Add PPDProvider barebones implementation and associated cache skeleton.

chromeos/printing/ppd_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.
+

[skau, 2016/09/17 00:59:59]

ppd_provider.h should be included first
https://google.github.io/styleguide/cppguide.html#Names_and_Order_of_Includes

[Carlson, 2016/10/06 15:56:05]

Done.

+#include "base/json/json_parser.h"
+#include "base/memory/ptr_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/time/time.h"
+#include "base/values.h"
+#include "chromeos/printing/ppd_cache.h"
+#include "chromeos/printing/ppd_provider.h"
+#include "net/base/load_flags.h"
+#include "net/http/http_status_code.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_fetcher_delegate.h"
+#include "net/url_request/url_request_context_getter.h"
+#include "url/gurl.h"
+
+using ::base::DictionaryValue;
+using ::base::Value;
+using ::net::URLFetcher;
+using ::net::URLFetcherDelegate;
+using ::std::string;
+using ::std::unique_ptr;
+
+namespace chromeos {
+namespace printing {
+namespace {
+
+const char* kJSONPPDKey = "compressedPpd";
+const char* kJSONLastUpdatedKey = "lastUpdatedTime";
+
+class PPDProviderImpl;
+
+// URLFetcherDelegate that just forwards the complete callback back to
+// the PPDProvider that owns the delegate.
+class ForwardingURLFetcherDelegate : public URLFetcherDelegate {
+ public:
+  ForwardingURLFetcherDelegate(PPDProviderImpl* owner) : owner_(owner) {}
+  ~ForwardingURLFetcherDelegate() override {}
+
+  // URLFetcherDelegate API method.  Defined below since we need the
+  // PPDProviderImpl definition first.
+  void OnURLFetchComplete(const URLFetcher* source) override;
+
+ private:
+  // owner of this delegate.
+  PPDProviderImpl* owner_;
+};
+
+// TODO(justincarlson) - Determine what concurrency this class
+// needs to deal with, particularly around the lifetime of files
+// in the cache, but also for concurrent Lookups.
+class PPDProviderImpl : public PPDProvider {
+ public:
+  PPDProviderImpl(
+      scoped_refptr<net::URLRequestContextGetter> url_context_getter,
+      ::std::unique_ptr<PPDCache> cache,
+      const PPDProvider::Options& options)
+      : forwarding_delegate_(this),
+        url_context_getter_(url_context_getter),
+        cache_(std::move(cache)),
+        options_(options) {}
+  ~PPDProviderImpl() override {}
+
+  void Lookup(const string& manufacturer,
+              const string& model,
+              PPDProvider::LookupCallback cb) override {
+    auto tmp = cache_->Lookup(manufacturer, model);
+    if (tmp != nullptr) {
+      // Cache hit.  Schedule the callback right now.
+      url_context_getter_->GetNetworkTaskRunner()->PostTask(
+          FROM_HERE, base::Bind(cb, PPDProvider::SUCCESS, *tmp));
+      return;
+    }
+
+    done_callback_ = cb;
+    fetcher_ = net::URLFetcher::Create(GetLookupURL(manufacturer, model),
+                                       URLFetcher::GET, &forwarding_delegate_);
+    fetcher_->SetRequestContext(url_context_getter_.get());
+    fetcher_->SetLoadFlags(net::LOAD_BYPASS_CACHE | net::LOAD_DISABLE_CACHE |
+                           net::LOAD_DO_NOT_SAVE_COOKIES |
+                           net::LOAD_DO_NOT_SEND_COOKIES |
+                           net::LOAD_DO_NOT_SEND_AUTH_DATA);
+    fetcher_->Start();
+  };
+
+  // Called when the fetcher completes its fetch.
+  void OnURLFetchComplete() {
+    // TODO(justincarlson) -- What does URLFetcher do with redirects?  Does it
+    // automatically resolve them, or do we need to do something else?
+    string contents;
+    if ((fetcher_->GetStatus().status() != net::URLRequestStatus::SUCCESS) ||
+        (fetcher_->GetResponseCode() != net::HTTP_OK) ||
+        !fetcher_->GetResponseAsString(&contents)) {
+      // Something went wrong with the fetch.
+      done_callback_.Run(PPDProvider::SERVER_ERROR, Printer::PPDFile());
+    } else {
+      auto parsed_json = ::base::JSONReader::Read(contents);
+      DictionaryValue* dict;
+      if (parsed_json == nullptr ||                            //
+          parsed_json->GetType() != Value::TYPE_DICTIONARY ||  //

[skau, 2016/09/17 00:59:59]

GetAsDictionary implies this check and will fail safely if the value isn't a
dictionary.

[Carlson, 2016/10/06 15:56:05]

Done.

+          !parsed_json->GetAsDictionary(&dict)) {
+        // Malformed response.  TODO(justincarlson) - LOG something here?
+        done_callback_.Run(PPDProvider::SERVER_ERROR, Printer::PPDFile());
+        return;
+      }
+      std::string compressed_ppd_contents;
+      std::string last_updated_time_string;
+      uint64_t last_updated_time;
+      if (!(dict->GetString(kJSONPPDKey, &compressed_ppd_contents) &&
+            dict->GetString(kJSONLastUpdatedKey, &last_updated_time_string) &&
+            ::base::StringToUint64(last_updated_time_string,
+                                   &last_updated_time))) {
+        // Malformed response.  TODO(justincarlson) - LOG something here?
+        done_callback_.Run(PPDProvider::SERVER_ERROR, Printer::PPDFile());
+        return;
+      }
+      auto ppd_file =
+          cache_->Store(manufacturer_, model_, base::Time::Now().ToJavaTime(),
+                        last_updated_time, compressed_ppd_contents);
+    }
+    done_callback_.Run(PPDProvider::SUCCESS, Printer::PPDFile());
+  }
+
+ private:
+  // Generate a url to look up a manufacturer/model from the quirks server
+  GURL GetLookupURL(const string& manufacturer, const string& model) const {
+    return GURL(::base::JoinString(
+        {
+            "https://",                    //
+            options_.quirks_server,        //
+            "/v2/printer/manufacturers/",  //
+            manufacturer,                  //
+            "/models/",                    //
+            model,                         //
+            "?key=",                       //
+            options_.api_key               //
+        },
+        ""));
+  }
+
+  // Manufacturer/model strings for the current lookup.
+  std::string manufacturer_;
+  std::string model_;
+
+  ForwardingURLFetcherDelegate forwarding_delegate_;
+  scoped_refptr<net::URLRequestContextGetter> url_context_getter_;
+  unique_ptr<PPDCache> cache_;
+
+  // Construction-time options, immutable.
+  const PPDProvider::Options options_;
+  unique_ptr<::net::URLFetcher> fetcher_;
+  PPDProvider::LookupCallback done_callback_;
+};
+
+void ForwardingURLFetcherDelegate::OnURLFetchComplete(
+    const URLFetcher* source) {
+  owner_->OnURLFetchComplete();
+}
+
+}  // namespace
+
+// static
+PPDProvider::Options PPDProvider::Defaults() {
+  PPDProvider::Options ret;
+  ret.quirks_server = "chromeosquirksserver-pa.googleapis.com";
+  // TODO(justincarlson) - How do we set a default api key?  Can't include
+  //  google_apis/google_api_keys directly.
+  // ret.api_key = ::google_apis::GetAPIKey();

[skau, 2016/09/17 00:59:59]

It'll need to be passed in as it depends on the platform.  The Chromium code
base tries to avoid assuming that Chromium is the only app that uses this code.

[Carlson, 2016/10/06 15:56:05]

Done.

+  return ret;
+}
+
+// static
+unique_ptr<PPDProvider> PPDProvider::Create(
+    scoped_refptr<net::URLRequestContextGetter> url_context_getter,
+    unique_ptr<PPDCache> cache,
+    const PPDProvider::Options& options) {
+  return ::base::MakeUnique<PPDProviderImpl>(url_context_getter,
+                                             std::move(cache), options);
+}
+
+// static
+unique_ptr<PPDProvider> PPDProvider::Create(
+    scoped_refptr<net::URLRequestContextGetter> url_context_getter,
+    unique_ptr<PPDCache> cache) {
+  return ::base::MakeUnique<PPDProviderImpl>(url_context_getter,
+                                             std::move(cache), Defaults());
+}
+
+}  // namespace printing
+}  // namespace chromeos