1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License
15 */
16
17package com.android.dialer.common;
18
19import android.support.annotation.CheckResult;
20import android.support.annotation.NonNull;
21import android.support.annotation.Nullable;
22import android.support.annotation.VisibleForTesting;
23import android.support.v4.app.Fragment;
24import android.support.v4.app.FragmentActivity;
25
26/** Utility methods for working with Fragments */
27public class FragmentUtils {
28
29  private static Object parentForTesting;
30
31  @VisibleForTesting(otherwise = VisibleForTesting.NONE)
32  public static void setParentForTesting(Object parentForTesting) {
33    FragmentUtils.parentForTesting = parentForTesting;
34  }
35
36  /**
37   * @return The parent of frag that implements the callbackInterface or null if no such parent can
38   *     be found
39   */
40  @CheckResult(suggest = "#checkParent(Fragment, Class)}")
41  @Nullable
42  public static <T> T getParent(@NonNull Fragment fragment, @NonNull Class<T> callbackInterface) {
43    if (callbackInterface.isInstance(parentForTesting)) {
44      @SuppressWarnings("unchecked") // Casts are checked using runtime methods
45      T parent = (T) parentForTesting;
46      return parent;
47    }
48
49    Fragment parentFragment = fragment.getParentFragment();
50    if (callbackInterface.isInstance(parentFragment)) {
51      @SuppressWarnings("unchecked") // Casts are checked using runtime methods
52      T parent = (T) parentFragment;
53      return parent;
54    } else {
55      FragmentActivity activity = fragment.getActivity();
56      if (callbackInterface.isInstance(activity)) {
57        @SuppressWarnings("unchecked") // Casts are checked using runtime methods
58        T parent = (T) activity;
59        return parent;
60      }
61    }
62    return null;
63  }
64
65  /** Returns the parent or throws. Should perform check elsewhere(e.g. onAttach, newInstance). */
66  @NonNull
67  public static <T> T getParentUnsafe(
68      @NonNull Fragment fragment, @NonNull Class<T> callbackInterface) {
69    return Assert.isNotNull(getParent(fragment, callbackInterface));
70  }
71
72  /**
73   * Ensures fragment has a parent that implements the corresponding interface
74   *
75   * @param frag The Fragment whose parents are to be checked
76   * @param callbackInterface The interface class that a parent should implement
77   * @throws IllegalStateException if no parents are found that implement callbackInterface
78   */
79  public static void checkParent(@NonNull Fragment frag, @NonNull Class<?> callbackInterface)
80      throws IllegalStateException {
81    if (parentForTesting != null) {
82      return;
83    }
84    if (FragmentUtils.getParent(frag, callbackInterface) == null) {
85      String parent =
86          frag.getParentFragment() == null
87              ? frag.getActivity().getClass().getName()
88              : frag.getParentFragment().getClass().getName();
89      throw new IllegalStateException(
90          frag.getClass().getName()
91              + " must be added to a parent"
92              + " that implements "
93              + callbackInterface.getName()
94              + ". Instead found "
95              + parent);
96    }
97  }
98}
99