/* 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 "nsXPCOMCIDInternal.h"
#include "nsNetSegmentUtils.h"
#include "nsTransportUtils.h"
#include "nsStreamUtils.h"
#include "nsError.h"
#include "nsNetCID.h"

#include "nsIAsyncInputStream.h"
#include "nsIAsyncOutputStream.h"
#include "nsISeekableStream.h"
#include "nsIPipe.h"
#include "nsITransport.h"
#include "nsIObserverService.h"
#include "nsIThreadPool.h"
#include "mozilla/Services.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 nsIInputStream
{
public:
    NS_DECL_THREADSAFE_ISUPPORTS
    NS_DECL_NSITRANSPORT
    NS_DECL_NSIINPUTSTREAM

    nsInputStreamTransport(nsIInputStream *source,
                           bool closeWhenDone)
        : mSource(source)
        , mOffset(0)
        , mCloseWhenDone(closeWhenDone)
        , mInProgress(false)
    {
    }

private:
    virtual ~nsInputStreamTransport()
    {
    }

    nsCOMPtr<nsIAsyncInputStream>   mPipeIn;

    // while the copy is active, these members may only be accessed from the
    // nsIInputStream implementation.
    nsCOMPtr<nsITransportEventSink> mEventSink;
    nsCOMPtr<nsIInputStream>        mSource;
    int64_t                         mOffset;
    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;
};

NS_IMPL_ISUPPORTS(nsInputStreamTransport,
                  nsITransport,
                  nsIInputStream)

/** 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 =
            do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID, &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;
    rv = NS_NewPipe2(getter_AddRefs(mPipeIn),
                     getter_AddRefs(pipeOut),
                     nonblocking, true,
                     segsize, segcount);
    if (NS_FAILED(rv)) return rv;

    mInProgress = true;

    // startup async copy process...
    rv = NS_AsyncCopy(this, pipeOut, target,
                      NS_ASYNCCOPY_VIA_WRITESEGMENTS, segsize);
    if (NS_SUCCEEDED(rv))
        NS_ADDREF(*result = mPipeIn);

    return rv;
}

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

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

nsStreamTransportService::~nsStreamTransportService()
{
    NS_ASSERTION(!mPool, "thread pool wasn't shutdown");
}

nsresult
nsStreamTransportService::Init()
{
    mPool = do_CreateInstance(NS_THREADPOOL_CONTRACTID);
    NS_ENSURE_STATE(mPool);

    // Configure the pool
    mPool->SetName(NS_LITERAL_CSTRING("StreamTrans"));
    mPool->SetThreadLimit(25);
    mPool->SetIdleThreadLimit(1);
    mPool->SetIdleThreadTimeout(PR_SecondsToInterval(30));

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

NS_IMPL_ISUPPORTS(nsStreamTransportService,
                  nsIStreamTransportService,
                  nsIEventTarget,
                  nsIObserver)

NS_IMETHODIMP
nsStreamTransportService::DispatchFromScript(nsIRunnable *task, uint32_t flags)
{
  nsCOMPtr<nsIRunnable> event(task);
  return Dispatch(event.forget(), flags);
}

NS_IMETHODIMP
nsStreamTransportService::Dispatch(already_AddRefed<nsIRunnable> task, uint32_t flags)
{
    nsCOMPtr<nsIRunnable> event(task); // so it gets released on failure paths
    nsCOMPtr<nsIThreadPool> pool;
    {
        mozilla::MutexAutoLock lock(mShutdownLock);
        if (mIsShutdown) {
            return NS_ERROR_NOT_INITIALIZED;
        }
        pool = mPool;
    }
    NS_ENSURE_TRUE(pool, NS_ERROR_NOT_INITIALIZED);
    return pool->Dispatch(event.forget(), flags);
}

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

NS_IMETHODIMP_(bool)
nsStreamTransportService::IsOnCurrentThreadInfallible()
{
    nsCOMPtr<nsIThreadPool> pool;
    {
        mozilla::MutexAutoLock lock(mShutdownLock);
        pool = mPool;
    }
    if (!pool) {
      return false;
    }
    return pool->IsOnCurrentThread();
}

NS_IMETHODIMP
nsStreamTransportService::IsOnCurrentThread(bool *result)
{
    nsCOMPtr<nsIThreadPool> pool;
    {
        mozilla::MutexAutoLock lock(mShutdownLock);
        if (mIsShutdown) {
            return NS_ERROR_NOT_INITIALIZED;
        }
        pool = mPool;
    }
    NS_ENSURE_TRUE(pool, NS_ERROR_NOT_INITIALIZED);
    return pool->IsOnCurrentThread(result);
}

NS_IMETHODIMP
nsStreamTransportService::CreateInputTransport(nsIInputStream *stream,
                                               bool closeWhenDone,
                                               nsITransport **result)
{
    nsInputStreamTransport *trans =
        new nsInputStreamTransport(stream, closeWhenDone);
    if (!trans)
        return NS_ERROR_OUT_OF_MEMORY;
    NS_ADDREF(*result = trans);
    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");

  {
    mozilla::MutexAutoLock lock(mShutdownLock);
    mIsShutdown = true;
  }

  if (mPool) {
    mPool->Shutdown();
    mPool = nullptr;
  }
  return NS_OK;
}

class AvailableEvent final : public Runnable
{
public:
  AvailableEvent(nsIInputStream* stream,
                 nsIInputAvailableCallback* callback)
    : Runnable("net::AvailableEvent")
    , mStream(stream)
    , mCallback(callback)
    , mDoingCallback(false)
    , mSize(0)
    , mResultForCallback(NS_OK)
  {
    mCallbackTarget = GetCurrentThreadEventTarget();
  }

    NS_IMETHOD Run() override
    {
        if (mDoingCallback) {
            // pong
            mCallback->OnInputAvailableComplete(mSize, mResultForCallback);
            mCallback = nullptr;
        } else {
            // ping
            mResultForCallback = mStream->Available(&mSize);
            mStream = nullptr;
            mDoingCallback = true;

            nsCOMPtr<nsIRunnable> event(this); // overly cute
            mCallbackTarget->Dispatch(event.forget(), NS_DISPATCH_NORMAL);
            mCallbackTarget = nullptr;
        }
        return NS_OK;
    }

private:
    virtual ~AvailableEvent() { }

    nsCOMPtr<nsIInputStream> mStream;
    nsCOMPtr<nsIInputAvailableCallback> mCallback;
    nsCOMPtr<nsIEventTarget> mCallbackTarget;
    bool mDoingCallback;
    uint64_t mSize;
    nsresult mResultForCallback;
};

NS_IMETHODIMP
nsStreamTransportService::InputAvailable(nsIInputStream *stream,
                                         nsIInputAvailableCallback *callback)
{
    nsCOMPtr<nsIThreadPool> pool;
    {
        mozilla::MutexAutoLock lock(mShutdownLock);
        if (mIsShutdown) {
            return NS_ERROR_NOT_INITIALIZED;
        }
        pool = mPool;
    }
    nsCOMPtr<nsIRunnable> event = new AvailableEvent(stream, callback);
    return pool->Dispatch(event.forget(), NS_DISPATCH_NORMAL);
}

} // namespace net
} // namespace mozilla