Implement first version of OfflinePageSuggestionsProvider

components/ntp_snippets/offline_pages/offline_page_suggestions_provider.cc

+// 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/offline_pages/offline_page_suggestions_provider.h"
+
+#include "base/bind.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
+
+using offline_pages::MultipleOfflinePageItemResult;
+using offline_pages::OfflinePageModel;
+using offline_pages::OfflinePageItem;
+
+namespace ntp_snippets {
+
+OfflinePageSuggestionsProvider::OfflinePageSuggestionsProvider(
+    OfflinePageModel* offline_page_model)
+    : ContentSuggestionsProvider({ContentSuggestionsCategory::OFFLINE_PAGES}),
+      category_status_(ContentSuggestionsCategoryStatus::AVAILABLE_LOADING),
+      observer_(nullptr),
+      offline_page_model_(offline_page_model) {
+  offline_page_model_->AddObserver(this);
+}
+
+OfflinePageSuggestionsProvider::~OfflinePageSuggestionsProvider() {}
+
+// Inherited from KeyedService.
+void OfflinePageSuggestionsProvider::Shutdown() {
+  offline_page_model_->RemoveObserver(this);
+  category_status_ = ContentSuggestionsCategoryStatus::NOT_PROVIDED;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Private methods
+
+void OfflinePageSuggestionsProvider::SetObserver(
+    ContentSuggestionsProvider::Observer* observer) {
+  observer_ = observer;
+  if (observer) {

[Bernhard Bauer, 2016/07/14 18:47:43]

Nit: no braces for single-line bodies.

[Philipp Keck, 2016/07/15 09:08:42]

Done.

+    FetchOfflinePages();
+  }
+}
+
+ContentSuggestionsCategoryStatus
+OfflinePageSuggestionsProvider::GetCategoryStatus(
+    ContentSuggestionsCategory category) {
+  return category_status_;
+}
+
+void OfflinePageSuggestionsProvider::DiscardSuggestion(
+    const std::string& suggestion_id) {
+  // TODO(pke): Implement some "dont show on NTP anymore" behaviour,
+  // then also implement ClearDiscardedSuggestionsForDebugging.
+}
+
+void OfflinePageSuggestionsProvider::FetchSuggestionImage(
+    const std::string& suggestion_id,
+    const ImageFetchedCallback& callback) {
+  // TODO(pke): Implement

[dewittj, 2016/07/14 18:13:28]

Nit: Implement.

[Philipp Keck, 2016/07/15 09:08:42]

Done.

+}
+
+void OfflinePageSuggestionsProvider::ClearCachedSuggestionsForDebugging() {
+  // Ignore

[dewittj, 2016/07/14 18:13:29]

Nit: Ignored.

[Philipp Keck, 2016/07/15 09:08:42]

Done.

+}
+
+void OfflinePageSuggestionsProvider::ClearDiscardedSuggestionsForDebugging() {
+  // Ignore

[dewittj, 2016/07/14 18:13:28]

Ignored.

Or possibly put a TODO(pke): Implement when discarded suggestions are supported.

[Philipp Keck, 2016/07/15 09:08:42]

Done.

+}
+
+void OfflinePageSuggestionsProvider::OfflinePageModelLoaded(
+    OfflinePageModel* model) {
+  DCHECK_EQ(model, offline_page_model_);

[Bernhard Bauer, 2016/07/14 18:47:44]

Expected value goes first, for nicer error messages in case of failure.

[Philipp Keck, 2016/07/15 09:08:42]

I know. Depends on whether you expect "ours" to be "theirs" or "theirs" to be
"ours". So you could ask "Is the passed parameter valid?" (but that's
unnecessary since we never use it anyway) or you could ask "Is our stored model
still up to date?".

I swapped it now.

+  // Ignore (when offline pages have been loaded, OnOfflinePagesLoaded will be
+  // called as a delayed callback, see ctor).

[dewittj, 2016/07/14 18:13:28]

This comment seems out of date, there's nothing in the constructor that makes it
clear that SetObserver will asynchronous fetch the pages after load.

I think this comment could be just deleted.

[Philipp Keck, 2016/07/15 09:08:42]

Done.

+}
+
+void OfflinePageSuggestionsProvider::OfflinePageModelChanged(
+    OfflinePageModel* model) {
+  DCHECK_EQ(model, offline_page_model_);
+  FetchOfflinePages();

[dewittj, 2016/07/14 18:13:28]

This is probably the best we can do for now, but seems like a lot of work to do
on every change (this will happen on every single navigation.)

[Philipp Keck, 2016/07/15 09:08:42]

The OfflinePageModel currently does not have a OfflinePageAdded event. Actually,
we are discussing these fine-grained events (added, changed, removed) instead of
the overall "something changed, reload everything" because the UI might want
such fine-grained updates for nicer animations, etc. So far, we haven't
considered the performance aspect of this.

+}
+
+void OfflinePageSuggestionsProvider::OfflinePageDeleted(
+    int64_t offline_id,
+    const offline_pages::ClientId& client_id) {
+  // TODO(pke): Implement, suggestion has to be removed from UI immediately.
+}
+
+void OfflinePageSuggestionsProvider::FetchOfflinePages() {
+  offline_page_model_->GetAllPages(
+      base::Bind(&OfflinePageSuggestionsProvider::OnOfflinePagesLoaded,
+                 base::Unretained(this)));
+}
+
+void OfflinePageSuggestionsProvider::OnOfflinePagesLoaded(
+    const MultipleOfflinePageItemResult& result) {
+  if (!observer_) {
+    category_status_ = ContentSuggestionsCategoryStatus::AVAILABLE;
+    return;
+  }
+
+  if (category_status_ != ContentSuggestionsCategoryStatus::AVAILABLE) {
+    category_status_ = ContentSuggestionsCategoryStatus::AVAILABLE;
+    observer_->OnCategoryStatusChanged(
+        ContentSuggestionsCategory::OFFLINE_PAGES, category_status_);
+  }
+
+  std::vector<ContentSuggestion> suggestions;
+  for (const OfflinePageItem& item : result) {
+    ContentSuggestion suggestion(
+        MakeUniqueID(ContentSuggestionsCategory::OFFLINE_PAGES,
+                     base::IntToString(item.offline_id)),
+        item.GetOfflineURL());
+
+    // TODO(pke): Sort my most recently visited and only keep the top one of
+    // multiple entries for the same URL.
+    // TODO(pke): Get more reasonable data from the OfflinePageModel here.
+    suggestion.set_title(item.url.spec());
+    suggestion.set_snippet_text(std::string());
+    suggestion.set_publish_date(item.creation_time);
+    suggestion.set_publisher_name(item.url.host());
+    suggestions.emplace_back(std::move(suggestion));
+  }
+
+  observer_->OnNewSuggestions(ContentSuggestionsCategory::OFFLINE_PAGES,
+                              std::move(suggestions));
+}
+
+}  // namespace ntp_snippets