/**
 * 
 */
package at.gv.egiz.pdfas.impl.input;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import at.gv.egiz.pdfas.framework.input.TextDataSource;
import at.gv.egiz.pdfas.impl.input.helper.DataSourceHelper;

/**
 * @author wprinz
 * 
 */
public class FileBasedTextDataSourceImpl implements TextDataSource, FileBased
{
  /**
   * The log.
   */
  private static final Log log = LogFactory.getLog(FileBasedTextDataSourceImpl.class);

  protected File file = null;

  protected String characterEncoding = null;

  public FileBasedTextDataSourceImpl(File file, String characterEncoding) throws IOException
  {
    if (!file.exists())
    {
      throw new FileNotFoundException("The file '" + file + "' does not exist.");
    }
    if (!file.canRead())
    {
      throw new IOException("The file '" + file + "' cannot be read.");
    }

    this.file = file;
    this.characterEncoding = characterEncoding;
  }

  /**
   * @see at.gv.egiz.pdfas.impl.input.FileBased#getFile()
   */
  public File getFile()
  {
    return this.file;
  }

  /**
   * Returns the character encoding.
   * 
   * @return Returns the character encoding.
   */
  public String getCharacterEncoding()
  {
    return this.characterEncoding;
  }

  /**
   * @see at.gv.egiz.pdfas.framework.input.TextDataSource#getText()
   */
  public String getText()
  {
    try
    {
      InputStream is = createInputStream();
      byte[] data = new byte[getLength()];
      int read = 0;
      int n = 0;
      while ((n = is.read(data, read, data.length - read)) > 0)
      {
        read += n;
      }
      is.close();

      String text = new String(data, getCharacterEncoding());

      data = null;

      return text;
    }
    catch (IOException e)
    {
      log.error("Couldn't read text for file " + getFile() + ". Returning null.", e);

      return null;
    }
  }

  /**
   * @see at.gv.egiz.pdfas.framework.input.DataSource#createInputStream()
   */
  public InputStream createInputStream()
  {
    try
    {
      FileInputStream fis = new FileInputStream(getFile());
      return fis;
    }
    catch (IOException e)
    {
      log.error("Couldn't create InputStream for file " + getFile() + ". Returning null.", e);

      return null;
    }
  }

  /**
   * @see at.gv.egiz.pdfas.framework.input.DataSource#getLength()
   */
  public int getLength()
  {
    return (int) getFile().length();
  }

  byte [] cache = null;
  
  /**
   * @see at.gv.egiz.pdfas.framework.input.DataSource#getAsByteArray()
   */
  public byte[] getAsByteArray()
  {
    if (cache != null)
    {
      return cache;
    }
    
    cache = DataSourceHelper.convertInputStreamToByteArray(createInputStream());
    
    return cache;
  }

}