Experimental AutocompleteProvider for zerosuggest.

chrome/browser/autocomplete/zerosuggest_provider.cc

+// 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/autocomplete/zerosuggest_provider.h"
+
+#include "base/callback.h"
+#include "base/i18n/icu_string_conversions.h"
+#include "base/json/json_string_value_serializer.h"
+#include "base/string16.h"
+#include "base/string_util.h"
+#include "base/time.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/browser/autocomplete/autocomplete_input.h"
+#include "chrome/browser/autocomplete/autocomplete_match.h"
+#include "chrome/browser/autocomplete/autocomplete_provider_listener.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/search_engines/template_url_service.h"
+#include "chrome/browser/search_engines/template_url_service_factory.h"
+#include "chrome/common/url_constants.h"
+#include "googleurl/src/gurl.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_response_headers.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_request_status.h"
+
+ZerosuggestProvider::ZerosuggestProvider(
+  AutocompleteProviderListener* listener,
+  Profile* profile,
+  const std::string& url_prefix)
+    : AutocompleteProvider(listener, profile, "Zerosuggest"),
+      url_prefix_(url_prefix),
+      template_url_service_(TemplateURLServiceFactory::GetForProfile(profile)) {
+}
+
+void ZerosuggestProvider::Start(const AutocompleteInput& input,
+                                bool /*minimal_changes*/) {
+  UpdateMatches(input.text());
+}
+
+void ZerosuggestProvider::StartZerosuggest(
+    const GURL& url,
+    const string16& user_text) {
+  const std::string& spec = url.possibly_invalid_spec();
+  if (spec.empty() || url.scheme() != chrome::kHttpScheme)

[samarth, 2012/08/13 17:42:37]

You should also consider checking the scheme for url_prefix and only sending
requests over HTTPS.

[Jered, 2012/08/13 22:23:59]

I'm not sure we need that for testing. Seems like it'd confuse us but not have
much security benefit.

+    // Do not query empty URLs nor non-http URLs. There will be no useful
+    // suggestions for https or chrome URLs.
+    return;
+  matches_.clear();
+  done_ = false;
+  user_text_ = user_text;
+  current_query_ = spec;
+  current_query_text_ = ASCIIToUTF16(spec);
+  Run();
+}
+
+void ZerosuggestProvider::Stop(bool clear_cached_results) {
+  fetcher_.reset();
+  done_ = true;
+  if (clear_cached_results) {
+    results_.clear();
+    current_query_.clear();
+    current_query_text_.clear();
+  }
+}
+
+void ZerosuggestProvider::OnURLFetchComplete(const net::URLFetcher* source) {
+  const net::HttpResponseHeaders* const response_headers =
+      source->GetResponseHeaders();
+  std::string json_data;
+  source->GetResponseAsString(&json_data);
+  if (response_headers) {
+    std::string charset;
+    if (response_headers->GetCharset(&charset)) {
+      string16 data_16;
+      if (base::CodepageToUTF16(json_data, charset.c_str(),
+                                base::OnStringConversionError::FAIL,
+                                &data_16))
+        json_data = UTF16ToUTF8(data_16);
+    }
+  }
+  const bool request_succeeded =

[samarth, 2012/08/13 17:42:37]

If json_data is empty at this point, do we still consider request to have
succeeded?

[Jered, 2012/08/13 22:23:59]

Yep, but results_updated will be true only if the json parses (it won't if it's
empty). This is mostly ripped off from SearchProvider.

+      source->GetStatus().is_success() && source->GetResponseCode() == 200;
+
+  bool results_updated = false;
+  if (request_succeeded) {
+    JSONStringValueSerializer deserializer(json_data);
+    deserializer.set_allow_trailing_comma(true);
+    scoped_ptr<Value> data(deserializer.Deserialize(NULL, NULL));
+    results_updated = data.get() && ParseSuggestResults(data.get());
+  }
+  done_ = true;
+
+  ConvertResultsToAutocompleteMatches();
+  if (results_updated)
+    listener_->OnProviderUpdate(results_updated);
+}
+
+ZerosuggestProvider::~ZerosuggestProvider() {
+}
+
+void ZerosuggestProvider::Run() {
+  const int kFetcherID = 1;
+  fetcher_.reset(
+      net::URLFetcher::Create(kFetcherID,
+          GURL(url_prefix_ + current_query_),
+          net::URLFetcher::GET, this));
+  fetcher_->SetRequestContext(profile_->GetRequestContext());
+  fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SAVE_COOKIES);
+  fetcher_->Start();
+}
+
+void ZerosuggestProvider::UpdateMatches(const string16& user_text) {
+  user_text_ = user_text;
+  const size_t prev_num_matches = matches_.size();
+  ConvertResultsToAutocompleteMatches();
+  if (matches_.size() != prev_num_matches)
+    listener_->OnProviderUpdate(true);
+}
+
+bool ZerosuggestProvider::ParseSuggestResults(Value* root_val) {
+  std::string query;
+  ListValue* root_list = NULL;
+  ListValue* results = NULL;
+  if (!root_val->GetAsList(&root_list) || !root_list->GetString(0, &query) ||
+      (query != current_query_) || !root_list->GetList(1, &results))
+    return false;
+
+  results_.clear();
+  ListValue* one_result = NULL;
+  for (size_t index = 0; results->GetList(index, &one_result); ++index) {
+    string16 result;
+    one_result->GetString(0, &result);
+    if (result.empty())
+      continue;
+    results_.push_back(result);
+  }
+
+  return true;
+}
+
+void ZerosuggestProvider::ConvertResultsToAutocompleteMatches() {
+  const TemplateURL* search_provider =
+      template_url_service_->GetDefaultSearchProvider();
+  if (search_provider == NULL || !search_provider->SupportsReplacement())
+    // Fail if we can't set the clickthrough URL for query suggestions.
+    return;
+  matches_.clear();
+  if (results_.empty())
+    // Do not add anything if there are no results for this URL.
+    return;
+  AddMatchForCurrentURL();
+  for (size_t i = 0; i < results_.size(); ++i)
+    AddMatchForResult(search_provider, i, results_[i]);
+}
+
+// TODO(jered): Rip this out once the first match is decoupled from the current
+// typing in the omnibox.
+void ZerosuggestProvider::AddMatchForCurrentURL() {
+  // If the user has typed something besides the current url, they probably
+  // don't intend to refresh it.
+  const bool user_text_is_url = user_text_ == current_query_text_;
+  if (user_text_.empty() || user_text_is_url) {
+    AutocompleteMatch match(this, 2000, false,

[samarth, 2012/08/13 17:42:37]

Make 2000 a constant, and add TODO about getting scores from the backend.

[Jered, 2012/08/13 22:23:59]

Done. I added a comment about why 2000 here, and added a TODO for the other
relevance magic number below.

+                            AutocompleteMatch::SEARCH_ZEROSUGGEST_URL);
+    match.destination_url = GURL(current_query_);
+    match.contents = current_query_text_;
+    if (!user_text_is_url) {
+      match.fill_into_edit = current_query_text_;
+      match.inline_autocomplete_offset = 0;
+    }
+    AutocompleteMatch::ClassifyLocationInString(0, current_query_.size(),
+        match.contents.length(), ACMatchClassification::URL,
+        &match.contents_class);
+    matches_.push_back(match);
+  }
+}
+
+void ZerosuggestProvider::AddMatchForResult(
+    const TemplateURL* search_provider,
+    size_t result_index,
+    const string16& result) {
+  // TODO(jered): Rip out user_text_is_url logic when AddMatchForCurrentURL goes.

[samarth, 2012/08/13 17:42:37]

nit: long line

[Jered, 2012/08/13 22:23:59]

Done.

+  const bool user_text_is_url = user_text_ == current_query_text_;
+  const bool kCaseInsensitve = false;
+  if (!user_text_.empty() && !user_text_is_url &&
+      !StartsWith(result, user_text_, kCaseInsensitve))
+    // This suggestion isn't relevant for the current prefix.
+    return;
+  const int kRelevance = 1999;
+  AutocompleteMatch match(this, kRelevance, false,
+      AutocompleteMatch::SEARCH_ZEROSUGGEST);
+  match.contents = result;
+  match.fill_into_edit = result;
+  if (!user_text_is_url && user_text_ != result)
+    match.inline_autocomplete_offset = user_text_.length();
+
+  // Build a URL for this query using the default search provider.
+  const TemplateURLRef& search_url = search_provider->url_ref();
+  DCHECK(search_url.SupportsReplacement());
+  match.search_terms_args.reset(
+      new TemplateURLRef::SearchTermsArgs(result));
+  match.search_terms_args->original_query = string16();
+  match.search_terms_args->accepted_suggestion = result_index;
+  match.destination_url =
+      GURL(search_url.ReplaceSearchTerms(*match.search_terms_args.get()));
+
+  if (user_text_.empty() || user_text_is_url || user_text_ == result) {
+    match.contents_class.push_back(
+        ACMatchClassification(0, ACMatchClassification::NONE));
+  } else {
+    // Style to look like normal search suggestions.
+    match.contents_class.push_back(
+       ACMatchClassification(0, ACMatchClassification::DIM));
+    match.contents_class.push_back(
+       ACMatchClassification(user_text_.length(), ACMatchClassification::NONE));
+  }
+  match.transition = content::PAGE_TRANSITION_GENERATED;
+
+  matches_.push_back(match);
+}