material-components_material-components-android/lib/java/com/google/android/material/internal/CheckableGroup.java

/*
 * Copyright 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.android.material.internal;

import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP;

import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.IdRes;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RestrictTo;
import androidx.annotation.UiThread;
import com.google.android.material.internal.MaterialCheckable.OnCheckedChangeListener;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * A helper class to support check group logic.
 *
 * @hide
 */
@UiThread
@RestrictTo(LIBRARY_GROUP)
public class CheckableGroup<T extends MaterialCheckable<T>> {
  private final Map<Integer, T> checkables = new HashMap<>();
  private final Set<Integer> checkedIds = new HashSet<>();

  private OnCheckedStateChangeListener onCheckedStateChangeListener;
  private boolean singleSelection;
  private boolean selectionRequired;

  public void setSingleSelection(boolean singleSelection) {
    if (this.singleSelection != singleSelection) {
      this.singleSelection = singleSelection;
      clearCheck();
    }
  }

  public boolean isSingleSelection() {
    return singleSelection;
  }

  public void setSelectionRequired(boolean selectionRequired) {
    this.selectionRequired = selectionRequired;
  }

  public boolean isSelectionRequired() {
    return selectionRequired;
  }

  public void setOnCheckedStateChangeListener(@Nullable OnCheckedStateChangeListener listener) {
    this.onCheckedStateChangeListener = listener;
  }

  public void addCheckable(T checkable) {
    checkables.put(checkable.getId(), checkable);
    if (checkable.isChecked()) {
      checkInternal(checkable);
    }
    checkable.setInternalOnCheckedChangeListener(new OnCheckedChangeListener<T>() {
      @Override
      public void onCheckedChanged(T checkable, boolean isChecked) {
        if (isChecked ? checkInternal(checkable) : uncheckInternal(checkable, selectionRequired)) {
          onCheckedStateChanged();
        }
      }
    });
  }

  public void removeCheckable(T checkable) {
    checkable.setInternalOnCheckedChangeListener(null);
    checkables.remove(checkable.getId());
    checkedIds.remove(checkable.getId());
  }

  public void check(@IdRes int id) {
    MaterialCheckable<T> checkable = checkables.get(id);
    if (checkable == null) {
      return;
    }
    if (checkInternal(checkable)) {
      onCheckedStateChanged();
    }
  }

  public void uncheck(@IdRes int id) {
    MaterialCheckable<T> checkable = checkables.get(id);
    if (checkable == null) {
      return;
    }
    if (uncheckInternal(checkable, selectionRequired)) {
      onCheckedStateChanged();
    }
  }

  public void clearCheck() {
    boolean checkedStateChanged = !checkedIds.isEmpty();
    for (MaterialCheckable<T> checkable : checkables.values()) {
      uncheckInternal(checkable, false);
    }
    if (checkedStateChanged) {
      onCheckedStateChanged();
    }
  }

  @IdRes
  public int getSingleCheckedId() {
    return singleSelection && !checkedIds.isEmpty() ? checkedIds.iterator().next() : View.NO_ID;
  }

  @NonNull
  public Set<Integer> getCheckedIds() {
    return new HashSet<>(checkedIds);
  }

  @NonNull
  public List<Integer> getCheckedIdsSortedByChildOrder(@NonNull ViewGroup parent) {
    Set<Integer> checkedIds = getCheckedIds();
    List<Integer> sortedCheckedIds = new ArrayList<>();
    for (int i = 0; i < parent.getChildCount(); i++) {
      View child = parent.getChildAt(i);
      if (child instanceof MaterialCheckable<?> && checkedIds.contains(child.getId())) {
        sortedCheckedIds.add(child.getId());
      }
    }
    return sortedCheckedIds;
  }

  private boolean checkInternal(@NonNull MaterialCheckable<T> checkable) {
    int id = checkable.getId();
    if (checkedIds.contains(id)) {
      return false;
    }
    MaterialCheckable<T> singleCheckedItem = checkables.get(getSingleCheckedId());
    if (singleCheckedItem != null) {
      uncheckInternal(singleCheckedItem, false);
    }
    boolean checkedStateChanged = checkedIds.add(id);
    if (!checkable.isChecked()) {
      checkable.setChecked(true);
    }
    return checkedStateChanged;
  }

  private boolean uncheckInternal(
      @NonNull MaterialCheckable<T> checkable, boolean selectionRequired) {
    int id = checkable.getId();
    if (!checkedIds.contains(id)) {
      return false;
    }
    if (selectionRequired && checkedIds.size() == 1 && checkedIds.contains(id)) {
      // It's the only checked item, cannot be unchecked if selection is required
      checkable.setChecked(true);
      return false;
    }
    boolean checkedStateChanged = checkedIds.remove(id);
    if (checkable.isChecked()) {
      checkable.setChecked(false);
    }
    return checkedStateChanged;
  }

  private void onCheckedStateChanged() {
    if (onCheckedStateChangeListener != null) {
      onCheckedStateChangeListener.onCheckedStateChanged(getCheckedIds());
    }
  }

  /**
   * A listener interface for checked state changes.
   */
  public interface OnCheckedStateChangeListener {
    void onCheckedStateChanged(@NonNull Set<Integer> checkedIds);
  }
}