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

#include "components/omnibox/browser/keyword_provider.h"

#include <string>
#include <string_view>
#include <utility>
#include <vector>

#include "base/containers/contains.h"
#include "base/memory/raw_ptr.h"
#include "base/strings/escape.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/trace_event/trace_event.h"
#include "components/omnibox/browser/autocomplete_enums.h"
#include "components/omnibox/browser/autocomplete_input.h"
#include "components/omnibox/browser/autocomplete_match.h"
#include "components/omnibox/browser/autocomplete_provider_client.h"
#include "components/omnibox/browser/autocomplete_provider_listener.h"
#include "components/omnibox/browser/keyword_extensions_delegate.h"
#include "components/omnibox/browser/omnibox_field_trial.h"
#include "components/omnibox/browser/search_provider.h"
#include "components/omnibox/common/omnibox_feature_configs.h"
#include "components/search_engines/template_url.h"
#include "components/search_engines/template_url_service.h"
#include "components/search_engines/template_url_starter_pack_data.h"
#include "components/strings/grit/components_strings.h"
#include "components/url_formatter/url_formatter.h"
#include "third_party/metrics_proto/omnibox_focus_type.pb.h"
#include "third_party/metrics_proto/omnibox_input_type.pb.h"
#include "ui/base/l10n/l10n_util.h"
#include "url/url_constants.h"

namespace {

// Helper functor for Start(), for sorting keyword matches by quality.
class CompareQuality {
 public:
  // A keyword is of higher quality when a greater fraction of it has been
  // typed, that is, when it is shorter.
  //
  // TODO(pkasting): Most recent and most frequent keywords are probably
  // better rankings than the fraction of the keyword typed.  We should
  // always put any exact matches first no matter what, since the code in
  // Start() assumes this (and it makes sense).
  bool operator()(const TemplateURL* t_url1, const TemplateURL* t_url2) const {
    return t_url1->keyword().length() < t_url2->keyword().length();
  }
};

// Helper for KeywordProvider::Start(), for ending keyword mode unless
// explicitly told otherwise.
class ScopedEndExtensionKeywordMode {
 public:
  explicit ScopedEndExtensionKeywordMode(KeywordExtensionsDelegate* delegate);
  ~ScopedEndExtensionKeywordMode();
  ScopedEndExtensionKeywordMode(const ScopedEndExtensionKeywordMode&) = delete;
  ScopedEndExtensionKeywordMode& operator=(
      const ScopedEndExtensionKeywordMode&) = delete;

  void StayInKeywordMode();

 private:
  raw_ptr<KeywordExtensionsDelegate> delegate_;
};

ScopedEndExtensionKeywordMode::ScopedEndExtensionKeywordMode(
    KeywordExtensionsDelegate* delegate)
    : delegate_(delegate) {}

ScopedEndExtensionKeywordMode::~ScopedEndExtensionKeywordMode() {
  if (delegate_)
    delegate_->MaybeEndExtensionKeywordMode();
}

void ScopedEndExtensionKeywordMode::StayInKeywordMode() {
  delegate_ = nullptr;
}

}  // namespace

KeywordProvider::KeywordProvider(AutocompleteProviderClient* client,
                                 AutocompleteProviderListener* listener)
    : AutocompleteProvider(AutocompleteProvider::TYPE_KEYWORD),
      model_(client->GetTemplateURLService()),
      extensions_delegate_(client->GetKeywordExtensionsDelegate(this)),
      client_(client) {
  AddListener(listener);
}

std::u16string KeywordProvider::GetKeywordForText(
    const std::u16string& text,
    TemplateURLService* template_url_service) const {
  // We want the Search button to persist as long as the input begins with a
  // keyword. This is found by taking the input until the first white space.
  std::u16string keyword = AutocompleteInput::CleanUserInputKeyword(
      template_url_service,
      AutocompleteInput::SplitKeywordFromInput(text, true, nullptr));

  if (keyword.empty())
    return u"";

  // Don't provide a keyword if it doesn't support replacement.
  const TemplateURL* const template_url =
      template_url_service->GetTemplateURLForKeyword(keyword);
  if (!template_url || !template_url->SupportsReplacement(
                           template_url_service->search_terms_data())) {
    return std::u16string();
  }

  // Don't provide a keyword for inactive/disabled extension keywords.
  if ((template_url->type() == TemplateURL::OMNIBOX_API_EXTENSION) &&
      extensions_delegate_ &&
      !extensions_delegate_->IsEnabledExtension(
          template_url->GetExtensionId())) {
    return std::u16string();
  }

  // Don't provide a keyword for inactive search engines (if the active search
  // engine flag is enabled). Prepopulated engines and extensions controlled
  // engines should always work regardless of is_active.
  if (template_url->type() != TemplateURL::OMNIBOX_API_EXTENSION &&
      template_url->prepopulate_id() == 0 &&
      template_url->is_active() != TemplateURLData::ActiveStatus::kTrue) {
    return std::u16string();
  }

  // The built-in history keyword mode is disabled in incognito mode. Don't
  // provide the "@history" keyword in that case.
  if (client_->IsOffTheRecord() &&
      template_url->starter_pack_id() ==
          template_url_starter_pack_data::kHistory) {
    return std::u16string();
  }

  return keyword;
}

AutocompleteMatch KeywordProvider::CreateVerbatimMatch(
    const std::u16string& text,
    const std::u16string& keyword,
    const AutocompleteInput& input) {
  // A verbatim match is allowed to be the default match when appropriate.
  return CreateAutocompleteMatch(
      GetTemplateURLService()->GetTemplateURLForKeyword(keyword), input,
      keyword.length(),
      AutocompleteInput::SplitReplacementStringFromInput(text, true),
      input.allow_exact_keyword_match(), 0, false);
}

void KeywordProvider::DeleteMatch(const AutocompleteMatch& match) {
  const std::u16string& suggestion_text = match.contents;

  const auto pred = [&match](const AutocompleteMatch& i) {
    return i.keyword == match.keyword &&
           i.fill_into_edit == match.fill_into_edit;
  };
  std::erase_if(matches_, pred);

  std::u16string keyword, remaining_input;
  if (!AutocompleteInput::ExtractKeywordFromInput(keyword_input_,
                                                  GetTemplateURLService(),
                                                  &keyword, &remaining_input)) {
    return;
  }
  const TemplateURL* const template_url =
      GetTemplateURLService()->GetTemplateURLForKeyword(keyword);

  if ((template_url->type() == TemplateURL::OMNIBOX_API_EXTENSION) &&
      extensions_delegate_ &&
      extensions_delegate_->IsEnabledExtension(
          template_url->GetExtensionId())) {
    extensions_delegate_->DeleteSuggestion(template_url, suggestion_text);
  }
}

void KeywordProvider::Start(const AutocompleteInput& input,
                            bool minimal_changes) {
  TRACE_EVENT0("omnibox", "KeywordProvider::Start");
  // This object ensures we end keyword mode if we exit the function without
  // toggling keyword mode to on.
  ScopedEndExtensionKeywordMode keyword_mode_toggle(extensions_delegate_.get());

  matches_.clear();

  if (!minimal_changes) {
    done_ = true;

    // Input has changed. Increment the input ID so that we can discard any
    // stale extension suggestions that may be incoming.
    if (extensions_delegate_)
      extensions_delegate_->IncrementInputId();
  }

  if (input.IsZeroSuggest()) {
    return;
  }

  GetTemplateURLService();
  DCHECK(model_);
  // Split user input into a keyword and some query input.
  //
  // We want to suggest keywords even when users have started typing URLs, on
  // the assumption that they might not realize they no longer need to go to a
  // site to be able to search it.  So we call
  // AutocompleteInput::CleanUserInputKeyword() to strip any initial scheme
  // and/or "www.".  NOTE: Any heuristics or UI used to automatically/manually
  // create keywords will need to be in sync with whatever we do here!
  //
  // TODO(pkasting): http://crbug/347744 If someday we remember usage frequency
  // for keywords, we might suggest keywords that haven't even been partially
  // typed, if the user uses them enough and isn't obviously typing something
  // else.  In this case we'd consider all input here to be query input.
  std::u16string keyword, remaining_input;
  if (!AutocompleteInput::ExtractKeywordFromInput(input, model_, &keyword,
                                                  &remaining_input)) {
    return;
  }

  keyword_input_ = input;

  // Get the best matches for this keyword.
  //
  // NOTE: We could cache the previous keywords and reuse them here in the
  // |minimal_changes| case, but since we'd still have to recalculate their
  // relevances and we can just recreate the results synchronously anyway, we
  // don't bother.
  TemplateURLService::TemplateURLVector turls;
  model_->AddMatchingKeywords(keyword, !remaining_input.empty(), &turls);

  for (auto i(turls.begin()); i != turls.end();) {
    const TemplateURL* template_url = *i;

    // Prune any extension keywords that are disallowed in incognito mode (if
    // we're incognito), or disabled.
    if (template_url->type() == TemplateURL::OMNIBOX_API_EXTENSION &&
        extensions_delegate_ &&
        !extensions_delegate_->IsEnabledExtension(
            template_url->GetExtensionId())) {
      i = turls.erase(i);
      continue;
    }

    // Prune any substituting keywords if there is no substitution.
    if (template_url->SupportsReplacement(model_->search_terms_data()) &&
        remaining_input.empty() && !input.allow_exact_keyword_match()) {
      i = turls.erase(i);
      continue;
    }

    // Prune any keywords for inactive search engines (if the active search
    // engine flag is enabled). Prepopulated engines and extensions controlled
    // engines should always work regardless of is_active.
    if (template_url->type() != TemplateURL::OMNIBOX_API_EXTENSION &&
        template_url->prepopulate_id() == 0 &&
        template_url->is_active() != TemplateURLData::ActiveStatus::kTrue) {
      i = turls.erase(i);
      continue;
    }

    ++i;
  }
  if (turls.empty()) {
    return;
  }
  std::sort(turls.begin(), turls.end(), CompareQuality());

  // Limit to one exact or three inexact matches, and mark them up for display
  // in the autocomplete popup.
  // Any exact match is going to be the highest quality match, and thus at the
  // front of our vector.
  if (turls.front()->keyword() == keyword) {
    const TemplateURL* template_url = turls.front();
    const bool is_extension_keyword =
        template_url->type() == TemplateURL::OMNIBOX_API_EXTENSION;

    // Only create an exact match if |remaining_input| is empty or if
    // this is an extension keyword.  If |remaining_input| is a
    // non-empty non-extension keyword (i.e., a regular keyword that
    // supports replacement and that has extra text following it),
    // then SearchProvider creates the exact (a.k.a. verbatim) match.
    if (!remaining_input.empty() && !is_extension_keyword) {
      return;
    }
    // TODO(pkasting): We should probably check that if the user explicitly
    // typed a scheme, that scheme matches the one in |template_url|.

    // When creating an exact match (either for the keyword itself, no
    // remaining query or an extension keyword, possibly with remaining
    // input), allow the match to be the default match when appropriate.
    // For exactly-typed non-substituting keywords, it's always appropriate.
    auto match = CreateAutocompleteMatch(
        template_url, input, keyword.length(), remaining_input,
        input.allow_exact_keyword_match() ||
            !template_url->SupportsReplacement(model_->search_terms_data()),
        -1, false);
    if (match.destination_url.is_empty() || match.destination_url.is_valid()) {
      matches_.push_back(std::move(match));
    }

    // Having extension-provided suggestions appear outside keyword mode can
    // be surprising, so only query for suggestions when in keyword mode.
    if (is_extension_keyword && extensions_delegate_ &&
        input.allow_exact_keyword_match()) {
      if (extensions_delegate_->Start(input, minimal_changes, template_url,
                                      remaining_input))
        keyword_mode_toggle.StayInKeywordMode();
    }
  } else {
    for (TemplateURLService::TemplateURLVector::const_iterator i(turls.begin());
         (i != turls.end()) && (matches_.size() < provider_max_matches_); ++i) {
      auto match = CreateAutocompleteMatch(*i, input, keyword.length(),
                                           remaining_input, false, -1, false);
      if (match.destination_url.is_empty() ||
          match.destination_url.is_valid()) {
        matches_.push_back(std::move(match));
      }
    }
  }
}

void KeywordProvider::Stop(AutocompleteStopReason stop_reason) {
  AutocompleteProvider::Stop(stop_reason);

  // Only end an extension's request if the user did something to explicitly
  // cancel it; mere inactivity shouldn't terminate long-running extension
  // operations since the user likely explicitly requested them.
  if (extensions_delegate_ &&
      stop_reason != AutocompleteStopReason::kInactivity) {
    extensions_delegate_->MaybeEndExtensionKeywordMode();
  }
}

KeywordProvider::~KeywordProvider() = default;

// static
int KeywordProvider::CalculateRelevance(metrics::OmniboxInputType type,
                                        bool complete,
                                        bool supports_replacement,
                                        bool prefer_keyword,
                                        bool allow_exact_keyword_match) {
  if (!complete) {
    return (type == metrics::OmniboxInputType::URL) ? 700 : 450;
  }
  if (!supports_replacement)
    return 1500;
  return SearchProvider::CalculateRelevanceForKeywordVerbatim(
      type, allow_exact_keyword_match, prefer_keyword);
}

AutocompleteMatch KeywordProvider::CreateAutocompleteMatch(
    const TemplateURL* template_url,
    const AutocompleteInput& input,
    size_t prefix_length,
    const std::u16string& remaining_input,
    bool allowed_to_be_default_match,
    int relevance,
    bool deletable) {
  DCHECK(template_url);
  const bool supports_replacement = template_url->url_ref().SupportsReplacement(
      GetTemplateURLService()->search_terms_data());

  // Create an edit entry of "[keyword] [remaining input]".  This is helpful
  // even when [remaining input] is empty, as the user can select the popup
  // choice and immediately begin typing in query input.
  const std::u16string& keyword = template_url->keyword();
  const bool keyword_complete = (prefix_length == keyword.length());
  if (relevance < 0) {
    relevance =
        CalculateRelevance(input.type(), keyword_complete,
                           // When the user wants keyword matches to take
                           // preference, score them highly regardless of
                           // whether the input provides query text.
                           supports_replacement, input.prefer_keyword(),
                           input.allow_exact_keyword_match());
  }

  AutocompleteMatch match(this, relevance, deletable,
                          supports_replacement
                              ? AutocompleteMatchType::SEARCH_OTHER_ENGINE
                              : AutocompleteMatchType::HISTORY_KEYWORD);
  match.allowed_to_be_default_match = allowed_to_be_default_match;
  match.fill_into_edit = keyword;
  if (!remaining_input.empty() || supports_replacement)
    match.fill_into_edit.push_back(L' ');
  match.fill_into_edit.append(remaining_input);
  // If we wanted to set |result.inline_autocompletion| correctly, we'd need
  // AutocompleteInput::CleanUserInputKeyword() to return the amount of
  // adjustment it's made to the user's input.  Because right now inexact
  // keyword matches can't score more highly than a "what you typed" match from
  // one of the other providers, we just don't bother to do this, and leave
  // inline autocompletion off.

  // Create destination URL and popup entry content by substituting user input
  // into keyword templates.
  FillInUrlAndContents(remaining_input, template_url, &match);

  // TODO(manukh) Consider not showing HISTORY_KEYWORD suggestions; i.e. not
  //   showing keyword matches for keywords that don't support replacement; they
  //   don't seem useful.
  if (supports_replacement) {
    match.keyword = keyword;
    match.from_keyword = true;
    match.transition = ui::PAGE_TRANSITION_KEYWORD;
  }

  return match;
}

void KeywordProvider::FillInUrlAndContents(
    const std::u16string& remaining_input,
    const TemplateURL* turl,
    AutocompleteMatch* match) const {
  DCHECK(!turl->short_name().empty());
  const TemplateURLRef& turl_ref = turl->url_ref();
  DCHECK(turl_ref.IsValid(GetTemplateURLService()->search_terms_data()));
  if (remaining_input.empty()) {
    // Null match; e.g. "<Type search term>".
    if (turl->starter_pack_id() == template_url_starter_pack_data::kAiMode) {
      match->contents.assign(
          l10n_util::GetStringUTF16(IDS_EMPTY_STARTER_PACK_AI_MODE_VALUE));
      match->contents_class.emplace_back(0, ACMatchClassification::DIM);
    } else if (turl_ref.SupportsReplacement(
                   GetTemplateURLService()->search_terms_data()) &&
               (turl->type() != TemplateURL::OMNIBOX_API_EXTENSION)) {
      // Substituting site search.
      match->contents.assign(
          l10n_util::GetStringUTF16(IDS_EMPTY_KEYWORD_VALUE));
      match->contents_class.emplace_back(0, ACMatchClassification::DIM);
    } else {
      // Keyword or extension that has no replacement text (aka a shorthand for
      // a URL).
      match->destination_url = GURL(turl->url());
      match->contents.assign(turl->short_name());
      if (!turl->short_name().empty())
        match->contents_class.emplace_back(0, ACMatchClassification::MATCH);
    }
  } else {
    // Create destination URL by escaping user input and substituting into
    // keyword template URL.  The escaping here handles whitespace in user
    // input, but we rely on later canonicalization functions to do more fixup
    // to make the URL valid if necessary.
    DCHECK(turl_ref.SupportsReplacement(
        GetTemplateURLService()->search_terms_data()));
    TemplateURLRef::SearchTermsArgs search_terms_args(remaining_input);
    search_terms_args.append_extra_query_params_from_command_line =
        turl == GetTemplateURLService()->GetDefaultSearchProvider();
    match->destination_url = GURL(turl_ref.ReplaceSearchTerms(
        search_terms_args, GetTemplateURLService()->search_terms_data()));
    match->contents = remaining_input;
    match->contents_class.emplace_back(0, ACMatchClassification::NONE);
  }
}

TemplateURLService* KeywordProvider::GetTemplateURLService() const {
  // Make sure the model is loaded. This is cheap and quickly bails out if the
  // model is already loaded.
  model_->Load();
  return model_;
}