_lang_; }

  void SetCurrentLanguage(const std::string& language);
  const std::string& current_language() const { return current_lang_; }

  bool page_needs_translation() const { return page_needs_translation_; }

  // Whether the page is currently in the process of being translated.
  bool translation_pending() const { return translation_pending_; }
  void set_translation_pending(bool value) { translation_pending_ = value; }

  // Whether the user has already declined to translate the page.
  bool translation_declined() const { return translation_declined_; }
  void set_translation_declined(bool value) { translation_declined_ = value; }

  // Whether the current page was navigated through an in-page (fragment)
  // navigation.
  bool in_page_navigation() const { return in_page_navigation_; }

  // Whether the translate is enabled. This value is supposed to be used for the
  // Translate icon on the Omnibox.
  bool translate_enabled() const { return translate_enabled_; }
  void SetTranslateEnabled(bool value);

  // Whether the current page's language is different from the previous
  // language.
  bool HasLanguageChanged() const;

  void set_observer(LanguageStateObserver* observer) { observer_ = observer; }

 private:
  void SetIsPageTranslated(bool value);

  // Whether the page is translated or not.
  bool is_page_translated_;

  // The languages this page is in. Note that current_lang_ is different from
  // original_lang_ when the page has been translated.
  // Note that these might be empty if the page language has not been determined
  // yet.
  std::string original_lang_;
  std::string current_lang_;

  // Same as above but for the previous page.
  std::string prev_original_lang_;
  std::string prev_current_lang_;

  // The navigation controller of the tab we are associated with.
  content::NavigationController* navigation_controller_;

  // Whether it is OK to offer to translate the page.  Some pages explictly
  // specify that they should not be translated by the browser (this is the case
  // for GMail for example, which provides its own translation features).
  bool page_needs_translation_;

  // Whether a translation is currently pending (WebContents waiting for the
  // PAGE_TRANSLATED notification).  This is needed to avoid sending duplicate
  // translate requests to a page.  TranslateManager initiates translations
  // when it received the LANGUAGE_DETERMINED notification.  This is sent by
  // the renderer with the page contents, every time the load stops for the
  // main frame, so we may get several.
  // TODO(jcampan): make the renderer send the language just once per navigation
  //                then we can get rid of that state.
  bool translation_pending_;

  // Whether the user has declined to translate the page (by closing the infobar
  // for example).  This is necessary as a new infobar could be shown if a new
  // load happens in the page after the user closed the infobar.
  bool translation_declined_;

  // Whether the current navigation is a fragment navigation (in page).
  bool in_page_navigation_;

  // Whether the Translate is enabled.
  bool translate_enabled_;

  LanguageStateObserver* observer_;

  DISALLOW_COPY_AND_ASSIGN(LanguageState);
};

#endif  // CHROME_BROWSER_TAB_CONTENTS_LANGUAGE_STATE_H_