/*
    * Copyright (c) 2002-2012, the original author or authors.
    *
    * This software is distributable under the BSD license. See the terms of the
    * BSD license in the documentation provided with this software.
    *
    * http://www.opensource.org/licenses/bsd-license.php
    */
   package jline.console.history;
  
  import java.io.BufferedOutputStream;
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.FileReader;
  import java.io.Flushable;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintStream;
  import java.io.Reader;
  
  import jline.internal.Log;
  
  import static jline.internal.Preconditions.checkNotNull;
  
  /**
   * {@link History} using a file for persistent backing.
   * <p/>
   * Implementers should install shutdown hook to call {@link FileHistory#flush}
   * to save history to disk.
   *
   * @author <a href="mailto:jason@planet57.com">Jason Dillon</a>
   * @since 2.0
   */
  public class FileHistory
      extends MemoryHistory
      implements PersistentHistory, Flushable
  {
      private final File file;
  
      public FileHistory(final File file) throws IOException {
          this.file = checkNotNull(file);
          load(file);
      }
  
      public File getFile() {
          return file;
      }
  
      public void load(final File file) throws IOException {
          checkNotNull(file);
          if (file.exists()) {
              Log.trace("Loading history from: ", file);
              load(new FileReader(file));
          }
      }
  
      public void load(final InputStream input) throws IOException {
          checkNotNull(input);
          load(new InputStreamReader(input));
      }
  
      public void load(final Reader reader) throws IOException {
          checkNotNull(reader);
          BufferedReader input = new BufferedReader(reader);
  
          String item;
          while ((item = input.readLine()) != null) {
              internalAdd(item);
          }
      }
  
      public void flush() throws IOException {
          Log.trace("Flushing history");
  
          if (!file.exists()) {
              File dir = file.getParentFile();
              if (!dir.exists() && !dir.mkdirs()) {
                  Log.warn("Failed to create directory: ", dir);
              }
              if (!file.createNewFile()) {
                  Log.warn("Failed to create file: ", file);
              }
          }
  
          PrintStream out = new PrintStream(new BufferedOutputStream(new FileOutputStream(file)));
          try {
              for (Entry entry : this) {
                  out.println(entry.value());
              }
          }
          finally {
              out.close();
          }
      }
  
      public void purge() throws IOException {
          Log.trace("Purging history");
 
         clear();
 
         if (!file.delete()) {
             Log.warn("Failed to delete history file: ", file);
         }
     }
 }