text: // 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_PROVIDER_H_
  #define COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_PROVIDER_H_
  
  #include <stddef.h>
  
  #include "base/gtest_prod_util.h"
  #include "base/macros.h"
  #include "base/memory/ref_counted.h"
  #include "base/strings/string16.h"
  #include "components/metrics/proto/omnibox_event.pb.h"
  #include "components/omnibox/browser/autocomplete_match.h"
  
  class AutocompleteInput;
  
  typedef std::vector<metrics::OmniboxEventProto_ProviderInfo> ProvidersInfo;
  
  // The AutocompleteProviders each return different kinds of matches,
  // such as history or search matches.  These matches are given
  // "relevance" scores.  Higher scores are better matches than lower
  // scores.  The relevance scores and classes providing the respective
  // matches are as listed below.
  //
  // IMPORTANT CAVEAT: The tables below are NOT COMPLETE.  Developers
  // often forget to keep these tables in sync with the code when they
  // change scoring algorithms or add new providers.  For example,
  // neither the HistoryQuickProvider (which is a provider that appears
  // often) nor the ShortcutsProvider are listed here.  For the best
  // idea of how scoring works and what providers are affecting which
  // queries, play with chrome://omnibox/ for a while.  While the tables
  // below may have some utility, nothing compares with first-hand
  // investigation and experience.
  //
  // UNKNOWN input type:
  // --------------------------------------------------------------------|-----
  // Keyword (non-substituting or in keyword UI mode, exact match)       | 1500
  // HistoryURL (good exact or inline autocomplete matches, some inexact)| 1410++
  // HistoryURL (intranet url never visited match, some inexact matches) | 1400++
  // Search Primary Provider (past query in history within 2 days)       | 1399**
  // Search Primary Provider (what you typed)                            | 1300
  // HistoryURL (what you typed, some inexact matches)                   | 1200++
  // Keyword (substituting, exact match)                                 | 1100
  // Search Primary Provider (past query in history older than 2 days)   | 1050--
  // HistoryURL (some inexact matches)                                   |  900++
  // BookmarkProvider (prefix match in bookmark title)                   |  900+-
  // Built-in                                                            |  860++
  // Search Primary Provider (navigational suggestion)                   |  800++
  // Search Primary Provider (suggestion)                                |  600++
  // Keyword (inexact match)                                             |  450
  // Search Secondary Provider (what you typed)                          |  250
  // Search Secondary Provider (past query in history)                   |  200--
  // Search Secondary Provider (navigational suggestion)                 |  150++
  // Search Secondary Provider (suggestion)                              |  100++
  //
  // URL input type:
  // --------------------------------------------------------------------|-----
  // Keyword (non-substituting or in keyword UI mode, exact match)       | 1500
  // HistoryURL (good exact or inline autocomplete matches, some inexact)| 1410++
  // HistoryURL (intranet url never visited match, some inexact matches) | 1400++
  // HistoryURL (what you typed, some inexact matches)                   | 1200++
  // Keyword (substituting, exact match)                                 | 1100
  // HistoryURL (some inexact matches)                                   |  900++
  // Built-in                                                            |  860++
  // Search Primary Provider (what you typed)                            |  850
  // Search Primary Provider (navigational suggestion)                   |  800++
  // Search Primary Provider (past query in history)                     |  750--
  // Keyword (inexact match)                                             |  700
  // Search Primary Provider (suggestion)                                |  300++
  // Search Secondary Provider (what you typed)                          |  250
  // Search Secondary Provider (past query in history)                   |  200--
  // Search Secondary Provider (navigational suggestion)                 |  150++
  // Search Secondary Provider (suggestion)                              |  100++
  //
  // QUERY input type:
  // --------------------------------------------------------------------|-----
  // Search Primary or Secondary (past query in history within 2 days)   | 1599**
  // Keyword (non-substituting or in keyword UI mode, exact match)       | 1500
  // Keyword (substituting, exact match)                                 | 1450
  // Search Primary Provider (past query in history within 2 days)       | 1399**
  // Search Primary Provider (what you typed)                            | 1300
  // Search Primary Provider (past query in history older than 2 days)   | 1050--
  // HistoryURL (inexact match)                                          |  900++
  // BookmarkProvider (prefix match in bookmark title)                   |  900+-
  // Search Primary Provider (navigational suggestion)                   |  800++
  // Search Primary Provider (suggestion)                                |  600++
  // Keyword (inexact match)                                             |  450
  // Search Secondary Provider (what you typed)                          |  250
  // Search Secondary Provider (past query in history)                   |  200--
  // Search Secondary Provider (navigational suggestion)                 |  150++
  // Search Secondary Provider (suggestion)                              |  100++
  //
  // (A search keyword is a keyword with a replacement string; a bookmark keyword
  // is a keyword with no replacement string, that is, a shortcut for a URL.)
  //
  // There are two possible providers for search suggestions. If the user has
  // typed a keyword, then the primary provider is the keyword provider and the
  // secondary provider is the default provider. If the user has not typed a
  // keyword, then the primary provider corresponds to the default provider.
  //
  // Search providers may supply relevance values along with their results to be
  // used in place of client-side calculated values.
  //
  // The value column gives the ranking returned from the various providers.
  // ++: a series of matches with relevance from n up to (n + max_matches).
  // --: relevance score falls off over time (discounted 50 points @ 15 minutes,
  //     450 points @ two weeks)
  // **: relevance score falls off over two days (discounted 99 points after two
  //     days).
  // +-: A base score that the provider will adjust upward or downward based on
  //     provider-specific metrics.
  //
  // A single result provider for the autocomplete system.  Given user input, the
  // provider decides what (if any) matches to return, their relevance, and their
  // classifications.
  class AutocompleteProvider
      : public base::RefCountedThreadSafe<AutocompleteProvider> {
   public:
    // Different AutocompleteProvider implementations.
    enum Type {
      TYPE_BOOKMARK         = 1 << 0,
      TYPE_BUILTIN          = 1 << 1,
      TYPE_HISTORY_QUICK    = 1 << 2,
      TYPE_HISTORY_URL      = 1 << 3,
      TYPE_KEYWORD          = 1 << 4,
      TYPE_SEARCH           = 1 << 5,
      TYPE_SHORTCUTS        = 1 << 6,
      TYPE_ZERO_SUGGEST     = 1 << 7,
      TYPE_CLIPBOARD_URL    = 1 << 8,
      TYPE_PHYSICAL_WEB     = 1 << 9,
    };
  
    explicit AutocompleteProvider(Type type);
  
    // Returns a string describing a particular AutocompleteProvider type.
    static const char* TypeToString(Type type);
  
    // Called to start an autocomplete query.  The provider is responsible for
    // tracking its matches for this query and whether it is done processing the
    // query.  When new matches are available or the provider finishes, it
    // calls the controller's OnProviderUpdate() method.  The controller can then
    // get the new matches using the provider's accessors.
    // Exception: Matches available immediately after starting the query (that
    // is, synchronously) do not cause any notifications to be sent.  The
    // controller is expected to check for these without prompting (since
    // otherwise, starting each provider running would result in a flurry of
    // notifications).
    //
    // Once Stop() has been called, usually no more notifications should be sent.
    // (See comments on Stop() below.)
    //
    // |minimal_changes| is an optimization that lets the provider do less work
    // when the |input|'s text hasn't changed.  See the body of
    // OmniboxPopupModel::StartAutocomplete().
    virtual void Start(const AutocompleteInput& input, bool minimal_changes) = 0;
  
    // Advises the provider to stop processing.  This may be called even if the
    // provider is already done.  If the provider caches any results, it should
    // clear the cache based on the value of |clear_cached_results|.  Normally,
    // once this is called, the provider should not send more notifications to
    // the controller.
    //
    // If |user_inactivity_timer| is true, Stop() is being called because it's
    // been a long time since the user started the current query, and returning
    // further asynchronous results would normally just be disruptive.  Most
    // providers should still stop processing in this case, but continuing is
    // legal if there's a good reason the user is likely to want even long-
    // delayed asynchronous results, e.g. the user has explicitly invoked a
    // keyword extension and the extension is still processing the request.
    virtual void Stop(bool clear_cached_results,
                      bool due_to_user_inactivity);
  
    // Returns the enum equivalent to the name of this provider.
    // TODO(derat): Make metrics use AutocompleteProvider::Type directly, or at
    // least move this method to the metrics directory.
    metrics::OmniboxEventProto_ProviderType AsOmniboxEventProviderType() const;
  
    // Called to delete a match and the backing data that produced it.  This
    // match should not appear again in this or future queries.  This can only be
    // called for matches the provider marks as deletable.  This should only be
    // called when no query is running.
    // NOTE: Do NOT call OnProviderUpdate() in this method, it is the
    // responsibility of the caller to do so after calling us.
    virtual void DeleteMatch(const AutocompleteMatch& match);
  
    // Called when an omnibox event log entry is generated.  This gives
    // a provider the opportunity to add diagnostic information to the
    // logs.  A provider is expected to append a single entry of whatever
    // information it wants to |provider_info|.
    virtual void AddProviderInfo(ProvidersInfo* provider_info) const;
  
    // Called when a new omnibox session starts or the current session ends.
    // This gives the opportunity to reset the internal state, if any, associated
    // with the previous session.
    virtual void ResetSession();
  
    // Returns the set of matches for the current query.
    const ACMatches& matches() const { return matches_; }
  
    // Returns whether the provider is done processing the query.
    bool done() const { return done_; }
  
    // Returns this provider's type.
    Type type() const { return type_; }
  
    // Returns a string describing this provider's type.
    const char* GetName() const;
  
    // A suggested upper bound for how many matches a provider should return.
    // TODO(pkasting): http://b/1111299 , http://b/933133 This should go away once
    // we have good relevance heuristics; the controller should handle all
    // culling.
    static const size_t kMaxMatches;
  
   protected:
    friend class base::RefCountedThreadSafe<AutocompleteProvider>;
    FRIEND_TEST_ALL_PREFIXES(BookmarkProviderTest, InlineAutocompletion);
  
    typedef std::pair<bool, base::string16> FixupReturn;
  
    virtual ~AutocompleteProvider();
  
    // Fixes up user URL input to make it more possible to match against.  Among
    // many other things, this takes care of the following:
    // * Prepending file:// to file URLs
    // * Converting drive letters in file URLs to uppercase
    // * Converting case-insensitive parts of URLs (like the scheme and domain)
    //   to lowercase
    // * Convert spaces to %20s
    // Note that we don't do this in AutocompleteInput's constructor, because if
    // e.g. we convert a Unicode hostname to punycode, other providers will show
    // output that surprises the user ("Search Google for xn--6ca.com").
    // Returns a bool indicating whether fixup succeeded, as well as the fixed-up
    // input text.  The returned string will be the same as the input string if
    // fixup failed; this lets callers who don't care about failure simply use the
    // string unconditionally.
    static FixupReturn FixupUserInput(const AutocompleteInput& input);
  
    // Trims "http:" and up to two subsequent slashes from |url|.  Returns the
    // number of characters that were trimmed.
    // NOTE: For a view-source: URL, this will trim from after "view-source:" and
    // return 0.
    static size_t TrimHttpPrefix(base::string16* url);
  
    ACMatches matches_;
    bool done_;
  
    Type type_;
  
   private:
    DISALLOW_COPY_AND_ASSIGN(AutocompleteProvider);
  };
  
  #endif  // COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_PROVIDER_H_
  