Issue 5010 - Allow to preload subscription files

libadblockplus-android/src/org/adblockplus/libadblockplus/android/AndroidWebRequestResourceWrapper.java

Index: libadblockplus-android/src/org/adblockplus/libadblockplus/android/AndroidWebRequestResourceWrapper.java
diff --git a/libadblockplus-android/src/org/adblockplus/libadblockplus/android/AndroidWebRequestResourceWrapper.java b/libadblockplus-android/src/org/adblockplus/libadblockplus/android/AndroidWebRequestResourceWrapper.java
new file mode 100644
index 0000000000000000000000000000000000000000..4af10c8cfbabeee4ebfad686df38e9c8ae7dab60
--- /dev/null
+++ b/libadblockplus-android/src/org/adblockplus/libadblockplus/android/AndroidWebRequestResourceWrapper.java
@@ -0,0 +1,256 @@
+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-2016 Eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.adblockplus.libadblockplus.android;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.util.Log;
+
+import org.adblockplus.libadblockplus.HeaderEntry;
+import org.adblockplus.libadblockplus.ServerResponse;
+import org.adblockplus.libadblockplus.WebRequest;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * WebRequest wrapper to return request response from android resources for selected URLs
+ */
+public class AndroidWebRequestResourceWrapper extends WebRequest
+{
+  private static final String TAG = Utils.getTag(AndroidWebRequestResourceWrapper.class);
+
+  public static final String EASYLIST =
+    "https://easylist-downloads.adblockplus.org/easylist.txt";
+  public static final String EASYLIST_INDONESIAN =
+    "https://easylist-downloads.adblockplus.org/abpindo+easylist.txt";
+  public static final String EASYLIST_BULGARIAN =
+    "https://easylist-downloads.adblockplus.org/bulgarian_list+easylist.txt";
+  public static final String EASYLIST_CHINESE =
+    "https://easylist-downloads.adblockplus.org/easylistchina+easylist.txt";
+  public static final String EASYLIST_CZECH_SLOVAK =
+    "https://easylist-downloads.adblockplus.org/easylistczechslovak+easylist.txt";
+  public static final String EASYLIST_DUTCH =
+    "https://easylist-downloads.adblockplus.org/easylistdutch+easylist.txt";
+  public static final String EASYLIST_GERMAN =
+    "https://easylist-downloads.adblockplus.org/easylistgermany+easylist.txt";
+  public static final String EASYLIST_ISRAELI =
+    "https://easylist-downloads.adblockplus.org/israellist+easylist.txt";
+  public static final String EASYLIST_ITALIAN =
+    "https://easylist-downloads.adblockplus.org/easylistitaly+easylist.txt";
+  public static final String EASYLIST_LITHUANIAN =
+    "https://easylist-downloads.adblockplus.org/easylistlithuania+easylist.txt";
+  public static final String EASYLIST_LATVIAN =
+    "https://easylist-downloads.adblockplus.org/latvianlist+easylist.txt";
+  public static final String EASYLIST_ARABIAN_FRENCH =
+    "https://easylist-downloads.adblockplus.org/liste_ar+liste_fr+easylist.txt";
+  public static final String EASYLIST_FRENCH =
+    "https://easylist-downloads.adblockplus.org/liste_fr+easylist.txt";
+  public static final String EASYLIST_ROMANIAN =
+    "https://easylist-downloads.adblockplus.org/rolist+easylist.txt";
+  public static final String EASYLIST_RUSSIAN =
+    "https://easylist-downloads.adblockplus.org/ruadlist+easylist.txt";
+  public static final String ACCEPTABLE_ADS =
+    "https://easylist-downloads.adblockplus.org/exceptionrules.txt";
+
+  private Context context;
+  private WebRequest request;
+  private Map<String, Integer> urlToResourceIdMap;
+  private Storage storage;
+  private Listener listener;
+
+  /**
+   * Constructor
+   * @param context android context
+   * @param request wrapped request to perform the request if it's not preloaded subscription requested
+   * @param urlToResourceIdMap map URL -> android resource id for preloaded subscriptions
+   *                           See AndroidWebRequestResourceWrapper.EASYLIST_... constants
+   * @param storage Storage impl to remember served interceptions
+   */
+  public AndroidWebRequestResourceWrapper(Context context, WebRequest request,
+                                          Map<String, Integer> urlToResourceIdMap,
+                                          Storage storage)
+  {
+    this.context = context;
+    this.request = request;
+    this.urlToResourceIdMap = Collections.synchronizedMap(urlToResourceIdMap);
+    this.storage = storage;
+  }
+
+  public Listener getListener()
+  {
+    return listener;
+  }
+
+  public void setListener(Listener listener)
+  {
+    this.listener = listener;
+  }
+
+  @Override
+  public ServerResponse httpGET(String url, List<HeaderEntry> headers)
+  {
+    // since parameters may vary we need to ignore them
+    String urlWithoutParams = url.substring(0, url.indexOf("?"));
+    Integer resourceId = urlToResourceIdMap.get(urlWithoutParams);
+
+    if (resourceId != null)
+    {
+      if (!storage.contains(urlWithoutParams))
+      {
+        Log.w(TAG, "Intercepting request for " + url + " with resource #" + resourceId.intValue());
+        ServerResponse response = buildResourceContentResponse(resourceId);
+        storage.put(urlWithoutParams);
+
+        if (listener != null)
+        {
+          listener.onIntercepted(url, resourceId);
+        }
+
+        return response;
+      }
+      else
+      {
+        Log.d(TAG, "Skip intercepting");
+      }
+    }
+
+    // delegate to wrapper request
+    return request.httpGET(url, headers);
+  }
+
+  protected String readResourceContent(int resourceId) throws IOException
+  {
+    Log.d(TAG, "Reading from resource ...");
+
+    InputStream is = null;
+
+    try
+    {
+      is = context.getResources().openRawResource(resourceId);
+      BufferedReader br = new BufferedReader(new InputStreamReader(is));
+      StringBuilder sb = new StringBuilder();
+      String line;
+      boolean firstLine = true;
+      while ((line = br.readLine()) != null)
+      {
+        if (firstLine)
+        {
+          firstLine = false;
+        }
+        else
+        {
+          sb.append("\r\n");
+        }
+        sb.append(line);
+      }
+
+      Log.d(TAG, "Resource read (" + sb.length() + " bytes)");
+      return sb.toString();
+    }
+    finally
+    {
+      if (is != null)
+      {
+        is.close();
+      }
+    }
+  }
+
+  protected ServerResponse buildResourceContentResponse(int resourceId)
+  {
+    ServerResponse response = new ServerResponse();
+    try
+    {
+      response.setResponse(readResourceContent(resourceId));
+      response.setResponseStatus(200);
+      response.setStatus(ServerResponse.NsStatus.OK);
+    }
+    catch (IOException e)
+    {
+      Log.e(TAG, "Error injecting response", e);
+      response.setStatus(ServerResponse.NsStatus.ERROR_FAILURE);
+    }
+
+    return response;
+  }
+
+  @Override
+  public void dispose()
+  {
+    request.dispose();
+    super.dispose();
+  }
+
+  /**
+   * Listener for events
+   */
+  public interface Listener
+  {
+    void onIntercepted(String url, int resourceId);
+  }
+
+  /**
+   * Interface to remember intercepted subscription requests
+   */
+  public interface Storage
+  {
+    void put(String url);
+    boolean contains(String url);
+  }
+
+  /**
+   * Storage impl in Shared Preferences
+   */
+  public static class SharedPrefsStorage implements Storage
+  {
+    private static final String URLS = "urls";
+
+    private SharedPreferences prefs;
+    private Set<String> urls;
+
+    public SharedPrefsStorage(SharedPreferences prefs)
+    {
+      this.prefs = prefs;
+      this.urls = prefs.getStringSet(URLS, new HashSet<String>());
+    }
+
+    @Override
+    public synchronized void put(String url)
+    {
+      urls.add(url);
+
+      prefs
+        .edit()
+        .putStringSet(URLS, urls)
+        .commit();
+    }
+
+    @Override
+    public synchronized boolean contains(String url)
+    {
+      return urls.contains(url);
+    }
+  }
+}