/* -*- Mode: C++; tab-width: 4; 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 nsAsyncRedirectVerifyHelper_h
#define nsAsyncRedirectVerifyHelper_h

#include "nsIRunnable.h"
#include "nsIChannelEventSink.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsINamed.h"
#include "nsCOMPtr.h"
#include "nsCycleCollectionParticipant.h"
#include "mozilla/Attributes.h"

class nsIChannel;

namespace mozilla {
namespace net {

/**
 * This class simplifies call of OnChannelRedirect of IOService and
 * the sink bound with the channel being redirected while the result of
 * redirect decision is returned through the callback.
 */
class nsAsyncRedirectVerifyHelper final
    : public nsIRunnable,
      public nsINamed,
      public nsIAsyncVerifyRedirectCallback {
  NS_DECL_THREADSAFE_ISUPPORTS
  NS_DECL_NSIRUNNABLE
  NS_DECL_NSINAMED
  NS_DECL_NSIASYNCVERIFYREDIRECTCALLBACK

 public:
  nsAsyncRedirectVerifyHelper() = default;

  /*
   * Calls AsyncOnChannelRedirect() on the given sink with the given
   * channels and flags. Keeps track of number of async callbacks to expect.
   */
  nsresult DelegateOnChannelRedirect(nsIChannelEventSink* sink,
                                     nsIChannel* oldChannel,
                                     nsIChannel* newChannel, uint32_t flags);

  /**
   * Initialize and run the chain of AsyncOnChannelRedirect calls. OldChannel
   * is QI'ed for nsIAsyncVerifyRedirectCallback. The result of the redirect
   * decision is passed through this interface back to the oldChannel.
   *
   * @param oldChan
   *    channel being redirected, MUST implement
   *    nsIAsyncVerifyRedirectCallback
   * @param newChan
   *    target of the redirect channel
   * @param flags
   *    redirect flags
   * @param mainThreadEventTarget
   *    a labeled event target for dispatching runnables
   * @param synchronize
   *    set to TRUE if you want the Init method wait synchronously for
   *    all redirect callbacks
   */
  nsresult Init(nsIChannel* oldChan, nsIChannel* newChan, uint32_t flags,
                nsIEventTarget* mainThreadEventTarget,
                bool synchronize = false);

 protected:
  nsCOMPtr<nsIChannel> mOldChan;
  nsCOMPtr<nsIChannel> mNewChan;
  uint32_t mFlags{0};
  bool mWaitingForRedirectCallback{false};
  nsCOMPtr<nsIEventTarget> mCallbackEventTarget;
  bool mCallbackInitiated{false};
  int32_t mExpectedCallbacks{0};
  nsresult mResult{NS_OK};  // value passed to callback

  void InitCallback();

  /**
   * Calls back to |oldChan| as described in Init()
   */
  void ExplicitCallback(nsresult result);

 private:
  ~nsAsyncRedirectVerifyHelper();

  bool IsOldChannelCanceled();
};

/*
 * Helper to make the call-stack handle some control-flow for us
 */
class nsAsyncRedirectAutoCallback {
 public:
  explicit nsAsyncRedirectAutoCallback(
      nsIAsyncVerifyRedirectCallback* aCallback)
      : mCallback(aCallback) {
    mResult = NS_OK;
  }
  ~nsAsyncRedirectAutoCallback() {
    if (mCallback) mCallback->OnRedirectVerifyCallback(mResult);
  }
  /*
   * Call this is you want it to call back with a different result-code
   */
  void SetResult(nsresult aRes) { mResult = aRes; }
  /*
   * Call this is you want to avoid the callback
   */
  void DontCallback() { mCallback = nullptr; }

 private:
  nsIAsyncVerifyRedirectCallback* mCallback;
  nsresult mResult;
};

}  // namespace net
}  // namespace mozilla
#endif