/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 nsPACMan_h__
#define nsPACMan_h__

#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "mozilla/DataMutex.h"
#include "mozilla/LinkedList.h"
#include "mozilla/Logging.h"
#include "mozilla/net/NeckoTargetHolder.h"
#include "mozilla/TimeStamp.h"
#include "nsCOMPtr.h"
#include "nsIChannelEventSink.h"
#include "nsIInterfaceRequestor.h"
#include "nsIStreamLoader.h"
#include "nsThreadUtils.h"
#include "nsIURI.h"
#include "nsString.h"
#include "ProxyAutoConfig.h"

class nsISystemProxySettings;
class nsIDHCPClient;
class nsIThread;

namespace mozilla {
namespace net {

class nsPACMan;
class WaitForThreadShutdown;

/**
 * This class defines a callback interface used by AsyncGetProxyForURI.
 */
class NS_NO_VTABLE nsPACManCallback : public nsISupports {
 public:
  /**
   * This method is invoked on the same thread that called AsyncGetProxyForURI.
   *
   * @param status
   *        This parameter indicates whether or not the PAC query succeeded.
   * @param pacString
   *        This parameter holds the value of the PAC string.  It is empty when
   *        status is a failure code.
   * @param newPACURL
   *        This parameter holds the URL of a new PAC file that should be loaded
   *        before the query is evaluated again. At least one of pacString and
   *        newPACURL should be 0 length.
   */
  virtual void OnQueryComplete(nsresult status, const nsACString& pacString,
                               const nsACString& newPACURL) = 0;
};

class PendingPACQuery final : public Runnable,
                              public LinkedListElement<PendingPACQuery> {
 public:
  PendingPACQuery(nsPACMan* pacMan, nsIURI* uri, nsPACManCallback* callback,
                  uint32_t flags, bool mainThreadResponse);

  // can be called from either thread
  void Complete(nsresult status, const nsACString& pacString);
  void UseAlternatePACFile(const nsACString& pacURL);

  nsCString mSpec;
  nsCString mScheme;
  nsCString mHost;
  int32_t mPort;
  uint32_t mFlags;

  NS_IMETHOD Run(void) override; /* Runnable */

 private:
  nsPACMan* mPACMan;  // weak reference

 private:
  RefPtr<nsPACManCallback> mCallback;
  bool mOnMainThreadOnly;
};

/**
 * This class provides an abstraction layer above the PAC thread.  The methods
 * defined on this class are intended to be called on the main thread only.
 */

class nsPACMan final : public nsIStreamLoaderObserver,
                       public nsIInterfaceRequestor,
                       public nsIChannelEventSink,
                       public NeckoTargetHolder {
 public:
  NS_DECL_THREADSAFE_ISUPPORTS

  explicit nsPACMan(nsISerialEventTarget* mainThreadEventTarget);

  /**
   * This method may be called to shutdown the PAC manager.  Any async queries
   * that have not yet completed will either finish normally or be canceled by
   * the time this method returns.
   */
  void Shutdown();

  /**
   * This method queries a PAC result asynchronously.  The callback runs on the
   * calling thread.  If the PAC file has not yet been loaded, then this method
   * will queue up the request, and complete it once the PAC file has been
   * loaded.
   *
   * @param uri
   *        The URI to query.
   * @param callback
   *        The callback to run once the PAC result is available.
   * @param flags
   *        A bit-wise combination of the RESOLVE_ flags defined above.  Pass
   *        0 to specify the default behavior.
   * @param mustCallbackOnMainThread
   *        If set to false the callback can be made from the PAC thread
   */
  nsresult AsyncGetProxyForURI(nsIURI* uri, nsPACManCallback* callback,
                               uint32_t flags, bool mustCallbackOnMainThread);

  /**
   * This method may be called to reload the PAC file.  While we are loading
   * the PAC file, any asynchronous PAC queries will be queued up to be
   * processed once the PAC file finishes loading.
   *
   * @param aSpec
   *        The non normalized uri spec of this URI used for comparison with
   *        system proxy settings to determine if the PAC uri has changed.
   */
  nsresult LoadPACFromURI(const nsACString& aSpec);

  /**
   * Returns true if we are currently loading the PAC file.
   */
  bool IsLoading() {
    auto loader = mLoader.Lock();
    return loader.ref() != nullptr;
  }

  /**
   * Returns true if the given URI matches the URI of our PAC file or the
   * URI it has been redirected to. In the case of a chain of redirections
   * only the current one being followed and the original are considered
   * becuase this information is used, respectively, to determine if we
   * should bypass the proxy (to fetch the pac file) or if the pac
   * configuration has changed (and we should reload the pac file)
   */
  bool IsPACURI(const nsACString& spec) {
    return mPACURISpec.Equals(spec) || mPACURIRedirectSpec.Equals(spec) ||
           mNormalPACURISpec.Equals(spec);
  }

  bool IsPACURI(nsIURI* uri) {
    if (mPACURISpec.IsEmpty() && mPACURIRedirectSpec.IsEmpty()) {
      return false;
    }

    nsAutoCString tmp;
    nsresult rv = uri->GetSpec(tmp);
    if (NS_FAILED(rv)) {
      return false;
    }

    return IsPACURI(tmp);
  }

  bool IsUsingWPAD() { return mAutoDetect; }

  nsresult Init(nsISystemProxySettings*);
  static nsPACMan* sInstance;

  // PAC thread operations only
  void ProcessPendingQ();
  void CancelPendingQ(nsresult, bool aShutdown);

  void SetWPADOverDHCPEnabled(bool aValue) { mWPADOverDHCPEnabled = aValue; }

 private:
  NS_DECL_NSISTREAMLOADEROBSERVER
  NS_DECL_NSIINTERFACEREQUESTOR
  NS_DECL_NSICHANNELEVENTSINK

  friend class PendingPACQuery;
  friend class PACLoadComplete;
  friend class ConfigureWPADComplete;
  friend class ExecutePACThreadAction;
  friend class WaitForThreadShutdown;
  friend class TestPACMan;

  ~nsPACMan();

  /**
   * Cancel any existing load if any.
   */
  void CancelExistingLoad();

  /**
   * Start loading the PAC file.
   */
  void StartLoading();

  /**
   * Continue loading the PAC file.
   */
  void ContinueLoadingAfterPACUriKnown();

  /**
   * This method may be called to reload the PAC file.  While we are loading
   * the PAC file, any asynchronous PAC queries will be queued up to be
   * processed once the PAC file finishes loading.
   *
   * @param aSpec
   *        The non normalized uri spec of this URI used for comparison with
   *        system proxy settings to determine if the PAC uri has changed.
   * @param aResetLoadFailureCount
   *        A flag saying whether the exponential back-off for attempting to
   * reload the PAC should be reset.
   */
  nsresult LoadPACFromURI(const nsACString& aSpec, bool aResetLoadFailureCount);

  /**
   * Reload the PAC file if there is reason to.
   */
  void MaybeReloadPAC();

  /**
   * Called when we fail to load the PAC file.
   */
  void OnLoadFailure();

  /**
   * PostQuery() only runs on the PAC thread and it is used to
   * place a pendingPACQuery into the queue and potentially
   * execute the queue if it was otherwise empty
   */
  nsresult PostQuery(PendingPACQuery* query);

  // Having found the PAC URI on the PAC thread, copy it to a string which
  // can be altered on the main thread.
  void AssignPACURISpec(const nsACString& aSpec);

  // PAC thread operations only
  void PostProcessPendingQ();
  void PostCancelPendingQ(nsresult, bool aShutdown = false);
  bool ProcessPending();
  nsresult GetPACFromDHCP(nsACString& aSpec);
  nsresult ConfigureWPAD(nsACString& aSpec);

 private:
  /**
   * Dispatches a runnable to the PAC processing thread. Handles lazy
   * instantiation of the thread.
   *
   * @param aEvent The event to disptach.
   * @param aSync Whether or not this should be synchronous dispatch.
   */
  nsresult DispatchToPAC(already_AddRefed<nsIRunnable> aEvent,
                         bool aSync = false);

  ProxyAutoConfig mPAC;
  nsCOMPtr<nsIThread> mPACThread;
  nsCOMPtr<nsISystemProxySettings> mSystemProxySettings;
  nsCOMPtr<nsIDHCPClient> mDHCPClient;

  LinkedList<PendingPACQuery> mPendingQ; /* pac thread only */

  // These specs are not nsIURI so that they can be used off the main thread.
  // The non-normalized versions are directly from the configuration, the
  // normalized version has been extracted from an nsIURI
  nsCString mPACURISpec;
  nsCString mPACURIRedirectSpec;
  nsCString mNormalPACURISpec;

  DataMutex<nsCOMPtr<nsIStreamLoader>> mLoader;
  bool mLoadPending;
  Atomic<bool, Relaxed> mShutdown;
  TimeStamp mScheduledReload;
  uint32_t mLoadFailureCount;

  bool mInProgress;
  bool mIncludePath;
  bool mAutoDetect;
  bool mWPADOverDHCPEnabled;
  int32_t mProxyConfigType;
};

extern LazyLogModule gProxyLog;

}  // namespace net
}  // namespace mozilla

#endif  // nsPACMan_h__