/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsCOMPtr.h"
#include "nsProxyRelease.h"
#include "nsComponentManagerUtils.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include "nsXPCOM.h"
#include "nsXPCOMCID.h"
#include "nsIObserver.h"
#include "nsIObserverService.h"
#include "nsWifiMonitor.h"
#include "nsWifiAccessPoint.h"

#include "nsServiceManagerUtils.h"
#include "nsComponentManagerUtils.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/Services.h"

using namespace mozilla;

LazyLogModule gWifiMonitorLog("WifiMonitor");

NS_IMPL_ISUPPORTS(nsWifiMonitor, nsIRunnable, nsIObserver, nsIWifiMonitor)

nsWifiMonitor::nsWifiMonitor()
    : mKeepGoing(true),
      mThreadComplete(false),
      mReentrantMonitor("nsWifiMonitor.mReentrantMonitor") {
  nsCOMPtr<nsIObserverService> obsSvc = mozilla::services::GetObserverService();
  if (obsSvc) obsSvc->AddObserver(this, "xpcom-shutdown", false);

  LOG(("@@@@@ wifimonitor created\n"));
}

NS_IMETHODIMP
nsWifiMonitor::Observe(nsISupports* subject, const char* topic,
                       const char16_t* data) {
  MOZ_ASSERT(NS_IsMainThread());
  if (!strcmp(topic, "xpcom-shutdown")) {
    LOG(("Shutting down\n"));

    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
    mKeepGoing = false;
    mon.Notify();
    mThread = nullptr;
  }
  return NS_OK;
}

NS_IMETHODIMP nsWifiMonitor::StartWatching(nsIWifiListener* aListener) {
  LOG(("nsWifiMonitor::StartWatching %p thread %p listener %p\n", this,
       mThread.get(), aListener));
  MOZ_ASSERT(NS_IsMainThread());

  if (!aListener) {
    return NS_ERROR_NULL_POINTER;
  }
  if (!mKeepGoing) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  nsresult rv = NS_OK;

  ReentrantMonitorAutoEnter mon(mReentrantMonitor);
  if (mThreadComplete) {
    // generally there is just one thread for the lifetime of the service,
    // but if DoScan returns with an error before shutdown (i.e. !mKeepGoing)
    // then we will respawn the thread.
    LOG(("nsWifiMonitor::StartWatching %p restarting thread\n", this));
    mThreadComplete = false;
    mThread = nullptr;
  }

  if (!mThread) {
    rv = NS_NewNamedThread("Wifi Monitor", getter_AddRefs(mThread), this);
    if (NS_FAILED(rv)) {
      return rv;
    }
  }

  mListeners.AppendElement(
      nsWifiListener(new nsMainThreadPtrHolder<nsIWifiListener>(
          "nsIWifiListener", aListener)));

  // tell ourselves that we have a new watcher.
  mon.Notify();
  return NS_OK;
}

NS_IMETHODIMP nsWifiMonitor::StopWatching(nsIWifiListener* aListener) {
  LOG(("nsWifiMonitor::StopWatching %p thread %p listener %p\n", this,
       mThread.get(), aListener));
  MOZ_ASSERT(NS_IsMainThread());

  if (!aListener) {
    return NS_ERROR_NULL_POINTER;
  }

  ReentrantMonitorAutoEnter mon(mReentrantMonitor);

  for (uint32_t i = 0; i < mListeners.Length(); i++) {
    if (mListeners[i].mListener == aListener) {
      mListeners.RemoveElementAt(i);
      break;
    }
  }

  return NS_OK;
}

using WifiListenerArray = nsTArray<nsMainThreadPtrHandle<nsIWifiListener>>;

class nsPassErrorToWifiListeners final : public nsIRunnable {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIRUNNABLE

  nsPassErrorToWifiListeners(UniquePtr<WifiListenerArray>&& aListeners,
                             nsresult aResult)
      : mListeners(std::move(aListeners)), mResult(aResult) {}

 private:
  ~nsPassErrorToWifiListeners() = default;
  UniquePtr<WifiListenerArray> mListeners;
  nsresult mResult;
};

NS_IMPL_ISUPPORTS(nsPassErrorToWifiListeners, nsIRunnable)

NS_IMETHODIMP nsPassErrorToWifiListeners::Run() {
  LOG(("About to send error to the wifi listeners\n"));
  for (size_t i = 0; i < mListeners->Length(); i++) {
    (*mListeners)[i]->OnError(mResult);
  }
  return NS_OK;
}

NS_IMETHODIMP nsWifiMonitor::Run() {
  LOG(("@@@@@ wifi monitor run called\n"));

  nsresult rv = DoScan();
  LOG(("@@@@@ wifi monitor run::doscan complete %" PRIx32 "\n",
       static_cast<uint32_t>(rv)));

  UniquePtr<WifiListenerArray> currentListeners;
  bool doError = false;

  {
    ReentrantMonitorAutoEnter mon(mReentrantMonitor);
    if (mKeepGoing && NS_FAILED(rv)) {
      doError = true;
      currentListeners = MakeUnique<WifiListenerArray>(mListeners.Length());
      for (uint32_t i = 0; i < mListeners.Length(); i++) {
        currentListeners->AppendElement(mListeners[i].mListener);
      }
    }
    mThreadComplete = true;
  }

  if (doError) {
    nsCOMPtr<nsIEventTarget> target = GetMainThreadEventTarget();
    if (!target) return NS_ERROR_UNEXPECTED;

    nsCOMPtr<nsIRunnable> runnable(
        new nsPassErrorToWifiListeners(std::move(currentListeners), rv));
    if (!runnable) return NS_ERROR_OUT_OF_MEMORY;

    target->Dispatch(runnable, NS_DISPATCH_SYNC);
  }

  LOG(("@@@@@ wifi monitor run complete\n"));
  return NS_OK;
}

class nsCallWifiListeners final : public nsIRunnable {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIRUNNABLE

  nsCallWifiListeners(WifiListenerArray&& aListeners,
                      nsTArray<RefPtr<nsIWifiAccessPoint>>&& aAccessPoints)
      : mListeners(std::move(aListeners)),
        mAccessPoints(std::move(aAccessPoints)) {}

 private:
  ~nsCallWifiListeners() = default;
  const WifiListenerArray mListeners;
  const nsTArray<RefPtr<nsIWifiAccessPoint>> mAccessPoints;
};

NS_IMPL_ISUPPORTS(nsCallWifiListeners, nsIRunnable)

NS_IMETHODIMP nsCallWifiListeners::Run() {
  LOG(("About to send data to the wifi listeners\n"));
  for (const auto& listener : mListeners) {
    listener->OnChange(mAccessPoints);
  }
  return NS_OK;
}

nsresult nsWifiMonitor::CallWifiListeners(
    const nsCOMArray<nsWifiAccessPoint>& aAccessPoints,
    bool aAccessPointsChanged) {
  WifiListenerArray currentListeners;
  {
    ReentrantMonitorAutoEnter mon(mReentrantMonitor);

    currentListeners.SetCapacity(mListeners.Length());

    for (auto& listener : mListeners) {
      if (!listener.mHasSentData || aAccessPointsChanged) {
        listener.mHasSentData = true;
        currentListeners.AppendElement(listener.mListener);
      }
    }
  }

  if (!currentListeners.IsEmpty()) {
    uint32_t resultCount = aAccessPoints.Count();
    nsTArray<RefPtr<nsIWifiAccessPoint>> accessPoints(resultCount);

    for (uint32_t i = 0; i < resultCount; i++) {
      accessPoints.AppendElement(aAccessPoints[i]);
    }

    nsCOMPtr<nsIThread> thread = do_GetMainThread();
    if (!thread) return NS_ERROR_UNEXPECTED;

    nsCOMPtr<nsIRunnable> runnable(new nsCallWifiListeners(
        std::move(currentListeners), std::move(accessPoints)));
    if (!runnable) return NS_ERROR_OUT_OF_MEMORY;

    thread->Dispatch(runnable, NS_DISPATCH_SYNC);
  }

  return NS_OK;
}