printing: implement PpdMetadataManager

This change implements the PpdMetadataManager class and provides unit
tests for the same.

Bug: chromium:888189
Change-Id: Ifb9672258a747722c3d48bd1a1f1095365555e49
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2261972
Commit-Queue: Kalvin Lee <kdlee@chromium.org>
Reviewed-by: Sean Kau <skau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#784552}

chromeos/BUILD.gn

@@ -92,6 +92,8 @@ component("chromeos") {
 
   if (is_printing_ppd_provider_v3) {
     sources += [
+      "printing/ppd_metadata_manager.cc",
+      "printing/ppd_metadata_manager.h",
       "printing/ppd_metadata_parser.cc",
       "printing/ppd_metadata_parser.h",
       "printing/ppd_provider_v3.cc",
@@ -219,6 +221,8 @@ test("chromeos_unittests") {
     sources += [
       "printing/fake_printer_config_cache.cc",
       "printing/fake_printer_config_cache.h",
+      "printing/ppd_metadata_manager_unittest.cc",
+      "printing/ppd_metadata_matchers.h",
       "printing/ppd_metadata_parser_unittest.cc",
       "printing/printer_config_cache_unittest.cc",
     ]

chromeos/printing/ppd_metadata_manager.h

+// Copyright 2020 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.
+
+#ifndef CHROMEOS_PRINTING_PPD_METADATA_MANAGER_H_
+#define CHROMEOS_PRINTING_PPD_METADATA_MANAGER_H_
+
+#include <memory>
+#include <string>
+
+#include "base/containers/flat_map.h"
+#include "base/optional.h"
+#include "base/strings/string_piece.h"
+#include "base/time/time.h"
+#include "base/values.h"
+#include "chromeos/chromeos_export.h"
+#include "chromeos/printing/ppd_metadata_parser.h"
+#include "chromeos/printing/ppd_provider.h"
+#include "chromeos/printing/printer_config_cache.h"
+
+namespace chromeos {
+
+// A PpdMetadataManager is the class responsible for fetching and
+// parsing PPD metadata to answer high-level queries about metadata.
+//
+// This class must be called from a sequenced context.
+class CHROMEOS_EXPORT PpdMetadataManager {
+ public:
+  // Used by GetLocale().
+  // Argument denotes success of setting metadata locale for |this|.
+  using GetLocaleCallback = base::OnceCallback<void(bool)>;
+
+  // Used by GetPrinters().
+  // Arguments denote
+  // *  whether the call succeeded and
+  // *  upon success, ParsedPrinters as requested.
+  using GetPrintersCallback =
+      base::OnceCallback<void(bool, const ParsedPrinters&)>;
+
+  // Assumes ownership of |config_cache|.
+  static std::unique_ptr<PpdMetadataManager> Create(
+      base::StringPiece browser_locale,
+      base::Clock* clock,
+      std::unique_ptr<PrinterConfigCache> config_cache);
+
+  virtual ~PpdMetadataManager() = default;
+
+  // Primes |this| with the best-fit locale advertised by the Chrome OS
+  // Printing serving root. The best-fit locale is the one closest to
+  // the |browser_locale| passed to Create(). "Closest" is an
+  // implementation-defined concept.
+  //
+  // If a best-fit locale is already set in |this|, |this| invokes |cb|
+  // immediately and indicates success.
+  //
+  // With few exceptions, caller must not call any other method of
+  // |this| until the |cb| indicates success. Exceptional methods are
+  // documented in this header file.
+  //
+  // See also: SetLocaleForTesting()
+  virtual void GetLocale(GetLocaleCallback cb) = 0;
+
+  // Calls |cb| with a list of manufacturers.
+  // *  On success, the list is created from metadata no older than
+  //    |age|.
+  // *  On failure, the first argument to |cb| is set accordingly.
+  virtual void GetManufacturers(
+      base::TimeDelta age,
+      PpdProvider::ResolveManufacturersCallback cb) = 0;
+
+  // Calls |cb| with a map of printers made by |manufacturer|.
+  // *  Caller must have previously successfully called
+  //    GetManufacturers().
+  // *  On success, the map is created from metadata no older than
+  //    |age|.
+  // *  On failure, the first argument to |cb| is set accordingly.
+  virtual void GetPrinters(base::StringPiece manufacturer,
+                           base::TimeDelta age,
+                           GetPrintersCallback cb) = 0;
+
+  // Calls |cb| with the make and model of
+  // |effective_make_and_model|.
+  // *  On success, the split is performed against metadata no older than
+  //    |age|.
+  // *  On failure, the first argument to |cb| is set accordingly.
+  //
+  // The split is defined by the reverse index metadata that this method
+  // fetches, appropriate to the |effective_make_and_model|.
+  // Googlers: you may consult
+  // go/cros-printing:ppd-metadata#reverse-index
+  virtual void SplitMakeAndModel(base::StringPiece effective_make_and_model,
+                                 base::TimeDelta age,
+                                 PpdProvider::ReverseLookupCallback cb) = 0;
+
+  // Returns a borrowed pointer to the PrinterConfigCache passed to
+  // Create(); |this| retains ownership.
+  virtual PrinterConfigCache* GetPrinterConfigCacheForTesting() const = 0;
+
+  // Fakes a successful call to GetLocale(), setting the internal
+  // locale of |this| to |locale|.
+  //
+  // This method is useful for bypassing a real call to GetLocale(),
+  // which consumers of this class ordinarily must complete successfully
+  // before calling any other method of |this|.
+  virtual void SetLocaleForTesting(base::StringPiece locale) = 0;
+
+  // Fakes a successful call to GetManufacturers(), providing |this|
+  // with a list of manufacturers.
+  //
+  // This method returns true if |this| successfully parses and stores
+  // off the list of |manufacturers_json|. Caller must verify that this
+  // method returns true.
+  virtual bool SetManufacturersForTesting(
+      base::StringPiece manufacturers_json) = 0;
+
+  // Returns the metadata locale currently set in |this|.
+  virtual base::StringPiece ExposeMetadataLocaleForTesting() const = 0;
+};
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_PRINTING_PPD_METADATA_MANAGER_H_

chromeos/printing/ppd_metadata_matchers.h

+// Copyright 2020 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.
+
+// This file contains matchers useful for testing with parsed PPD
+// metadata.
+
+#include <string>
+
+#include "testing/gmock/include/gmock/gmock-matchers.h"
+
+#ifndef CHROMEOS_PRINTING_PPD_METADATA_MATCHERS_H_
+#define CHROMEOS_PRINTING_PPD_METADATA_MATCHERS_H_
+
+namespace chromeos {
+
+using ::testing::ExplainMatchResult;
+using ::testing::Field;
+using ::testing::StrEq;
+
+// Matches a ReverseIndexLeaf struct against its |manufacturer| and
+// |model| members.
+MATCHER_P2(ReverseIndexLeafLike,
+           manufacturer,
+           model,
+           "is a ReverseIndexLeaf with manufacturer ``" +
+               std::string(manufacturer) + "'' and model ``" +
+               std::string(model) + "''") {
+  return ExplainMatchResult(
+             Field(&ReverseIndexLeaf::manufacturer, StrEq(manufacturer)), arg,
+             result_listener) &&
+         ExplainMatchResult(Field(&ReverseIndexLeaf::model, StrEq(model)), arg,
+                            result_listener);
+}
+
+// Matches a ParsedPrinter struct against its
+// |user_visible_printer_name| and |effective_make_and_model| members.
+MATCHER_P2(ParsedPrinterLike,
+           name,
+           emm,
+           "is a ParsedPrinter with user_visible_printer_name``" +
+               std::string(name) + "'' and effective_make_and_model ``" +
+               std::string(emm) + "''") {
+  return ExplainMatchResult(
+             Field(&ParsedPrinter::user_visible_printer_name, StrEq(name)), arg,
+             result_listener) &&
+         ExplainMatchResult(
+             Field(&ParsedPrinter::effective_make_and_model, StrEq(emm)), arg,
+             result_listener);
+}
+
+}  // namespace chromeos
+
+#endif  // CHROMEOS_PRINTING_PPD_METADATA_MATCHERS_H_

chromeos/printing/ppd_metadata_parser_unittest.cc

@@ -5,6 +5,7 @@
 #include "chromeos/printing/ppd_metadata_parser.h"
 
 #include "base/strings/string_piece.h"
+#include "chromeos/printing/ppd_metadata_matchers.h"
 #include "testing/gmock/include/gmock/gmock-matchers.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -15,44 +16,12 @@ namespace {
 using ::testing::ElementsAre;
 using ::testing::ExplainMatchResult;
 using ::testing::Field;
-using ::testing::IsEmpty;
 using ::testing::Pair;
 using ::testing::StrEq;
 using ::testing::UnorderedElementsAre;
 
 constexpr base::StringPiece kInvalidJson = "blah blah invalid JSON";
 
-// Matches a ReverseIndexLeaf struct against its |manufacturer| and
-// |model| members.
-MATCHER_P2(ReverseIndexLeafLike,
-           manufacturer,
-           model,
-           "is a ReverseIndexLeaf with manufacturer ``" +
-               std::string(manufacturer) + "'' and model ``" +
-               std::string(model) + "''") {
-  return ExplainMatchResult(
-             Field(&ReverseIndexLeaf::manufacturer, StrEq(manufacturer)), arg,
-             result_listener) &&
-         ExplainMatchResult(Field(&ReverseIndexLeaf::model, StrEq(model)), arg,
-                            result_listener);
-}
-
-// Matches a ParsedPrinter struct against its
-// |user_visible_printer_name| and |effective_make_and_model| members.
-MATCHER_P2(ParsedPrinterLike,
-           name,
-           emm,
-           "is a ParsedPrinter with user_visible_printer_name``" +
-               std::string(name) + "'' and effective_make_and_model ``" +
-               std::string(emm) + "''") {
-  return ExplainMatchResult(
-             Field(&ParsedPrinter::user_visible_printer_name, StrEq(name)), arg,
-             result_listener) &&
-         ExplainMatchResult(
-             Field(&ParsedPrinter::effective_make_and_model, StrEq(emm)), arg,
-             result_listener);
-}
-
 // Verifies that ParseLocales() can parse locales metadata.
 TEST(PpdMetadataParserTest, CanParseLocales) {
   constexpr base::StringPiece kLocalesJson = R"(