/*
    * Copyright 2019 the original author or authors.
    *
    * 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 org.bremersee.dccon.repository.ldap.transcoder;
  
  import java.io.ByteArrayInputStream;
  import java.io.DataInputStream;
  import java.io.IOException;
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.function.Supplier;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.commons.io.IOUtils;
  import org.bremersee.dccon.model.DnsRecord;
  import org.bremersee.exception.ServiceException;
  import org.ldaptive.io.Hex;
  import org.springframework.util.StringUtils;
  
  /**
   * The dns record data mapper.
   *
   * @author Christian Bremer
   */
  @Slf4j
  public abstract class DnsRecordDataMapper {
  
    private DnsRecordDataMapper() {
    }
  
    /**
     * Parse a dns record.
     *
     * @param data the data
     * @param dnsRecordSupplier the dns record supplier
     * @return the dns record
     */
    public static DnsRecord parseA(final byte[] data, final Supplier<DnsRecord> dnsRecordSupplier) {
      final DnsRecord dnsRecord = dnsRecordSupplier.get();
      if (data.length >= 4) {
        try (DataInputStream dis = new DataInputStream(new ByteArrayInputStream(data))) {
          String ip = String.valueOf(dis.readUnsignedByte())
              + '.'
              + dis.readUnsignedByte()
              + '.'
              + dis.readUnsignedByte()
              + '.'
              + dis.readUnsignedByte();
          dnsRecord.setRecordValue(ip);
        } catch (IOException ioe) {
          final ServiceException se = ServiceException.internalServerError(
              "Parsing data of A record failed.",
              "org.bremersee:dc-con-app:7279a7e9-69a8-4d30-b1c2-14c10a3a705f",
              ioe);
          log.error("msg=[Parsing data of A record failed.]", se);
          throw se;
        }
      } else {
        dnsRecord.setRecordValue(new String(Hex.encode(data)));
      }
      log.debug("msg=[A record parsed.] recordValue=[{}] correlatedRecordValue=[{}]",
          dnsRecord.getRecordValue(), dnsRecord.getCorrelatedRecordValue());
      return dnsRecord;
    }
  
    /**
     * Parse cname dns record.
     *
     * @param data the data
     * @param dnsRecordSupplier the dns record supplier
     * @return the dns record
     */
    public static DnsRecord parseCname(
        final byte[] data,
        final Supplier<DnsRecord> dnsRecordSupplier) {
      return parsePtr(data, dnsRecordSupplier);
    }
  
    /**
     * Parse ptr dns record.
     *
     * @param data the data
     * @param dnsRecordSupplier the dns record supplier
     * @return the dns record
    */
   public static DnsRecord parsePtr(final byte[] data, final Supplier<DnsRecord> dnsRecordSupplier) {
     final DnsRecord dnsRecord = dnsRecordSupplier.get();
     if (data != null && data.length > 1) {
       try (final DataInputStream dis = new DataInputStream(new ByteArrayInputStream(data))) {
         int expectedLength = dis.readUnsignedByte();
         int actualLength = 0;
         final List<String> values = new ArrayList<>();
         StringBuilder valueBuilder = new StringBuilder();
         for (char c : IOUtils.toString(dis, StandardCharsets.UTF_8).toCharArray()) {
           actualLength++;
           if (c > 32) {
             valueBuilder.append(c);
           } else if (valueBuilder.length() > 0) {
             values.add(valueBuilder.toString());
             valueBuilder = new StringBuilder();
           }
         }
         if (valueBuilder.length() > 0) {
           values.add(valueBuilder.toString());
         }
         final String value = StringUtils.collectionToDelimitedString(values, ".");
         log.debug("msg=[PTR record parsed.] ptrValue=[{}] expectedLength=[{}] actualLength=[{}]",
             value, expectedLength, actualLength);
 
         try {
           final InetAddress inetAddress = InetAddress.getByName(value);
           dnsRecord.setRecordValue(inetAddress.getHostName());
           dnsRecord.setCorrelatedRecordValue(inetAddress.getHostAddress());
 
         } catch (UnknownHostException e) {
           dnsRecord.setRecordValue(value);
         }
 
       } catch (IOException e) {
         log.error("Parsing PTR record value failed.", e);
       }
     }
     return dnsRecord;
   }
 }