Fetch snippets from ChromeReader and show them on the NTP

components/ntp_snippets/ntp_snippets_fetcher.cc

Index: components/ntp_snippets/ntp_snippets_fetcher.cc
diff --git a/components/ntp_snippets/ntp_snippets_fetcher.cc b/components/ntp_snippets/ntp_snippets_fetcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7c74fcfe7e5f2c65b44061d4af0eab9e98be78e6
--- /dev/null
+++ b/components/ntp_snippets/ntp_snippets_fetcher.cc
@@ -0,0 +1,191 @@
+// 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/ntp_snippets_fetcher.h"
+
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/path_service.h"
+#include "base/strings/stringprintf.h"
+#include "base/task_runner_util.h"
+#include "components/signin/core/browser/profile_oauth2_token_service.h"
+#include "components/signin/core/browser/signin_manager.h"
+#include "components/signin/core/browser/signin_tracker.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_request_headers.h"
+#include "net/http/http_response_headers.h"
+#include "net/http/http_status_code.h"
+#include "net/url_request/url_fetcher.h"
+
+using net::URLFetcher;
+using net::URLRequestContextGetter;
+using net::HttpRequestHeaders;
+using net::URLRequestStatus;
+
+namespace ntp_snippets {
+
+const char kSnippetSuggestionsFilename[] = "ntp_snippets.json";
+const char kApiScope[] = "https://www.googleapis.com/auth/webhistory";
+const char kContentSnippetsServer[] =
+    "https://chromereader-pa.googleapis.com/v1/fetch";
+const char kAuthorizationRequestHeaderFormat[] = "Bearer %s";
+
+const char kUnpersonalizedRequestParameters[] =
+    "{ \"response_detail_level\": \"FULL_DEBUG\", \"advanced_options\": { "
+    "\"local_scoring_params\": {\"content_params\" : { "
+    "\"only_return_personalized_results\": false } }, "
+    "\"global_scoring_params\": { \"num_to_return\": 10 } } }";
+
+base::FilePath GetSnippetsSuggestionsPath(const base::FilePath& base_dir) {
+  return base_dir.AppendASCII(kSnippetSuggestionsFilename);
+}
+
+NTPSnippetsFetcher::NTPSnippetsFetcher(
+    scoped_refptr<base::SequencedTaskRunner> file_task_runner,
+    SigninManagerBase* signin_manager,
+    OAuth2TokenService* token_service,
+    scoped_refptr<URLRequestContextGetter> url_request_context_getter,
+    const base::FilePath& base_download_path)
+    : OAuth2TokenService::Consumer("NTP_snippets"),
+      file_task_runner_(file_task_runner),
+      url_request_context_getter_(url_request_context_getter),
+      signin_manager_(signin_manager),
+      token_service_(token_service),
+      download_path_(GetSnippetsSuggestionsPath(base_download_path)),
+      waiting_for_refresh_token_(false),
+      weak_ptr_factory_(this) {}
+
+NTPSnippetsFetcher::~NTPSnippetsFetcher() {
+  if (waiting_for_refresh_token_)
+    token_service_->RemoveObserver(this);
+}
+
+scoped_ptr<NTPSnippetsFetcher::SnippetsAvailableCallbackList::Subscription>
+NTPSnippetsFetcher::AddCallback(const SnippetsAvailableCallback& callback) {
+  return callback_list_.Add(callback);
+}
+
+void NTPSnippetsFetcher::FetchSnippets(bool overwrite) {
+  if (overwrite) {
+    StartFetch();
+  } else {
+    base::PostTaskAndReplyWithResult(
+        file_task_runner_.get(), FROM_HERE,
+        base::Bind(&base::PathExists, download_path_),
+        base::Bind(&NTPSnippetsFetcher::OnFileExistsCheckDone,
+                   weak_ptr_factory_.GetWeakPtr()));
+  }
+}
+
+void NTPSnippetsFetcher::OnFileExistsCheckDone(bool exists) {
+  if (exists) {
+    NotifyObservers();
+  } else {
+    StartFetch();
+  }
+}
+
+void NTPSnippetsFetcher::StartFetch() {
+  if (signin_manager_->IsAuthenticated()) {
+    StartTokenRequest();
+  } else {
+    if (!waiting_for_refresh_token_) {
+      // Wait until we get a refresh token.
+      waiting_for_refresh_token_ = true;
+      token_service_->AddObserver(this);
+    }
+  }
+}
+
+void NTPSnippetsFetcher::StartTokenRequest() {
+  OAuth2TokenService::ScopeSet scopes;
+  scopes.insert(kApiScope);
+  oauth_request_ = token_service_->StartRequest(
+      signin_manager_->GetAuthenticatedAccountId(), scopes, this);
+}
+
+void NTPSnippetsFetcher::NotifyObservers() {
+  callback_list_.Notify(download_path_);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// OAuth2TokenService::Consumer overrides
+void NTPSnippetsFetcher::OnGetTokenSuccess(
+    const OAuth2TokenService::Request* request,
+    const std::string& access_token,
+    const base::Time& expiration_time) {
+  oauth_request_.reset();
+  url_fetcher_ =
+      URLFetcher::Create(GURL(kContentSnippetsServer), URLFetcher::POST, this);
+  url_fetcher_->SetRequestContext(url_request_context_getter_.get());
+  url_fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
+                             net::LOAD_DO_NOT_SAVE_COOKIES);
+  HttpRequestHeaders headers;
+  headers.SetHeader("Authorization",
+                    base::StringPrintf(kAuthorizationRequestHeaderFormat,
+                                       access_token.c_str()));
+  headers.SetHeader("Content-Type", "application/json; charset=UTF-8");
+  url_fetcher_->SetExtraRequestHeaders(headers.ToString());
+  url_fetcher_->SetUploadData("application/json",
+                              kUnpersonalizedRequestParameters);
+  url_fetcher_->SaveResponseToTemporaryFile(file_task_runner_.get());
+  url_fetcher_->Start();
+}
+
+void NTPSnippetsFetcher::OnGetTokenFailure(
+    const OAuth2TokenService::Request* request,
+    const GoogleServiceAuthError& error) {
+  oauth_request_.reset();
+  DLOG(ERROR) << "Unable to get token: " << error.ToString();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// OAuth2TokenService::Observer overrides
+void NTPSnippetsFetcher::OnRefreshTokenAvailable(
+    const std::string& account_id) {
+  token_service_->RemoveObserver(this);
+  waiting_for_refresh_token_ = false;
+  StartTokenRequest();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// URLFetcherDelegate overrides
+void NTPSnippetsFetcher::OnURLFetchComplete(const URLFetcher* source) {
+  DCHECK_EQ(url_fetcher_.get(), source);
+
+  const URLRequestStatus& status = source->GetStatus();
+  if (!status.is_success()) {
+    DLOG(WARNING) << "URLRequestStatus error " << status.error()
+                  << " while trying to download " << source->GetURL().spec();
+    return;
+  }
+
+  int response_code = source->GetResponseCode();
+  if (response_code != net::HTTP_OK) {
+    DLOG(WARNING) << "HTTP error " << response_code
+                  << " while trying to download " << source->GetURL().spec();
+    return;
+  }
+
+  base::FilePath response_path;
+  source->GetResponseAsFilePath(false, &response_path);
+
+  base::PostTaskAndReplyWithResult(
+      file_task_runner_.get(), FROM_HERE,
+      base::Bind(&base::Move, response_path, download_path_),
+      base::Bind(&NTPSnippetsFetcher::OnFileMoveDone,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void NTPSnippetsFetcher::OnFileMoveDone(bool success) {
+  if (!success) {
+    DLOG(WARNING) << "Could not move file to "
+                  << download_path_.LossyDisplayName();
+    return;
+  }
+
+  NotifyObservers();
+}
+
+}  // namespace ntp_snippets