/* -*- 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 __nsRFPService_h__
#define __nsRFPService_h__

#include "mozilla/Atomics.h"
#include "mozilla/EventForwards.h"
#include "mozilla/Mutex.h"
#include "nsIDocument.h"
#include "nsIObserver.h"

#include "nsDataHashtable.h"
#include "nsString.h"

// Defines regarding spoofed values of Navigator object. These spoofed values
// are returned when 'privacy.resistFingerprinting' is true.
// We decided to give different spoofed values according to the platform. The
// reason is that it is easy to detect the real platform. So there is no benefit
// for hiding the platform: it only brings breakages, like keyboard shortcuts won't
// work in MAC OS if we spoof it as a window platform.
#ifdef XP_WIN
#define SPOOFED_UA_OS      "Windows NT 6.1; Win64; x64"
#define SPOOFED_APPVERSION "5.0 (Windows)"
#define SPOOFED_OSCPU      "Windows NT 6.1; Win64; x64"
#define SPOOFED_PLATFORM   "Win64"
#elif defined(XP_MACOSX)
#define SPOOFED_UA_OS      "Macintosh; Intel Mac OS X 10.13"
#define SPOOFED_APPVERSION "5.0 (Macintosh)"
#define SPOOFED_OSCPU      "Intel Mac OS X 10.13"
#define SPOOFED_PLATFORM   "MacIntel"
#elif defined(MOZ_WIDGET_ANDROID)
#define SPOOFED_UA_OS      "Android 6.0; Mobile"
#define SPOOFED_APPVERSION "5.0 (Android 6.0)"
#define SPOOFED_OSCPU      "Linux armv7l"
#define SPOOFED_PLATFORM   "Linux armv7l"
#else
// For Linux and other platforms, like BSDs, SunOS and etc, we will use Linux
// platform.
#define SPOOFED_UA_OS      "X11; Linux x86_64"
#define SPOOFED_APPVERSION "5.0 (X11)"
#define SPOOFED_OSCPU      "Linux x86_64"
#define SPOOFED_PLATFORM   "Linux x86_64"
#endif

#define SPOOFED_APPNAME    "Netscape"
#define LEGACY_BUILD_ID    "20100101"

// Forward declare LRUCache, defined in nsRFPService.cpp
class LRUCache;

namespace mozilla {

enum KeyboardLang {
  EN = 0x01
};

#define RFP_KEYBOARD_LANG_STRING_EN "en"

typedef uint8_t KeyboardLangs;

enum KeyboardRegion {
  US = 0x01
};

#define RFP_KEYBOARD_REGION_STRING_US "US"

typedef uint8_t KeyboardRegions;

// This struct has the information about how to spoof the keyboardEvent.code,
// keyboardEvent.keycode and modifier states.
struct SpoofingKeyboardCode
{
  CodeNameIndex mCode;
  uint8_t mKeyCode;
  Modifiers mModifierStates;
};

struct SpoofingKeyboardInfo
{
  KeyNameIndex mKeyIdx;
  nsString mKey;
  SpoofingKeyboardCode mSpoofingCode;
};

class KeyboardHashKey : public PLDHashEntryHdr
{
public:
  typedef const KeyboardHashKey& KeyType;
  typedef const KeyboardHashKey* KeyTypePointer;

  KeyboardHashKey(const KeyboardLangs aLang,
                  const KeyboardRegions aRegion,
                  const KeyNameIndexType aKeyIdx,
                  const nsAString &aKey)
    : mLang(aLang)
    , mRegion(aRegion)
    , mKeyIdx(aKeyIdx)
    , mKey(aKey)
  {}

  explicit KeyboardHashKey(KeyTypePointer aOther)
    : mLang(aOther->mLang)
    , mRegion(aOther->mRegion)
    , mKeyIdx(aOther->mKeyIdx)
    , mKey(aOther->mKey)
  {}

  KeyboardHashKey(KeyType aOther)
    : mLang(aOther.mLang)
    , mRegion(aOther.mRegion)
    , mKeyIdx(aOther.mKeyIdx)
    , mKey(aOther.mKey)
  {}

  ~KeyboardHashKey()
  {}

  bool KeyEquals(KeyTypePointer aOther) const
  {
    return mLang == aOther->mLang &&
           mRegion == aOther->mRegion &&
           mKeyIdx == aOther->mKeyIdx &&
           mKey == aOther->mKey;
  }

  static KeyTypePointer KeyToPointer(KeyType aKey)
  {
    return &aKey;
  }

  static PLDHashNumber HashKey(KeyTypePointer aKey)
  {
    PLDHashNumber hash = mozilla::HashString(aKey->mKey);
    return mozilla::AddToHash(hash,
                              aKey->mRegion,
                              aKey->mKeyIdx,
                              aKey->mLang);
  }

  enum { ALLOW_MEMMOVE = true };

  KeyboardLangs mLang;
  KeyboardRegions mRegion;
  KeyNameIndexType mKeyIdx;
  nsString mKey;
};

enum TimerPrecisionType {
  All = 1,
  RFPOnly = 2
};

class nsRFPService final : public nsIObserver
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIOBSERVER

  static nsRFPService* GetOrCreate();
  static bool IsResistFingerprintingEnabled();
  static bool IsTimerPrecisionReductionEnabled(TimerPrecisionType aType);

  enum TimeScale {
    Seconds      = 1,
    MilliSeconds = 1000,
    MicroSeconds = 1000000
  };

  // The following Reduce methods can be called off main thread.
  static double ReduceTimePrecisionAsUSecs(
    double aTime,
    int64_t aContextMixin,
    TimerPrecisionType aType = TimerPrecisionType::All);
  static double ReduceTimePrecisionAsMSecs(
    double aTime,
    int64_t aContextMixin,
    TimerPrecisionType aType = TimerPrecisionType::All);
  static double ReduceTimePrecisionAsSecs(
    double aTime,
    int64_t aContextMixin,
    TimerPrecisionType aType = TimerPrecisionType::All);

  // Used by the JS Engine, as it doesn't know about the TimerPrecisionType enum
  static double ReduceTimePrecisionAsUSecsWrapper(
    double aTime);

  // Public only for testing purposes
  static double ReduceTimePrecisionImpl(
    double aTime,
    TimeScale aTimeScale,
    double aResolutionUSec,
    int64_t aContextMixin,
    TimerPrecisionType aType);
  static nsresult RandomMidpoint(long long aClampedTimeUSec,
                                 long long aResolutionUSec,
                                 int64_t aContextMixin,
                                 long long* aMidpointOut,
                                 uint8_t * aSecretSeed = nullptr);

  // This method calculates the video resolution (i.e. height x width) based
  // on the video quality (480p, 720p, etc).
  static uint32_t CalculateTargetVideoResolution(uint32_t aVideoQuality);

  // Methods for getting spoofed media statistics and the return value will
  // depend on the video resolution.
  static uint32_t GetSpoofedTotalFrames(double aTime);
  static uint32_t GetSpoofedDroppedFrames(double aTime, uint32_t aWidth, uint32_t aHeight);
  static uint32_t GetSpoofedPresentedFrames(double aTime, uint32_t aWidth, uint32_t aHeight);

  // This method generates the spoofed value of User Agent.
  static nsresult GetSpoofedUserAgent(nsACString &userAgent);

  /**
   * This method for getting spoofed modifier states for the given keyboard event.
   *
   * @param aDoc           [in]  the owner's document for getting content language.
   * @param aKeyboardEvent [in]  the keyboard event that needs to be spoofed.
   * @param aModifier      [in]  the modifier that needs to be spoofed.
   * @param aOut           [out] the spoofed state for the given modifier.
   * @return               true if there is a spoofed state for the modifier.
   */
  static bool GetSpoofedModifierStates(const nsIDocument* aDoc,
                                       const WidgetKeyboardEvent* aKeyboardEvent,
                                       const Modifiers aModifier,
                                       bool& aOut);

  /**
   * This method for getting spoofed code for the given keyboard event.
   *
   * @param aDoc           [in]  the owner's document for getting content language.
   * @param aKeyboardEvent [in]  the keyboard event that needs to be spoofed.
   * @param aOut           [out] the spoofed code.
   * @return               true if there is a spoofed code in the fake keyboard layout.
   */
  static bool GetSpoofedCode(const nsIDocument* aDoc,
                             const WidgetKeyboardEvent* aKeyboardEvent,
                             nsAString& aOut);

  /**
   * This method for getting spoofed keyCode for the given keyboard event.
   *
   * @param aDoc           [in]  the owner's document for getting content language.
   * @param aKeyboardEvent [in]  the keyboard event that needs to be spoofed.
   * @param aOut           [out] the spoofed keyCode.
   * @return               true if there is a spoofed keyCode in the fake keyboard layout.
   */
  static bool GetSpoofedKeyCode(const nsIDocument* aDoc,
                                const WidgetKeyboardEvent* aKeyboardEvent,
                                uint32_t& aOut);

private:
  nsresult Init();

  nsRFPService() {}

  ~nsRFPService() {}

  void UpdateTimers();
  void UpdateRFPPref();
  void StartShutdown();

  static void MaybeCreateSpoofingKeyCodes(const KeyboardLangs aLang,
                                          const KeyboardRegions aRegion);
  static void MaybeCreateSpoofingKeyCodesForEnUS();

  static void GetKeyboardLangAndRegion(const nsAString& aLanguage,
                                       KeyboardLangs& aLang,
                                       KeyboardRegions& aRegion);
  static bool GetSpoofedKeyCodeInfo(const nsIDocument* aDoc,
                                    const WidgetKeyboardEvent* aKeyboardEvent,
                                    SpoofingKeyboardCode& aOut);

  static Atomic<bool, Relaxed> sPrivacyResistFingerprinting;
  static Atomic<bool, Relaxed> sPrivacyTimerPrecisionReduction;

  static nsDataHashtable<KeyboardHashKey, const SpoofingKeyboardCode*>* sSpoofingKeyboardCodes;

  nsCString mInitialTZValue;
};

} // mozilla namespace

#endif /* __nsRFPService_h__ */