/**
 * 
 */
package at.gv.egiz.pdfas.web.helper;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.Iterator;
import java.util.List;

import javax.servlet.http.HttpServletResponse;

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

import at.gv.egiz.pdfas.framework.input.DataSource;
import at.gv.egiz.pdfas.framework.input.TextDataSource;
import at.gv.egiz.pdfas.framework.output.DataSink;
import at.gv.egiz.pdfas.impl.input.FileBased;
import at.gv.egiz.pdfas.impl.input.FileBasedPdfDataSourceImpl;
import at.gv.egiz.pdfas.impl.input.FileBasedTextDataSourceImpl;
import at.gv.egiz.pdfas.impl.input.TextDataSourceImpl;
import at.gv.egiz.pdfas.impl.output.FileBasedDataSink;
import at.knowcenter.wag.egov.egiz.cfg.SettingsReader;
import at.knowcenter.wag.egov.egiz.pdf.SignatureHolder;
import at.knowcenter.wag.egov.egiz.pdf.TextualSignatureHolder;

/**
 * @author wprinz
 * 
 */
public class TempDirHelper
{
  /**
   * The log.
   */
  private static Log log = LogFactory.getLog(TempDirHelper.class);

  protected static long runningIndex = 0;

  public static void storeTextSignatureHoldersIfApplicable(List shs, String fileNameSuffix) throws IOException
  {
    Iterator it = shs.iterator();
    while (it.hasNext())
    {
      SignatureHolder sh = (SignatureHolder) it.next();
      if (sh instanceof TextualSignatureHolder)
      {
        TextualSignatureHolder tsh = (TextualSignatureHolder) sh;
        if (!(tsh.getDataSource() instanceof FileBased))
        {
          TextDataSource tds = (TextDataSource) tsh.getDataSource();
          if (isReasonableToStore(tds.getText().length()))
          {
            TextDataSource fbtds = placeTextIntoTempDir(tds.getText(), fileNameSuffix);
            tsh.exchangeDataSource(fbtds);
          }
        }
      }
    }
  }

  /**
   * Places the text into the temp dir if reasonable.
   * 
   * <p>
   * Reasonable means that the text is longer than a certain threshold.
   * Otherwise a short text is simply held in memory.
   * </p>
   * 
   * @param text
   *          The text to be stored.
   * @param fileNameSuffix
   *          A file name suffix so that the temp file gets a more "readable"
   *          name.
   * @return Returns the TextDataSource.
   * @throws IOException
   *           F.e.
   */
  public static TextDataSource placeTextIntoTempDir(String text, String fileNameSuffix) throws IOException
  {
    if (isReasonableToStore(text.length()))
    {
      String fileName = formatFileName(fileNameSuffix);

      File tmpFile = createTempFileInDir(fileName);

      FileOutputStream fos = new FileOutputStream(tmpFile);
      OutputStreamWriter osw = new OutputStreamWriter(fos, "UTF-8");
      osw.write(text);
      osw.close();

      FileBasedTextDataSourceImpl textDataSource = new FileBasedTextDataSourceImpl(tmpFile, "UTF-8");
      return textDataSource;
    }
    else
    {
      return new TextDataSourceImpl(text);
    }
  }

  /**
   * Tells, if it is reasonable to store the text of the given length onto the
   * disk.
   * 
   * @param textLength
   *          The length of the text under question.
   * @return Returns true if the text should be stored on the disk.
   */
  public static boolean isReasonableToStore(int textLength)
  {
    return textLength >= 10000;
  }

  public static FileBasedPdfDataSourceImpl placePdfIntoTempDir(InputStream pdfInput, String fileNameSuffix) throws IOException
  {
    File pdfFile = placeInputIntoTempDirFile(pdfInput, fileNameSuffix);

    FileBasedPdfDataSourceImpl pdfDataSource = new FileBasedPdfDataSourceImpl(pdfFile, (int) pdfFile.length());
    return pdfDataSource;
  }

  protected static File placeInputIntoTempDirFile(InputStream input, String fileNameSuffix) throws IOException
  {
    String fileName = formatFileName(fileNameSuffix);

    File tmpFile = createTempFileInDir(fileName);

    FileOutputStream fos = new FileOutputStream(tmpFile);

    byte[] buffer = new byte[2048];
    int read = -1;
    while ((read = input.read(buffer)) > 0)
    {
      fos.write(buffer, 0, read);
    }
    fos.close();
    input.close();

    return tmpFile;
  }

  protected static String formatFileName(String fileNameSuffix)
  {
    String fileName = "tmp" + formatIndex(runningIndex) + "_" + fileNameSuffix;
    runningIndex++;

    return fileName;
  }

  protected static String formatIndex(long index)
  {
    NumberFormat nf = new DecimalFormat("00000000");

    return nf.format(index);
  }

  protected static File createTempFileInDir(String fileName) throws IOException
  {
    File tempDir = new File(new File(SettingsReader.RESOURCES_PATH), "pdfastmp");

    File tmpFile = new File(tempDir, fileName);

    tmpFile.createNewFile();

    tmpFile.deleteOnExit();

    return tmpFile;
  }

  public static FileBasedDataSink createTempDataSink(String fileNameSuffix) throws IOException
  {
    String fileName = formatFileName(fileNameSuffix);

    File tmpFile = createTempFileInDir(fileName);

    FileBasedDataSink fbds = new FileBasedDataSink(tmpFile);

    return fbds;
  }

  public static void writeDataSinkToHttpResponse(FileBasedDataSink fbds, HttpServletResponse response) throws IOException
  {

    response.setContentType(fbds.getMimeType());
    response.setCharacterEncoding(fbds.getCharacterEncoding());

    OutputStream os = response.getOutputStream();

    byte[] buffer = new byte[2048];
    FileInputStream fis = new FileInputStream(fbds.getFile());
    int n = -1;
    while ((n = fis.read(buffer)) > 0)
    {
      os.write(buffer, 0, n);
    }
    fis.close();
    os.close();
  }

  /**
   * Deletes the underlying file of the FileBased DataSource.
   * 
   * <p>
   * If the DataSource is not FileBased, nothing is done.
   * </p>
   * <p>
   * This is usually used by the application to delete temporary files.
   * </p>
   * 
   * @param dataSource
   */
  public static void deleteDataSourceIfFileBased(DataSource dataSource)
  {
    if (dataSource instanceof FileBased)
    {
      FileBased fb = (FileBased) dataSource;
      log.debug("Deleting temp file " + fb.getFile());
      boolean deleted = fb.getFile().delete();
      log.debug("deleted = " + deleted);
    }
  }

  public static void deleteDataSinkIfFileBased(DataSink dataSink)
  {
    if (dataSink instanceof FileBased)
    {
      FileBased fb = (FileBased) dataSink;
      log.debug("Deleting temp file " + fb.getFile());
      boolean deleted = fb.getFile().delete();
      log.debug("deleted = " + deleted);
    }
  }

}