// Copyright 2022 The Cobalt Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "cobalt/browser/service_worker_registry.h"

#include <string>

#include "base/bind.h"
#include "base/message_loop/message_loop.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/thread.h"
#include "base/trace_event/trace_event.h"
#include "cobalt/network/network_module.h"
#include "cobalt/watchdog/watchdog.h"

namespace cobalt {
namespace browser {

namespace {
// Signals the given WaitableEvent.
void SignalWaitableEvent(base::WaitableEvent* event) { event->Signal(); }

// The watchdog time interval in microseconds allowed between pings before
// triggering violations.
const int64_t kWatchdogTimeInterval = 15000000;
// The watchdog time wait in microseconds to initially wait before triggering
// violations.
const int64_t kWatchdogTimeWait = 15000000;
// The watchdog time interval in milliseconds between pings.
const int64_t kWatchdogTimePing = 5000;

}  // namespace

void ServiceWorkerRegistry::WillDestroyCurrentMessageLoop() {
  // Clear all member variables allocated from the thread.
  service_worker_context_.reset();
}

ServiceWorkerRegistry::ServiceWorkerRegistry(
    web::WebSettings* web_settings, network::NetworkModule* network_module,
    web::UserAgentPlatformInfo* platform_info)
    : thread_("ServiceWorkerRegistry") {
  if (!thread_.Start()) return;
  DCHECK(message_loop());

  watchdog::Watchdog* watchdog = watchdog::Watchdog::GetInstance();

  // Registers service worker thread as a watchdog client.
  if (watchdog) {
    watchdog_registered_ = true;
    watchdog->Register(worker::WorkerConsts::kServiceWorkerRegistryName,
                       worker::WorkerConsts::kServiceWorkerRegistryName,
                       base::kApplicationStateStarted, kWatchdogTimeInterval,
                       kWatchdogTimeWait, watchdog::PING);
    message_loop()->task_runner()->PostDelayedTask(
        FROM_HERE,
        base::Bind(&ServiceWorkerRegistry::PingWatchdog,
                   base::Unretained(this)),
        base::TimeDelta::FromMilliseconds(kWatchdogTimePing));
  }

  message_loop()->task_runner()->PostTask(
      FROM_HERE,
      base::Bind(&ServiceWorkerRegistry::Initialize, base::Unretained(this),
                 web_settings, network_module, platform_info));

  // Register as a destruction observer to shut down the Web Agent once all
  // pending tasks have been executed and the message loop is about to be
  // destroyed. This allows us to safely stop the thread, drain the task queue,
  // then destroy the internal components before the message loop is reset.
  // No posted tasks will be executed once the thread is stopped.
  message_loop()->task_runner()->PostTask(
      FROM_HERE,
      base::Bind(&base::MessageLoop::AddDestructionObserver,
                 base::Unretained(message_loop()), base::Unretained(this)));

  // This works almost like a PostBlockingTask, except that any blocking that
  // may be necessary happens when Stop() is called instead of right now.
  message_loop()->task_runner()->PostTask(
      FROM_HERE, base::Bind(&SignalWaitableEvent,
                            base::Unretained(&destruction_observer_added_)));
}

ServiceWorkerRegistry::~ServiceWorkerRegistry() {
  DCHECK(message_loop());
  DCHECK(thread_.IsRunning());

  // Unregisters service worker thread as a watchdog client.
  watchdog::Watchdog* watchdog = watchdog::Watchdog::GetInstance();
  if (watchdog) {
    watchdog_registered_ = false;
    watchdog->Unregister(worker::WorkerConsts::kServiceWorkerRegistryName);
  }

  // Ensure that the destruction observer got added before stopping the thread.
  // Stop the thread. This will cause the destruction observer to be notified.
  destruction_observer_added_.Wait();
  DCHECK_NE(thread_.message_loop(), base::MessageLoop::current());
  thread_.Stop();
  DCHECK(!service_worker_context_);
}

// Ping watchdog every 5 second, otherwise a violation will be triggered.
void ServiceWorkerRegistry::PingWatchdog() {
  DCHECK_EQ(base::MessageLoop::current(), message_loop());

  watchdog::Watchdog* watchdog = watchdog::Watchdog::GetInstance();
  // If watchdog is already unregistered or shut down, stop ping watchdog.
  if (!watchdog_registered_ || !watchdog) return;

  watchdog->Ping(worker::WorkerConsts::kServiceWorkerRegistryName);
  message_loop()->task_runner()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&ServiceWorkerRegistry::PingWatchdog, base::Unretained(this)),
      base::TimeDelta::FromMilliseconds(kWatchdogTimePing));
}

void ServiceWorkerRegistry::EnsureServiceWorkerStarted(
    const url::Origin& storage_key, const GURL& client_url,
    base::WaitableEvent* done_event) {
  service_worker_context()->EnsureServiceWorkerStarted(storage_key, client_url,
                                                       done_event);
}

void ServiceWorkerRegistry::EraseRegistrationMap() {
  service_worker_context()->EraseRegistrationMap();
}

worker::ServiceWorkerContext* ServiceWorkerRegistry::service_worker_context() {
  // Ensure that the thread had a chance to allocate the object.
  destruction_observer_added_.Wait();
  return service_worker_context_.get();
}

void ServiceWorkerRegistry::Initialize(
    web::WebSettings* web_settings, network::NetworkModule* network_module,
    web::UserAgentPlatformInfo* platform_info) {
  TRACE_EVENT0("cobalt::browser", "ServiceWorkerRegistry::Initialize()");
  DCHECK_EQ(base::MessageLoop::current(), message_loop());
  service_worker_context_.reset(new worker::ServiceWorkerContext(
      web_settings, network_module, platform_info, message_loop()));
}

}  // namespace browser
}  // namespace cobalt