// Copyright (c) 2012 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 UI_AURA_ENV_H_
#define UI_AURA_ENV_H_

#include <memory>

#include "base/macros.h"
#include "base/observer_list.h"
#include "base/supports_user_data.h"
#include "ui/aura/aura_export.h"
#include "ui/events/event_handler.h"
#include "ui/events/event_target.h"
#include "ui/gfx/geometry/point.h"

namespace ui {
class ContextFactory;
class PlatformEventSource;
}
namespace aura {

namespace client {
class FocusClient;
}

namespace test {
class EnvTestHelper;
}

class EnvObserver;
class InputStateLookup;
class Window;
class WindowPort;
class WindowTreeClient;
class WindowTreeHost;

// A singleton object that tracks general state within Aura.
class AURA_EXPORT Env : public ui::EventTarget, public base::SupportsUserData {
 public:
  enum class Mode {
    // Classic aura.
    LOCAL,

    // Aura with a backend of mus.
    MUS,
  };

  ~Env() override;

  // NOTE: if you pass in Mode::MUS it is expected that you call
  // SetWindowTreeClient() before any windows are created.
  static std::unique_ptr<Env> CreateInstance(Mode mode = Mode::LOCAL);
  static Env* GetInstance();
  static Env* GetInstanceDontCreate();

  // Called internally to create the appropriate WindowPort implementation.
  std::unique_ptr<WindowPort> CreateWindowPort(Window* window);

  void AddObserver(EnvObserver* observer);
  void RemoveObserver(EnvObserver* observer);

  int mouse_button_flags() const { return mouse_button_flags_; }
  void set_mouse_button_flags(int mouse_button_flags) {
    mouse_button_flags_ = mouse_button_flags;
  }
  // Returns true if a mouse button is down. This may query the native OS,
  // otherwise it uses |mouse_button_flags_|.
  bool IsMouseButtonDown() const;

  // Gets/sets the last mouse location seen in a mouse event in the screen
  // coordinates.
  const gfx::Point& last_mouse_location() const { return last_mouse_location_; }
  void set_last_mouse_location(const gfx::Point& last_mouse_location) {
    last_mouse_location_ = last_mouse_location;
  }

  // Whether any touch device is currently down.
  bool is_touch_down() const { return is_touch_down_; }
  void set_touch_down(bool value) { is_touch_down_ = value; }

  void set_context_factory(ui::ContextFactory* context_factory) {
    context_factory_ = context_factory;
  }
  ui::ContextFactory* context_factory() { return context_factory_; }

  // See CreateInstance() for description.
  void SetWindowTreeClient(WindowTreeClient* window_tree_client);

  // Sets the active FocusClient and the window the FocusClient is associated
  // with. |window| is not necessarily the window that actually has focus.
  // |window| may be null, which indicates all windows share a FocusClient.
  void SetActiveFocusClient(client::FocusClient* focus_client,
                            Window* focus_client_root);
  client::FocusClient* active_focus_client() { return active_focus_client_; }
  Window* active_focus_client_root() { return active_focus_client_root_; }

 private:
  class ActiveFocusClientWindowObserver;

  friend class test::EnvTestHelper;
  friend class Window;
  friend class WindowTreeHost;

  explicit Env(Mode mode);

  void Init();

  // Called by the Window when it is initialized. Notifies observers.
  void NotifyWindowInitialized(Window* window);

  // Called by the WindowTreeHost when it is initialized. Notifies observers.
  void NotifyHostInitialized(WindowTreeHost* host);

  // Invoked by WindowTreeHost when it is activated. Notifies observers.
  void NotifyHostActivated(WindowTreeHost* host);

  void OnActiveFocusClientWindowDestroying();

  // Overridden from ui::EventTarget:
  bool CanAcceptEvent(const ui::Event& event) override;
  ui::EventTarget* GetParentTarget() override;
  std::unique_ptr<ui::EventTargetIterator> GetChildIterator() const override;
  ui::EventTargeter* GetEventTargeter() override;

  // This is not const for tests, which may share Env across tests and so needs
  // to reset the value.
  Mode mode_;
  WindowTreeClient* window_tree_client_ = nullptr;

  base::ObserverList<EnvObserver> observers_;

  int mouse_button_flags_;
  // Location of last mouse event, in screen coordinates.
  gfx::Point last_mouse_location_;
  bool is_touch_down_;

  std::unique_ptr<InputStateLookup> input_state_lookup_;
  std::unique_ptr<ui::PlatformEventSource> event_source_;

  ui::ContextFactory* context_factory_;

  Window* active_focus_client_root_ = nullptr;
  client::FocusClient* active_focus_client_ = nullptr;
  std::unique_ptr<ActiveFocusClientWindowObserver>
      active_focus_client_window_observer_;

  DISALLOW_COPY_AND_ASSIGN(Env);
};

}  // namespace aura

#endif  // UI_AURA_ENV_H_