//* -*- 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 EffectiveTLDService_h
#define EffectiveTLDService_h

#include "nsIEffectiveTLDService.h"

#include "nsIMemoryReporter.h"
#include "nsString.h"
#include "nsCOMPtr.h"
#include "mozilla/Attributes.h"
#include "mozilla/Dafsa.h"
#include "mozilla/MemoryReporting.h"

class nsIIDNService;

class nsEffectiveTLDService final
  : public nsIEffectiveTLDService
  , public nsIMemoryReporter
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIEFFECTIVETLDSERVICE
  NS_DECL_NSIMEMORYREPORTER

  nsEffectiveTLDService();
  nsresult Init();

  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf);

private:
  nsresult GetBaseDomainInternal(nsCString &aHostname, int32_t aAdditionalParts, nsACString &aBaseDomain);
  nsresult NormalizeHostname(nsCString &aHostname);
  ~nsEffectiveTLDService();

  nsCOMPtr<nsIIDNService>     mIDNService;

  // The DAFSA provides a compact encoding of the rather large eTLD list.
  mozilla::Dafsa mGraph;

  struct TLDCacheEntry
  {
    nsCString mHost;
    nsCString mBaseDomain;
  };

  // We use a small most recently used cache to compensate for DAFSA lookups
  // being slightly slower than a binary search on a larger table of strings.
  //
  // We first check the cache for a matching result and avoid a DAFSA lookup
  // if a match is found. Otherwise we lookup the domain in the DAFSA and then
  // cache the result. During standard browsing the same domains are repeatedly
  // fed into |GetBaseDomainInternal| so this ends up being an effective
  // mitigation getting about a 99% hit rate with four tabs open.
  //
  // A size of 31 is used rather than a more logical power-of-two such as 32
  // since it is a prime number and provides fewer collisions when when used
  // with our hash algorithms.
  static const uint32_t kTableSize = 31;
  TLDCacheEntry mMruTable[kTableSize];

  /**
   * Performs a lookup on the MRU table and provides a pointer to the hash
   * entry that matched or should be used for adding this host.
   *
   * @param aHost The host to lookup.
   * @param aEntry Out param, the entry in the MRU table to use.
   * @return True if a match was found, false if there was a miss.
   */
  inline bool LookupForAdd(const nsACString& aHost, TLDCacheEntry** aEntry);
};

#endif // EffectiveTLDService_h