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.ambari.server.serveraction.kerberos;
  
  import java.io.File;
  import java.io.IOException;
  import java.nio.charset.Charset;
  import java.util.Iterator;
  import java.util.Map;
  
  import org.apache.commons.csv.CSVFormat;
  import org.apache.commons.csv.CSVParser;
  import org.apache.commons.csv.CSVRecord;
  
  /**
   * AbstractKerberosDataFileReader implements common code to read existing Kerberos data files.
   * <p/>
   * This class encapsulates a {@link org.apache.commons.csv.CSVParser} to read a CSV-formatted file.
   */
  public abstract class AbstractKerberosDataFileReader implements Iterable<Map<String, String>> {
  
    private File file;
    private CSVParser csvParser = null;
  
    /**
     * Creates a new AbstractKerberosDataFileReader
     * <p/>
     * The file is opened upon creation, so there is no need to manually open it unless manually
     * closed before using.
     *
     * @param file a File declaring where to write the data
     * @throws java.io.IOException
     */
    protected AbstractKerberosDataFileReader(File file) throws IOException {
      this.file = file;
      open();
    }
  
    /**
     * Opens the data file for reading.
     * <p/>
     * This may be called multiple times and the appropriate action will occur depending on if the
     * file has been previously opened or closed.
     *
     * @throws java.io.IOException if an error occurs while accessing the file
     */
    public void open() throws IOException {
      if (isClosed()) {
        csvParser = CSVParser.parse(file, Charset.defaultCharset(), CSVFormat.DEFAULT.withHeader());
      }
    }
  
    /**
     * Tests this AbstractKerberosDataFileReader to see if the data file is closed.
     *
     * @return true if closed; otherwise false
     */
    public boolean isClosed() {
      return csvParser == null;
    }
  
    public void close() throws IOException {
      if (csvParser != null) {
        csvParser.close();
        csvParser = null;
      }
    }
  
    /**
     * Gets an iterator to use to access the records in the data file.
     * <p/>
     * Each item is a Map of column names to values.
     *
     * @return an Iterator of records from the data file, each record is represented as a Map of
     * column name (String) to column value (String)
     */
    @Override
    public Iterator<Map<String, String>> iterator() {
      return new Iterator<Map<String, String>>() {
        Iterator<CSVRecord> iterator = (csvParser == null) ? null : csvParser.iterator();
  
        @Override
        public boolean hasNext() {
          return (iterator != null) && iterator.hasNext();
        }
  
        @Override
        public Map<String, String> next() {
          return (iterator == null) ? null : iterator.next().toMap();
        }
  
        @Override
        public void remove() {
          if (iterator != null) {
            iterator.remove();
          }
        }
      };
    }
  }
  