/*
    * Copyright 2020 The Netty Project
    *
    * The Netty Project licenses this file to you 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:
    *
    * https://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 io.netty.handler.pcap;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  import java.io.Closeable;
  import java.io.IOException;
  import java.io.OutputStream;
  
  final class PcapWriter implements Closeable {
  
      /**
       * Logger
       */
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(PcapWriter.class);
  
      private final PcapWriteHandler pcapWriteHandler;
  
      /**
       * Reference declared so that we can use this as mutex in clean way.
       */
      private final OutputStream outputStream;
  
      /**
       * This uses {@link OutputStream} for writing Pcap data.
       *
       * @throws IOException If {@link OutputStream#write(byte[])} throws an exception
       */
      PcapWriter(PcapWriteHandler pcapWriteHandler) throws IOException {
          this.pcapWriteHandler = pcapWriteHandler;
          outputStream = pcapWriteHandler.outputStream();
  
          // If OutputStream is not shared then we have to write Global Header.
          if (!pcapWriteHandler.sharedOutputStream()) {
              PcapHeaders.writeGlobalHeader(pcapWriteHandler.outputStream());
          }
      }
  
      /**
       * Write Packet in Pcap OutputStream.
       *
       * @param packetHeaderBuf Packer Header {@link ByteBuf}
       * @param packet          Packet
       * @throws IOException If {@link OutputStream#write(byte[])} throws an exception
       */
      void writePacket(ByteBuf packetHeaderBuf, ByteBuf packet) throws IOException {
          if (pcapWriteHandler.state() == State.CLOSED) {
              logger.debug("Pcap Write attempted on closed PcapWriter");
          }
  
          long timestamp = System.currentTimeMillis();
  
          PcapHeaders.writePacketHeader(
                  packetHeaderBuf,
                  (int) (timestamp / 1000L),
                  (int) (timestamp % 1000L * 1000L),
                  packet.readableBytes(),
                  packet.readableBytes()
          );
  
          if (pcapWriteHandler.sharedOutputStream()) {
              synchronized (outputStream) {
                  packetHeaderBuf.readBytes(outputStream, packetHeaderBuf.readableBytes());
                  packet.readBytes(outputStream, packet.readableBytes());
              }
          } else {
              packetHeaderBuf.readBytes(outputStream, packetHeaderBuf.readableBytes());
              packet.readBytes(outputStream, packet.readableBytes());
          }
      }
  
      @Override
      public String toString() {
          return "PcapWriter{" +
                  "outputStream=" + outputStream +
                  '}';
      }
  
      @Override
      public void close() throws IOException {
          if (pcapWriteHandler.state() == State.CLOSED) {
              logger.debug("PcapWriter is already closed");
          } else {
             if (pcapWriteHandler.sharedOutputStream()) {
                 synchronized (outputStream) {
                     outputStream.flush();
                 }
             } else {
                 outputStream.flush();
                 outputStream.close();
             }
             pcapWriteHandler.markClosed();
             logger.debug("PcapWriter is now closed");
         }
     }
 }