/*
 *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef WEBRTC_MODULES_DESKTOP_CAPTURE_FAKE_DESKTOP_CAPTURER_H_
#define WEBRTC_MODULES_DESKTOP_CAPTURE_FAKE_DESKTOP_CAPTURER_H_

#include <memory>
#include <utility>

#include "webrtc/modules/desktop_capture/desktop_capturer.h"
#include "webrtc/modules/desktop_capture/desktop_frame_generator.h"
#include "webrtc/modules/desktop_capture/shared_desktop_frame.h"
#include "webrtc/modules/desktop_capture/shared_memory.h"

namespace webrtc {

// A fake implementation of DesktopCapturer or its derived interfaces to
// generate DesktopFrame for testing purpose.
//
// Consumers can provide a FrameGenerator instance to generate instances of
// DesktopFrame to return for each Capture() function call.
// If no FrameGenerator provided, FakeDesktopCapturer will always return a
// nullptr DesktopFrame.
//
// Double buffering is guaranteed by the FrameGenerator. FrameGenerator
// implements in desktop_frame_generator.h guarantee double buffering, they
// creates a new instance of DesktopFrame each time.
//
// T must be DesktopCapturer or its derived interfaces.
//
// TODO(zijiehe): Remove template T once we merge ScreenCapturer and
// WindowCapturer.
template <typename T>
class FakeDesktopCapturer : public T {
 public:
  FakeDesktopCapturer()
      : callback_(nullptr),
        result_(DesktopCapturer::Result::SUCCESS),
        generator_(nullptr) {}

  ~FakeDesktopCapturer() override {}

  // Decides the result which will be returned in next Capture() callback.
  void set_result(DesktopCapturer::Result result) { result_ = result; }

  // Uses the |generator| provided as DesktopFrameGenerator, FakeDesktopCapturer
  // does
  // not take the ownership of |generator|.
  void set_frame_generator(DesktopFrameGenerator* generator) {
    generator_ = generator;
  }

  // DesktopCapturer interface
  void Start(DesktopCapturer::Callback* callback) override {
    callback_ = callback;
  }

  void Capture(const DesktopRegion& region) override {
    if (generator_) {
      std::unique_ptr<DesktopFrame> frame(
          generator_->GetNextFrame(shared_memory_factory_.get()));
      if (frame) {
        callback_->OnCaptureResult(result_, std::move(frame));
      } else {
        callback_->OnCaptureResult(DesktopCapturer::Result::ERROR_TEMPORARY,
                                   nullptr);
      }
      return;
    }
    callback_->OnCaptureResult(DesktopCapturer::Result::ERROR_PERMANENT,
                               nullptr);
  }

  void SetSharedMemoryFactory(
      std::unique_ptr<SharedMemoryFactory> shared_memory_factory) override {
    shared_memory_factory_ = std::move(shared_memory_factory);
  }

 private:
  DesktopCapturer::Callback* callback_;
  std::unique_ptr<SharedMemoryFactory> shared_memory_factory_;
  DesktopCapturer::Result result_;
  DesktopFrameGenerator* generator_;
};

}  // namespace webrtc

#endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_FAKE_DESKTOP_CAPTURER_H_