// Copyright (c) 2014 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.

#include <windows.h>
#include <sddl.h>

#include <utility>

#include "base/at_exit.h"
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback_helpers.h"
#include "base/command_line.h"
#include "base/environment.h"
#include "base/file_version_info.h"
#include "base/files/file_path.h"
#include "base/logging_win.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/process/process.h"
#include "base/run_loop.h"
#include "base/sequenced_task_runner.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string16.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_piece.h"
#include "base/strings/utf_string_conversions.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/time.h"
#include "base/win/scoped_handle.h"
#include "base/win/win_util.h"
#include "chrome/chrome_watcher/chrome_watcher_main_api.h"
#include "chrome/common/chrome_constants.h"
#include "chrome/install_static/install_details.h"
#include "components/browser_watcher/endsession_watcher_window_win.h"
#include "components/browser_watcher/exit_code_watcher_win.h"
#include "components/browser_watcher/window_hang_monitor_win.h"

namespace {

// Use the same log facility as Chrome for convenience.
// {7FE69228-633E-4f06-80C1-527FEA23E3A7}
const GUID kChromeWatcherTraceProviderName = {
    0x7fe69228, 0x633e, 0x4f06,
        { 0x80, 0xc1, 0x52, 0x7f, 0xea, 0x23, 0xe3, 0xa7 } };

// The amount of time we wait around for a WM_ENDSESSION or a process exit.
const int kDelayTimeSeconds = 30;

// Takes care of monitoring a browser. This class watches for a browser's exit
// code, as well as listening for WM_ENDSESSION messages. Events are recorded in
// an exit funnel, for reporting the next time Chrome runs.
class BrowserMonitor {
 public:
  BrowserMonitor(base::StringPiece16 registry_path, base::RunLoop* run_loop);
  ~BrowserMonitor();

  // Initiates the asynchronous monitoring process, returns true on success.
  // |on_initialized_event| will be signaled immediately before blocking on the
  // exit of |process|.
  bool StartWatching(base::Process process,
                     base::win::ScopedHandle on_initialized_event);

 private:
  // Called from EndSessionWatcherWindow on a end session messages.
  void OnEndSessionMessage(UINT message, LPARAM lparam);

  // Blocking function that runs on |background_thread_|. Signals
  // |on_initialized_event| before waiting for the browser process to exit.
  void Watch(base::win::ScopedHandle on_initialized_event);

  // Posted to main thread from Watch when browser exits.
  void BrowserExited();

  browser_watcher::ExitCodeWatcher exit_code_watcher_;
  browser_watcher::EndSessionWatcherWindow end_session_watcher_window_;

  // The thread that runs Watch().
  base::Thread background_thread_;

  // Set when the browser has exited, used to stretch the watcher's lifetime
  // when WM_ENDSESSION occurs before browser exit.
  base::WaitableEvent browser_exited_;

  // The run loop for the main thread and its task runner.
  base::RunLoop* run_loop_;
  scoped_refptr<base::SequencedTaskRunner> main_thread_;

  DISALLOW_COPY_AND_ASSIGN(BrowserMonitor);
};

BrowserMonitor::BrowserMonitor(base::StringPiece16 registry_path,
                               base::RunLoop* run_loop)
    : exit_code_watcher_(registry_path),
      end_session_watcher_window_(
          base::Bind(&BrowserMonitor::OnEndSessionMessage,
                     base::Unretained(this))),
      background_thread_("BrowserWatcherThread"),
      browser_exited_(base::WaitableEvent::ResetPolicy::MANUAL,
                      base::WaitableEvent::InitialState::NOT_SIGNALED),
      run_loop_(run_loop),
      main_thread_(base::ThreadTaskRunnerHandle::Get()) {}

BrowserMonitor::~BrowserMonitor() {
}

bool BrowserMonitor::StartWatching(
    base::Process process,
    base::win::ScopedHandle on_initialized_event) {
  if (!exit_code_watcher_.Initialize(std::move(process)))
    return false;

  if (!background_thread_.StartWithOptions(
        base::Thread::Options(base::MessageLoop::TYPE_IO, 0))) {
    return false;
  }

  if (!background_thread_.task_runner()->PostTask(
          FROM_HERE, base::Bind(&BrowserMonitor::Watch, base::Unretained(this),
                                base::Passed(&on_initialized_event)))) {
    background_thread_.Stop();
    return false;
  }

  return true;
}

void BrowserMonitor::OnEndSessionMessage(UINT message, LPARAM lparam) {
  DCHECK_EQ(main_thread_, base::ThreadTaskRunnerHandle::Get());

  // If the browser hasn't exited yet, dally for a bit to try and stretch this
  // process' lifetime to give it some more time to capture the browser exit.
  browser_exited_.TimedWait(base::TimeDelta::FromSeconds(kDelayTimeSeconds));

  run_loop_->Quit();
}

void BrowserMonitor::Watch(base::win::ScopedHandle on_initialized_event) {
  // This needs to run on an IO thread.
  DCHECK_NE(main_thread_, base::ThreadTaskRunnerHandle::Get());

  // Signal our client now that the Kasko reporter is initialized and we have
  // cleared all of the obstacles that might lead to an early exit.
  ::SetEvent(on_initialized_event.Get());
  on_initialized_event.Close();

  exit_code_watcher_.WaitForExit();

  // Note that the browser has exited.
  browser_exited_.Signal();

  main_thread_->PostTask(FROM_HERE,
      base::Bind(&BrowserMonitor::BrowserExited, base::Unretained(this)));
}

void BrowserMonitor::BrowserExited() {
  // This runs in the main thread.
  DCHECK_EQ(main_thread_, base::ThreadTaskRunnerHandle::Get());

  // Our background thread has served it's purpose.
  background_thread_.Stop();

  const int exit_code = exit_code_watcher_.exit_code();
  if (exit_code >= 0 && exit_code <= 28) {
    // The browser exited with a well-known exit code, quit this process
    // immediately.
    run_loop_->Quit();
  } else {
    // The browser exited abnormally, wait around for a little bit to see
    // whether this instance will get a logoff message.
    main_thread_->PostDelayedTask(
        FROM_HERE,
        run_loop_->QuitClosure(),
        base::TimeDelta::FromSeconds(kDelayTimeSeconds));
  }
}

}  // namespace

// The main entry point to the watcher, declared as extern "C" to avoid name
// mangling.
extern "C" int WatcherMain(const base::char16* registry_path,
                           HANDLE process_handle,
                           DWORD main_thread_id,
                           HANDLE on_initialized_event_handle,
                           const base::char16* browser_data_directory) {
  install_static::InstallDetails::InitializeFromPrimaryModule(
      chrome::kChromeElfDllName);
  base::Process process(process_handle);
  base::win::ScopedHandle on_initialized_event(on_initialized_event_handle);

  // The exit manager is in charge of calling the dtors of singletons.
  base::AtExitManager exit_manager;
  // Initialize the commandline singleton from the environment.
  base::CommandLine::Init(0, nullptr);

  logging::LogEventProvider::Initialize(kChromeWatcherTraceProviderName);

  // Arrange to be shut down as late as possible, as we want to outlive
  // chrome.exe in order to report its exit status.
  ::SetProcessShutdownParameters(0x100, SHUTDOWN_NORETRY);

  // Run a UI message loop on the main thread.
  base::PlatformThread::SetName("WatcherMainThread");
  base::MessageLoop msg_loop(base::MessageLoop::TYPE_UI);

  base::RunLoop run_loop;
  BrowserMonitor monitor(registry_path, &run_loop);
  if (!monitor.StartWatching(process.Duplicate(),
                             std::move(on_initialized_event))) {
    return 1;
  }
  run_loop.Run();
  // TODO(manzagop): hang monitoring using WindowHangMonitor.

  // Wind logging down.
  logging::LogEventProvider::Uninitialize();

  return 0;
}

static_assert(
    std::is_same<decltype(&WatcherMain), ChromeWatcherMainFunction>::value,
    "WatcherMain() has wrong type");