/*
 * 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.extractor;

import com.google.android.exoplayer2.util.Util;

/**
 * Defines chunks of samples within a media stream.
 */
public final class ChunkIndex implements SeekMap {

  /**
   * The number of chunks.
   */
  public final int length;

  /**
   * The chunk sizes, in bytes.
   */
  public final int[] sizes;

  /**
   * The chunk byte offsets.
   */
  public final long[] offsets;

  /**
   * The chunk durations, in microseconds.
   */
  public final long[] durationsUs;

  /**
   * The start time of each chunk, in microseconds.
   */
  public final long[] timesUs;

  private final long durationUs;

  /**
   * @param sizes The chunk sizes, in bytes.
   * @param offsets The chunk byte offsets.
   * @param durationsUs The chunk durations, in microseconds.
   * @param timesUs The start time of each chunk, in microseconds.
   */
  public ChunkIndex(int[] sizes, long[] offsets, long[] durationsUs, long[] timesUs) {
    this.sizes = sizes;
    this.offsets = offsets;
    this.durationsUs = durationsUs;
    this.timesUs = timesUs;
    length = sizes.length;
    if (length > 0) {
      durationUs = durationsUs[length - 1] + timesUs[length - 1];
    } else {
      durationUs = 0;
    }
  }

  /**
   * Obtains the index of the chunk corresponding to a given time.
   *
   * @param timeUs The time, in microseconds.
   * @return The index of the corresponding chunk.
   */
  public int getChunkIndex(long timeUs) {
    return Util.binarySearchFloor(timesUs, timeUs, true, true);
  }

  // SeekMap implementation.

  @Override
  public boolean isSeekable() {
    return true;
  }

  @Override
  public long getDurationUs() {
    return durationUs;
  }

  @Override
  public long getPosition(long timeUs) {
    return offsets[getChunkIndex(timeUs)];
  }

}
