Move DownloadSharedPreferenceEntry handling into another class

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadSharedPreferenceHelper.java

+// Copyright 2017 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.
+
+package org.chromium.chrome.browser.download;
+
+import android.content.SharedPreferences;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.VisibleForTesting;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * Class for maintaining all entries of DownloadSharedPreferenceEntry.
+ */
+public class DownloadSharedPreferenceHelper {
+    @VisibleForTesting
+    static final String KEY_PENDING_DOWNLOAD_NOTIFICATIONS = "PendingDownloadNotifications";
+    private final List<DownloadSharedPreferenceEntry> mDownloadSharedPreferenceEntries =
+            new ArrayList<DownloadSharedPreferenceEntry>();
+    private SharedPreferences mSharedPrefs;
+
+    // "Initialization on demand holder idiom"
+    private static class LazyHolder {
+        private static final DownloadSharedPreferenceHelper INSTANCE =
+                new DownloadSharedPreferenceHelper();
+    }
+
+    /**
+     * Creates DownloadSharedPreferenceHelper.
+     */
+    public static DownloadSharedPreferenceHelper getInstance() {
+        ThreadUtils.assertOnUiThread();
+        return LazyHolder.INSTANCE;
+    }
+
+    private DownloadSharedPreferenceHelper() {
+        mSharedPrefs = ContextUtils.getAppSharedPreferences();
+        parseDownloadSharedPrefs();
+    }
+
+    /**
+     * Adds a DownloadSharedPreferenceEntry to SharedPrefs. If an entry with the GUID already exists
+     * in SharedPrefs, update it if it has changed.
+     * @param pendingEntry A DownloadSharedPreferenceEntry to be added.
+     */
+    public void addOrReplaceSharedPreferenceEntry(DownloadSharedPreferenceEntry pendingEntry) {
+        ThreadUtils.assertOnUiThread();
+        Iterator<DownloadSharedPreferenceEntry> iterator =
+                mDownloadSharedPreferenceEntries.iterator();
+        while (iterator.hasNext()) {
+            DownloadSharedPreferenceEntry entry = iterator.next();
+            if (entry.downloadGuid.equals(pendingEntry.downloadGuid)) {
+                if (entry.equals(pendingEntry)) return;
+                iterator.remove();
+                break;
+            }
+        }
+        mDownloadSharedPreferenceEntries.add(pendingEntry);
+        storeDownloadSharedPreferenceEntries();
+    }
+
+    /**
+     * Removes a DownloadSharedPreferenceEntry from SharedPrefs given by the GUID.
+     * @param guid Download GUID to be removed.
+     */
+    public void removeSharedPreferenceEntry(String guid) {
+        ThreadUtils.assertOnUiThread();
+        Iterator<DownloadSharedPreferenceEntry> iterator =
+                mDownloadSharedPreferenceEntries.iterator();
+        boolean found = false;
+        while (iterator.hasNext()) {
+            DownloadSharedPreferenceEntry entry = iterator.next();
+            if (entry.downloadGuid.equals(guid)) {
+                iterator.remove();
+                found = true;
+                break;
+            }
+        }
+        if (found) {
+            storeDownloadSharedPreferenceEntries();
+        }
+    }
+
+    /**
+     * Gets a list of stored SharedPreference entries.
+     * @param a list of DownloadSharedPreferenceEntry stored in SharedPrefs.
+     */
+    public List<DownloadSharedPreferenceEntry> getEntries() {
+        ThreadUtils.assertOnUiThread();
+        return mDownloadSharedPreferenceEntries;
+    }
+
+    /**
+     * Parse a list of the DownloadSharedPreferenceEntry from |mSharedPrefs|.
+     */
+    private void parseDownloadSharedPrefs() {
+        if (!mSharedPrefs.contains(KEY_PENDING_DOWNLOAD_NOTIFICATIONS)) return;
+        Set<String> entries = DownloadManagerService.getStoredDownloadInfo(
+                mSharedPrefs, KEY_PENDING_DOWNLOAD_NOTIFICATIONS);
+        for (String entryString : entries) {
+            DownloadSharedPreferenceEntry entry =
+                    DownloadSharedPreferenceEntry.parseFromString(entryString);
+            if (entry.notificationId > 0) {
+                mDownloadSharedPreferenceEntries.add(
+                        DownloadSharedPreferenceEntry.parseFromString(entryString));
+            }
+        }
+    }
+
+    /**
+     * Gets a DownloadSharedPreferenceEntry that has the given GUID.
+     * @param guid GUID to query.
+     * @return a DownloadSharedPreferenceEntry that has the specified GUID.
+     */
+    public DownloadSharedPreferenceEntry getDownloadSharedPreferenceEntry(String guid) {
+        ThreadUtils.assertOnUiThread();
+        for (int i = 0; i < mDownloadSharedPreferenceEntries.size(); ++i) {
+            if (mDownloadSharedPreferenceEntries.get(i).downloadGuid.equals(guid)) {
+                return mDownloadSharedPreferenceEntries.get(i);
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Helper method to store all the SharedPreferences entries.
+     */
+    private void storeDownloadSharedPreferenceEntries() {
+        Set<String> entries = new HashSet<String>();
+        for (int i = 0; i < mDownloadSharedPreferenceEntries.size(); ++i) {
+            entries.add(mDownloadSharedPreferenceEntries.get(i).getSharedPreferenceString());
+        }
+        DownloadManagerService.storeDownloadInfo(
+                mSharedPrefs, KEY_PENDING_DOWNLOAD_NOTIFICATIONS, entries);
+    }
+}