content: /*
   * Copyright (C) 2017 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.metadata.emsg;
  
  import java.io.ByteArrayOutputStream;
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  /**
   * Encodes data that can be decoded by {@link EventMessageDecoder}. This class isn't thread safe.
   */
  public final class EventMessageEncoder {
  
    private final ByteArrayOutputStream byteArrayOutputStream;
    private final DataOutputStream dataOutputStream;
  
    public EventMessageEncoder() {
      byteArrayOutputStream = new ByteArrayOutputStream(512);
      dataOutputStream = new DataOutputStream(byteArrayOutputStream);
    }
  
    /**
     * Encodes an {@link EventMessage} to a byte array that can be decoded by {@link
     * EventMessageDecoder}.
     *
     * @param eventMessage The event message to be encoded.
     * @return The serialized byte array.
     */
    public byte[] encode(EventMessage eventMessage) {
      byteArrayOutputStream.reset();
      try {
        writeNullTerminatedString(dataOutputStream, eventMessage.schemeIdUri);
        String nonNullValue = eventMessage.value != null ? eventMessage.value : "";
        writeNullTerminatedString(dataOutputStream, nonNullValue);
        dataOutputStream.writeLong(eventMessage.durationMs);
        dataOutputStream.writeLong(eventMessage.id);
        dataOutputStream.write(eventMessage.messageData);
        dataOutputStream.flush();
        return byteArrayOutputStream.toByteArray();
      } catch (IOException e) {
        // Should never happen.
        throw new RuntimeException(e);
      }
    }
  
    private static void writeNullTerminatedString(DataOutputStream dataOutputStream, String value)
        throws IOException {
      dataOutputStream.writeBytes(value);
      dataOutputStream.writeByte(0);
    }
  }
  