Introduce a Doodle Fetcher for NTP

components/doodle/doodle_fetcher.cc

Index: components/doodle/doodle_fetcher.cc
diff --git a/components/doodle/doodle_fetcher.cc b/components/doodle/doodle_fetcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..96a74cd3ff3735fc5b00c0a62136287ca243e58d
--- /dev/null
+++ b/components/doodle/doodle_fetcher.cc
@@ -0,0 +1,238 @@
+// Copyright 2017 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 "components/doodle/doodle_fetcher.h"
+
+#include <utility>
+
+#include "base/strings/string_number_conversions.h"
+#include "base/time/clock.h"
+#include "base/time/default_clock.h"
+#include "base/time/time.h"
+#include "base/values.h"
+#include "components/safe_json/safe_json_parser.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_status_code.h"
+#include "net/url_request/url_fetcher.h"
+#include "url/gurl.h"
+
+using net::URLFetcher;
+
+namespace doodle {
+
+const char kDoodleConfigUrl[] = "/async/ddljson?ogdeb=ct~2000000007";
+
+namespace {
+
+void ParseJson(
+    const std::string& json,
+    const base::Callback<void(std::unique_ptr<base::Value>)>& success_callback,
+    const base::Callback<void(const std::string&)>& error_callback) {
+  // The response may start with )]}'. Ignore this.
+  const char kResponsePreamble[] = ")]}'";
+
+  base::StringPiece json_sp(json);
+  if (json_sp.starts_with(kResponsePreamble)) {
+    json_sp.remove_prefix(strlen(kResponsePreamble));
+  }
+
+  safe_json::SafeJsonParser::Parse(json_sp.as_string(), success_callback,
+                                   error_callback);
+}
+
+DoodleType ParseDoodleType(const base::DictionaryValue* ddljson) {
+  std::string type_str;
+  ddljson->GetString("doodle_type", &type_str);
+  if (type_str == "SIMPLE") {
+    return DoodleType::SIMPLE;
+  }
+  if (type_str == "RANDOM") {
+    return DoodleType::RANDOM;
+  }
+  if (type_str == "VIDEO") {
+    return DoodleType::VIDEO;
+  }
+  if (type_str == "INTERACTIVE") {
+    return DoodleType::INTERACTIVE;
+  }
+  if (type_str == "INLINE_INTERACTIVE") {
+    return DoodleType::INLINE_INTERACTIVE;
+  }
+  if (type_str == "SLIDESHOW") {
+    return DoodleType::SLIDESHOW;
+  }
+  return DoodleType::SIMPLE;
+}
+
+}  // namespace
+
+DoodleImage::DoodleImage()
+    : height(0),
+      width(0),
+      background_color("#ffffff"),
+      is_animated_gif(false),
+      is_cta(false) {}
+DoodleImage::DoodleImage(const DoodleImage& image) = default;
+DoodleImage::~DoodleImage() = default;
+
+DoodleConfig::DoodleConfig(DoodleState doodle_state)
+    : state(doodle_state),
+      doodle_type(DoodleType::SIMPLE),
+      expiry_date(base::Time::Now()) {}
+DoodleConfig::~DoodleConfig() = default;
+DoodleConfig::DoodleConfig(const DoodleConfig& config) = default;
+
+DoodleFetcher::DoodleFetcher(net::URLRequestContextGetter* download_context,
+                             GURL base_url)
+    : DoodleFetcher(download_context, base_url, base::Bind(ParseJson)) {}
+
+DoodleFetcher::DoodleFetcher(net::URLRequestContextGetter* download_context,
+                             GURL base_url,
+                             ParseJSONCallback json_parsing_callback)
+    : download_context_(download_context),
+      json_parsing_callback_(json_parsing_callback),
+      base_url_(base_url),
+      clock_(new base::DefaultClock()),
+      weak_ptr_factory_(this) {}
+
+DoodleFetcher::~DoodleFetcher() {}
+
+void DoodleFetcher::FetchDoodle(FinishedCallback callback) {
+  callback_lock_.Acquire();

[Marc Treib, 2017/02/01 10:55:58]

Is this required? I don't see why we would ever use one DoodleFetcher instance
on multiple threads - with very few exceptions, we generally don't share objects
across threads in Chromium.

[fhorschig, 2017/02/01 11:16:13]

Removed.

+  callbacks_.push_back(std::move(callback));
+  if (callbacks_.size() > 1) {
+    callback_lock_.Release();
+    return;  // With 2 or more callbacks, a fetcher is already running.
+  }
+  callback_lock_.Release();
+  fetcher_ = URLFetcher::Create(base_url_.Resolve(kDoodleConfigUrl),
+                                URLFetcher::GET, this);
+  fetcher_->SetRequestContext(download_context_);
+  fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
+                         net::LOAD_DO_NOT_SAVE_COOKIES);
+  fetcher_->SetAutomaticallyRetryOnNetworkChanges(1);
+  fetcher_->Start();
+}
+
+// net::URLFetcherDelegate implementation.
+void DoodleFetcher::OnURLFetchComplete(const net::URLFetcher* source) {
+  DCHECK_EQ(fetcher_.get(), source);
+  std::unique_ptr<net::URLFetcher> free_fetcher = std::move(fetcher_);
+
+  std::string json_string;
+  if (!(source->GetStatus().is_success() &&
+        source->GetResponseCode() == net::HTTP_OK &&
+        source->GetResponseAsString(&json_string))) {
+    RespondToAllCallbacks(DoodleConfig(DoodleState::DOWNLOAD_ERROR));
+    return;
+  }
+
+  ParseJson(json_string, base::Bind(&DoodleFetcher::OnJsonParsed,
+                                    weak_ptr_factory_.GetWeakPtr()),
+            base::Bind(&DoodleFetcher::OnJsonParseFailed,
+                       weak_ptr_factory_.GetWeakPtr()));
+}
+
+// ParseJSONCallback Success callback
+void DoodleFetcher::OnJsonParsed(std::unique_ptr<base::Value> json) {
+  std::unique_ptr<base::DictionaryValue> dict =
+      base::DictionaryValue::From(std::move(json));
+  if (!dict.get()) {
+    LOG(ERROR) << "Doodle JSON is not valid";
+    RespondToAllCallbacks(DoodleConfig(DoodleState::PARSING_ERROR));
+    return;
+  }
+
+  ParseDoodle(std::move(dict));
+}
+
+// ParseJSONCallback Failure callback
+void DoodleFetcher::OnJsonParseFailed(const std::string& error_message) {
+  LOG(ERROR) << "JSON parsing failed: " << error_message;
+  RespondToAllCallbacks(DoodleConfig(DoodleState::PARSING_ERROR));
+}
+
+void DoodleFetcher::ParseDoodle(std::unique_ptr<base::DictionaryValue> config) {
+  const base::DictionaryValue* ddljson = nullptr;
+  if (!config->GetDictionary("ddljson", &ddljson)) {
+    LOG(ERROR) << "Doodle JSON reponse did not contain 'ddljson' key.";
+    RespondToAllCallbacks(DoodleConfig(DoodleState::PARSING_ERROR));
+    return;
+  }
+
+  DoodleConfig result(DoodleState::AVAILABLE);
+  ParseBaseInformation(ddljson, &result);
+
+  if (!ParseImage(ddljson, "large_image", &result.large_image)) {
+    RespondToAllCallbacks(DoodleConfig(DoodleState::NO_DOODLE));
+    return;
+  }
+  ParseImage(ddljson, "transparent_large_image",
+             &result.transparent_large_image);
+  ParseImage(ddljson, "hires_image", &result.hires_image);
+  ParseImage(ddljson, "medium_image", &result.medium_image);
+  ParseImage(ddljson, "small_image", &result.small_image);
+
+  RespondToAllCallbacks(std::move(result));
+}
+
+bool DoodleFetcher::ParseImage(const base::DictionaryValue* image_parent,
+                               const std::string& image_name,
+                               DoodleImage* image) const {
+  DCHECK(image);
+  const base::DictionaryValue* image_dict = nullptr;
+  if (!(image && image_parent &&
+        image_parent->GetDictionary(image_name, &image_dict))) {
+    return false;
+  }
+  std::string url;
+  image_dict->GetString("url", &url);
+  image->url = base_url_.Resolve(url);
+  image_dict->GetString("background_color", &image->background_color);
+  image_dict->GetInteger("height", &image->height);
+  image_dict->GetInteger("width", &image->width);
+  image_dict->GetBoolean("is_animated_gif", &image->is_animated_gif);
+  image_dict->GetBoolean("is_cta", &image->is_cta);
+  return true;
+}
+
+void DoodleFetcher::ParseBaseInformation(const base::DictionaryValue* ddljson,
+                                         DoodleConfig* config) const {
+  ParseRelativeUrl(ddljson, "search_url", &config->search_url);
+  ParseRelativeUrl(ddljson, "target_url", &config->target_url);
+  ParseRelativeUrl(ddljson, "fullpage_interactive_url",
+                   &config->fullpage_interactive_url);
+
+  config->doodle_type = ParseDoodleType(ddljson);
+  ddljson->GetString("alt_text", &config->alt_text);
+
+  // TODO(fhorschig): Inject TickClock and test that.
+  // The JSON doesn't garantuee the number to fit into an int.
+  double ttl;
+  ddljson->GetDouble("time_to_live_ms", &ttl);
+  config->expiry_date = clock_->Now() + base::TimeDelta::FromMillisecondsD(ttl);
+}
+
+void DoodleFetcher::ParseRelativeUrl(const base::DictionaryValue* dict_value,
+                                     const std::string& key,
+                                     GURL* url) const {
+  std::string str_url;
+  dict_value->GetString(key, &str_url);
+  if (str_url.empty()) {
+    *url = GURL();
+  } else {
+    *url = base_url_.Resolve(str_url);
+  }
+}
+
+void DoodleFetcher::RespondToAllCallbacks(const DoodleConfig& response) {
+  callback_lock_.Acquire();
+  while (!callbacks_.empty()) {
+    std::move(callbacks_.front()).Run(response);
+    callbacks_.pop_front();
+  }
+  callback_lock_.Release();
+}
+
+}  // namespace doodle