components/omnibox/browser/autocomplete_result.h

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_RESULT_H_
#define COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_RESULT_H_

#include <stddef.h>

#include <map>
#include <vector>

#include "build/build_config.h"
#include "components/omnibox/browser/autocomplete_match.h"
#include "components/omnibox/browser/match_compare.h"
#include "components/omnibox/browser/search_suggestion_parser.h"
#include "url/gurl.h"

#if defined(OS_ANDROID)
#include "base/android/jni_array.h"
#include "base/android/scoped_java_ref.h"
#endif

class AutocompleteInput;
class AutocompleteProvider;
class AutocompleteProviderClient;
class PrefService;
class TemplateURLService;

// All matches from all providers for a particular query.  This also tracks
// what the default match should be if the user doesn't manually select another
// match.
class AutocompleteResult {
 public:
  typedef ACMatches::const_iterator const_iterator;
  typedef ACMatches::iterator iterator;
  using MatchDedupComparator = std::pair<GURL, bool>;

  // Max number of matches we'll show from the various providers. This limit
  // may be different for zero suggest and non zero suggest. Does not take into
  // account the boost conditionally provided by the
  // omnibox::kDynamicMaxAutocomplete feature.
  static size_t GetMaxMatches(bool is_zero_suggest = false);
  // Defaults to GetMaxMatches if omnibox::kDynamicMaxAutocomplete is disabled;
  // otherwise returns the boosted dynamic limit.
  static size_t GetDynamicMaxMatches();

  AutocompleteResult();
  ~AutocompleteResult();
  AutocompleteResult(const AutocompleteResult&) = delete;
  AutocompleteResult& operator=(const AutocompleteResult&) = delete;

#if defined(OS_ANDROID)
  // Returns a corresponding Java object, creating it if necessary.
  // NOTE: Android specific methods are defined in autocomplete_match_android.cc
  base::android::ScopedJavaLocalRef<jobject> GetOrCreateJavaObject(
      JNIEnv* env) const;

  // Notify the Java object that its native counterpart is about to be
  // destroyed.
  void DestroyJavaObject() const;

  // Construct an array of AutocompleteMatch objects arranged in the exact same
  // order as |matches_|.
  base::android::ScopedJavaLocalRef<jobjectArray> BuildJavaMatches(
      JNIEnv* env) const;

  // Group suggestions in specified range by search vs url.
  // The range used is [first_index, last_index), which contains all the
  // elements between first_index and last_index, including the element pointed
  // by first_index, but not the element pointed by last_index.
  void GroupSuggestionsBySearchVsURL(JNIEnv* env,
                                     int firstIndex,
                                     int lastIndex);

  // Compares the set of AutocompleteMatch references held by Java with the
  // AutocompleteMatch objects held by this instance of the AutocompleteResult
  // and returns true if the two sets are same.
  bool VerifyCoherency(JNIEnv* env,
                       const base::android::JavaParamRef<jlongArray>& matches);
#endif

  // Moves matches from |old_matches| to provide a consistent result set.
  // |old_matches| is mutated during this, and should not be used afterwards.
  void TransferOldMatches(const AutocompleteInput& input,
                          AutocompleteResult* old_matches,
                          TemplateURLService* template_url_service);

  // Adds a new set of matches to the result set.  Does not re-sort.  Calls
  // PossiblySwapContentsAndDescriptionForURLSuggestion(input) on all added
  // matches; see comments there for more information.
  void AppendMatches(const AutocompleteInput& input,
                     const ACMatches& matches);

  // Removes duplicates, puts the list in sorted order and culls to leave only
  // the best GetMaxMatches() matches. Sets the default match to the best match
  // and updates the alternate nav URL.
  //
  // |preserve_default_match| can be used to prevent the default match from
  // being surprisingly swapped out during the asynchronous pass. If it has a
  // value, this method searches the results for that match, and promotes it to
  // the top. But we don't add back that match if it doesn't already exist.
  //
  // On desktop, it filters the matches to be either all tail suggestions
  // (except for the first match) or no tail suggestions.
  void SortAndCull(const AutocompleteInput& input,
                   TemplateURLService* template_url_service,
                   const AutocompleteMatch* preserve_default_match = nullptr);

  // Ensures that matches with headers, i.e., matches with a suggestion_group_id
  // value, are grouped together at the bottom of result set based on their
  // suggestion_group_id values and in the order the group IDs first appear.
  // Certain types of remote zero-prefix matches need to appear under a header
  // for transparency reasons. This information is sent to Chrome by the server.
  // Also it is possible for zero-prefix matches from different providers (e.g.,
  // local and remote) to mix and match. Hence, we group matches with the same
  // headers and demote them to the bottom of the result set to ensure, one,
  // matches without headers appear at the top of the result set, and two, there
  // are no interleaving headers whether this is caused by bad server data or by
  // mixing of local and remote zero-prefix suggestions.
  // Note that prior to grouping and demoting the matches with headers, we strip
  // all match group IDs that don't have an equivalent header string;
  // essentially treating those matches as if they did not belong to any
  // suggestion group.
  // Called after matches are deduped and sorted and before they are culled.
  void GroupAndDemoteMatchesWithHeaders();

  // Sets |action| in matches that have Pedal-triggering text.
  void AttachPedalsToMatches(const AutocompleteInput& input,
                             const AutocompleteProviderClient& client);

  // Sets |has_tab_match| in matches whose URL matches an open tab's URL.
  // Also, fixes up the description if not using another UI element to
  // annotate (e.g. tab switch button). |input| can be null; if provided,
  // the match can be more precise (e.g. scheme presence).
  void ConvertOpenTabMatches(AutocompleteProviderClient* client,
                             const AutocompleteInput* input);

  // Returns true if at least one match was copied from the last result.
  bool HasCopiedMatches() const;

  // Vector-style accessors/operators.
  size_t size() const;
  bool empty() const;
  const_iterator begin() const;
  iterator begin();
  const_iterator end() const;
  iterator end();

  // Returns the match at the given index.
  const AutocompleteMatch& match_at(size_t index) const;
  AutocompleteMatch* match_at(size_t index);

  // Returns the default match if it exists, or nullptr otherwise.
  const AutocompleteMatch* default_match() const;

  // Returns the first match in |matches| which might be chosen as default.
  // If the page is not the fake box, the scores are not demoted by type.
  static ACMatches::const_iterator FindTopMatch(const AutocompleteInput& input,
                                                const ACMatches& matches);
  static ACMatches::iterator FindTopMatch(const AutocompleteInput& input,
                                          ACMatches* matches);

  // If the top match is a Search Entity, and it was deduplicated with a
  // non-entity match, split off the non-entity match from the list of
  // duplicates and promote it to the top.
  static void DiscourageTopMatchFromBeingSearchEntity(ACMatches* matches);

  // Just a helper function to encapsulate the logic of deciding how many
  // matches to keep, with respect to configured maximums, URL limits,
  // and relevancies.
  static size_t CalculateNumMatches(
      bool is_zero_suggest,
      const ACMatches& matches,
      const CompareWithDemoteByType<AutocompleteMatch>& comparing_object);
  // Determines how many matches to keep depending on how many URLs would be
  // shown. CalculateNumMatches defers to CalculateNumMatchesPerUrlCount if the
  // kDynamicMaxAutocomplete feature is enabled.
  static size_t CalculateNumMatchesPerUrlCount(
      const ACMatches& matches,
      const CompareWithDemoteByType<AutocompleteMatch>& comparing_object);

  const SearchSuggestionParser::HeadersMap& headers_map() const {
    return headers_map_;
  }

  const std::set<int>& hidden_group_ids() const { return hidden_group_ids_; }

  // Clears the matches for this result set.
  void Reset();

  void Swap(AutocompleteResult* other);

  // operator=() by another name.
  void CopyFrom(const AutocompleteResult& other);

#if DCHECK_IS_ON()
  // Does a data integrity check on this result.
  void Validate() const;
#endif  // DCHECK_IS_ON()

  // Returns a URL to offer the user as an alternative navigation when they
  // open |match| after typing in |input|.
  static GURL ComputeAlternateNavUrl(
      const AutocompleteInput& input,
      const AutocompleteMatch& match,
      AutocompleteProviderClient* provider_client);

  // Prepend missing tail suggestion prefixes in results, if present.
  void InlineTailPrefixes();

  // Estimates dynamic memory usage.
  // See base/trace_event/memory_usage_estimator.h for more info.
  size_t EstimateMemoryUsage() const;

  // Get a list of comparators used for deduping for the matches in this result.
  // This is only used for logging.
  std::vector<MatchDedupComparator> GetMatchDedupComparators() const;

  // Gets the header string associated with |suggestion_group_id|. Returns an
  // empty string if no header is found.
  std::u16string GetHeaderForGroupId(int suggestion_group_id) const;

  // Returns whether or not |suggestion_group_id| should be collapsed in the UI.
  // This method takes into account both the user's stored |prefs| as well as
  // the server-provided visibility hint for |suggestion_group_id|.
  bool IsSuggestionGroupIdHidden(PrefService* prefs,
                                 int suggestion_group_id) const;

  void MergeHeadersMap(const SearchSuggestionParser::HeadersMap& headers_map);

  void MergeHiddenGroupIds(const std::vector<int>& hidden_group_ids);

  // Logs metrics for when |new_result| replaces |old_result| asynchronously.
  // |old_result| a list of the comparators for the old matches.
  static void LogAsynchronousUpdateMetrics(
      const std::vector<MatchDedupComparator>& old_result,
      const AutocompleteResult& new_result);

  // This value should be comfortably larger than any max-autocomplete-matches
  // under consideration.
  static constexpr size_t kMaxAutocompletePositionValue = 30;

 private:
  FRIEND_TEST_ALL_PREFIXES(AutocompleteResultTest,
                           DemoteOnDeviceSearchSuggestions);
  FRIEND_TEST_ALL_PREFIXES(
      AutocompleteResultTest,
      GroupSuggestionsBySearchVsURLHonorsProtectedSuggestions);
  friend class HistoryURLProviderTest;

  typedef std::map<AutocompleteProvider*, ACMatches> ProviderToMatches;

#if defined(OS_ANDROID)
  // iterator::difference_type is not defined in the STL that we compile with on
  // Android.
  typedef int matches_difference_type;
#else
  typedef ACMatches::iterator::difference_type matches_difference_type;
#endif

  // Modifies |matches| such that any duplicate matches are coalesced into
  // representative "best" matches. The erased matches are moved into the
  // |duplicate_matches| members of their representative matches.
  static void DeduplicateMatches(ACMatches* matches);

  // Returns true if |matches| contains a match with the same destination as
  // |match|.
  static bool HasMatchByDestination(const AutocompleteMatch& match,
                                    const ACMatches& matches);

  // If there are both tail and non-tail suggestions (ignoring one default
  // match), remove the tail suggestions.  If the only default matches are tail
  // suggestions, remove the non-tail suggestions.
  static void MaybeCullTailSuggestions(
      ACMatches* matches,
      const CompareWithDemoteByType<AutocompleteMatch>& comparing_object);

  // Populates |provider_to_matches| from |matches_|. This AutocompleteResult
  // should not be used after the 'move' version.
  void BuildProviderToMatchesCopy(ProviderToMatches* provider_to_matches) const;
  void BuildProviderToMatchesMove(ProviderToMatches* provider_to_matches);

  // Moves matches into this result. |old_matches| gives the matches from the
  // last result, and |new_matches| the results from this result. |old_matches|
  // should not be used afterwards.
  void MergeMatchesByProvider(ACMatches* old_matches,
                              const ACMatches& new_matches);

  // This pulls the relevant fields out of a match for comparison with other
  // matches for the purpose of deduping. It uses the stripped URL, so that we
  // collapse similar URLs if necessary, and whether the match is a calculator
  // suggestion, because we don't want to dedupe them against URLs that simply
  // happen to go to the same destination.
  static MatchDedupComparator GetMatchComparisonFields(
      const AutocompleteMatch& match);

  // This method reduces the number of navigation suggestions to that of
  // |max_url_matches| but will allow more if there are no other types to
  // replace them.
  void LimitNumberOfURLsShown(
      size_t max_matches,
      size_t max_url_count,
      const CompareWithDemoteByType<AutocompleteMatch>& comparing_object);

  // This method implements a stateful stable partition. Matches which are
  // search types, and their submatches regardless of type, are shifted
  // earlier in the range, while non-search types and their submatches
  // are shifted later.
  static void GroupSuggestionsBySearchVsURL(iterator begin, iterator end);

  // If we have SearchProvider search suggestions, demote OnDeviceProvider
  // search suggestions, since, which in general have lower quality than
  // SearchProvider search suggestions. The demotion can happen in two ways,
  // controlled by Finch (1. decrease-relevances or 2. remove-suggestions):
  // 1. Decrease the on device search suggestion relevances that they will
  //    always be shown after SearchProvider search suggestions.
  // 2. Set the relevances of OnDeviceProvider search suggestions to 0, such
  //    that they will be removed from result list later.
  void DemoteOnDeviceSearchSuggestions();

  ACMatches matches_;

  // The server supplied map of suggestion group IDs to header labels.
  SearchSuggestionParser::HeadersMap headers_map_;

  // The server supplied list of group IDs that should be hidden-by-default.
  std::set<int> hidden_group_ids_;

#if defined(OS_ANDROID)
  // Corresponding Java object.
  // This object should be ignored when AutocompleteResult is copied or moved.
  // This object should never be accessed directly. To acquire a reference to
  // java object, call the GetOrCreateJavaObject().
  // Note that this object is lazily constructed to avoid creating Java matches
  // for throw away AutocompleteMatch objects, eg. during Classify() or
  // QualifyPartialUrlQuery() calls.
  // See AutocompleteControllerAndroid for more details.
  mutable base::android::ScopedJavaGlobalRef<jobject> java_result_;
#endif
};

#endif  // COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_RESULT_H_