/*
 *  Copyright (c) 2014 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.
 */

#include "modules/desktop_capture/mac/full_screen_chrome_window_detector.h"

#include <libproc.h>

#include <string>

#include "modules/desktop_capture/mac/window_list_utils.h"
#include "rtc_base/logging.h"
#include "rtc_base/time_utils.h"

namespace webrtc {

namespace {

const int64_t kUpdateIntervalMs = 500;

// Returns the window that is full-screen and has the same title and owner pid
// as the input window.
CGWindowID FindFullScreenWindowWithSamePidAndTitle(CGWindowID id) {
  const int pid = GetWindowOwnerPid(id);
  std::string title = GetWindowTitle(id);
  if (title.empty())
    return kCGNullWindowID;

  // Only get on screen, non-desktop windows.
  CFArrayRef window_array = CGWindowListCopyWindowInfo(
      kCGWindowListOptionOnScreenOnly | kCGWindowListExcludeDesktopElements,
      kCGNullWindowID);
  if (!window_array)
    return kCGNullWindowID;

  CGWindowID full_screen_window = kCGNullWindowID;

  MacDesktopConfiguration desktop_config = MacDesktopConfiguration::GetCurrent(
      MacDesktopConfiguration::TopLeftOrigin);

  // Check windows to make sure they have an id, title, and use window layer
  // other than 0.
  CFIndex count = CFArrayGetCount(window_array);
  for (CFIndex i = 0; i < count; ++i) {
    CFDictionaryRef window = reinterpret_cast<CFDictionaryRef>(
        CFArrayGetValueAtIndex(window_array, i));

    CGWindowID window_id = GetWindowId(window);
    if (window_id == kNullWindowId)
      continue;

    if (GetWindowOwnerPid(window) != pid)
      continue;

    std::string window_title = GetWindowTitle(window);
    if (window_title != title)
      continue;

    if (IsWindowFullScreen(desktop_config, window)) {
      full_screen_window = window_id;
      break;
    }
  }

  CFRelease(window_array);
  return full_screen_window;
}

bool IsChromeWindow(CGWindowID id) {
  int pid = GetWindowOwnerPid(id);
  char buffer[PROC_PIDPATHINFO_MAXSIZE];
  int path_length = proc_pidpath(pid, buffer, sizeof(buffer));
  if (path_length <= 0)
    return false;

  const char* last_slash = strrchr(buffer, '/');
  std::string name(last_slash ? last_slash + 1 : buffer);
  return name.find("Google Chrome") == 0 || name == "Chromium";
}

}  // namespace

FullScreenChromeWindowDetector::FullScreenChromeWindowDetector()
    : last_update_time_ns_(0) {}

FullScreenChromeWindowDetector::~FullScreenChromeWindowDetector() {}

CGWindowID FullScreenChromeWindowDetector::FindFullScreenWindow(
    CGWindowID original_window) {
  if (!IsChromeWindow(original_window) || IsWindowOnScreen(original_window))
    return kCGNullWindowID;

  CGWindowID full_screen_window_id =
      FindFullScreenWindowWithSamePidAndTitle(original_window);

  if (full_screen_window_id == kCGNullWindowID)
    return kCGNullWindowID;

  for (const auto& window : previous_window_list_) {
    if (static_cast<CGWindowID>(window.id) != full_screen_window_id)
      continue;

    RTC_LOG(LS_WARNING) << "The full-screen window exists in the list.";
    return kCGNullWindowID;
  }

  return full_screen_window_id;
}

void FullScreenChromeWindowDetector::UpdateWindowListIfNeeded(
    CGWindowID original_window) {
  if (IsChromeWindow(original_window) &&
      (rtc::TimeNanos() - last_update_time_ns_) / rtc::kNumNanosecsPerMillisec >
          kUpdateIntervalMs) {
    previous_window_list_.clear();
    previous_window_list_.swap(current_window_list_);

    // No need to update the window list when the window is minimized.
    if (!IsWindowOnScreen(original_window)) {
      previous_window_list_.clear();
      return;
    }

    GetWindowList(&current_window_list_, false);
    last_update_time_ns_ = rtc::TimeNanos();
  }
}

}  // namespace webrtc