[Suggestions] Move ImageManager to the component

components/suggestions/image_manager.h

 // Copyright 2014 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 COMPONENTS_SUGGESTIONS_IMAGE_MANAGER_H_
 #define COMPONENTS_SUGGESTIONS_IMAGE_MANAGER_H_
 
+#include <map>
+#include <string>
+#include <vector>
+
 #include "base/basictypes.h"
 #include "base/callback.h"
+#include "base/containers/hash_tables.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "components/leveldb_proto/proto_database.h"
+#include "components/suggestions/image_fetcher_delegate.h"
 #include "components/suggestions/proto/suggestions.pb.h"
 #include "ui/gfx/image/image_skia.h"
 #include "url/gurl.h"
 
+namespace net {
+class URLRequestContextGetter;
+}
+
 namespace suggestions {
 
-// An interface to retrieve images related to a specific URL.
-class ImageManager {
+class ImageData;
+class ImageFetcher;
+class SuggestionsProfile;
+
+// A class used to fetch server images asynchronously and manage the caching
+// layer (both in memory and on disk).
+class ImageManager : public ImageFetcherDelegate {
  public:
-  ImageManager() {}
-  virtual ~ImageManager() {}
+  typedef std::vector<ImageData> ImageDataVector;
 
-  // (Re)Initializes states using data received from a SuggestionService. We're
-  // not doing this in the constructor because an instance may be long-lived.
-  virtual void Initialize(const SuggestionsProfile& suggestions) = 0;
+  ImageManager(scoped_ptr<ImageFetcher> image_fetcher,
+               scoped_ptr<leveldb_proto::ProtoDatabase<ImageData> > database,
+               const base::FilePath& database_dir);
+  virtual ~ImageManager();
 
-  // Retrieves stored image for website |url| asynchronously. Calls |callback|
-  // with Bitmap pointer if found, and NULL otherwise.
+  virtual void Initialize(const SuggestionsProfile& suggestions);
+
+  // Should be called from the UI thread.
   virtual void GetImageForURL(
       const GURL& url,
-      base::Callback<void(const GURL&, const SkBitmap*)> callback) = 0;
+      base::Callback<void(const GURL&, const SkBitmap*)> callback);
+
+ protected:
+  // Perform additional tasks when an image has been fetched.
+  virtual void OnImageFetched(const GURL& url, const SkBitmap* bitmap) OVERRIDE;
 
  private:
+  friend class MockImageManager;
+  friend class ImageManagerTest;
+  FRIEND_TEST_ALL_PREFIXES(ImageManagerTest, InitializeTest);
+  FRIEND_TEST_ALL_PREFIXES(ImageManagerTest, GetImageForURLNetworkCacheHit);
+  FRIEND_TEST_ALL_PREFIXES(ImageManagerTest,
+                           GetImageForURLNetworkCacheNotInitialized);
+
+  // Used for testing.
+  ImageManager();
+
+  typedef std::vector<base::Callback<void(const GURL&, const SkBitmap*)> >
+      CallbackVector;
+  typedef base::hash_map<std::string, SkBitmap> ImageMap;
+
+  // State related to an image fetch (associated website url, image_url,
+  // pending callbacks).
+  struct ImageCacheRequest {
+    ImageCacheRequest();
+    ~ImageCacheRequest();
+
+    GURL url;
+    GURL image_url;
+    // Queue for pending callbacks, which may accumulate while the request is in
+    // flight.
+    CallbackVector callbacks;
+  };
+
+  typedef std::map<const GURL, ImageCacheRequest> ImageCacheRequestMap;
+
+  // Looks up image URL for |url|. If found, writes the result to |image_url|
+  // and returns true. Otherwise just returns false.
+  bool GetImageURL(const GURL& url, GURL* image_url);
+
+  void QueueCacheRequest(
+      const GURL& url, const GURL& image_url,
+      base::Callback<void(const GURL&, const SkBitmap*)> callback);
+
+  void ServeFromCacheOrNetwork(
+      const GURL& url, const GURL& image_url,
+      base::Callback<void(const GURL&, const SkBitmap*)> callback);
+
+  // Will return false if no bitmap was found corresponding to |url|, else
+  // return true and call |callback| with the found bitmap.
+  bool ServeFromCache(
+      const GURL& url,
+      base::Callback<void(const GURL&, const SkBitmap*)> callback);
+
+  // Returns null if the |url| had no entry in the cache.
+  SkBitmap* GetBitmapFromCache(const GURL& url);
+
+  // Save the image bitmap in the cache and in the database.
+  void SaveImage(const GURL& url, const SkBitmap& bitmap);
+
+  // Database callback methods.
+  // Will initiate loading the entries.
+  void OnDatabaseInit(bool success);
+  // Will transfer the loaded |entries| in memory (|image_map_|).
+  void OnDatabaseLoad(bool success, scoped_ptr<ImageDataVector> entries);
+  void OnDatabaseSave(bool success);
+
+  // Take entries from the database and put them in the local cache.
+  void LoadEntriesInCache(scoped_ptr<ImageDataVector> entries);
+
+  void ServePendingCacheRequests();
+
+  // From SkBitmap to the vector of JPEG-encoded bytes, |dst|. Visible only for
+  // testing.
+  static bool EncodeImage(const SkBitmap& bitmap,
+                          std::vector<unsigned char>* dest);
+
+  // Map from URL to image URL. Should be kept up to date when a new
+  // SuggestionsProfile is available.
+  std::map<GURL, GURL> image_url_map_;
+
+  // Map from website URL to request information, used for pending cache
+  // requests while the database hasn't loaded.
+  ImageCacheRequestMap pending_cache_requests_;
+
+  // Holding the bitmaps in memory, keyed by website URL string.
+  ImageMap image_map_;
+
+  scoped_ptr<ImageFetcher> image_fetcher_;
+
+  scoped_ptr<leveldb_proto::ProtoDatabase<ImageData> > database_;
+
+  bool database_ready_;
+
+  base::WeakPtrFactory<ImageManager> weak_ptr_factory_;
+
+  base::ThreadChecker thread_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(ImageManager);
 };
 
 }  // namespace suggestions
 
 #endif  // COMPONENTS_SUGGESTIONS_IMAGE_MANAGER_H_