[NTP Snippets] Persist snippets in a LevelDB instead of prefs

components/ntp_snippets/ntp_snippet.cc

Index: components/ntp_snippets/ntp_snippet.cc
diff --git a/components/ntp_snippets/ntp_snippet.cc b/components/ntp_snippets/ntp_snippet.cc
index 037fe51b2c11abc029ec88884aa1c92b4d133224..d7ca20c3392fd76c088a5de45aff7ebf92527627 100644
--- a/components/ntp_snippets/ntp_snippet.cc
+++ b/components/ntp_snippets/ntp_snippet.cc
@@ -7,6 +7,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/values.h"
+#include "components/ntp_snippets/proto/ntp_snippets.pb.h"
 
 namespace {
 
@@ -30,7 +31,7 @@ const char kAmpUrl[] = "ampUrl";
 namespace ntp_snippets {
 
 NTPSnippet::NTPSnippet(const std::string& id)
-    : id_(id), score_(0), best_source_index_(0) {}
+    : id_(id), score_(0), is_discarded_(false), best_source_index_(0) {}
 
 NTPSnippet::~NTPSnippet() {}
 
@@ -41,9 +42,9 @@ std::unique_ptr<NTPSnippet> NTPSnippet::CreateFromDictionary(
   if (!dict.GetDictionary(kContentInfo, &content))
     return nullptr;
 
-  // Need at least the url.
+  // Need at least the id.
   std::string id;
-  if (!content->GetString(kId, &id))
+  if (!content->GetString(kId, &id) || id.empty())
     return nullptr;
 
   std::unique_ptr<NTPSnippet> snippet(new NTPSnippet(id));
@@ -112,33 +113,14 @@ std::unique_ptr<NTPSnippet> NTPSnippet::CreateFromDictionary(
                          amp_url.is_valid() ? amp_url : GURL());
     snippet->add_source(source);
   }
-  // The previous url we have saved can be one of several sources for the
-  // article. For example, the same article can be hosted by nytimes.com,
-  // cnn.com, etc. We need to parse the list of sources for this article and
-  // find the best match. In order of preference:
-  //  1) A source that has url, publisher name, AMP url
-  //  2) A source that has url, publisher name
-  //  3) A source that has url and AMP url, or url only (since we won't show
-  //  the snippet to users if the article does not have a publisher name, it
-  //  doesn't matter whether the snippet has the AMP url or not)
-  size_t best_source_index = 0;
-  for (size_t i = 0; i < snippet->sources_.size(); ++i) {
-    const SnippetSource& source = snippet->sources_[i];
-    if (!source.publisher_name.empty()) {
-      best_source_index = i;
-      if (!source.amp_url.is_empty()) {
-        // This is the best possible source, stop looking.
-        break;
-      }
-    }
-  }
-  snippet->set_source_index(best_source_index);
 
   if (snippet->sources_.empty()) {
     DLOG(WARNING) << "No sources found for article " << id;
     return nullptr;
   }
 
+  snippet->FindBestSource();
+
   double score;
   if (dict.GetDouble(kScore, &score))
     snippet->set_score(score);
@@ -147,6 +129,53 @@ std::unique_ptr<NTPSnippet> NTPSnippet::CreateFromDictionary(
 }
 
 // static
+std::unique_ptr<NTPSnippet> NTPSnippet::CreateFromProto(
+    const SnippetProto& proto) {
+  // Need at least the id.
+  if (!proto.has_id() || proto.id().empty())
+    return nullptr;
+
+  std::unique_ptr<NTPSnippet> snippet(new NTPSnippet(proto.id()));
+
+  snippet->set_title(proto.title());
+  snippet->set_snippet(proto.snippet());
+  snippet->set_salient_image_url(GURL(proto.salient_image_url()));
+  snippet->set_publish_date(
+      base::Time::FromInternalValue(proto.publish_date()));
+  snippet->set_expiry_date(base::Time::FromInternalValue(proto.expiry_date()));
+  snippet->set_score(proto.score());
+  snippet->set_discarded(proto.discarded());
+
+  for (int i = 0; i < proto.sources_size(); ++i) {
+    const SnippetSourceProto& source_proto = proto.sources(i);
+    GURL url(source_proto.url());
+    if (!url.is_valid()) {
+      // We must at least have a valid source URL.
+      DLOG(WARNING) << "Invalid article url " << source_proto.url();
+      continue;
+    }
+    std::string publisher_name = source_proto.publisher_name();
+    GURL amp_url;
+    if (source_proto.has_amp_url()) {
+      amp_url = GURL(source_proto.amp_url());
+      DLOG_IF(WARNING, !amp_url.is_valid()) << "Invalid AMP URL "
+                                            << source_proto.amp_url();
+    }
+
+    snippet->add_source(SnippetSource(url, publisher_name, amp_url));
+  }
+
+  if (snippet->sources_.empty()) {
+    DLOG(WARNING) << "No sources found for article " << snippet->id();
+    return nullptr;
+  }
+
+  snippet->FindBestSource();
+
+  return snippet;
+}
+
+// static
 bool NTPSnippet::AddFromListValue(const base::ListValue& list,
                                   PtrVector* snippets) {
   for (const auto& value : list) {
@@ -163,44 +192,32 @@ bool NTPSnippet::AddFromListValue(const base::ListValue& list,
   return true;
 }
 
-std::unique_ptr<base::DictionaryValue> NTPSnippet::ToDictionary() const {
-  std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue);
+SnippetProto NTPSnippet::ToProto() const {
+  SnippetProto result;
 
-  dict->SetString(kId, id_);
+  result.set_id(id_);
   if (!title_.empty())
-    dict->SetString(kTitle, title_);
-  if (salient_image_url_.is_valid())
-    dict->SetString(kSalientImageUrl, salient_image_url_.spec());
+    result.set_title(title_);
   if (!snippet_.empty())
-    dict->SetString(kSnippet, snippet_);
+    result.set_snippet(snippet_);
+  if (salient_image_url_.is_valid())
+    result.set_salient_image_url(salient_image_url_.spec());
   if (!publish_date_.is_null())
-    dict->SetString(kPublishDate, TimeToJsonString(publish_date_));
+    result.set_publish_date(publish_date_.ToInternalValue());
   if (!expiry_date_.is_null())
-    dict->SetString(kExpiryDate, TimeToJsonString(expiry_date_));
+    result.set_expiry_date(expiry_date_.ToInternalValue());
+  result.set_score(score_);
+  result.set_discarded(is_discarded_);
 
-  std::unique_ptr<base::ListValue> corpus_infos_list(new base::ListValue);
   for (const SnippetSource& source : sources_) {
-    std::unique_ptr<base::DictionaryValue> corpus_info_dict(
-        new base::DictionaryValue);
-
-    corpus_info_dict->SetString(kCorpusId, source.url.spec());
-    if (!source.amp_url.is_empty())
-      corpus_info_dict->SetString(kAmpUrl, source.amp_url.spec());
+    SnippetSourceProto* source_proto = result.add_sources();
+    source_proto->set_url(source.url.spec());
     if (!source.publisher_name.empty())
-      corpus_info_dict->SetString(
-          base::StringPrintf("%s.%s", kPublisherData, kSiteTitle),
-          source.publisher_name);
-
-    corpus_infos_list->Append(std::move(corpus_info_dict));
+      source_proto->set_publisher_name(source.publisher_name);
+    if (source.amp_url.is_valid())
+      source_proto->set_amp_url(source.amp_url.spec());
   }
 
-  dict->Set(kSourceCorpusInfo, std::move(corpus_infos_list));
-
-  std::unique_ptr<base::DictionaryValue> result(new base::DictionaryValue);
-  result->Set(kContentInfo, std::move(dict));
-
-  result->SetDouble(kScore, score_);
-
   return result;
 }
 
@@ -220,4 +237,26 @@ std::string NTPSnippet::TimeToJsonString(const base::Time& time) {
   return base::Int64ToString((time - base::Time::UnixEpoch()).InSeconds());
 }
 
+void NTPSnippet::FindBestSource() {
+  // The same article can be hosted by multiple sources, e.g. nytimes.com,
+  // cnn.com, etc. We need to parse the list of sources for this article and
+  // find the best match. In order of preference:
+  //  1) A source that has URL, publisher name, AMP URL
+  //  2) A source that has URL, publisher name
+  //  3) A source that has URL and AMP URL, or URL only (since we won't show
+  //  the snippet to users if the article does not have a publisher name, it
+  //  doesn't matter whether the snippet has the AMP URL or not)
+  best_source_index_ = 0;
+  for (size_t i = 0; i < sources_.size(); ++i) {
+    const SnippetSource& source = sources_[i];
+    if (!source.publisher_name.empty()) {
+      best_source_index_ = i;
+      if (!source.amp_url.is_empty()) {
+        // This is the best possible source, stop looking.
+        break;
+      }
+    }
+  }
+}
+
 }  // namespace ntp_snippets