// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "remoting/host/persistent_display_layout_manager.h"

#include <memory>

#include "base/files/file.h"
#include "base/files/file_error_or.h"
#include "base/files/file_path.h"
#include "base/functional/bind.h"
#include "base/logging.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "base/task/task_traits.h"
#include "base/task/thread_pool.h"
#include "base/time/time.h"
#include "remoting/base/async_file_util.h"
#include "remoting/base/constants.h"
#include "remoting/base/logging.h"
#include "remoting/proto/control.pb.h"
#include "third_party/webrtc/modules/desktop_capture/desktop_capture_types.h"

namespace remoting {

namespace {

// Delay to throttle writes to the display layout file.
constexpr base::TimeDelta kWriteDisplayLayoutDelay = base::Seconds(10);

bool IsLayoutValid(const protocol::VideoLayout& layout) {
  if (layout.video_track_size() < 1 || layout.video_track_size() > 4) {
    LOG(ERROR) << "Invalid track count: " << layout.video_track_size();
    return false;
  }

  for (const auto& track : layout.video_track()) {
    if (track.position_x() < 0 || track.position_y() < 0) {
      LOG(ERROR) << "Invalid position: " << track.position_x() << ","
                 << track.position_y();
      return false;
    }
    if (track.width() < 1 || track.width() > 32767 || track.height() < 1 ||
        track.height() > 32767) {
      LOG(ERROR) << "Invalid size: " << track.width() << "x" << track.height();
      return false;
    }
    if (track.x_dpi() < 1) {
      LOG(ERROR) << "Invalid x_dpi: " << track.x_dpi();
      return false;
    }
    if (track.has_y_dpi() && track.y_dpi() != track.x_dpi()) {
      LOG(ERROR) << "Invalid y_dpi: " << track.y_dpi()
                 << " (must match x_dpi or be unset)";
      return false;
    }
  }
  return true;
}

std::unique_ptr<protocol::VideoLayout> CreateDefaultLayout() {
  auto default_layout = std::make_unique<protocol::VideoLayout>();
  default_layout->set_pixel_type(
      protocol::VideoLayout::PixelType::VideoLayout_PixelType_LOGICAL);
  protocol::VideoTrackLayout* track = default_layout->add_video_track();
  track->set_position_x(0);
  track->set_position_y(0);
  track->set_width(1280);
  track->set_height(960);
  track->set_x_dpi(kDefaultDpi);
  track->set_y_dpi(kDefaultDpi);
  return default_layout;
}

}  // namespace

PersistentDisplayLayoutManager::PersistentDisplayLayoutManager(
    const base::FilePath& display_layout_file_path,
    std::unique_ptr<DesktopDisplayInfoMonitor> display_info_monitor,
    base::WeakPtr<DesktopResizer> desktop_resizer)
    : display_layout_file_path_(display_layout_file_path),
      display_info_monitor_(std::move(display_info_monitor)),
      desktop_resizer_(std::move(desktop_resizer)),
      io_task_runner_(base::ThreadPool::CreateSequencedTaskRunner(
          {base::MayBlock(), base::TaskPriority::BEST_EFFORT})),
      write_display_layout_timer_(
          FROM_HERE,
          kWriteDisplayLayoutDelay,
          base::BindRepeating(
              &PersistentDisplayLayoutManager::WriteDisplayLayout,
              base::Unretained(this))) {}

PersistentDisplayLayoutManager::~PersistentDisplayLayoutManager() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}

void PersistentDisplayLayoutManager::Start(base::OnceClosure on_done) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  ReadFileAsync(
      display_layout_file_path_,
      base::BindOnce(&PersistentDisplayLayoutManager::OnDisplayLayoutFileLoaded,
                     weak_ptr_factory_.GetWeakPtr(), std::move(on_done)));
}

void PersistentDisplayLayoutManager::OnDisplayLayoutFileLoaded(
    base::OnceClosure on_done,
    base::FileErrorOr<std::string> load_file_result) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  ApplyDisplayLayout(load_file_result);
  display_info_subscription_ =
      display_info_monitor_->AddCallback(base::BindRepeating(
          &PersistentDisplayLayoutManager::OnDisplayInfoReceived,
          weak_ptr_factory_.GetWeakPtr()));
  display_info_monitor_->Start();
  std::move(on_done).Run();
}

void PersistentDisplayLayoutManager::OnDisplayInfoReceived() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  const auto* display_info = display_info_monitor_->GetLatestDisplayInfo();
  DCHECK(display_info);
  latest_display_layout_ = display_info->GetVideoLayoutProto();
  // This either starts or delays the timer.
  write_display_layout_timer_.Reset();
}

void PersistentDisplayLayoutManager::ApplyDisplayLayout(
    const base::FileErrorOr<std::string>& load_file_result) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  bool success = false;
  if (load_file_result.has_value()) {
    auto display_layout_from_file = std::make_unique<protocol::VideoLayout>();
    if (display_layout_from_file->ParseFromString(*load_file_result)) {
      // Run some simple checks to make sure the file is not corrupted.
      if (IsLayoutValid(*display_layout_from_file)) {
        for (protocol::VideoTrackLayout& track :
             *display_layout_from_file->mutable_video_track()) {
          // Clear the screen ID to indicate that a new display should be
          // created. See comment in protobuf.
          track.clear_screen_id();
        }
        if (desktop_resizer_) {
          HOST_LOG << "Applying display layout from file: "
                   << display_layout_file_path_;
          desktop_resizer_->SetVideoLayout(*display_layout_from_file);
          success = true;
        }
      } else {
        LOG(ERROR) << "Invalid display layout from file.";
      }
    } else {
      LOG(ERROR) << "Failed to parse display layout.";
    }
  } else if (load_file_result.error() !=
             base::File::Error::FILE_ERROR_NOT_FOUND) {
    LOG(ERROR) << "Failed to read file " << display_layout_file_path_ << ": "
               << base::File::ErrorToString(load_file_result.error());
  }

  if (!success && desktop_resizer_) {
    auto default_layout = CreateDefaultLayout();
    HOST_LOG << "Applying standard default display layout ("
             << default_layout->video_track(0).width() << "x"
             << default_layout->video_track(0).height() << ").";
    desktop_resizer_->SetVideoLayout(*default_layout);
  }
}

void PersistentDisplayLayoutManager::WriteDisplayLayout() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  if (!latest_display_layout_) {
    return;
  }

  WriteImportantFileAndEnsureParentDirAsync(
      display_layout_file_path_, latest_display_layout_->SerializeAsString(),
      io_task_runner_,
      base::BindOnce(
          [](const base::FilePath& path, base::FileErrorOr<void> result) {
            if (!result.has_value()) {
              LOG(ERROR) << "Failed to write display layout to file " << path
                         << ": " << base::File::ErrorToString(result.error());
            }
          },
          display_layout_file_path_));
}

}  // namespace remoting