/* 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 "nsStreamTransportService.h"

#include "ErrorList.h"
#include "mozilla/Components.h"
#include "mozilla/Services.h"
#include "nsError.h"
#include "nsIAsyncInputStream.h"
#include "nsIAsyncOutputStream.h"
#include "nsIObserverService.h"
#include "nsIPipe.h"
#include "nsITransport.h"
#include "nsNetCID.h"
#include "nsNetSegmentUtils.h"
#include "nsStreamUtils.h"
#include "nsThreadPool.h"
#include "nsTransportUtils.h"
#include "nsXPCOMCIDInternal.h"

namespace mozilla {
namespace net {

//-----------------------------------------------------------------------------
// nsInputStreamTransport
//
// Implements nsIInputStream as a wrapper around the real input stream.  This
// allows the transport to support seeking, range-limiting, progress reporting,
// and close-when-done semantics while utilizing NS_AsyncCopy.
//-----------------------------------------------------------------------------

class nsInputStreamTransport : public nsITransport,
                               public nsIAsyncInputStream,
                               public nsIInputStreamCallback {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSITRANSPORT
  NS_DECL_NSIINPUTSTREAM
  NS_DECL_NSIASYNCINPUTSTREAM
  NS_DECL_NSIINPUTSTREAMCALLBACK

  nsInputStreamTransport(nsIInputStream* source, bool closeWhenDone)
      : mSource(source), mCloseWhenDone(closeWhenDone) {
    mAsyncSource = do_QueryInterface(mSource);
  }

 private:
  virtual ~nsInputStreamTransport() = default;

  Mutex mMutex{"nsInputStreamTransport::mMutex"};

  // This value is protected by mutex.
  nsCOMPtr<nsIInputStreamCallback> mAsyncWaitCallback MOZ_GUARDED_BY(mMutex);

  nsCOMPtr<nsIAsyncInputStream> mPipeIn;

  // while the copy is active, these members may only be accessed from the
  // nsIInputStream implementation.
  nsCOMPtr<nsITransportEventSink> mEventSink;
  nsCOMPtr<nsIInputStream> mSource;

  // It can be null.
  nsCOMPtr<nsIAsyncInputStream> mAsyncSource;

  int64_t mOffset{0};
  const bool mCloseWhenDone;

  // this variable serves as a lock to prevent the state of the transport
  // from being modified once the copy is in progress.
  bool mInProgress{false};
};

NS_IMPL_ADDREF(nsInputStreamTransport);
NS_IMPL_RELEASE(nsInputStreamTransport);

NS_INTERFACE_MAP_BEGIN(nsInputStreamTransport)
  NS_INTERFACE_MAP_ENTRY(nsITransport)
  NS_INTERFACE_MAP_ENTRY(nsIInputStream)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIAsyncInputStream, !!mAsyncSource)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIInputStreamCallback, !!mAsyncSource)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsITransport)
NS_INTERFACE_MAP_END

/** nsITransport **/

NS_IMETHODIMP
nsInputStreamTransport::OpenInputStream(uint32_t flags, uint32_t segsize,
                                        uint32_t segcount,
                                        nsIInputStream** result) {
  NS_ENSURE_TRUE(!mInProgress, NS_ERROR_IN_PROGRESS);

  nsresult rv;
  nsCOMPtr<nsIEventTarget> target;
  target = mozilla::components::StreamTransport::Service(&rv);
  if (NS_FAILED(rv)) return rv;

  // XXX if the caller requests an unbuffered stream, then perhaps
  //     we'd want to simply return mSource; however, then we would
  //     not be reading mSource on a background thread.  is this ok?

  bool nonblocking = !(flags & OPEN_BLOCKING);

  net_ResolveSegmentParams(segsize, segcount);

  nsCOMPtr<nsIAsyncOutputStream> pipeOut;
  NS_NewPipe2(getter_AddRefs(mPipeIn), getter_AddRefs(pipeOut), nonblocking,
              true, segsize, segcount);

  mInProgress = true;

  // startup async copy process...
  rv = NS_AsyncCopy(this, pipeOut, target, NS_ASYNCCOPY_VIA_WRITESEGMENTS,
                    segsize);
  if (NS_FAILED(rv)) {
    return rv;
  }
  *result = do_AddRef(mPipeIn).take();
  return NS_OK;
}

NS_IMETHODIMP
nsInputStreamTransport::OpenOutputStream(uint32_t flags, uint32_t segsize,
                                         uint32_t segcount,
                                         nsIOutputStream** result) {
  // this transport only supports reading!
  MOZ_ASSERT_UNREACHABLE("nsInputStreamTransport::OpenOutputStream");
  return NS_ERROR_UNEXPECTED;
}

NS_IMETHODIMP
nsInputStreamTransport::Close(nsresult reason) {
  if (NS_SUCCEEDED(reason)) reason = NS_BASE_STREAM_CLOSED;

  return mPipeIn->CloseWithStatus(reason);
}

NS_IMETHODIMP
nsInputStreamTransport::SetEventSink(nsITransportEventSink* sink,
                                     nsIEventTarget* target) {
  NS_ENSURE_TRUE(!mInProgress, NS_ERROR_IN_PROGRESS);

  if (target) {
    return net_NewTransportEventSinkProxy(getter_AddRefs(mEventSink), sink,
                                          target);
  }

  mEventSink = sink;
  return NS_OK;
}

/** nsIInputStream **/

NS_IMETHODIMP
nsInputStreamTransport::Close() {
  if (mCloseWhenDone) mSource->Close();

  // make additional reads return early...
  mOffset = 0;
  return NS_OK;
}

NS_IMETHODIMP
nsInputStreamTransport::Available(uint64_t* result) {
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsInputStreamTransport::StreamStatus() { return mSource->StreamStatus(); }

NS_IMETHODIMP
nsInputStreamTransport::Read(char* buf, uint32_t count, uint32_t* result) {
  nsresult rv = mSource->Read(buf, count, result);

  if (NS_SUCCEEDED(rv)) {
    mOffset += *result;
    if (mEventSink) {
      mEventSink->OnTransportStatus(this, NS_NET_STATUS_READING, mOffset, -1);
    }
  }
  return rv;
}

NS_IMETHODIMP
nsInputStreamTransport::ReadSegments(nsWriteSegmentFun writer, void* closure,
                                     uint32_t count, uint32_t* result) {
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsInputStreamTransport::IsNonBlocking(bool* result) {
  *result = false;
  return NS_OK;
}

// nsIAsyncInputStream interface

NS_IMETHODIMP
nsInputStreamTransport::CloseWithStatus(nsresult aStatus) { return Close(); }

NS_IMETHODIMP
nsInputStreamTransport::AsyncWait(nsIInputStreamCallback* aCallback,
                                  uint32_t aFlags, uint32_t aRequestedCount,
                                  nsIEventTarget* aEventTarget) {
  NS_ENSURE_STATE(!!mAsyncSource);

  nsCOMPtr<nsIInputStreamCallback> callback = aCallback ? this : nullptr;

  {
    MutexAutoLock lock(mMutex);

    if (NS_WARN_IF(mAsyncWaitCallback && aCallback &&
                   mAsyncWaitCallback != aCallback)) {
      return NS_ERROR_FAILURE;
    }

    mAsyncWaitCallback = aCallback;
  }

  return mAsyncSource->AsyncWait(callback, aFlags, aRequestedCount,
                                 aEventTarget);
}

// nsIInputStreamCallback

NS_IMETHODIMP
nsInputStreamTransport::OnInputStreamReady(nsIAsyncInputStream* aStream) {
  nsCOMPtr<nsIInputStreamCallback> callback;
  {
    MutexAutoLock lock(mMutex);

    // We have been canceled in the meanwhile.
    if (!mAsyncWaitCallback) {
      return NS_OK;
    }

    callback.swap(mAsyncWaitCallback);
  }

  MOZ_ASSERT(callback);
  return callback->OnInputStreamReady(this);
}

//-----------------------------------------------------------------------------
// nsStreamTransportService
//-----------------------------------------------------------------------------

/* static */
already_AddRefed<nsStreamTransportService> nsStreamTransportService::Create() {
  nsCOMPtr<nsIThreadPool> pool = new nsThreadPool();
  pool->SetName("StreamTrans"_ns);
  // TODO: Make these settings configurable.
  pool->SetThreadLimit(25);
  pool->SetIdleThreadLimit(4);
  pool->SetIdleThreadMaximumTimeout(30 * 1000);
  pool->SetIdleThreadGraceTimeout(500);

  RefPtr<nsStreamTransportService> svc =
      new nsStreamTransportService(pool.forget());

  nsCOMPtr<nsIObserverService> obsSvc = mozilla::services::GetObserverService();
  if (obsSvc) {
    obsSvc->AddObserver(svc, "xpcom-shutdown-threads", false);
  }

  return svc.forget();
}

nsStreamTransportService::nsStreamTransportService(
    already_AddRefed<nsIThreadPool> aPool)
    : mPool(aPool) {}

nsStreamTransportService::~nsStreamTransportService() = default;

NS_IMPL_ISUPPORTS(nsStreamTransportService, nsIStreamTransportService,
                  nsIEventTarget, nsIObserver)

NS_IMETHODIMP
nsStreamTransportService::DispatchFromScript(nsIRunnable* task,
                                             DispatchFlags flags) {
  return Dispatch(do_AddRef(task), flags);
}

NS_IMETHODIMP
nsStreamTransportService::Dispatch(already_AddRefed<nsIRunnable> task,
                                   DispatchFlags flags) {
  return mPool->Dispatch(std::move(task), flags);
}

NS_IMETHODIMP
nsStreamTransportService::DelayedDispatch(already_AddRefed<nsIRunnable> aEvent,
                                          uint32_t aDelayMs) {
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsStreamTransportService::RegisterShutdownTask(nsITargetShutdownTask* aTask) {
  return mPool->RegisterShutdownTask(aTask);
}

NS_IMETHODIMP
nsStreamTransportService::UnregisterShutdownTask(nsITargetShutdownTask* aTask) {
  return mPool->UnregisterShutdownTask(aTask);
}

nsIEventTarget::FeatureFlags nsStreamTransportService::GetFeatures() {
  return mPool->GetFeatures();
}

NS_IMETHODIMP_(bool)
nsStreamTransportService::IsOnCurrentThreadInfallible() {
  return mPool->IsOnCurrentThread();
}

NS_IMETHODIMP
nsStreamTransportService::IsOnCurrentThread(bool* result) {
  return mPool->IsOnCurrentThread(result);
}

NS_IMETHODIMP
nsStreamTransportService::CreateInputTransport(nsIInputStream* stream,
                                               bool closeWhenDone,
                                               nsITransport** result) {
  RefPtr<nsInputStreamTransport> trans =
      new nsInputStreamTransport(stream, closeWhenDone);
  trans.forget(result);
  return NS_OK;
}

NS_IMETHODIMP
nsStreamTransportService::Observe(nsISupports* subject, const char* topic,
                                  const char16_t* data) {
  NS_ASSERTION(strcmp(topic, "xpcom-shutdown-threads") == 0, "oops");

  mPool->Shutdown();
  return NS_OK;
}

}  // namespace net
}  // namespace mozilla