1/*
2 * Copyright (C) 2012 Google Inc.
3 * Licensed to The Android Open Source Project.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 *      http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17package com.android.mail.preferences;
18
19import android.content.Context;
20
21import java.util.concurrent.atomic.AtomicBoolean;
22
23/**
24 * Interface to allow migrating preferences from other projects into the UnifiedEmail code, so apps
25 * can slowly move their preferences into the shared code.
26 */
27public abstract class BasePreferenceMigrator {
28    /** If <code>true</code>, we have not attempted a migration since the app started. */
29    private static final AtomicBoolean sMigrationNecessary = new AtomicBoolean(true);
30
31    public final boolean performMigration(
32            final Context context, final int oldVersion, final int newVersion) {
33        // Ensure we only run this once
34        if (sMigrationNecessary.getAndSet(false)) {
35            migrate(context, oldVersion, newVersion);
36            return true;
37        }
38
39        return false;
40    }
41
42    /**
43     * Migrates preferences to UnifiedEmail.
44     *
45     * @param oldVersion The previous version of UnifiedEmail's preferences
46     * @param newVersion The new version of UnifiedEmail's preferences
47     */
48    protected abstract void migrate(final Context context, int oldVersion, int newVersion);
49}
50