/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/**
 * ChildSHistory represents a view of session history from a child process. It
 * exposes getters for some cached history state, and mutators which are
 * implemented by communicating with the actual history storage in
 * ParentSHistory.
 *
 * NOTE: Currently session history is in transition, meaning that we're still
 * using the legacy nsSHistory class internally. The API exposed from this class
 * should be only the API which we expect to expose when this transition is
 * complete, and special cases will need to call through the LegacySHistory()
 * getters.
 */

#ifndef mozilla_dom_ChildSHistory_h
#define mozilla_dom_ChildSHistory_h

#include "nsCOMPtr.h"
#include "mozilla/ErrorResult.h"
#include "nsWrapperCache.h"

class nsSHistory;
class nsDocShell;
class nsISHistory;
class nsIWebNavigation;
class nsIGlobalObject;

namespace mozilla {
namespace dom {

class ParentSHistory;

class ChildSHistory : public nsISupports, public nsWrapperCache {
 public:
  friend class ParentSHistory;

  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ChildSHistory)
  nsISupports* GetParentObject() const;
  JSObject* WrapObject(JSContext* cx,
                       JS::Handle<JSObject*> aGivenProto) override;

  explicit ChildSHistory(nsDocShell* aDocShell);

  int32_t Count();
  int32_t Index();

  /**
   * Reload the current entry in the session history.
   */
  void Reload(uint32_t aReloadFlags, ErrorResult& aRv);

  /**
   * The CanGo and Go methods are called with an offset from the current index.
   * Positive numbers go forward in history, while negative numbers go
   * backwards.
   */
  bool CanGo(int32_t aOffset);
  void Go(int32_t aOffset, ErrorResult& aRv);

  /**
   * Evicts all content viewers within the current process.
   */
  void EvictLocalContentViewers();

  nsISHistory* LegacySHistory();

  ParentSHistory* GetParentIfSameProcess();

 private:
  virtual ~ChildSHistory();

  RefPtr<nsDocShell> mDocShell;
  RefPtr<nsSHistory> mHistory;
};

}  // namespace dom
}  // namespace mozilla

#endif /* mozilla_dom_ChildSHistory_h */