/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 nsBaseChannel_h__
#define nsBaseChannel_h__

#include "mozilla/Maybe.h"
#include "mozilla/MozPromise.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/net/NeckoTargetHolder.h"
#include "mozilla/net/PrivateBrowsingChannel.h"
#include "nsCOMPtr.h"
#include "nsHashPropertyBag.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsIChannel.h"
#include "nsIInterfaceRequestor.h"
#include "nsILoadGroup.h"
#include "nsILoadInfo.h"
#include "nsIProgressEventSink.h"
#include "nsIStreamListener.h"
#include "nsIThreadRetargetableRequest.h"
#include "nsIThreadRetargetableStreamListener.h"
#include "nsITransport.h"
#include "nsITransportSecurityInfo.h"
#include "nsIURI.h"
#include "nsInputStreamPump.h"
#include "nsString.h"
#include "nsThreadUtils.h"

class nsIInputStream;
class nsICancelable;

//-----------------------------------------------------------------------------
// nsBaseChannel is designed to be subclassed.  The subclass is responsible for
// implementing the OpenContentStream method, which will be called by the
// nsIChannel::AsyncOpen and nsIChannel::Open implementations.
//
// nsBaseChannel implements nsIInterfaceRequestor to provide a convenient way
// for subclasses to query both the nsIChannel::notificationCallbacks and
// nsILoadGroup::notificationCallbacks for supported interfaces.
//
// nsBaseChannel implements nsITransportEventSink to support progress & status
// notifications generated by the transport layer.

class nsBaseChannel
    : public nsHashPropertyBag,
      public nsIChannel,
      public nsIThreadRetargetableRequest,
      public nsIInterfaceRequestor,
      public nsITransportEventSink,
      public nsIAsyncVerifyRedirectCallback,
      public mozilla::net::PrivateBrowsingChannel<nsBaseChannel>,
      public mozilla::net::NeckoTargetHolder,
      protected nsIStreamListener,
      protected nsIThreadRetargetableStreamListener {
 public:
  NS_DECL_ISUPPORTS_INHERITED
  NS_DECL_NSIREQUEST
  NS_DECL_NSICHANNEL
  NS_DECL_NSIINTERFACEREQUESTOR
  NS_DECL_NSITRANSPORTEVENTSINK
  NS_DECL_NSIASYNCVERIFYREDIRECTCALLBACK
  NS_DECL_NSITHREADRETARGETABLEREQUEST
  NS_DECL_NSITHREADRETARGETABLESTREAMLISTENER

  nsBaseChannel();

 protected:
  // -----------------------------------------------
  // Methods to be implemented by the derived class:

  virtual ~nsBaseChannel();

  using BlockingPromise = mozilla::MozPromise<nsresult, nsresult, true>;

 private:
  // Implemented by subclass to supply data stream.  The parameter, async, is
  // true when called from nsIChannel::AsyncOpen and false otherwise.  When
  // async is true, the resulting stream will be used with a nsIInputStreamPump
  // instance.  This means that if it is a non-blocking stream that supports
  // nsIAsyncInputStream that it will be read entirely on the main application
  // thread, and its AsyncWait method will be called whenever ReadSegments
  // returns NS_BASE_STREAM_WOULD_BLOCK.  Otherwise, if the stream is blocking,
  // then it will be read on one of the background I/O threads, and it does not
  // need to implement ReadSegments.  If async is false, this method may return
  // NS_ERROR_NOT_IMPLEMENTED to cause the basechannel to implement Open in
  // terms of AsyncOpen (see NS_ImplementChannelOpen).
  // A callee is allowed to return an nsIChannel instead of an nsIInputStream.
  // That case will be treated as a redirect to the new channel.  By default
  // *channel will be set to null by the caller, so callees who don't want to
  // return one an just not touch it.
  virtual nsresult OpenContentStream(bool async, nsIInputStream** stream,
                                     nsIChannel** channel) = 0;

  // Implemented by subclass to begin pumping data for an async channel, in
  // lieu of returning a stream. If implemented, OpenContentStream will never
  // be called for async channels. If not implemented, AsyncOpen will fall
  // back to OpenContentStream.
  //
  // On success, the callee must begin pumping data to the stream listener,
  // and at some point call OnStartRequest followed by OnStopRequest.
  //
  // Additionally, when a successful nsresult is returned, then the subclass
  // should be setting  through its two out params either:
  // - a request object, which may be used to suspend, resume, and cancel
  //   the underlying request.
  // - or a cancelable object (e.g. when a request can't be returned right away
  //   due to some async work needed to retrieve it). which may be used to
  //   cancel the underlying request (e.g. because the channel has been
  //   canceled)
  //
  // Not returning a request or cancelable leads to potentially leaking the
  // an underling stream pump (which would keep to be pumping data even after
  // the channel has been canceled and nothing is going to handle the data
  // available, e.g. see Bug 1706594).
  virtual nsresult BeginAsyncRead(nsIStreamListener* listener,
                                  nsIRequest** request,
                                  nsICancelable** cancelableRequest) {
    return NS_ERROR_NOT_IMPLEMENTED;
  }

  // This method may return a promise that will keep the input stream pump
  // suspended until the promise is resolved or rejected.  On resolution the
  // pump is resumed.  On rejection the channel is canceled with the resulting
  // error and then the pump is also resumed to propagate the error to the
  // channel listener.  Use it to do any asynchronous/background tasks you need
  // to finish prior calling OnStartRequest of the listener.  This method is
  // called right after OpenContentStream() with async == true, after the input
  // stream pump has already been called asyncRead().
  virtual nsresult ListenerBlockingPromise(BlockingPromise** aPromise) {
    NS_ENSURE_ARG(aPromise);
    *aPromise = nullptr;
    return NS_OK;
  }

  // The basechannel calls this method from its OnTransportStatus method to
  // determine whether to call nsIProgressEventSink::OnStatus in addition to
  // nsIProgressEventSink::OnProgress.  This method may be overriden by the
  // subclass to enable nsIProgressEventSink::OnStatus events.  If this method
  // returns true, then the statusArg out param specifies the "statusArg" value
  // to pass to the OnStatus method.  By default, OnStatus messages are
  // suppressed.  The status parameter passed to this method is the status value
  // from the OnTransportStatus method.
  virtual bool GetStatusArg(nsresult status, nsString& statusArg) {
    return false;
  }

  // Called when the callbacks available to this channel may have changed.
  virtual void OnCallbacksChanged() {}

  // Called when our channel is done, to allow subclasses to drop resources.
  virtual void OnChannelDone() {}

 public:
  // ----------------------------------------------
  // Methods provided for use by the derived class:

  // Redirect to another channel.  This method takes care of notifying
  // observers of this redirect as well as of opening the new channel, if asked
  // to do so.  It also cancels |this| with the status code
  // NS_BINDING_REDIRECTED.  A failure return from this method means that the
  // redirect could not be performed (no channel was opened; this channel
  // wasn't canceled.)  The redirectFlags parameter consists of the flag values
  // defined on nsIChannelEventSink.
  nsresult Redirect(nsIChannel* newChannel, uint32_t redirectFlags,
                    bool openNewChannel);

  // Tests whether a type hint was set. Subclasses can use this to decide
  // whether to call SetContentType.
  // NOTE: This is only reliable if the subclass didn't itself call
  // SetContentType, and should also not be called after OpenContentStream.
  bool HasContentTypeHint() const;

  // The URI member should be initialized before the channel is used, and then
  // it should never be changed again until the channel is destroyed.
  nsIURI* URI() { return mURI; }
  void SetURI(nsIURI* uri) {
    NS_ASSERTION(uri, "must specify a non-null URI");
    NS_ASSERTION(!mURI, "must not modify URI");
    NS_ASSERTION(!mOriginalURI, "how did that get set so early?");
    mURI = uri;
    mOriginalURI = uri;
  }
  nsIURI* OriginalURI() { return mOriginalURI; }

  // The security info is a property of the transport-layer, which should be
  // assigned by the subclass.
  nsITransportSecurityInfo* SecurityInfo() { return mSecurityInfo; }
  void SetSecurityInfo(nsITransportSecurityInfo* info) { mSecurityInfo = info; }

  // Test the load flags
  bool HasLoadFlag(uint32_t flag) { return (mLoadFlags & flag) != 0; }

  // This is a short-cut to calling nsIRequest::IsPending()
  virtual bool Pending() const {
    return mPumpingData || mWaitingOnAsyncRedirect;
  }

  // Helper function for querying the channel's notification callbacks.
  template <class T>
  void GetCallback(nsCOMPtr<T>& result) {
    GetInterface(NS_GET_TEMPLATE_IID(T), getter_AddRefs(result));
  }

  // If a subclass does not want to feed transport-layer progress events to the
  // base channel via nsITransportEventSink, then it may set this flag to cause
  // the base channel to synthesize progress events when it receives data from
  // the content stream.  By default, progress events are not synthesized.
  void EnableSynthesizedProgressEvents(bool enable) {
    mSynthProgressEvents = enable;
  }

  // Some subclasses may wish to manually insert a stream listener between this
  // and the channel's listener.  The following methods make that possible.
  void SetStreamListener(nsIStreamListener* listener) { mListener = listener; }
  nsIStreamListener* StreamListener() { return mListener; }

  // Pushes a new stream converter in front of the channel's stream listener.
  // The fromType and toType values are passed to nsIStreamConverterService's
  // AsyncConvertData method.  If invalidatesContentLength is true, then the
  // channel's content-length property will be assigned a value of -1.  This is
  // necessary when the converter changes the length of the resulting data
  // stream, which is almost always the case for a "stream converter" ;-)
  // This function optionally returns a reference to the new converter.
  nsresult PushStreamConverter(const char* fromType, const char* toType,
                               bool invalidatesContentLength = true,
                               nsIStreamListener** result = nullptr);

 protected:
  void DisallowThreadRetargeting() { mAllowThreadRetargeting = false; }

  virtual void SetupNeckoTarget();

 private:
  NS_DECL_NSISTREAMLISTENER
  NS_DECL_NSIREQUESTOBSERVER

  // Called to setup mPump and call AsyncRead on it.
  nsresult BeginPumpingData();

  // Called when the callbacks available to this channel may have changed.
  void CallbacksChanged() {
    mProgressSink = nullptr;
    mQueriedProgressSink = false;
    OnCallbacksChanged();
  }

  // Called when our channel is done.  This should drop no-longer-needed
  // pointers.
  void ChannelDone() {
    mListener = nullptr;
    OnChannelDone();
  }

  // Handle an async redirect callback.  This will only be called if we
  // returned success from AsyncOpen while posting a redirect runnable.
  void HandleAsyncRedirect(nsIChannel* newChannel);
  void ContinueHandleAsyncRedirect(nsresult result);
  nsresult ContinueRedirect();

  // start URI classifier if requested
  void ClassifyURI();

  class RedirectRunnable : public mozilla::Runnable {
   public:
    RedirectRunnable(nsBaseChannel* chan, nsIChannel* newChannel)
        : mozilla::Runnable("nsBaseChannel::RedirectRunnable"),
          mChannel(chan),
          mNewChannel(newChannel) {
      MOZ_ASSERT(newChannel, "Must have channel to redirect to");
    }

    NS_IMETHOD Run() override {
      mChannel->HandleAsyncRedirect(mNewChannel);
      return NS_OK;
    }

   private:
    RefPtr<nsBaseChannel> mChannel;
    nsCOMPtr<nsIChannel> mNewChannel;
  };
  friend class RedirectRunnable;

  RefPtr<nsInputStreamPump> mPump;
  RefPtr<nsIRequest> mRequest;
  nsCOMPtr<nsICancelable> mCancelableAsyncRequest;
  bool mPumpingData{false};
  nsCOMPtr<nsIProgressEventSink> mProgressSink;
  nsCOMPtr<nsIURI> mOriginalURI;
  nsCOMPtr<nsISupports> mOwner;
  nsCOMPtr<nsITransportSecurityInfo> mSecurityInfo;
  nsCOMPtr<nsIChannel> mRedirectChannel;
  uint32_t mLoadFlags{LOAD_NORMAL};
  bool mQueriedProgressSink{true};
  bool mSynthProgressEvents{false};
  bool mAllowThreadRetargeting{true};
  bool mWaitingOnAsyncRedirect{false};
  bool mOpenRedirectChannel{false};
  uint32_t mRedirectFlags{0};

 protected:
  nsCString mContentType;
  nsCString mContentCharset;
  nsCOMPtr<nsIURI> mURI;
  nsCOMPtr<nsILoadGroup> mLoadGroup;
  nsCOMPtr<nsILoadInfo> mLoadInfo;
  nsCOMPtr<nsIInterfaceRequestor> mCallbacks;
  nsCOMPtr<nsIStreamListener> mListener;
  nsresult mStatus{NS_OK};
  uint32_t mContentDispositionHint{UINT32_MAX};
  mozilla::UniquePtr<nsString> mContentDispositionFilename;
  int64_t mContentLength{-1};
  bool mWasOpened{false};
  bool mCanceled{false};

  friend class mozilla::net::PrivateBrowsingChannel<nsBaseChannel>;
};

#endif  // !nsBaseChannel_h__