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/*_##########################################################################
  _##
  _##  Copyright (C) 2016-2017  Pcap4J.org
  _##
  _##########################################################################
*/

package org.pcap4j.packet;

import static org.pcap4j.util.ByteArrays.*;

import java.net.Inet4Address;
import java.net.UnknownHostException;
import org.pcap4j.packet.DnsResourceRecord.DnsRData;
import org.pcap4j.util.ByteArrays;

/**
 * DNS A RDATA
 *
 *  * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 * |                    ADDRESS                    |
 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
 *
 * where:
 *
 * ADDRESS         A 32 bit Internet address.
 * 
 *
 * @see RFC 1035
 * @author Kaito Yamada
 * @since pcap4j 1.7.1
 */
public final class DnsRDataA implements DnsRData {

  /** */
  private static final long serialVersionUID = 6539022022231148667L;

  private final Inet4Address address;
  private final boolean addressPlainText;

  /**
   * A static factory method. This method validates the arguments by {@link
   * ByteArrays#validateBounds(byte[], int, int)}, which may throw exceptions undocumented here.
   *
   * @param rawData rawData
   * @param offset offset
   * @param length length
   * @return a new DnsRDataA object.
   * @throws IllegalRawDataException if parsing the raw data fails.
   */
  public static DnsRDataA newInstance(byte[] rawData, int offset, int length)
      throws IllegalRawDataException {
    ByteArrays.validateBounds(rawData, offset, length);
    return new DnsRDataA(rawData, offset, length);
  }

  private DnsRDataA(byte[] rawData, int offset, int length) throws IllegalRawDataException {
    if (length < INET4_ADDRESS_SIZE_IN_BYTES) {
      StringBuilder sb = new StringBuilder(200);
      sb.append("The data is too short to build a DnsRDataA (Min: ")
          .append(INET4_ADDRESS_SIZE_IN_BYTES)
          .append(" bytes). data: ")
          .append(ByteArrays.toHexString(rawData, " "))
          .append(", offset: ")
          .append(offset)
          .append(", length: ")
          .append(length);
      throw new IllegalRawDataException(sb.toString());
    }

    if (length == INET4_ADDRESS_SIZE_IN_BYTES) {
      this.address = ByteArrays.getInet4Address(rawData, offset);
      this.addressPlainText = false;
    } else {
      String addr = new String(ByteArrays.getSubArray(rawData, offset, length));
      try {
        byte[] octets = ByteArrays.parseInet4Address(addr);
        this.address = (Inet4Address) Inet4Address.getByAddress(octets);
      } catch (IllegalArgumentException e) {
        StringBuilder sb = new StringBuilder(200);
        sb.append("Couldn't get an Inet4Address from ")
            .append(addr)
            .append(". data: ")
            .append(ByteArrays.toHexString(rawData, " "))
            .append(", offset: ")
            .append(offset)
            .append(", length: ")
            .append(length);
        throw new IllegalRawDataException(sb.toString(), e);
      } catch (UnknownHostException e) {
        throw new AssertionError("Never get here.");
      }
      this.addressPlainText = true;
    }
  }

  private DnsRDataA(Builder builder) {
    if (builder == null || builder.address == null) {
      StringBuilder sb = new StringBuilder();
      sb.append("builder: ").append(builder).append(" builder.address: ").append(builder.address);
      throw new NullPointerException(sb.toString());
    }

    this.address = builder.address;
    this.addressPlainText = builder.addressPlainText;
  }

  /** @return address */
  public Inet4Address getAddress() {
    return address;
  }

  /** @return true if the ADDRESS field is a plain text; false otherwise. */
  public boolean isAddressPlainText() {
    return addressPlainText;
  }

  @Override
  public int length() {
    if (addressPlainText) {
      return address.getHostAddress().length();
    } else {
      return INET4_ADDRESS_SIZE_IN_BYTES;
    }
  }

  @Override
  public byte[] getRawData() {
    if (addressPlainText) {
      return address.getHostAddress().getBytes();
    } else {
      return address.getAddress();
    }
  }

  /** @return a new Builder object populated with this object's fields. */
  public Builder getBuilder() {
    return new Builder(this);
  }

  @Override
  public String toString() {
    return convertToString("", null);
  }

  @Override
  public String toString(String indent) {
    return convertToString(indent, null);
  }

  @Override
  public String toString(String indent, byte[] headerRawData) {
    if (headerRawData == null) {
      throw new NullPointerException("headerRawData is null.");
    }
    return convertToString(indent, headerRawData);
  }

  private String convertToString(String indent, byte[] headerRawData) {
    StringBuilder sb = new StringBuilder();
    String ls = System.getProperty("line.separator");

    sb.append(indent)
        .append("A RDATA:")
        .append(ls)
        .append(indent)
        .append("  ADDRESS: ")
        .append(address.getHostAddress())
        .append(" (")
        .append(addressPlainText ? "text" : "encoded")
        .append(")")
        .append(ls);

    return sb.toString();
  }

  @Override
  public int hashCode() {
    int result = address.hashCode();
    result = 31 * result + (addressPlainText ? 1 : 0);
    return result;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }

    DnsRDataA dnsRDataA = (DnsRDataA) o;

    if (addressPlainText != dnsRDataA.addressPlainText) {
      return false;
    }
    return address.equals(dnsRDataA.address);
  }

  /**
   * @author Kaito Yamada
   * @since pcap4j 1.7.1
   */
  public static final class Builder {

    private Inet4Address address;
    private boolean addressPlainText;

    /** */
    public Builder() {}

    private Builder(DnsRDataA obj) {
      this.address = obj.address;
      this.addressPlainText = obj.addressPlainText;
    }

    /**
     * @param address address
     * @return this Builder object for method chaining.
     */
    public Builder address(Inet4Address address) {
      this.address = address;
      return this;
    }

    /**
     * @param addressPlainText addressPlainText
     * @return this Builder object for method chaining.
     */
    public Builder addressPlainText(boolean addressPlainText) {
      this.addressPlainText = addressPlainText;
      return this;
    }

    /** @return a new DnsRDataA object. */
    public DnsRDataA build() {
      return new DnsRDataA(this);
    }
  }
}