Add ContentSuggestionsService

components/ntp_snippets/content_suggestions_service.cc

Index: components/ntp_snippets/content_suggestions_service.cc
diff --git a/components/ntp_snippets/content_suggestions_service.cc b/components/ntp_snippets/content_suggestions_service.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5b86d95762303e6662ad7e1569dad31efca147f0
--- /dev/null
+++ b/components/ntp_snippets/content_suggestions_service.cc
@@ -0,0 +1,207 @@
+// Copyright 2016 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/ntp_snippets/content_suggestions_service.h"
+
+#include <algorithm>
+#include <iterator>
+
+#include "base/bind.h"
+#include "base/strings/string_number_conversions.h"
+#include "ui/gfx/image/image.h"
+
+namespace ntp_snippets {
+
+ContentSuggestionsService::ContentSuggestionsService(State state)
+    : state_(state) {}
+
+ContentSuggestionsService::~ContentSuggestionsService() {}
+
+void ContentSuggestionsService::Shutdown() {
+  DCHECK(providers_.empty());
+  DCHECK(categories_.empty());
+  DCHECK(suggestions_by_category_.empty());
+  DCHECK(id_category_map_.empty());
+  state_ = State::DISABLED;
+  FOR_EACH_OBSERVER(Observer, observers_, ContentSuggestionsServiceShutdown());
+}
+
+ContentSuggestionsCategoryStatus ContentSuggestionsService::GetCategoryStatus(
+    ContentSuggestionsCategory category) const {
+  if (state_ == State::DISABLED) {
+    return ContentSuggestionsCategoryStatus::
+        ALL_SUGGESTIONS_EXPLICITLY_DISABLED;
+  }
+
+  auto iterator = providers_.find(category);
+  if (iterator == providers_.end())
+    return ContentSuggestionsCategoryStatus::NOT_PROVIDED;
+
+  return iterator->second->GetCategoryStatus(category);
+}
+
+const std::vector<ContentSuggestion>&
+ContentSuggestionsService::GetSuggestionsForCategory(
+    ContentSuggestionsCategory category) const {
+  auto iterator = suggestions_by_category_.find(category);
+  if (iterator == suggestions_by_category_.end())
+    return no_suggestions_;
+  return iterator->second;
+}
+
+void ContentSuggestionsService::FetchSuggestionImage(
+    const std::string& suggestion_id,
+    const ImageFetchedCallback& callback) {
+  if (!id_category_map_.count(suggestion_id)) {
+    LOG(WARNING) << "Requested image for unknown suggestion " << suggestion_id;
+    callback.Run(suggestion_id, gfx::Image());
+    return;
+  }
+  ContentSuggestionsCategory category = id_category_map_[suggestion_id];
+  if (!providers_.count(category)) {
+    LOG(WARNING) << "Requested image for suggestion " << suggestion_id
+                 << " for unavailable category " << int(category);
+    callback.Run(suggestion_id, gfx::Image());
+    return;
+  }
+  providers_[category]->FetchSuggestionImage(suggestion_id, callback);
+}
+
+void ContentSuggestionsService::ClearCachedSuggestionsForDebugging() {
+  suggestions_by_category_.clear();
+  id_category_map_.clear();
+  for (auto& category_provider_pair : providers_) {
+    category_provider_pair.second->ClearCachedSuggestionsForDebugging();
+  }
+  FOR_EACH_OBSERVER(Observer, observers_, OnNewSuggestions());
+}
+
+void ContentSuggestionsService::ClearDiscardedSuggestionsForDebugging() {
+  for (auto& category_provider_pair : providers_) {
+    category_provider_pair.second->ClearDiscardedSuggestionsForDebugging();
+  }
+}
+
+void ContentSuggestionsService::DiscardSuggestion(
+    const std::string& suggestion_id) {
+  if (!id_category_map_.count(suggestion_id)) {
+    LOG(WARNING) << "Discarded unknown suggestion " << suggestion_id;
+    return;
+  }
+  ContentSuggestionsCategory category = id_category_map_[suggestion_id];
+  if (!providers_.count(category)) {
+    LOG(WARNING) << "Discarded suggestion " << suggestion_id
+                 << " for unavailable category " << int(category);
+    return;
+  }
+  providers_[category]->DiscardSuggestion(suggestion_id);
+
+  // Remove the suggestion locally.
+  id_category_map_.erase(suggestion_id);
+  std::vector<ContentSuggestion>* suggestions =
+      &suggestions_by_category_[category];
+  auto position =
+      std::find_if(suggestions->begin(), suggestions->end(),
+                   [&suggestion_id](const ContentSuggestion& suggestion) {
+                     return suggestion_id == suggestion.id();
+                   });
+  DCHECK(position != suggestions->end());
+  suggestions->erase(position);
+}
+
+void ContentSuggestionsService::AddObserver(Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void ContentSuggestionsService::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void ContentSuggestionsService::RegisterProvider(
+    ContentSuggestionsProvider* provider) {
+  // TODO(pke): When NTPSnippetsService is purely a provider, think about
+  // removing this state check.
+  if (state_ == State::DISABLED)
+    return;
+
+  for (ContentSuggestionsCategory category : provider->provided_categories()) {
+    DCHECK_EQ(0ul, providers_.count(category));
+    providers_[category] = provider;
+    // TODO(pke): In the future, make sure that the categories have some useful
+    // (maybe constant, at least consistent) ordering for the UI.
+    categories_.push_back(category);
+    if (IsContentSuggestionsCategoryStatusAvailable(
+            provider->GetCategoryStatus(category))) {
+      suggestions_by_category_[category] = std::vector<ContentSuggestion>();
+    }
+    NotifyCategoryStatusChanged(category);
+  }
+  provider->SetObserver(this);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Private methods
+
+void ContentSuggestionsService::OnNewSuggestions(
+    ContentSuggestionsCategory changed_category,
+    std::vector<ContentSuggestion> new_suggestions) {
+  DCHECK(IsCategoryRegistered(changed_category));
+
+  for (const ContentSuggestion& suggestion :
+       suggestions_by_category_[changed_category]) {
+    id_category_map_.erase(suggestion.id());
+  }
+
+  for (const ContentSuggestion& suggestion : new_suggestions) {
+    id_category_map_[suggestion.id()] = changed_category;
+  }
+
+  suggestions_by_category_[changed_category] = std::move(new_suggestions);
+
+  FOR_EACH_OBSERVER(Observer, observers_, OnNewSuggestions());
+}
+
+void ContentSuggestionsService::OnCategoryStatusChanged(
+    ContentSuggestionsCategory changed_category,
+    ContentSuggestionsCategoryStatus new_status) {
+  if (!IsContentSuggestionsCategoryStatusAvailable(new_status)) {
+    for (const ContentSuggestion& suggestion :
+         suggestions_by_category_[changed_category]) {
+      id_category_map_.erase(suggestion.id());
+    }
+    suggestions_by_category_.erase(changed_category);
+  }
+  NotifyCategoryStatusChanged(changed_category);
+}
+
+void ContentSuggestionsService::OnProviderShutdown(
+    ContentSuggestionsProvider* provider) {
+  for (ContentSuggestionsCategory category : provider->provided_categories()) {
+    auto iterator = std::find(categories_.begin(), categories_.end(), category);
+    DCHECK(iterator != categories_.end());
+    categories_.erase(iterator);
+    for (const ContentSuggestion& suggestion :
+         suggestions_by_category_[category]) {
+      id_category_map_.erase(suggestion.id());
+    }
+    suggestions_by_category_.erase(category);
+    providers_.erase(category);
+    NotifyCategoryStatusChanged(category);
+  }
+}
+
+bool ContentSuggestionsService::IsCategoryRegistered(
+    ContentSuggestionsCategory category) const {
+  return std::find(categories_.begin(), categories_.end(), category) !=
+         categories_.end();
+}
+
+void ContentSuggestionsService::NotifyCategoryStatusChanged(
+    ContentSuggestionsCategory category) {
+  FOR_EACH_OBSERVER(
+      Observer, observers_,
+      OnCategoryStatusChanged(category, GetCategoryStatus(category)));
+}
+
+}  // namespace ntp_snippets