content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements. See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF 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
   *
   *    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.apache.kafka.storage.internals.checkpoint;
  
  import org.apache.kafka.common.Uuid;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.util.regex.Pattern;
  
  public class PartitionMetadataReadBuffer {
      private static final Pattern WHITE_SPACES_PATTERN = Pattern.compile(":\\s+");
  
      private final String location;
      private final BufferedReader reader;
  
      public PartitionMetadataReadBuffer(
          String location,
          BufferedReader reader
      ) {
          this.location = location;
          this.reader = reader;
      }
  
      PartitionMetadata read() throws IOException {
          String line = null;
          Uuid metadataTopicId;
  
          try {
              line = reader.readLine();
              String[] versionArr = WHITE_SPACES_PATTERN.split(line);
  
              if (versionArr.length == 2) {
                  int version = Integer.parseInt(versionArr[1]);
                  // To ensure downgrade compatibility, check if version is at least 0
                  if (version >= PartitionMetadataFile.CURRENT_VERSION) {
                      line = reader.readLine();
                      String[] topicIdArr = WHITE_SPACES_PATTERN.split(line);
  
                      if (topicIdArr.length == 2) {
                          metadataTopicId = Uuid.fromString(topicIdArr[1]);
  
                          if (metadataTopicId.equals(Uuid.ZERO_UUID)) {
                              throw new IOException("Invalid topic ID in partition metadata file (" + location + ")");
                          }
  
                          return new PartitionMetadata(version, metadataTopicId);
                      } else {
                          throw malformedLineException(line);
                      }
                  } else {
                      throw new IOException("Unrecognized version of partition metadata file + (" + location + "): " + version);
                  }
              } else {
                  throw malformedLineException(line);
              }
  
          } catch (NumberFormatException e) {
              throw malformedLineException(line, e);
          }
      }
  
      private IOException malformedLineException(String line) {
          return new IOException(String.format("Malformed line in checkpoint file [%s]: %s", location, line));
      }
  
      private IOException malformedLineException(String line, Exception e) {
          return new IOException(String.format("Malformed line in checkpoint file [%s]: %s", location, line), e);
      }
  }
  