// 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_BOOKMARKS_BROWSER_BOOKMARK_INDEX_H_
#define COMPONENTS_BOOKMARKS_BROWSER_BOOKMARK_INDEX_H_

#include <map>
#include <set>
#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/strings/string16.h"
#include "components/query_parser/query_parser.h"

class BookmarkNode;

namespace bookmarks {

class BookmarkClient;
struct BookmarkMatch;

// BookmarkIndex maintains an index of the titles and URLs of bookmarks for
// quick look up. BookmarkIndex is owned and maintained by BookmarkModel, you
// shouldn't need to interact directly with BookmarkIndex.
//
// BookmarkIndex maintains the index (index_) as a map of sets. The map (type
// Index) maps from a lower case string to the set (type NodeSet) of
// BookmarkNodes that contain that string in their title or URL.
class BookmarkIndex {
 public:
  // |languages| is used to help parse IDNs in URLs for the bookmark index.
  BookmarkIndex(BookmarkClient* client,
                const std::string& languages);
  ~BookmarkIndex();

  // Invoked when a bookmark has been added to the model.
  void Add(const BookmarkNode* node);

  // Invoked when a bookmark has been removed from the model.
  void Remove(const BookmarkNode* node);

  // Returns up to |max_count| of bookmarks containing each term from
  // the text |query| in either the title or the URL.
  void GetBookmarksMatching(
      const base::string16& query,
      size_t max_count,
      std::vector<BookmarkMatch>* results);

 private:
  typedef std::vector<const BookmarkNode*> Nodes;
  typedef std::set<const BookmarkNode*> NodeSet;
  typedef std::map<base::string16, NodeSet> Index;

  struct Match;
  typedef std::vector<Match> Matches;

  // Extracts |matches.nodes| into Nodes, sorts the pairs in decreasing order of
  // typed count (if supported by the client), and then de-dupes the matches.
  void SortMatches(const Matches& matches, Nodes* sorted_nodes) const;

  // Add |node| to |results| if the node matches the query.
  void AddMatchToResults(
      const BookmarkNode* node,
      query_parser::QueryParser* parser,
      const query_parser::QueryNodeStarVector& query_nodes,
      std::vector<BookmarkMatch>* results);

  // Populates |matches| for the specified term. If |first_term| is true, this
  // is the first term in the query. Returns true if there is at least one node
  // matching the term.
  bool GetBookmarksMatchingTerm(const base::string16& term,
                                bool first_term,
                                Matches* matches);

  // Iterates over |matches| updating each Match's nodes to contain the
  // intersection of the Match's current nodes and the nodes at |index_i|.
  // If the intersection is empty, the Match is removed.
  //
  // This is invoked from GetBookmarksMatchingTerm.
  void CombineMatchesInPlace(const Index::const_iterator& index_i,
                             Matches* matches);

  // Iterates over |current_matches| calculating the intersection between the
  // Match's nodes and the nodes at |index_i|. If the intersection between the
  // two is non-empty, a new match is added to |result|.
  //
  // This differs from CombineMatchesInPlace in that if the intersection is
  // non-empty the result is added to result, not combined in place. This
  // variant is used for prefix matching.
  //
  // This is invoked from GetBookmarksMatchingTerm.
  void CombineMatches(const Index::const_iterator& index_i,
                      const Matches& current_matches,
                      Matches* result);

  // Returns the set of query words from |query|.
  std::vector<base::string16> ExtractQueryWords(const base::string16& query);

  // Adds |node| to |index_|.
  void RegisterNode(const base::string16& term, const BookmarkNode* node);

  // Removes |node| from |index_|.
  void UnregisterNode(const base::string16& term, const BookmarkNode* node);

  Index index_;

  BookmarkClient* const client_;

  // Languages used to help parse IDNs in URLs for the bookmark index.
  const std::string languages_;

  DISALLOW_COPY_AND_ASSIGN(BookmarkIndex);
};

}  // namespace bookmarks

#endif  // COMPONENTS_BOOKMARKS_BROWSER_BOOKMARK_INDEX_H_