[NTPSnippets] Show all downloads on the NTP (3/3): Downloads provider.

components/ntp_snippets/downloads/download_suggestions_provider.cc

Index: components/ntp_snippets/downloads/download_suggestions_provider.cc
diff --git a/components/ntp_snippets/downloads/download_suggestions_provider.cc b/components/ntp_snippets/downloads/download_suggestions_provider.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3649b4937e66a066025e53ecdb3cf3cb6664b99b
--- /dev/null
+++ b/components/ntp_snippets/downloads/download_suggestions_provider.cc
@@ -0,0 +1,487 @@
+// 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/downloads/download_suggestions_provider.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "base/bind.h"
+#include "base/guid.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "components/ntp_snippets/pref_names.h"
+#include "components/ntp_snippets/pref_util.h"
+#include "components/offline_pages/client_namespace_constants.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+#include "grit/components_strings.h"
+#include "net/base/filename_util.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/image/image.h"
+
+using content::DownloadItem;
+using content::DownloadManager;
+using offline_pages::OfflinePageItem;
+
+namespace ntp_snippets {
+
+namespace {
+
+const int kMaxSuggestionsCount = 5;
+const char kDownloadsPrefix[] = "D";
+const char kOfflinePagesPrefix[] = "O";
+
+std::string GetOfflinePagePerCategoryID(int64_t raw_offline_page_id) {
+  // Raw ID is prefixed in order to avoid conflicts with Downloads.
+  return base::JoinString(
+      {kOfflinePagesPrefix, base::IntToString(raw_offline_page_id)}, "");
+}
+
+std::string GetAssetDownloadPerCategoryID(uint32_t raw_download_id) {
+  // Raw ID is prefixed in order to avoid conflicts with OfflinePages.
+  return base::JoinString(
+      {kDownloadsPrefix, base::UintToString(raw_download_id)}, "");
+}
+
+bool IsOfflinePageID(const std::string& within_category_id) {
+  if (!within_category_id.empty()) {
+    if (within_category_id[0] == kOfflinePagesPrefix[0])
+      return true;
+    if (within_category_id[0] == kDownloadsPrefix[0])
+      return false;
+  }
+  NOTREACHED() << "Unknown within_category_id " << within_category_id;
+  return false;
+}
+
+struct OrderOfflinePagesByMostRecentlyVisitedFirst {
+  bool operator()(const OfflinePageItem* left,
+                  const OfflinePageItem* right) const {
+    return left->last_access_time > right->last_access_time;
+  }
+};
+
+bool IsOfflinePageDownload(const offline_pages::ClientId& client_id) {
+  return (client_id.name_space == offline_pages::kAsyncNamespace ||
+          client_id.name_space == offline_pages::kDownloadNamespace ||
+          client_id.name_space == offline_pages::kNTPSuggestionsNamespace) &&
+         base::IsValidGUID(client_id.id);
+}
+
+bool IsDownloadCompleted(const DownloadItem* item) {
+  return item->GetState() == content::DownloadItem::DownloadState::COMPLETE &&
+         !item->GetFileExternallyRemoved();
+}
+
+struct OrderDownloadsMostRecentlyDownloadedCompletedFirst {
+  bool operator()(const DownloadItem* left, const DownloadItem* right) const {
+    if (IsDownloadCompleted(left) != IsDownloadCompleted(right))
+      return IsDownloadCompleted(left);
+    return left->GetEndTime() > right->GetEndTime();
+  }
+};
+
+struct SuggestionItemWrapper {
+  base::Time time;
+  bool is_offline_page;
+  int index;
+  bool operator<(const SuggestionItemWrapper& other) const {
+    return time > other.time;
+  }
+};
+
+}  // namespace
+
+DownloadSuggestionsProvider::DownloadSuggestionsProvider(
+    ContentSuggestionsProvider::Observer* observer,
+    CategoryFactory* category_factory,
+    const scoped_refptr<OfflinePageProxy>& offline_page_proxy,
+    content::DownloadManager* download_manager,
+    PrefService* pref_service,
+    bool download_manager_ui_enabled)
+    : ContentSuggestionsProvider(observer, category_factory),
+      category_status_(CategoryStatus::AVAILABLE_LOADING),
+      provided_category_(
+          category_factory->FromKnownCategory(KnownCategories::DOWNLOADS)),
+      offline_page_proxy_(offline_page_proxy),
+      download_manager_notifier_(download_manager, this),
+      pref_service_(pref_service),
+      download_manager_ui_enabled_(download_manager_ui_enabled),
+      weak_ptr_factory_(this) {
+  observer->OnCategoryStatusChanged(this, provided_category_, category_status_);
+  offline_page_proxy_->AddObserver(this);
+  FetchAllDownloadsAndSubmitSuggestions();
+}
+
+DownloadSuggestionsProvider::~DownloadSuggestionsProvider() {
+  offline_page_proxy_->RemoveObserver(this);
+}
+
+CategoryStatus DownloadSuggestionsProvider::GetCategoryStatus(
+    Category category) {
+  if (category == provided_category_)
+    return category_status_;
+  NOTREACHED() << "Unknown category " << category.id();
+  return CategoryStatus::NOT_PROVIDED;
+}
+
+CategoryInfo DownloadSuggestionsProvider::GetCategoryInfo(Category category) {
+  if (category == provided_category_) {
+    return CategoryInfo(
+        l10n_util::GetStringUTF16(IDS_NTP_DOWNLOAD_SUGGESTIONS_SECTION_HEADER),
+        ContentSuggestionsCardLayout::MINIMAL_CARD,
+        /*has_more_button=*/download_manager_ui_enabled_,
+        /*show_if_empty=*/false);
+  }
+  NOTREACHED() << "Unknown category " << category.id();
+  return CategoryInfo(base::string16(),
+                      ContentSuggestionsCardLayout::MINIMAL_CARD,
+                      /*has_more_button=*/false,
+                      /*show_if_empty=*/false);
+}
+
+void DownloadSuggestionsProvider::DismissSuggestion(
+    const std::string& suggestion_id) {
+  DCHECK_EQ(provided_category_, GetCategoryFromUniqueID(suggestion_id));
+  std::string within_category_id =
+      GetWithinCategoryIDFromUniqueID(suggestion_id);
+  std::set<std::string> dismissed_ids =
+      (IsOfflinePageID(within_category_id)
+           ? ReadOfflinePageDismissedIDsFromPrefs()
+           : ReadAssetDismissedIDsFromPrefs());
+
+  dismissed_ids.insert(within_category_id);
+  if (IsOfflinePageID(within_category_id))
+    StoreOfflinePageDismissedIDsToPrefs(dismissed_ids);
+  else
+    StoreAssetDismissedIDsToPrefs(dismissed_ids);
+}
+
+void DownloadSuggestionsProvider::FetchSuggestionImage(
+    const std::string& suggestion_id,
+    const ImageFetchedCallback& callback) {
+  // TODO(vitaliii): Fetch proper thumbnail from OfflinePageModel once it's
+  // available there.
+  // TODO(vitaliii): Provide site's favicon for assets downloads.
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(callback, gfx::Image()));
+}
+
+void DownloadSuggestionsProvider::ClearHistory(
+    base::Time begin,
+    base::Time end,
+    const base::Callback<bool(const GURL& url)>& filter) {
+  ClearDismissedSuggestionsForDebugging(provided_category_);
+  cached_offline_page_downloads_.clear();
+  cached_asset_downloads_.clear();
+  FetchAllDownloadsAndSubmitSuggestions();
+}
+
+void DownloadSuggestionsProvider::ClearCachedSuggestions(Category category) {
+  // Ignored.
+}
+
+void DownloadSuggestionsProvider::GetDismissedSuggestionsForDebugging(
+    Category category,
+    const DismissedSuggestionsCallback& callback) {
+  DCHECK_EQ(provided_category_, category);
+  // TODO(vitaliii): Implement.
+  callback.Run(std::vector<ContentSuggestion>());
+}
+
+void DownloadSuggestionsProvider::ClearDismissedSuggestionsForDebugging(
+    Category category) {
+  DCHECK_EQ(provided_category_, category);
+  StoreAssetDismissedIDsToPrefs(std::set<std::string>());
+  StoreOfflinePageDismissedIDsToPrefs(std::set<std::string>());
+  FetchAllDownloadsAndSubmitSuggestions();
+}
+
+// static
+void DownloadSuggestionsProvider::RegisterProfilePrefs(
+    PrefRegistrySimple* registry) {
+  registry->RegisterListPref(prefs::kDismissedAssetDownloadSuggestions);
+  registry->RegisterListPref(prefs::kDismissedOfflinePageDownloadSuggestions);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Private methods
+
+void DownloadSuggestionsProvider::OfflinePageModelChanged(
+    const std::vector<offline_pages::OfflinePageItem>& offline_pages) {
+  NotifyStatusChanged(CategoryStatus::AVAILABLE);
+
+  std::set<std::string> old_dismissed_ids =
+      ReadOfflinePageDismissedIDsFromPrefs();
+  std::set<std::string> new_dismissed_ids;
+  std::vector<const OfflinePageItem*> items;
+  for (const OfflinePageItem& item : offline_pages) {
+    std::string per_category_id = GetOfflinePagePerCategoryID(item.offline_id);
+    if (!IsOfflinePageDownload(item.client_id))
+      return;
+
+    if (!old_dismissed_ids.count(per_category_id))
+      items.push_back(&item);
+    else
+      new_dismissed_ids.insert(per_category_id);
+  }
+
+  if (static_cast<int>(items.size()) > kMaxSuggestionsCount) {
+    std::nth_element(items.begin(), items.begin() + kMaxSuggestionsCount,
+                     items.end(),
+                     OrderOfflinePagesByMostRecentlyVisitedFirst());
+    items.resize(kMaxSuggestionsCount);
+  }
+
+  cached_offline_page_downloads_.clear();
+  for (const OfflinePageItem* item : items) {
+    cached_offline_page_downloads_.push_back(*item);
+  }
+
+  if (old_dismissed_ids.size() != new_dismissed_ids.size()) {
+    StoreOfflinePageDismissedIDsToPrefs(new_dismissed_ids);
+  }
+
+  SubmitContentSuggestions();
+}
+
+void DownloadSuggestionsProvider::OfflinePageDeleted(
+    int64_t offline_id,
+    const offline_pages::ClientId& client_id) {
+  // Because we never switch to NOT_PROVIDED dynamically, there can be no open
+  // UI containing an invalidated suggestion unless the status is something
+  // other than NOT_PROVIDED, so only notify invalidation in that case.
+  if (category_status_ != CategoryStatus::NOT_PROVIDED &&
+      IsOfflinePageDownload(client_id)) {
+    InvalidateSuggestion(GetOfflinePagePerCategoryID(offline_id));
+  }
+}
+
+void DownloadSuggestionsProvider::OnDownloadCreated(
+    DownloadManager* manager,
+    content::DownloadItem* item) {
+  if (!IsDownloadCompleted(item))
+    return;
+  // TODO(vitaliii): Rewrite to not retrieve all downloads.
+  FetchAssetsDownloads();

[vitaliii, 2016/09/22 13:43:17]

Since this is called when each item is read, the overall complexity is O(N^2),
where N is number of downloads. I will add this to TODO.

[vitaliii, 2016/10/11 08:15:56]

I rewrote this to avoid fetching all items.

+  SubmitContentSuggestions();
+}
+
+void DownloadSuggestionsProvider::OnDownloadUpdated(
+    DownloadManager* manager,
+    content::DownloadItem* item) {
+  if (!IsDownloadCompleted(item))
+    return;
+  // TODO(vitaliii): Rewrite to not retrieve all downloads.
+  FetchAssetsDownloads();
+  SubmitContentSuggestions();
+}
+void DownloadSuggestionsProvider::OnDownloadOpened(
+    DownloadManager* manager,
+    content::DownloadItem* item) {
+  // Ignored.
+}
+void DownloadSuggestionsProvider::OnDownloadRemoved(
+    DownloadManager* manager,
+    content::DownloadItem* item) {
+  if (!IsDownloadCompleted(item))
+    return;
+  // TODO(vitaliii): Implement a better way to clean up dismissed IDs.
+  InvalidateSuggestion(GetAssetDownloadPerCategoryID(item->GetId()));
+}
+
+void DownloadSuggestionsProvider::NotifyStatusChanged(
+    CategoryStatus new_status) {
+  DCHECK_NE(CategoryStatus::NOT_PROVIDED, category_status_);
+  if (category_status_ == new_status)
+    return;
+  category_status_ = new_status;
+  observer()->OnCategoryStatusChanged(this, provided_category_, new_status);
+}
+
+void DownloadSuggestionsProvider::
+    FetchOfflinePagesDownloadsAndSubmitSuggestions() {
+  // TODO(vitaliii): When something other than |GetAllPages| is used here, the
+  // dismissed IDs cleanup in |OfflinePageModelChanged| needs to be changed to
+  // avoid accidentally undismissing suggestions.
+  offline_page_proxy_->GetAllPages(
+      base::Bind(&DownloadSuggestionsProvider::OfflinePageModelChanged,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void DownloadSuggestionsProvider::FetchAssetsDownloads() {
+  DownloadManager* manager = download_manager_notifier_.GetManager();
+  if (!manager) {
+    // The manager has gone down.
+    return;
+  }
+
+  NotifyStatusChanged(CategoryStatus::AVAILABLE);
+
+  std::vector<DownloadItem*> downloads;
+  manager->GetAllDownloads(&downloads);
+
+  std::set<std::string> dismissed_ids = ReadAssetDismissedIDsFromPrefs();
+  std::vector<DownloadItem*> not_dismissed_downloads;
+  for (DownloadItem* item : downloads) {
+    std::string within_category_id =
+        GetAssetDownloadPerCategoryID(item->GetId());
+    if (!dismissed_ids.count(within_category_id)) {
+      not_dismissed_downloads.push_back(item);
+    }
+
+    downloads = not_dismissed_downloads;
+
+    if (static_cast<int>(downloads.size()) > kMaxSuggestionsCount) {
+      std::nth_element(downloads.begin(),
+                       downloads.begin() + kMaxSuggestionsCount,
+                       downloads.end(),
+                       OrderDownloadsMostRecentlyDownloadedCompletedFirst());
+      downloads.resize(kMaxSuggestionsCount);
+    }
+
+    cached_asset_downloads_.clear();
+    for (DownloadItem* item : downloads) {
+      if (IsDownloadCompleted(item))
+        cached_asset_downloads_.push_back(item);
+    }
+  }
+}
+
+void DownloadSuggestionsProvider::FetchAllDownloadsAndSubmitSuggestions() {
+  FetchAssetsDownloads();
+  FetchOfflinePagesDownloadsAndSubmitSuggestions();
+}
+
+void DownloadSuggestionsProvider::SubmitContentSuggestions() {
+  NotifyStatusChanged(CategoryStatus::AVAILABLE);
+
+  std::vector<SuggestionItemWrapper> suggestion_items;
+  for (int i = 0; i < static_cast<int>(cached_offline_page_downloads_.size());
+       ++i) {
+    SuggestionItemWrapper wrapped_item;
+    wrapped_item.is_offline_page = true;
+    wrapped_item.index = i;
+    wrapped_item.time = cached_offline_page_downloads_[i].last_access_time;
+    suggestion_items.push_back(wrapped_item);
+  }
+
+  for (int i = 0; i < static_cast<int>(cached_asset_downloads_.size()); ++i) {
+    SuggestionItemWrapper wrapped_item;
+    wrapped_item.is_offline_page = false;
+    wrapped_item.index = i;
+    wrapped_item.time = cached_asset_downloads_[i]->GetEndTime();
+    suggestion_items.push_back(wrapped_item);
+  }
+
+  std::sort(suggestion_items.begin(), suggestion_items.end());
+
+  std::vector<ContentSuggestion> suggestions;
+  for (const SuggestionItemWrapper& wrapped_item : suggestion_items) {
+    if (suggestions.size() >= kMaxSuggestionsCount)
+      break;
+
+    if (wrapped_item.is_offline_page) {
+      suggestions.push_back(ConvertOfflinePage(
+          cached_offline_page_downloads_[wrapped_item.index]));
+    } else {
+      suggestions.push_back(
+          ConvertDownloadItem(cached_asset_downloads_[wrapped_item.index]));
+    }
+  }
+
+  observer()->OnNewSuggestions(this, provided_category_,
+                               std::move(suggestions));
+}
+
+ContentSuggestion DownloadSuggestionsProvider::ConvertOfflinePage(
+    const OfflinePageItem& offline_page) const {
+  // TODO(vitaliii): Make sure the URL is actually opened as an offline URL
+  // and not just as a downloaded file.
+  ContentSuggestion suggestion(
+      MakeUniqueID(provided_category_,
+                   GetOfflinePagePerCategoryID(offline_page.offline_id)),
+      offline_page.GetOfflineURL());
+
+  if (offline_page.title.empty()) {
+    // TODO(vitaliii): Remove this fallback once the OfflinePageModel provides
+    // titles for all (relevant) OfflinePageItems.
+    suggestion.set_title(base::UTF8ToUTF16(offline_page.url.spec()));
+  } else {
+    suggestion.set_title(offline_page.title);
+  }
+  suggestion.set_publish_date(offline_page.creation_time);
+  suggestion.set_publisher_name(base::UTF8ToUTF16(offline_page.url.host()));
+  return suggestion;
+}
+
+ContentSuggestion DownloadSuggestionsProvider::ConvertDownloadItem(
+    const content::DownloadItem* download_item) const {
+  std::string per_category_id =
+      MakeUniqueID(provided_category_,
+                   GetAssetDownloadPerCategoryID(download_item->GetId()));
+  // TODO(vitaliii): Ensure that files are opened in browser, but not
+  // downloaded
+  // again.
+  ContentSuggestion suggestion(
+      per_category_id,
+      net::FilePathToFileURL(download_item->GetTargetFilePath()));
+  // TODO(vitaliii): Set proper title.
+  suggestion.set_title(
+      base::UTF8ToUTF16(download_item->GetTargetFilePath().BaseName().value()));
+  suggestion.set_publish_date(download_item->GetEndTime());
+  suggestion.set_publisher_name(
+      base::UTF8ToUTF16(download_item->GetURL().host()));
+  // TODO(vitaliii): Set suggestion icon.
+  return suggestion;
+}
+
+void DownloadSuggestionsProvider::InvalidateSuggestion(
+    const std::string& per_category_id) {
+  observer()->OnSuggestionInvalidated(
+      this, provided_category_,
+      MakeUniqueID(provided_category_, per_category_id));
+
+  std::set<std::string> dismissed_ids =
+      (IsOfflinePageID(per_category_id) ? ReadOfflinePageDismissedIDsFromPrefs()
+                                        : ReadAssetDismissedIDsFromPrefs());
+  auto it = dismissed_ids.find(per_category_id);
+  if (it != dismissed_ids.end()) {
+    dismissed_ids.erase(it);
+    if (IsOfflinePageID(per_category_id))
+      StoreOfflinePageDismissedIDsToPrefs(dismissed_ids);
+    else
+      StoreAssetDismissedIDsToPrefs(dismissed_ids);
+  }
+}
+
+std::set<std::string>
+DownloadSuggestionsProvider::ReadAssetDismissedIDsFromPrefs() const {
+  return prefs::ReadDismissedIDsFromPrefs(
+      *pref_service_, prefs::kDismissedAssetDownloadSuggestions);
+}
+
+void DownloadSuggestionsProvider::StoreAssetDismissedIDsToPrefs(
+    const std::set<std::string>& dismissed_ids) {
+  prefs::StoreDismissedIDsToPrefs(
+      pref_service_, prefs::kDismissedAssetDownloadSuggestions, dismissed_ids);
+}
+
+std::set<std::string>
+DownloadSuggestionsProvider::ReadOfflinePageDismissedIDsFromPrefs() const {
+  return prefs::ReadDismissedIDsFromPrefs(
+      *pref_service_, prefs::kDismissedOfflinePageDownloadSuggestions);
+}
+
+void DownloadSuggestionsProvider::StoreOfflinePageDismissedIDsToPrefs(
+    const std::set<std::string>& dismissed_ids) {
+  prefs::StoreDismissedIDsToPrefs(
+      pref_service_, prefs::kDismissedOfflinePageDownloadSuggestions,
+      dismissed_ids);
+}
+
+}  // namespace ntp_snippets