/* 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/. */

#ifndef nsInputStreamPump_h_
#define nsInputStreamPump_h_

#include "nsIInputStreamPump.h"
#include "nsIAsyncInputStream.h"
#include "nsIThreadRetargetableRequest.h"
#include "nsCOMPtr.h"
#include "mozilla/Attributes.h"
#include "mozilla/RecursiveMutex.h"

#ifdef DEBUG
#  include "MainThreadUtils.h"
#  include "nsISerialEventTarget.h"
#endif

class nsIInputStream;
class nsILoadGroup;
class nsIStreamListener;

#define NS_INPUT_STREAM_PUMP_IID \
  {0x42f1cc9b, 0xdf5f, 0x4c9b, {0xbd, 0x71, 0x8d, 0x4a, 0xe2, 0x27, 0xc1, 0x8a}}

class nsInputStreamPump final : public nsIInputStreamPump,
                                public nsIInputStreamCallback,
                                public nsIThreadRetargetableRequest {
  ~nsInputStreamPump() = default;

 public:
  using RecursiveMutexAutoLock = mozilla::RecursiveMutexAutoLock;
  using RecursiveMutexAutoUnlock = mozilla::RecursiveMutexAutoUnlock;
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIREQUEST
  NS_DECL_NSIINPUTSTREAMPUMP
  NS_DECL_NSIINPUTSTREAMCALLBACK
  NS_DECL_NSITHREADRETARGETABLEREQUEST
  NS_INLINE_DECL_STATIC_IID(NS_INPUT_STREAM_PUMP_IID)

  nsInputStreamPump();

  static nsresult Create(nsInputStreamPump** result, nsIInputStream* stream,
                         uint32_t segsize = 0, uint32_t segcount = 0,
                         bool closeWhenDone = false,
                         nsISerialEventTarget* mainThreadTarget = nullptr);

  using PeekSegmentFun = void (*)(void*, const uint8_t*, uint32_t);
  /**
   * Peek into the first chunk of data that's in the stream. Note that this
   * method will not call the callback when there is no data in the stream.
   * The callback will be called at most once.
   *
   * The data from the stream will not be consumed, i.e. the pump's listener
   * can still read all the data
   *
   * Do not call before asyncRead. Do not call after onStopRequest.
   */
  nsresult PeekStream(PeekSegmentFun callback, void* closure);

  /**
   * Dispatched (to the main thread) by OnStateStop if it's called off main
   * thread. Updates mState based on return value of OnStateStop.
   */
  nsresult CallOnStateStop();

  /**
   * Used by nsPipe to dispatch events with increased priority.
   */
  void SetHighPriority(bool aHighPriority) {
    mHighPriorityStream = aHighPriority;
  }
  bool IsHighPriority() { return mHighPriorityStream; }

 protected:
  enum { STATE_IDLE, STATE_START, STATE_TRANSFER, STATE_STOP, STATE_DEAD };

  nsresult EnsureWaiting();
  uint32_t OnStateStart();
  uint32_t OnStateTransfer();
  uint32_t OnStateStop();
  nsresult CreateBufferedStreamIfNeeded() MOZ_REQUIRES(mMutex);

  // This should optimize away in non-DEBUG builds
  MOZ_ALWAYS_INLINE void AssertOnThread() const MOZ_REQUIRES(mMutex) {
    if (mOffMainThread) {
      MOZ_ASSERT(mTargetThread->IsOnCurrentThread());
    } else {
      MOZ_ASSERT(NS_IsMainThread());
    }
  }

  uint32_t mState MOZ_GUARDED_BY(mMutex){STATE_IDLE};
  nsCOMPtr<nsILoadGroup> mLoadGroup MOZ_GUARDED_BY(mMutex);
  // mListener is written on a single thread (either MainThread or an
  // off-MainThread thread), read from that thread and perhaps others (in
  // RetargetDeliveryTo)
  nsCOMPtr<nsIStreamListener> mListener MOZ_GUARDED_BY(mMutex);
  nsCOMPtr<nsISerialEventTarget> mTargetThread MOZ_GUARDED_BY(mMutex);
  nsCOMPtr<nsISerialEventTarget> mLabeledMainThreadTarget
      MOZ_GUARDED_BY(mMutex);
  nsCOMPtr<nsIInputStream> mStream MOZ_GUARDED_BY(mMutex);
  // mAsyncStream is written on a single thread (either MainThread or an
  // off-MainThread thread), and lives from AsyncRead() to OnStateStop().
  nsCOMPtr<nsIAsyncInputStream> mAsyncStream MOZ_GUARDED_BY(mMutex);
  uint64_t mStreamOffset MOZ_GUARDED_BY(mMutex){0};
  uint64_t mStreamLength MOZ_GUARDED_BY(mMutex){0};
  uint32_t mSegSize MOZ_GUARDED_BY(mMutex){0};
  uint32_t mSegCount MOZ_GUARDED_BY(mMutex){0};
  nsresult mStatus MOZ_GUARDED_BY(mMutex){NS_OK};
  uint32_t mSuspendCount MOZ_GUARDED_BY(mMutex){0};
  uint32_t mLoadFlags MOZ_GUARDED_BY(mMutex){LOAD_NORMAL};
  bool mIsPending MOZ_GUARDED_BY(mMutex){false};
  // True while in OnInputStreamReady, calling OnStateStart, OnStateTransfer
  // and OnStateStop. Used to prevent calls to AsyncWait during callbacks.
  bool mProcessingCallbacks MOZ_GUARDED_BY(mMutex){false};
  // True if waiting on the "input stream ready" callback.
  bool mWaitingForInputStreamReady MOZ_GUARDED_BY(mMutex){false};
  bool mCloseWhenDone MOZ_GUARDED_BY(mMutex){false};
  bool mRetargeting MOZ_GUARDED_BY(mMutex){false};
  bool mAsyncStreamIsBuffered MOZ_GUARDED_BY(mMutex){false};
  // Indicate whether nsInputStreamPump is used completely off main thread.
  // If true, OnStateStop() is executed off main thread. Set at creation.
  const bool mOffMainThread;
  // Protects state/member var accesses across multiple threads.
  mozilla::RecursiveMutex mMutex{"nsInputStreamPump"};
  // Whether events from this input stream should be dispatched
  // with increased priority
  mozilla::Atomic<bool, mozilla::Relaxed> mHighPriorityStream{false};
};

#endif  // !nsInputStreamChannel_h_