import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;

import org.apache.log4j.Logger;

import de.schlichtherle.io.ArchiveDetector;
import de.schlichtherle.io.DefaultArchiveDetector;
import de.schlichtherle.io.File;
import de.schlichtherle.io.FileInputStream;
import de.schlichtherle.io.FileOutputStream;

public class OpenOfficeXlsxRepair {

  private static final Logger log = Logger.getLogger(OpenOfficeXlsxRepair.class);

  public OpenOfficeXlsxRepair() {
    super();
    File.setDefaultArchiveDetector(new DefaultArchiveDetector(ArchiveDetector.NULL, new String[] { "xlsx",
        "de.schlichtherle.io.archive.zip.Zip32Driver" }));
  }

  public void repairFile(String xlsxFilePath) {

    StringBuilder sb = new StringBuilder();
    boolean changesRequired = readRelsFile(xlsxFilePath, sb);

    if (changesRequired) {
      writeRelsFile(xlsxFilePath, sb);
    }

  }

  private void writeRelsFile(String xlsxFilePath, StringBuilder sb) {

    log.debug("Fixing xlsx file for OpenOffice: " + xlsxFilePath);
    File xlsxFile = new File(xlsxFilePath);
    File relsFile = new File(xlsxFile, "_rels/.rels");
    OutputStream output = null;
    try {
      output = new FileOutputStream(relsFile);
      BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(output));
      writer.write(sb.toString());
      writer.flush();
    } catch (Throwable e) {
      log.error("Error updating for OpenOffice: " + xlsxFilePath, e);
      throw new RuntimeException("Error updating for OpenOffice: " + xlsxFilePath, e);
    } finally {
      if (output != null) {
        try {
          output.close();
          File.update(xlsxFile, true);
        } catch (IOException e) {
        }
      }
    }
  }

  private boolean readRelsFile(String xlsxFilePath, StringBuilder sb) {
    File relsFile = new File(xlsxFilePath, "_rels/.rels");

    InputStream workbookInputStream = null;
    boolean changesRequired = false;
    try {
      workbookInputStream = new FileInputStream(relsFile);
      BufferedReader br = new BufferedReader(new InputStreamReader(workbookInputStream));
      String line = null;
      while ((line = br.readLine()) != null) {
        // Remove the leading slashes from /xl/workbook entries for
        // compatibility
        // with OpenOffice
        if (line.indexOf("Target=\"/") >= 0) {
          line = line.replaceAll("Target=\"/", "Target=\"");
          changesRequired = true;
        }
        sb.append(line);
        sb.append("\n");
      }
    } catch (Throwable e) {
      log.error("Error updating for OpenOffice: " + xlsxFilePath, e);
      throw new RuntimeException("Error updating for OpenOffice: " + xlsxFilePath, e);
    } finally {
      if (workbookInputStream != null) {
        try {
          workbookInputStream.close();
        } catch (IOException e) {
        }
      }
    }
    return changesRequired;
  }

}