/*
 * Copyright (C) 2016 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
 *
 *      http://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.exoplayer2.source;

import android.os.Parcel;
import android.os.Parcelable;
import android.support.annotation.Nullable;
import com.google.android.exoplayer2.C;
import java.util.Arrays;

/** An array of {@link TrackGroup}s exposed by a {@link MediaPeriod}. */
public final class TrackGroupArray implements Parcelable {

  /**
   * The empty array.
   */
  public static final TrackGroupArray EMPTY = new TrackGroupArray();

  /**
   * The number of groups in the array. Greater than or equal to zero.
   */
  public final int length;

  private final TrackGroup[] trackGroups;

  // Lazily initialized hashcode.
  private int hashCode;

  /**
   * @param trackGroups The groups. Must not be null or contain null elements, but may be empty.
   */
  public TrackGroupArray(TrackGroup... trackGroups) {
    this.trackGroups = trackGroups;
    this.length = trackGroups.length;
  }

  /* package */ TrackGroupArray(Parcel in) {
    length = in.readInt();
    trackGroups = new TrackGroup[length];
    for (int i = 0; i < length; i++) {
      trackGroups[i] = in.readParcelable(TrackGroup.class.getClassLoader());
    }
  }

  /**
   * Returns the group at a given index.
   *
   * @param index The index of the group.
   * @return The group.
   */
  public TrackGroup get(int index) {
    return trackGroups[index];
  }

  /**
   * Returns the index of a group within the array.
   *
   * @param group The group.
   * @return The index of the group, or {@link C#INDEX_UNSET} if no such group exists.
   */
  @SuppressWarnings("ReferenceEquality")
  public int indexOf(TrackGroup group) {
    for (int i = 0; i < length; i++) {
      // Suppressed reference equality warning because this is looking for the index of a specific
      // TrackGroup object, not the index of a potential equal TrackGroup.
      if (trackGroups[i] == group) {
        return i;
      }
    }
    return C.INDEX_UNSET;
  }

  /**
   * Returns whether this track group array is empty.
   */
  public boolean isEmpty() {
    return length == 0;
  }

  @Override
  public int hashCode() {
    if (hashCode == 0) {
      hashCode = Arrays.hashCode(trackGroups);
    }
    return hashCode;
  }

  @Override
  public boolean equals(@Nullable Object obj) {
    if (this == obj) {
      return true;
    }
    if (obj == null || getClass() != obj.getClass()) {
      return false;
    }
    TrackGroupArray other = (TrackGroupArray) obj;
    return length == other.length && Arrays.equals(trackGroups, other.trackGroups);
  }

  // Parcelable implementation.

  @Override
  public int describeContents() {
    return 0;
  }

  @Override
  public void writeToParcel(Parcel dest, int flags) {
    dest.writeInt(length);
    for (int i = 0; i < length; i++) {
      dest.writeParcelable(trackGroups[i], 0);
    }
  }

  public static final Parcelable.Creator<TrackGroupArray> CREATOR =
      new Parcelable.Creator<TrackGroupArray>() {

        @Override
        public TrackGroupArray createFromParcel(Parcel in) {
          return new TrackGroupArray(in);
        }

        @Override
        public TrackGroupArray[] newArray(int size) {
          return new TrackGroupArray[size];
        }
      };
}
