// Copyright 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 "chrome/browser/extensions/api/runtime/chrome_runtime_api_delegate.h"

#include <memory>
#include <string>
#include <utility>
#include <vector>

#include "base/lazy_instance.h"
#include "base/location.h"
#include "base/metrics/histogram_macros.h"
#include "base/single_thread_task_runner.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "chrome/browser/extensions/extension_service.h"
#include "chrome/browser/extensions/extension_tab_util.h"
#include "chrome/browser/extensions/updater/extension_updater.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ui/browser_finder.h"
#include "chrome/browser/ui/browser_navigator.h"
#include "chrome/browser/ui/browser_navigator_params.h"
#include "chrome/browser/ui/browser_window.h"
#include "components/update_client/update_query_params.h"
#include "content/public/browser/notification_service.h"
#include "extensions/browser/extension_registry.h"
#include "extensions/browser/extension_system.h"
#include "extensions/browser/notification_types.h"
#include "extensions/browser/warning_service.h"
#include "extensions/browser/warning_set.h"
#include "extensions/common/api/runtime.h"
#include "extensions/common/constants.h"
#include "net/base/backoff_entry.h"

#if defined(OS_CHROMEOS)
#include "chromeos/dbus/dbus_thread_manager.h"
#include "chromeos/dbus/power_manager_client.h"
#include "components/user_manager/user_manager.h"
#endif

using extensions::Extension;
using extensions::ExtensionSystem;
using extensions::ExtensionUpdater;

using extensions::api::runtime::PlatformInfo;

namespace {

const char kUpdateThrottled[] = "throttled";
const char kUpdateNotFound[] = "no_update";
const char kUpdateFound[] = "update_available";

// If an extension reloads itself within this many miliseconds of reloading
// itself, the reload is considered suspiciously fast.
const int kFastReloadTime = 10000;

// After this many suspiciously fast consecutive reloads, an extension will get
// disabled.
const int kFastReloadCount = 5;

// A holder class for the policy we use for exponential backoff of update check
// requests.
class BackoffPolicy {
 public:
  BackoffPolicy();
  ~BackoffPolicy();

  // Returns the actual policy to use.
  static const net::BackoffEntry::Policy* Get();

 private:
  net::BackoffEntry::Policy policy_;
};

// We use a LazyInstance since one of the the policy values references an
// extern symbol, which would cause a static initializer to be generated if we
// just declared the policy struct as a static variable.
base::LazyInstance<BackoffPolicy>::DestructorAtExit g_backoff_policy =
    LAZY_INSTANCE_INITIALIZER;

BackoffPolicy::BackoffPolicy() {
  policy_ = {
      // num_errors_to_ignore
      0,

      // initial_delay_ms (note that we set 'always_use_initial_delay' to false
      // below)
      1000 * extensions::kDefaultUpdateFrequencySeconds,

      // multiply_factor
      1,

      // jitter_factor
      0.1,

      // maximum_backoff_ms (-1 means no maximum)
      -1,

      // entry_lifetime_ms (-1 means never discard)
      -1,

      // always_use_initial_delay
      false,
  };
}

BackoffPolicy::~BackoffPolicy() {}

// static
const net::BackoffEntry::Policy* BackoffPolicy::Get() {
  return &g_backoff_policy.Get().policy_;
}

base::TickClock* g_test_clock = nullptr;

}  // namespace

struct ChromeRuntimeAPIDelegate::UpdateCheckInfo {
 public:
  UpdateCheckInfo() {
    if (g_test_clock)
      backoff.reset(
          new net::BackoffEntry(BackoffPolicy::Get(), g_test_clock));
    else
      backoff.reset(new net::BackoffEntry(BackoffPolicy::Get()));
  }

  std::unique_ptr<net::BackoffEntry> backoff;
  std::vector<UpdateCheckCallback> callbacks;
};

ChromeRuntimeAPIDelegate::ChromeRuntimeAPIDelegate(
    content::BrowserContext* context)
    : browser_context_(context),
      registered_for_updates_(false),
      extension_registry_observer_(this) {
  registrar_.Add(this,
                 extensions::NOTIFICATION_EXTENSION_UPDATE_FOUND,
                 content::NotificationService::AllSources());
  extension_registry_observer_.Add(
      extensions::ExtensionRegistry::Get(browser_context_));
}

ChromeRuntimeAPIDelegate::~ChromeRuntimeAPIDelegate() {
}

// static
void ChromeRuntimeAPIDelegate::set_tick_clock_for_tests(
    base::TickClock* clock) {
  g_test_clock = clock;
}

void ChromeRuntimeAPIDelegate::AddUpdateObserver(
    extensions::UpdateObserver* observer) {
  registered_for_updates_ = true;
  ExtensionSystem::Get(browser_context_)
      ->extension_service()
      ->AddUpdateObserver(observer);
}

void ChromeRuntimeAPIDelegate::RemoveUpdateObserver(
    extensions::UpdateObserver* observer) {
  if (registered_for_updates_) {
    ExtensionSystem::Get(browser_context_)
        ->extension_service()
        ->RemoveUpdateObserver(observer);
  }
}

void ChromeRuntimeAPIDelegate::ReloadExtension(
    const std::string& extension_id) {
  std::pair<base::TimeTicks, int>& reload_info =
      last_reload_time_[extension_id];
  base::TimeTicks now = base::TimeTicks::Now();
  if (reload_info.first.is_null() ||
      (now - reload_info.first).InMilliseconds() > kFastReloadTime) {
    reload_info.second = 0;
  } else {
    reload_info.second++;
  }
  if (!reload_info.first.is_null()) {
    UMA_HISTOGRAM_LONG_TIMES("Extensions.RuntimeReloadTime",
                             now - reload_info.first);
  }
  UMA_HISTOGRAM_COUNTS_100("Extensions.RuntimeReloadFastCount",
                           reload_info.second);
  reload_info.first = now;

  ExtensionService* service =
      ExtensionSystem::Get(browser_context_)->extension_service();
  if (reload_info.second >= kFastReloadCount) {
    // Unloading an extension clears all warnings, so first terminate the
    // extension, and then add the warning. Since this is called from an
    // extension function unloading the extension has to be done
    // asynchronously. Fortunately PostTask guarentees FIFO order so just
    // post both tasks.
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE, base::BindOnce(&ExtensionService::TerminateExtension,
                                  service->AsWeakPtr(), extension_id));
    extensions::WarningSet warnings;
    warnings.insert(
        extensions::Warning::CreateReloadTooFrequentWarning(
            extension_id));
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE,
        base::BindOnce(&extensions::WarningService::NotifyWarningsOnUI,
                       browser_context_, warnings));
  } else {
    // We can't call ReloadExtension directly, since when this method finishes
    // it tries to decrease the reference count for the extension, which fails
    // if the extension has already been reloaded; so instead we post a task.
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE, base::BindOnce(&ExtensionService::ReloadExtension,
                                  service->AsWeakPtr(), extension_id));
  }
}

bool ChromeRuntimeAPIDelegate::CheckForUpdates(
    const std::string& extension_id,
    const UpdateCheckCallback& callback) {
  ExtensionSystem* system = ExtensionSystem::Get(browser_context_);
  ExtensionService* service = system->extension_service();
  ExtensionUpdater* updater = service->updater();
  if (!updater) {
    return false;
  }

  UpdateCheckInfo& info = update_check_info_[extension_id];

  // If not enough time has elapsed, or we have 10 or more outstanding calls,
  // return a status of throttled.
  if (info.backoff->ShouldRejectRequest() || info.callbacks.size() >= 10) {
    base::ThreadTaskRunnerHandle::Get()->PostTask(
        FROM_HERE, base::BindOnce(callback, UpdateCheckResult(
                                                true, kUpdateThrottled, "")));
  } else {
    info.callbacks.push_back(callback);
    updater->CheckExtensionSoon(
        extension_id, base::Bind(&ChromeRuntimeAPIDelegate::UpdateCheckComplete,
                                 base::Unretained(this), extension_id));
  }
  return true;
}

void ChromeRuntimeAPIDelegate::OpenURL(const GURL& uninstall_url) {
  Profile* profile = Profile::FromBrowserContext(browser_context_);
  Browser* browser = chrome::FindLastActiveWithProfile(profile);
  if (!browser)
    browser = new Browser(Browser::CreateParams(profile, false));

  chrome::NavigateParams params(
      browser, uninstall_url, ui::PAGE_TRANSITION_CLIENT_REDIRECT);
  params.disposition = WindowOpenDisposition::NEW_FOREGROUND_TAB;
  params.user_gesture = false;
  chrome::Navigate(&params);
}

bool ChromeRuntimeAPIDelegate::GetPlatformInfo(PlatformInfo* info) {
  const char* os = update_client::UpdateQueryParams::GetOS();
  if (strcmp(os, "mac") == 0) {
    info->os = extensions::api::runtime::PLATFORM_OS_MAC;
  } else if (strcmp(os, "win") == 0) {
    info->os = extensions::api::runtime::PLATFORM_OS_WIN;
  } else if (strcmp(os, "cros") == 0) {
    info->os = extensions::api::runtime::PLATFORM_OS_CROS;
  } else if (strcmp(os, "linux") == 0) {
    info->os = extensions::api::runtime::PLATFORM_OS_LINUX;
  } else if (strcmp(os, "openbsd") == 0) {
    info->os = extensions::api::runtime::PLATFORM_OS_OPENBSD;
  } else {
    NOTREACHED();
    return false;
  }

  const char* arch = update_client::UpdateQueryParams::GetArch();
  if (strcmp(arch, "arm") == 0) {
    info->arch = extensions::api::runtime::PLATFORM_ARCH_ARM;
  } else if (strcmp(arch, "x86") == 0) {
    info->arch = extensions::api::runtime::PLATFORM_ARCH_X86_32;
  } else if (strcmp(arch, "x64") == 0) {
    info->arch = extensions::api::runtime::PLATFORM_ARCH_X86_64;
  } else {
    NOTREACHED();
    return false;
  }

  const char* nacl_arch = update_client::UpdateQueryParams::GetNaclArch();
  if (strcmp(nacl_arch, "arm") == 0) {
    info->nacl_arch = extensions::api::runtime::PLATFORM_NACL_ARCH_ARM;
  } else if (strcmp(nacl_arch, "x86-32") == 0) {
    info->nacl_arch = extensions::api::runtime::PLATFORM_NACL_ARCH_X86_32;
  } else if (strcmp(nacl_arch, "x86-64") == 0) {
    info->nacl_arch = extensions::api::runtime::PLATFORM_NACL_ARCH_X86_64;
  } else {
    NOTREACHED();
    return false;
  }

  return true;
}

bool ChromeRuntimeAPIDelegate::RestartDevice(std::string* error_message) {
#if defined(OS_CHROMEOS)
  if (user_manager::UserManager::Get()->IsLoggedInAsKioskApp()) {
    chromeos::DBusThreadManager::Get()
        ->GetPowerManagerClient()
        ->RequestRestart();
    return true;
  }
#endif
  *error_message = "Function available only for ChromeOS kiosk mode.";
  return false;
}

bool ChromeRuntimeAPIDelegate::OpenOptionsPage(
    const Extension* extension,
    content::BrowserContext* browser_context) {
  return extensions::ExtensionTabUtil::OpenOptionsPageFromAPI(extension,
                                                              browser_context);
}

void ChromeRuntimeAPIDelegate::Observe(
    int type,
    const content::NotificationSource& source,
    const content::NotificationDetails& details) {
  DCHECK_EQ(extensions::NOTIFICATION_EXTENSION_UPDATE_FOUND, type);
  using UpdateDetails = const std::pair<std::string, base::Version>;
  const std::string& id = content::Details<UpdateDetails>(details)->first;
  const base::Version& version =
      content::Details<UpdateDetails>(details)->second;
  if (version.IsValid()) {
    CallUpdateCallbacks(
        id, UpdateCheckResult(true, kUpdateFound, version.GetString()));
  }
}

void ChromeRuntimeAPIDelegate::OnExtensionInstalled(
    content::BrowserContext* browser_context,
    const Extension* extension,
    bool is_update) {
  if (!is_update)
    return;
  auto info = update_check_info_.find(extension->id());
  if (info != update_check_info_.end()) {
    info->second.backoff->Reset();
  }
}

void ChromeRuntimeAPIDelegate::UpdateCheckComplete(
    const std::string& extension_id) {
  ExtensionSystem* system = ExtensionSystem::Get(browser_context_);
  ExtensionService* service = system->extension_service();
  const Extension* update = service->GetPendingExtensionUpdate(extension_id);
  UpdateCheckInfo& info = update_check_info_[extension_id];

  // We always inform the BackoffEntry of a "failure" here, because we only
  // want to consider an update check request a success from a throttling
  // standpoint once the extension goes on to actually update to a new
  // version. See OnExtensionInstalled for where we reset the BackoffEntry.
  info.backoff->InformOfRequest(false);

  if (update) {
    CallUpdateCallbacks(
        extension_id,
        UpdateCheckResult(true, kUpdateFound, update->VersionString()));
  } else {
    CallUpdateCallbacks(extension_id,
                        UpdateCheckResult(true, kUpdateNotFound, ""));
  }
}

void ChromeRuntimeAPIDelegate::CallUpdateCallbacks(
    const std::string& extension_id,
    const UpdateCheckResult& result) {
  auto it = update_check_info_.find(extension_id);
  if (it == update_check_info_.end())
    return;
  std::vector<UpdateCheckCallback> callbacks;
  it->second.callbacks.swap(callbacks);
  for (const auto& callback : callbacks) {
    callback.Run(result);
  }
}