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.FileWriter;
  import java.io.IOException;
  
  import org.apache.commons.csv.CSVFormat;
  import org.apache.commons.csv.CSVPrinter;
  
  /**
   * AbstractKerberosDataFileWriter provides a generic facility to write a data file using some
   * underlying record-based file writer.
   * <p/>
   * This class encapsulates a {@link org.apache.commons.csv.CSVPrinter} to create a CSV-formatted file.
   */
  public abstract class AbstractKerberosDataFileWriter {
  
    private File file;
    private CSVPrinter csvPrinter;
  
    /**
     * Creates a new KerberosConfigDataFileWriter
     * <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
     */
    public AbstractKerberosDataFileWriter(File file) throws IOException {
      this.file = file;
      open();
    }
  
  
    /**
     * Opens the data file for writing.
     * <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
     */
    public void open() throws IOException {
      if (isClosed()) {
        if (file == null) {
          throw new IOException("Missing file path");
        } else {
          csvPrinter = new CSVPrinter(new FileWriter(file, true), CSVFormat.DEFAULT);
  
          // If the file is empty, write the header; else don't write the header.
          if (file.length() == 0) {
            // Write the header....
            Iterable<?> headerRecord = getHeaderRecord();
            csvPrinter.printRecord(headerRecord);
          }
        }
      }
    }
  
    /**
     * Tests this KerberosConfigDataFileWriter to see if the data file is closed.
     *
     * @return true if closed; otherwise false
     */
    public boolean isClosed() {
      return csvPrinter == null;
    }
  
    /**
     * Closes the data file
     *
     * @throws java.io.IOException
     */
    public void close() throws IOException {
      if (csvPrinter != null) {
        csvPrinter.close();
        csvPrinter = null;
      }
    }
  
    /**
     * Appends a new record to the data file
     *
     * @param record a collection of Strings declaring values for the columns of the file
     * @throws java.io.IOException
     */
    protected void appendRecord(String... record) throws IOException {
  
      if (csvPrinter == null) {
        throw new IOException("Data file is not open");
      }
  
      csvPrinter.printRecord(record);
    }
  
  
    /**
     * Gets the header record for the CSV file
     *
     * @return an Iterable containing the (ordered) list of Strings declaring the columns names
     */
    protected abstract Iterable<String> getHeaderRecord();
  
  
  }
  