// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef REMOTING_HOST_REMOTE_INPUT_FILTER_H_
#define REMOTING_HOST_REMOTE_INPUT_FILTER_H_

#include <list>

#include "base/compiler_specific.h"
#include "base/functional/callback.h"
#include "base/time/time.h"
#include "remoting/protocol/input_filter.h"
#include "remoting/protocol/input_stub.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_geometry.h"
#include "ui/events/event.h"

namespace remoting {

// Filtering InputStub that filters remotely-injected input if it has been
// notified of local input recently.
class RemoteInputFilter : public protocol::InputFilter {
 public:
  // Creates a filter which forwards events to `input_stub`.
  // `release_all_keys`: A callback to release all currently pressed keys, mouse
  // buttons, and touch points. The callback will never be called after `this`
  // is destroyed.
  RemoteInputFilter(InputStub* input_stub, base::RepeatingClosure release_all);

  RemoteInputFilter(const RemoteInputFilter&) = delete;
  RemoteInputFilter& operator=(const RemoteInputFilter&) = delete;

  ~RemoteInputFilter() override;

  // Informs the filter that local mouse or touch activity has been detected.
  // If the activity does not match events we injected then we assume that it
  // is local, and block remote input for a short while. Returns true if the
  // input was local, or false if it was rejected as an echo.
  bool LocalPointerMoved(const webrtc::DesktopVector& pos, ui::EventType type);

  // Informs the filter that a local keypress event has been detected. If the
  // key does not correspond to one we injected then we assume that it is local,
  // and block remote input for a short while. Returns true if the input was
  // local, or false if it was rejected as an echo.
  bool LocalKeyPressed(uint32_t usb_keycode);

  // Informs the filter that injecting input causes an echo.
  void SetExpectLocalEcho(bool expect_local_echo);

  // InputStub overrides.
  void InjectKeyEvent(const protocol::KeyEvent& event) override;
  void InjectTextEvent(const protocol::TextEvent& event) override;
  void InjectMouseEvent(const protocol::MouseEvent& event) override;
  void InjectTouchEvent(const protocol::TouchEvent& event) override;

 private:
  bool ShouldIgnoreInput() const;
  void LocalInputDetected();

  base::RepeatingClosure release_all_;

  // Queue of recently-injected mouse positions and keypresses used to
  // distinguish echoes of injected events from movements from a local
  // input device.
  std::list<webrtc::DesktopVector> injected_mouse_positions_;
  std::list<uint32_t> injected_key_presses_;

  // Time at which local input events were most recently observed.
  base::TimeTicks latest_local_input_time_;

  // If |true| than the filter assumes that injecting input causes an echo.
  bool expect_local_echo_;
};

}  // namespace remoting

#endif  // REMOTING_HOST_REMOTE_INPUT_FILTER_H_