/* 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 nsPrefetchService_h_
#define nsPrefetchService_h_

#include "nsIObserver.h"
#include "nsIInterfaceRequestor.h"
#include "nsIChannelEventSink.h"
#include "nsIPrefetchService.h"
#include "nsIRedirectResultListener.h"
#include "nsIWebProgressListener.h"
#include "nsIStreamListener.h"
#include "nsIChannel.h"
#include "nsIURI.h"
#include "nsWeakReference.h"
#include "nsCOMPtr.h"
#include <deque>

class nsPrefetchService;
class nsPrefetchNode;
class nsIReferrerInfo;

//-----------------------------------------------------------------------------
// nsPrefetchService
//-----------------------------------------------------------------------------

class nsPrefetchService final : public nsIPrefetchService,
                                public nsIWebProgressListener,
                                public nsIObserver,
                                public nsSupportsWeakReference {
 public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIPREFETCHSERVICE
  NS_DECL_NSIWEBPROGRESSLISTENER
  NS_DECL_NSIOBSERVER

  nsPrefetchService();

  nsresult Init();
  void RemoveNodeAndMaybeStartNextPrefetchURI(nsPrefetchNode* aFinished);
  void ProcessNextPrefetchURI();

  void NotifyLoadRequested(nsPrefetchNode* node);
  void NotifyLoadCompleted(nsPrefetchNode* node);
  void DispatchEvent(nsPrefetchNode* node, bool aSuccess);

 private:
  ~nsPrefetchService();

  nsresult Prefetch(nsIURI* aURI, nsIReferrerInfo* aReferrerInfo,
                    nsINode* aSource, bool aExplicit);

  void AddProgressListener();
  void RemoveProgressListener();
  nsresult EnqueueURI(nsIURI* aURI, nsIReferrerInfo* aReferrerInfo,
                      nsINode* aSource, nsPrefetchNode** node);
  void EmptyPrefetchQueue();

  void StartPrefetching();
  void StopPrefetching();
  void StopCurrentPrefetchsPreloads(bool aPreload);
  void StopAll();
  nsresult CheckURIScheme(nsIURI* aURI, nsIReferrerInfo* aReferrerInfo);

  std::deque<RefPtr<nsPrefetchNode>> mPrefetchQueue;
  nsTArray<RefPtr<nsPrefetchNode>> mCurrentNodes;
  int32_t mMaxParallelism;
  int32_t mStopCount;
  bool mPrefetchDisabled;

  // In usual case prefetch does not start until all normal loads are done.
  // Aggressive mode ignores normal loads and just start prefetch ASAP.
  // It's mainly for testing purpose and discoraged for normal use;
  // see https://bugzilla.mozilla.org/show_bug.cgi?id=1281415 for details.
  bool mAggressive;
};

//-----------------------------------------------------------------------------
// nsPreFetchingNode
//-----------------------------------------------------------------------------

class nsPrefetchNode final : public nsIStreamListener,
                             public nsIInterfaceRequestor,
                             public nsIChannelEventSink,
                             public nsIRedirectResultListener {
 public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIREQUESTOBSERVER
  NS_DECL_NSISTREAMLISTENER
  NS_DECL_NSIINTERFACEREQUESTOR
  NS_DECL_NSICHANNELEVENTSINK
  NS_DECL_NSIREDIRECTRESULTLISTENER

  nsPrefetchNode(nsPrefetchService* aPrefetchService, nsIURI* aURI,
                 nsIReferrerInfo* aReferrerInfo, nsINode* aSource,
                 nsContentPolicyType aPolicyType, bool aPreload);

  nsresult OpenChannel();
  nsresult CancelChannel(nsresult error);

  nsCOMPtr<nsIURI> mURI;
  nsCOMPtr<nsIReferrerInfo> mReferrerInfo;
  nsTArray<nsWeakPtr> mSources;

  // The policy type to be used for fetching the resource.
  nsContentPolicyType mPolicyType;
  // nsPrefetchNode is used for prefetching and preloading resource.
  // mPreload is true if a resource is preloaded. Preloads and
  // prefetches are fetched in different phases (during load and
  // after a page load), therefore we need to distinguish them.
  bool mPreload;

 private:
  ~nsPrefetchNode() = default;

  RefPtr<nsPrefetchService> mService;
  nsCOMPtr<nsIChannel> mChannel;
  nsCOMPtr<nsIChannel> mRedirectChannel;
  int64_t mBytesRead;
  bool mShouldFireLoadEvent;
};

#endif  // !nsPrefetchService_h_