// Copyright (c) 2012 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.

#include "chrome/browser/instant/instant_controller.h"

#include "base/command_line.h"
#include "base/i18n/case_conversion.h"
#include "base/metrics/histogram.h"
#include "base/string_util.h"
#include "base/time.h"
#include "base/utf_string_conversions.h"
#include "chrome/browser/autocomplete/autocomplete_provider.h"
#include "chrome/browser/google/google_util.h"
#include "chrome/browser/history/history.h"
#include "chrome/browser/history/history_service_factory.h"
#include "chrome/browser/history/history_tab_helper.h"
#include "chrome/browser/instant/instant_loader.h"
#include "chrome/browser/platform_util.h"
#include "chrome/browser/prefs/pref_service.h"
#include "chrome/browser/search_engines/template_url_service.h"
#include "chrome/browser/search_engines/template_url_service_factory.h"
#include "chrome/browser/ui/browser_instant_controller.h"
#include "chrome/browser/ui/search/search.h"
#include "chrome/browser/ui/search/search_tab_helper.h"
#include "chrome/browser/ui/tab_contents/tab_contents.h"
#include "chrome/common/chrome_notification_types.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/pref_names.h"
#include "content/public/browser/favicon_status.h"
#include "content/public/browser/navigation_entry.h"
#include "content/public/browser/notification_service.h"
#include "content/public/browser/render_widget_host_view.h"
#include "content/public/browser/web_contents.h"
#include "net/base/escape.h"
#include "unicode/normalizer2.h"
#include "unicode/unistr.h"

#if defined(TOOLKIT_VIEWS)
#include "ui/views/widget/widget.h"
#endif

namespace {

enum PreviewUsageType {
  PREVIEW_CREATED = 0,
  PREVIEW_DELETED,
  PREVIEW_LOADED,
  PREVIEW_SHOWED,
  PREVIEW_COMMITTED,
  PREVIEW_NUM_TYPES,
};

// An artificial delay (in milliseconds) we introduce before telling the Instant
// page about the new omnibox bounds, in cases where the bounds shrink. This is
// to avoid the page jumping up/down very fast in response to bounds changes.
const int kUpdateBoundsDelayMS = 1000;

// The maximum number of times we'll load a non-Instant-supporting search engine
// before we give up and blacklist it for the rest of the browsing session.
const int kMaxInstantSupportFailures = 10;

// If an Instant page has not been used in these many milliseconds, it is
// reloaded so that the page does not become stale.
const int kStaleLoaderTimeoutMS = 3 * 3600 * 1000;

std::string ModeToString(InstantController::Mode mode) {
  switch (mode) {
    case InstantController::EXTENDED: return "_Extended";
    case InstantController::INSTANT:  return "_Instant";
    case InstantController::DISABLED: return "_Disabled";
  }

  NOTREACHED();
  return std::string();
}

void AddPreviewUsageForHistogram(InstantController::Mode mode,
                                 PreviewUsageType usage) {
  DCHECK(0 <= usage && usage < PREVIEW_NUM_TYPES) << usage;
  base::Histogram* histogram = base::LinearHistogram::FactoryGet(
      "Instant.Previews" + ModeToString(mode), 1, PREVIEW_NUM_TYPES,
      PREVIEW_NUM_TYPES + 1, base::Histogram::kUmaTargetedHistogramFlag);
  histogram->Add(usage);
}

void AddSessionStorageHistogram(InstantController::Mode mode,
                                const TabContents* tab1,
                                const TabContents* tab2) {
  base::Histogram* histogram = base::BooleanHistogram::FactoryGet(
      "Instant.SessionStorageNamespace" + ModeToString(mode),
      base::Histogram::kUmaTargetedHistogramFlag);
  const content::SessionStorageNamespaceMap& session_storage_map1 =
      tab1->web_contents()->GetController().GetSessionStorageNamespaceMap();
  const content::SessionStorageNamespaceMap& session_storage_map2 =
      tab2->web_contents()->GetController().GetSessionStorageNamespaceMap();
  bool is_session_storage_the_same =
      session_storage_map1.size() == session_storage_map2.size();
  if (is_session_storage_the_same) {
    // The size is the same, so let's check that all entries match.
    for (content::SessionStorageNamespaceMap::const_iterator
             it1 = session_storage_map1.begin(),
             it2 = session_storage_map2.begin();
         it1 != session_storage_map1.end() &&
             it2 != session_storage_map2.end();
         ++it1, ++it2) {
      if (it1->first != it2->first || it1->second != it2->second) {
        is_session_storage_the_same = false;
        break;
      }
    }
  }
  histogram->AddBoolean(is_session_storage_the_same);
}

InstantController::Mode GetModeForProfile(Profile* profile) {
  if (chrome::search::IsInstantExtendedAPIEnabled(profile))
    return InstantController::EXTENDED;

  if (!profile || profile->IsOffTheRecord() || !profile->GetPrefs() ||
      !profile->GetPrefs()->GetBoolean(prefs::kInstantEnabled))
    return InstantController::DISABLED;

  return InstantController::INSTANT;
}

string16 Normalize(const string16& str) {
  UErrorCode status = U_ZERO_ERROR;
  const icu::Normalizer2* normalizer =
      icu::Normalizer2::getInstance(NULL, "nfkc_cf", UNORM2_COMPOSE, status);
  if (normalizer == NULL || U_FAILURE(status))
    return str;
  icu::UnicodeString norm_str(normalizer->normalize(
      icu::UnicodeString(FALSE, str.c_str(), str.size()), status));
  if (U_FAILURE(status))
    return str;
  return string16(norm_str.getBuffer(), norm_str.length());
}

bool NormalizeAndStripPrefix(string16* text, const string16& prefix) {
  const string16 norm_prefix = Normalize(prefix);
  string16 norm_text = Normalize(*text);
  if (norm_prefix.size() <= norm_text.size() &&
      norm_text.compare(0, norm_prefix.size(), norm_prefix) == 0) {
    *text = norm_text.erase(0, norm_prefix.size());
    return true;
  }
  return false;
}

InstantModel::PreviewState GetNewPreviewState(InstantShownReason reason) {
  return reason == INSTANT_SHOWN_CUSTOM_NTP_CONTENT ?
      InstantModel::CUSTOM_NTP_CONTENT : InstantModel::QUERY_RESULTS;
}

}  // namespace

InstantController::~InstantController() {
  if (GetPreviewContents())
    AddPreviewUsageForHistogram(mode_, PREVIEW_DELETED);
}

// static
InstantController* InstantController::CreateInstant(
    Profile* profile,
    chrome::BrowserInstantController* browser) {
  const Mode mode = GetModeForProfile(profile);
  return mode == DISABLED ? NULL : new InstantController(browser, mode);
}

// static
bool InstantController::IsExtendedAPIEnabled(Profile* profile) {
  return GetModeForProfile(profile) == EXTENDED;
}

// static
bool InstantController::IsInstantEnabled(Profile* profile) {
  const Mode mode = GetModeForProfile(profile);
  return mode == EXTENDED || mode == INSTANT;
}

// static
void InstantController::RegisterUserPrefs(PrefService* prefs) {
  prefs->RegisterBooleanPref(prefs::kInstantConfirmDialogShown, false,
                             PrefService::SYNCABLE_PREF);
  prefs->RegisterBooleanPref(prefs::kInstantEnabled, false,
                             PrefService::SYNCABLE_PREF);
}

bool InstantController::Update(const AutocompleteMatch& match,
                               const string16& user_text,
                               const string16& full_text,
                               bool verbatim) {
  const TabContents* active_tab = browser_->GetActiveTabContents();

  // We could get here with no active tab if the Browser is closing.
  if (!active_tab) {
    Hide();
    return false;
  }

  std::string instant_url;
  Profile* profile = active_tab->profile();

  // If the match's TemplateURL is valid, it's a search query; use it. If it's
  // not valid, it's likely a URL; in EXTENDED mode, try using the default
  // search engine's TemplateURL instead.
  const GURL& tab_url = active_tab->web_contents()->GetURL();
  if (GetInstantURL(match.GetTemplateURL(profile, false), tab_url,
                    &instant_url)) {
    ResetLoader(instant_url, active_tab);
  } else if (mode_ != EXTENDED || !CreateDefaultLoader()) {
    Hide();
    return false;
  }

  if (full_text.empty()) {
    Hide();
    return false;
  }

  // Track the non-Instant search URL for this query.
  url_for_history_ = match.destination_url;
  last_transition_type_ = match.transition;
  last_match_was_search_ = AutocompleteMatch::IsSearchType(match.type);

  // The last suggestion and its associated parameters can be preserved if the
  // user continues typing the same query as the suggested text is showing.
  // Suggestions are only reused with INSTANT_COMPLETE_NEVER behavior.
  bool reused_suggestion = false;
  bool user_text_changed = user_text != last_user_text_;
  if (last_suggestion_.behavior == INSTANT_COMPLETE_NEVER &&
      user_text_changed) {
    if (StartsWith(user_text, last_user_text_, false)) {
      // If the new user text is longer than the last user text, we need
      // to normalize any added characters.
      reused_suggestion = NormalizeAndStripPrefix(&last_suggestion_.text,
          string16(user_text, last_user_text_.size()));
    } else if (StartsWith(last_user_text_, user_text, false)) {
      // If the new user text is a prefix of the last user text, no
      // normalization is necessary.
      last_suggestion_.text.insert(0, last_user_text_, user_text.size(),
          last_user_text_.size() - user_text.size());
      reused_suggestion = true;
    }
  }

  last_user_text_ = user_text;
  last_full_text_ = full_text;

  // Don't send an update to the loader if the query text hasn't changed.
  if (!user_text_changed && verbatim == last_verbatim_) {
    // Reuse the last suggestion, as it's still valid.
    browser_->SetInstantSuggestion(last_suggestion_);

    // We need to call Show() here because of this:
    // 1. User has typed a query (say Q). Instant overlay is showing results.
    // 2. User arrows-down to a URL entry or erases all omnibox text. Both of
    //    these cause the overlay to Hide().
    // 3. User arrows-up to Q or types Q again. The last text we processed is
    //    still Q, so we don't Update() the loader, but we do need to Show().
    if (loader_processed_last_update_)
      Show(INSTANT_SHOWN_QUERY_SUGGESTIONS, 100, INSTANT_SIZE_PERCENT);
    return true;
  }

  last_verbatim_ = verbatim;
  loader_processed_last_update_ = false;
  if (!reused_suggestion)
    last_suggestion_ = InstantSuggestion();
  if (model_.preview_state() == InstantModel::NOT_READY) {
    model_.SetPreviewState(InstantModel::AWAITING_SUGGESTIONS,
                           0, INSTANT_SIZE_PERCENT);
  }

  loader_->Update(mode_ == EXTENDED ? user_text : full_text, verbatim);

  content::NotificationService::current()->Notify(
      chrome::NOTIFICATION_INSTANT_CONTROLLER_UPDATED,
      content::Source<InstantController>(this),
      content::NotificationService::NoDetails());

  // We don't have new suggestions yet, but we can either reuse the existing
  // suggestion or reset the existing "gray text".
  browser_->SetInstantSuggestion(last_suggestion_);

  // Though we may have handled a URL match above, we return false here, so that
  // omnibox prerendering can kick in. TODO(sreeram): Remove this (and always
  // return true) once we are able to commit URLs as well.
  return last_match_was_search_;
}

// TODO(tonyg): This method only fires when the omnibox bounds change. It also
// needs to fire when the preview bounds change (e.g.: open/close info bar).
void InstantController::SetOmniboxBounds(const gfx::Rect& bounds) {
  if (omnibox_bounds_ == bounds)
    return;

  omnibox_bounds_ = bounds;
  if (omnibox_bounds_.height() > last_omnibox_bounds_.height()) {
    update_bounds_timer_.Stop();
    SendBoundsToPage();
  } else if (!update_bounds_timer_.IsRunning()) {
    update_bounds_timer_.Start(FROM_HERE,
        base::TimeDelta::FromMilliseconds(kUpdateBoundsDelayMS), this,
        &InstantController::SendBoundsToPage);
  }
}

void InstantController::HandleAutocompleteResults(
    const std::vector<AutocompleteProvider*>& providers) {
  if (mode_ != EXTENDED || !GetPreviewContents())
    return;

  std::vector<InstantAutocompleteResult> results;
  for (ACProviders::const_iterator provider = providers.begin();
       provider != providers.end(); ++provider) {
    for (ACMatches::const_iterator match = (*provider)->matches().begin();
         match != (*provider)->matches().end(); ++match) {
      InstantAutocompleteResult result;
      result.provider = UTF8ToUTF16((*provider)->GetName());
      result.is_search = AutocompleteMatch::IsSearchType(match->type);
      result.contents = match->description;
      result.destination_url = match->destination_url;
      result.relevance = match->relevance;
      results.push_back(result);
    }
  }

  loader_->SendAutocompleteResults(results);
}

bool InstantController::OnUpOrDownKeyPressed(int count) {
  if (mode_ != EXTENDED || !GetPreviewContents())
    return false;

  loader_->OnUpOrDownKeyPressed(count);
  return true;
}

void InstantController::OnEscapeKeyPressed() {
  if (model_.preview_state() != InstantModel::CUSTOM_NTP_CONTENT)
    Hide();
}

TabContents* InstantController::GetPreviewContents() const {
  return loader_.get() ? loader_->preview_contents() : NULL;
}

void InstantController::Hide() {
  // The only time when the preview is not already in the desired NOT_READY
  // state and GetPreviewContents() returns NULL is when we are in the commit
  // path. In that case, don't change the state just yet; otherwise we may
  // cause the preview to hide unnecessarily. Instead, the state will be set
  // correctly after the commit is done.
  if (GetPreviewContents())
    model_.SetPreviewState(InstantModel::NOT_READY, 0, INSTANT_SIZE_PERCENT);

  if (GetPreviewContents() && !last_full_text_.empty()) {
    // Send a blank query to ask the preview to clear out old results.
    last_full_text_.clear();
    last_user_text_.clear();
    loader_->Update(last_full_text_, true);
  }
}

bool InstantController::IsCurrent() const {
  return model_.preview_state() == InstantModel::QUERY_RESULTS &&
         GetPreviewContents() &&
         loader_->supports_instant() && last_match_was_search_;
}

void InstantController::CommitCurrentPreview(InstantCommitType type) {
  TabContents* preview = loader_->ReleasePreviewContents(type, last_full_text_);

  if (mode_ == EXTENDED) {
    // Consider what's happening:
    //   1. The user has typed a query in the omnibox and committed it (either
    //      by pressing Enter or clicking on the preview).
    //   2. We commit the preview to the tab strip, and tell the page.
    //   3. The page will update the URL hash fragment with the query terms.
    // After steps 1 and 3, the omnibox will show the query terms. However, if
    // the URL we are committing at step 2 doesn't already have query terms, it
    // will flash for a brief moment as a plain URL. So, avoid that flicker by
    // pretending that the plain URL is actually the typed query terms.
    // TODO(samarth,beaudoin): Instead of this hack, we should add a new field
    // to NavigationEntry to keep track of what the correct query, if any, is.
    content::NavigationEntry* entry =
        preview->web_contents()->GetController().GetVisibleEntry();
    std::string url = entry->GetVirtualURL().spec();
    if (!google_util::IsInstantExtendedAPIGoogleSearchUrl(url) &&
        google_util::IsGoogleDomainUrl(url, google_util::ALLOW_SUBDOMAIN,
                                       google_util::ALLOW_NON_STANDARD_PORTS)) {
      entry->SetVirtualURL(GURL(
          url + "#q=" +
          net::EscapeQueryParamValue(UTF16ToUTF8(last_full_text_), true)));
      chrome::search::SearchTabHelper::FromWebContents(
          preview->web_contents())->NavigationEntryUpdated();
    }
  }

  // If the preview page has navigated since the last Update(), we need to add
  // the navigation to history ourselves. Else, the page will navigate after
  // commit, and it will be added to history in the usual manner.
  const history::HistoryAddPageArgs& last_navigation =
      loader_->last_navigation();
  if (!last_navigation.url.is_empty()) {
    content::NavigationEntry* entry =
        preview->web_contents()->GetController().GetActiveEntry();
    DCHECK_EQ(last_navigation.url, entry->GetURL());

    // Add the page to history.
    HistoryTabHelper* history_tab_helper =
        HistoryTabHelper::FromWebContents(preview->web_contents());
    history_tab_helper->UpdateHistoryForNavigation(last_navigation);

    // Update the page title.
    history_tab_helper->UpdateHistoryPageTitle(*entry);
  }

  // Add a fake history entry with a non-Instant search URL, so that search
  // terms extraction (for autocomplete history matches) works.
  if (HistoryService* history = HistoryServiceFactory::GetForProfile(
          preview->profile(), Profile::EXPLICIT_ACCESS)) {
    history->AddPage(url_for_history_, base::Time::Now(), NULL, 0, GURL(),
                     history::RedirectList(), last_transition_type_,
                     history::SOURCE_BROWSED, false);
  }

  AddPreviewUsageForHistogram(mode_, PREVIEW_COMMITTED);
  DeleteLoader();

  preview->web_contents()->GetController().PruneAllButActive();

  if (type != INSTANT_COMMIT_PRESSED_ALT_ENTER) {
    const TabContents* active_tab = browser_->GetActiveTabContents();
    AddSessionStorageHistogram(mode_, active_tab, preview);
    preview->web_contents()->GetController().CopyStateFromAndPrune(
        &active_tab->web_contents()->GetController());
  }

  // Browser takes ownership of the preview.
  browser_->CommitInstant(preview, type == INSTANT_COMMIT_PRESSED_ALT_ENTER);

  content::NotificationService::current()->Notify(
      chrome::NOTIFICATION_INSTANT_COMMITTED,
      content::Source<content::WebContents>(preview->web_contents()),
      content::NotificationService::NoDetails());

  model_.SetPreviewState(InstantModel::NOT_READY, 0, INSTANT_SIZE_PERCENT);

  // Try to create another loader immediately so that it is ready for the next
  // user interaction.
  CreateDefaultLoader();
}

void InstantController::OnAutocompleteLostFocus(
    gfx::NativeView view_gaining_focus) {
  is_omnibox_focused_ = false;

  // If there is no preview, nothing to do.
  if (!GetPreviewContents())
    return;

  loader_->OnAutocompleteLostFocus();

  // It's bizarre if custom NTP content disappears when the user focuses
  // outside the omnibox.
  if (model_.preview_state() == InstantModel::CUSTOM_NTP_CONTENT)
    return;

  // If the preview is not showing, only need to check for loader staleness.
  if (model_.preview_state() == InstantModel::NOT_READY) {
    MaybeOnStaleLoader();
    return;
  }

#if defined(OS_MACOSX)
  if (!loader_->IsPointerDownFromActivate()) {
    Hide();
    MaybeOnStaleLoader();
  }
#else
  content::RenderWidgetHostView* rwhv =
      GetPreviewContents()->web_contents()->GetRenderWidgetHostView();
  if (!view_gaining_focus || !rwhv) {
    Hide();
    MaybeOnStaleLoader();
    return;
  }

#if defined(TOOLKIT_VIEWS)
  // For views the top level widget is always focused. If the focus change
  // originated in views determine the child Widget from the view that is being
  // focused.
  views::Widget* widget =
      views::Widget::GetWidgetForNativeView(view_gaining_focus);
  if (widget) {
    views::FocusManager* focus_manager = widget->GetFocusManager();
    if (focus_manager && focus_manager->is_changing_focus() &&
        focus_manager->GetFocusedView() &&
        focus_manager->GetFocusedView()->GetWidget()) {
      view_gaining_focus =
          focus_manager->GetFocusedView()->GetWidget()->GetNativeView();
    }
  }
#endif

  gfx::NativeView tab_view =
      GetPreviewContents()->web_contents()->GetNativeView();

  // Focus is going to the renderer.
  if (rwhv->GetNativeView() == view_gaining_focus ||
      tab_view == view_gaining_focus) {

    // If the mouse is not down, focus is not going to the renderer. Someone
    // else moved focus and we shouldn't commit.
    if (!loader_->IsPointerDownFromActivate()) {
      Hide();
      MaybeOnStaleLoader();
    }

    return;
  }

  // Walk up the view hierarchy. If the view gaining focus is a subview of the
  // WebContents view (such as a windowed plugin or http auth dialog), we want
  // to keep the preview contents. Otherwise, focus has gone somewhere else,
  // such as the JS inspector, and we want to cancel the preview.
  gfx::NativeView view_gaining_focus_ancestor = view_gaining_focus;
  while (view_gaining_focus_ancestor &&
         view_gaining_focus_ancestor != tab_view) {
    view_gaining_focus_ancestor =
        platform_util::GetParent(view_gaining_focus_ancestor);
  }

  if (view_gaining_focus_ancestor) {
    CommitCurrentPreview(INSTANT_COMMIT_FOCUS_LOST);
    return;
  }

  Hide();
  MaybeOnStaleLoader();
#endif
}

void InstantController::OnAutocompleteGotFocus() {
  is_omnibox_focused_ = true;
  if (GetPreviewContents())
    loader_->OnAutocompleteGotFocus();
  CreateDefaultLoader();
}

void InstantController::OnActiveTabModeChanged(bool active_tab_is_ntp) {
  active_tab_is_ntp_ = active_tab_is_ntp;
  if (GetPreviewContents()) {
    loader_->OnActiveTabModeChanged(active_tab_is_ntp_);
    // On navigation away from the NTP, hide custom content.
    if (!active_tab_is_ntp_ &&
        model_.preview_state() == InstantModel::CUSTOM_NTP_CONTENT)
      Hide();
  }
}

bool InstantController::commit_on_pointer_release() const {
  return GetPreviewContents() && loader_->IsPointerDownFromActivate();
}

void InstantController::SetSuggestions(
    InstantLoader* loader,
    const std::vector<InstantSuggestion>& suggestions) {
  if (loader_ != loader || model_.preview_state() == InstantModel::NOT_READY)
    return;

  loader_processed_last_update_ = true;

  InstantSuggestion suggestion;
  if (!suggestions.empty())
    suggestion = suggestions[0];

  if (suggestion.behavior == INSTANT_COMPLETE_REPLACE) {
    // We don't get an Update() when changing the omnibox due to a REPLACE
    // suggestion (so that we don't inadvertently cause the preview to change
    // what it's showing, as the user arrows up/down through the page-provided
    // suggestions). So, update these state variables here.
    last_full_text_ = suggestion.text;
    last_user_text_.clear();
    last_verbatim_ = true;
    last_suggestion_ = InstantSuggestion();
    last_match_was_search_ = suggestion.type == INSTANT_SUGGESTION_SEARCH;
    browser_->SetInstantSuggestion(suggestion);
  } else {
    // Suggestion text should be a full URL for URL suggestions, or the
    // completion of a query for query suggestions.
    if (suggestion.type == INSTANT_SUGGESTION_URL) {
      // If the suggestion is not a valid URL, perhaps it's something like
      // "foo.com". Try prefixing "http://". If it still isn't valid, drop it.
      if (!GURL(suggestion.text).is_valid()) {
        suggestion.text.insert(0, ASCIIToUTF16("http://"));
        if (!GURL(suggestion.text).is_valid())
          suggestion = InstantSuggestion();
      }
    } else if (StartsWith(suggestion.text, last_user_text_, true)) {
      // The user typed an exact prefix of the suggestion.
      suggestion.text.erase(0, last_user_text_.size());
    } else if (!NormalizeAndStripPrefix(&suggestion.text, last_user_text_)) {
      // Unicode normalize and case-fold the user text and suggestion. If the
      // user text is a prefix, suggest the normalized, case-folded completion;
      // for instance, if the user types 'i' and the suggestion is 'INSTANT',
      // suggestion 'nstant'. Otherwise, the user text really isn't a prefix,
      // so suggest nothing.
      suggestion = InstantSuggestion();
    }

    last_suggestion_ = suggestion;

    // Set the suggested text if the suggestion behavior is
    // INSTANT_COMPLETE_NEVER irrespective of verbatim because in this case
    // the suggested text does not get committed if the user presses enter.
    if (suggestion.behavior == INSTANT_COMPLETE_NEVER || !last_verbatim_)
      browser_->SetInstantSuggestion(suggestion);
  }

  Show(INSTANT_SHOWN_QUERY_SUGGESTIONS, 100, INSTANT_SIZE_PERCENT);
}

void InstantController::CommitInstantLoader(InstantLoader* loader) {
  if (loader_ != loader ||
      model_.preview_state() != InstantModel::QUERY_RESULTS)
    return;

  CommitCurrentPreview(INSTANT_COMMIT_FOCUS_LOST);
}

void InstantController::ShowInstantPreview(InstantLoader* loader,
                                           InstantShownReason reason,
                                           int height,
                                           InstantSizeUnits units) {
  if (loader_ != loader || mode_ != EXTENDED)
    return;

  Show(reason, height, units);
}

void InstantController::InstantLoaderPreviewLoaded(InstantLoader* loader) {
  AddPreviewUsageForHistogram(mode_, PREVIEW_LOADED);
}

void InstantController::InstantSupportDetermined(InstantLoader* loader,
                                                 bool supports_instant) {
  if (supports_instant) {
    blacklisted_urls_.erase(loader->instant_url());
  } else {
    ++blacklisted_urls_[loader->instant_url()];
    if (loader_ == loader)
      DeleteLoader();
  }

  content::NotificationService::current()->Notify(
      chrome::NOTIFICATION_INSTANT_SUPPORT_DETERMINED,
      content::Source<InstantController>(this),
      content::NotificationService::NoDetails());
}

void InstantController::SwappedTabContents(InstantLoader* loader) {
  if (loader_ == loader)
    model_.SetPreviewContents(GetPreviewContents());
}

void InstantController::InstantLoaderContentsFocused(InstantLoader* loader) {
#if defined(USE_AURA)
  // On aura the omnibox only receives a focus lost if we initiate the focus
  // change. This does that.
  if (model_.preview_state() != InstantModel::NOT_READY)
    browser_->InstantPreviewFocused();
#endif
}

InstantController::InstantController(chrome::BrowserInstantController* browser,
                                     Mode mode)
    : browser_(browser),
      model_(ALLOW_THIS_IN_INITIALIZER_LIST(this)),
      mode_(mode),
      last_verbatim_(false),
      last_transition_type_(content::PAGE_TRANSITION_LINK),
      last_match_was_search_(false),
      loader_processed_last_update_(false),
      is_omnibox_focused_(false),
      active_tab_is_ntp_(false) {
}

void InstantController::ResetLoader(const std::string& instant_url,
                                    const TabContents* active_tab) {
  if (GetPreviewContents() && loader_->instant_url() != instant_url)
    DeleteLoader();

  if (!GetPreviewContents()) {
    loader_.reset(new InstantLoader(this, instant_url, active_tab));
    loader_->Init();

    // Ensure the searchbox API has the correct focus state and context.
    if (is_omnibox_focused_)
      loader_->OnAutocompleteGotFocus();
    else
      loader_->OnAutocompleteLostFocus();
    loader_->OnActiveTabModeChanged(active_tab_is_ntp_);

    AddPreviewUsageForHistogram(mode_, PREVIEW_CREATED);

    // Reset the loader timer.
    stale_loader_timer_.Stop();
    stale_loader_timer_.Start(
        FROM_HERE,
        base::TimeDelta::FromMilliseconds(kStaleLoaderTimeoutMS), this,
        &InstantController::OnStaleLoader);
  }
}

bool InstantController::CreateDefaultLoader() {
  const TabContents* active_tab = browser_->GetActiveTabContents();

  // We could get here with no active tab if the Browser is closing.
  if (!active_tab)
    return false;

  const TemplateURL* template_url =
      TemplateURLServiceFactory::GetForProfile(active_tab->profile())->
                                 GetDefaultSearchProvider();
  const GURL& tab_url = active_tab->web_contents()->GetURL();
  std::string instant_url;
  if (!GetInstantURL(template_url, tab_url, &instant_url))
    return false;

  ResetLoader(instant_url, active_tab);
  return true;
}

void InstantController::OnStaleLoader() {
  // If the loader is showing, do not delete it. It will get deleted the next
  // time the autocomplete loses focus.
  if (model_.preview_state() != InstantModel::NOT_READY)
    return;

  DeleteLoader();
  CreateDefaultLoader();
}

void InstantController::MaybeOnStaleLoader() {
  if (!stale_loader_timer_.IsRunning())
    OnStaleLoader();
}

void InstantController::DeleteLoader() {
  last_full_text_.clear();
  last_user_text_.clear();
  last_verbatim_ = false;
  last_suggestion_ = InstantSuggestion();
  last_match_was_search_ = false;
  loader_processed_last_update_ = false;
  last_omnibox_bounds_ = gfx::Rect();
  url_for_history_ = GURL();
  if (GetPreviewContents()) {
    AddPreviewUsageForHistogram(mode_, PREVIEW_DELETED);
    model_.SetPreviewState(InstantModel::NOT_READY, 0, INSTANT_SIZE_PERCENT);
  }
  // Schedule the deletion for later, since we may have gotten here from a call
  // within a |loader_| method (i.e., it's still on the stack). If we deleted
  // the loader immediately, things would still be fine so long as the caller
  // doesn't access any instance members after we return, but why rely on that?
  MessageLoop::current()->DeleteSoon(FROM_HERE, loader_.release());
}

void InstantController::Show(InstantShownReason reason,
                             int height,
                             InstantSizeUnits units) {
  // Must be on NTP to show NTP content.
  if (reason == INSTANT_SHOWN_CUSTOM_NTP_CONTENT && !active_tab_is_ntp_)
    return;

  // Must have updated omnibox after most recent Hide() to show suggestions.
  if (reason == INSTANT_SHOWN_QUERY_SUGGESTIONS &&
      model_.preview_state() == InstantModel::NOT_READY)
    return;

  if (model_.preview_state() == InstantModel::NOT_READY ||
      model_.preview_state() == InstantModel::AWAITING_SUGGESTIONS)
    AddPreviewUsageForHistogram(mode_, PREVIEW_SHOWED);
  model_.SetPreviewState(GetNewPreviewState(reason), height, units);
}

void InstantController::SendBoundsToPage() {
  if (last_omnibox_bounds_ == omnibox_bounds_ ||
      model_.preview_state() == InstantModel::NOT_READY ||
      !GetPreviewContents() || loader_->IsPointerDownFromActivate())
    return;

  last_omnibox_bounds_ = omnibox_bounds_;
  gfx::Rect preview_bounds = browser_->GetInstantBounds();
  gfx::Rect intersection = gfx::IntersectRects(omnibox_bounds_, preview_bounds);

  // Translate into window coordinates.
  if (!intersection.IsEmpty()) {
    intersection.Offset(-preview_bounds.origin().x(),
                        -preview_bounds.origin().y());
  }

  // In the current Chrome UI, these must always be true so they sanity check
  // the above operations. In a future UI, these may be removed or adjusted.
  // There is no point in sanity-checking |intersection.y()| because the omnibox
  // can be placed anywhere vertically relative to the preview (for example, in
  // Mac fullscreen mode, the omnibox is fully enclosed by the preview bounds).
  DCHECK_LE(0, intersection.x());
  DCHECK_LE(0, intersection.width());
  DCHECK_LE(0, intersection.height());

  loader_->SetOmniboxBounds(intersection);
}

bool InstantController::GetInstantURL(const TemplateURL* template_url,
                                      const GURL& tab_url,
                                      std::string* instant_url) const {
  CommandLine* command_line = CommandLine::ForCurrentProcess();
  if (command_line->HasSwitch(switches::kInstantURL)) {
    *instant_url = command_line->GetSwitchValueASCII(switches::kInstantURL);
    return template_url != NULL;
  }

  if (!template_url)
    return false;

  const TemplateURLRef& instant_url_ref = template_url->instant_url_ref();
  if (!instant_url_ref.IsValid())
    return false;

  // Even if the URL template doesn't have search terms, it may have other
  // components (such as {google:baseURL}) that need to be replaced.
  *instant_url = instant_url_ref.ReplaceSearchTerms(
      TemplateURLRef::SearchTermsArgs(string16()));

  // Extended mode should always use HTTPS. TODO(sreeram): This section can be
  // removed if TemplateURLs supported "https://{google:host}/..." instead of
  // only supporting "{google:baseURL}...".
  if (mode_ == EXTENDED) {
    GURL url_obj(*instant_url);
    if (!url_obj.is_valid())
      return false;

    if (!url_obj.SchemeIsSecure()) {
      const std::string new_scheme = "https";
      const std::string new_port = "443";
      GURL::Replacements secure;
      secure.SetSchemeStr(new_scheme);
      secure.SetPortStr(new_port);
      url_obj = url_obj.ReplaceComponents(secure);

      if (!url_obj.is_valid())
        return false;

      *instant_url = url_obj.spec();
    }
  }

  std::map<std::string, int>::const_iterator iter =
      blacklisted_urls_.find(*instant_url);
  if (iter != blacklisted_urls_.end() &&
      iter->second > kMaxInstantSupportFailures)
    return false;

  return true;
}