/*
 * Copyright (C) 2014 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.exoplayer;

import java.io.IOException;

/**
 * A stream of media data.
 */
public interface TrackStream {

  /**
   * Nothing was read.
   */
  int NOTHING_READ = -1;
  /**
   * The buffer was populated.
   */
  int BUFFER_READ = -2;
  /**
   * A format was read.
   */
  int FORMAT_READ = -3;

  /**
   * Returns whether data is available to be read.
   * <p>
   * Note: If the stream has ended then a buffer with the end of stream flag can always be read from
   * {@link #readData(FormatHolder, DecoderInputBuffer)}. Hence an ended stream is always ready.
   *
   * @return True if data is available to be read. False otherwise.
   */
  boolean isReady();

  /**
   * Throws an error that's preventing data from being read. Does nothing if no such error exists.
   *
   * @throws IOException The underlying error.
   */
  void maybeThrowError() throws IOException;

  /**
   * Attempts to read from the stream.
   *
   * @param formatHolder A {@link FormatHolder} to populate in the case of reading a format.
   * @param buffer A {@link DecoderInputBuffer} to populate in the case of reading a sample or the
   *     end of the stream. If the end of the stream has been reached, the
   *     {@link C#BUFFER_FLAG_END_OF_STREAM} flag will be set on the buffer.
   * @return The result, which can be {@link #NOTHING_READ}, {@link #FORMAT_READ} or
   *     {@link #BUFFER_READ}.
   */
  int readData(FormatHolder formatHolder, DecoderInputBuffer buffer);

}