/*
 * Copyright (C) 2021 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 androidx.media3.datasource;

import androidx.annotation.Nullable;
import androidx.media3.common.C;
import androidx.media3.common.util.UnstableApi;
import java.io.IOException;
import java.util.Arrays;

/** Utility methods for {@link DataSource}. */
@UnstableApi
public final class DataSourceUtil {

  private DataSourceUtil() {}

  /**
   * Reads data from the specified opened {@link DataSource} until it ends, and returns a byte array
   * containing the read data.
   *
   * @param dataSource The source from which to read.
   * @return The concatenation of all read data.
   * @throws IOException If an error occurs reading from the source.
   */
  public static byte[] readToEnd(DataSource dataSource) throws IOException {
    byte[] data = new byte[1024];
    int position = 0;
    int bytesRead = 0;
    while (bytesRead != C.RESULT_END_OF_INPUT) {
      if (position == data.length) {
        data = Arrays.copyOf(data, data.length * 2);
      }
      bytesRead = dataSource.read(data, position, data.length - position);
      if (bytesRead != C.RESULT_END_OF_INPUT) {
        position += bytesRead;
      }
    }
    return Arrays.copyOf(data, position);
  }

  /**
   * Reads {@code length} bytes from the specified opened {@link DataSource}, and returns a byte
   * array containing the read data.
   *
   * @param dataSource The source from which to read.
   * @param length The number of bytes to read.
   * @return The read data.
   * @throws IOException If an error occurs reading from the source.
   * @throws IllegalStateException If the end of the source was reached before {@code length} bytes
   *     could be read.
   */
  public static byte[] readExactly(DataSource dataSource, int length) throws IOException {
    byte[] data = new byte[length];
    int position = 0;
    while (position < length) {
      int bytesRead = dataSource.read(data, position, data.length - position);
      if (bytesRead == C.RESULT_END_OF_INPUT) {
        throw new IllegalStateException(
            "Not enough data could be read: " + position + " < " + length);
      }
      position += bytesRead;
    }
    return data;
  }

  /**
   * Closes a {@link DataSource}, suppressing any {@link IOException} that may occur.
   *
   * @param dataSource The {@link DataSource} to close.
   */
  public static void closeQuietly(@Nullable DataSource dataSource) {
    try {
      if (dataSource != null) {
        dataSource.close();
      }
    } catch (IOException e) {
      // Ignore.
    }
  }
}