/*
    * 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.myfaces.commons.exporter.util;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.util.List;
  
  import javax.faces.component.UIColumn;
  import javax.faces.component.UIComponent;
  import javax.faces.component.ValueHolder;
  import javax.faces.component.html.HtmlDataTable;
  import javax.faces.context.FacesContext;
  import javax.servlet.ServletOutputStream;
  import javax.servlet.http.HttpServletResponse;
  
  import com.lowagie.text.Document;
  import com.lowagie.text.pdf.PdfPTable;
  import com.lowagie.text.pdf.PdfWriter;
  
  /**
   * This class is a utility class for serving PDF exporting.
   */
  public class PDFExporterUtil
  {
  
      /*
       * This method is used for setting the response headers of the pdf.
       */
      private static void setPDFResponseHeaders(HttpServletResponse response,
              ByteArrayOutputStream byteArrayStream, String fileName)
              throws IOException
      {
  
          // setting response headers.
          response.setHeader("Expires", "0");
          response.setHeader("Cache-Control",
                  "must-revalidate, post-check=0, pre-check=0");
          response.setHeader("Pragma", "public");
          response.setHeader("Content-disposition", "attachment;filename="
                  + fileName + ".pdf");
  
          // setting the content type.
          response.setContentType("application/pdf");
  
          // the contentlength is needed for MSIE.
          response.setContentLength(byteArrayStream.size());
  
          // write ByteArrayOutputStream to the ServletOutputStream.
          ServletOutputStream outputStream = response.getOutputStream();
  
          byteArrayStream.writeTo(outputStream);
          outputStream.flush();
      }
  
      /*
       * This method is used for adding the columns headers to the pdfTable.
       */
      private static void generateTableHeader(PdfPTable pdfTable, List columns)
      {
          for (int i = 0; i < columns.size(); i++)
          {
              UIColumn column = (UIColumn) columns.get(i);
              UIComponent columnHeaderCell = column.getHeader();
              if (columnHeaderCell instanceof ValueHolder)
              {
                  String cellValue = ComponentUtils.getStringValue(FacesContext
                          .getCurrentInstance(), columnHeaderCell);
                  pdfTable.addCell(cellValue);
              }
          }
      }
  
      /*
       * This method is used for adding the columns values to the pdfTable.
       */
      private static void generateTableContent(FacesContext facesContext,
              PdfPTable pdfTable, List columns, HtmlDataTable dataTable)
      {
          int numberOfColumns = columns.size();
          int numberOfRows = dataTable.getRowCount();
          int startFrom = 0;
          int endAt = numberOfRows;
 
         /* fill the table with the data. */
         for (int i = startFrom; i < endAt; ++i)
         {
             dataTable.setRowIndex(i);
             for (int j = 0; j < numberOfColumns; ++j)
             {
                 String cellValue = "";
                 UIColumn currentColumn = (UIColumn) columns.get(j);
 
                 for (int k = 0; k < currentColumn.getChildren().size(); ++k)
                 {
                     if (currentColumn.getChildren().get(k) instanceof ValueHolder)
                     {
                         cellValue += ((ValueHolder) currentColumn.getChildren()
                                 .get(k)).getValue();
                     }
                 }
 
                 pdfTable.addCell(cellValue);
             }
         }
     }
 
     /*
      * This method is used for creating the PDFTable model.
      */
     public static PdfPTable generatePDFTableModel(FacesContext facesContext,
             HtmlDataTable dataTable)
     {
         int numberOfColumns;
         List columns = null;
         PdfPTable pdfTable = null;
 
         /* getting the HTMLDataTable Columns */
         columns = ComponentUtils.getHTMLDataTableColumns(dataTable);
 
         if (columns.size() == 0)
         {
             return null;
         }
         else
         {
             numberOfColumns = columns.size();
         }
 
         /* creating the PDF Table */
         pdfTable = new PdfPTable(numberOfColumns);
 
         generateTableHeader(pdfTable, columns);
 
         generateTableContent(facesContext, pdfTable, columns, dataTable);
 
         return pdfTable;
     }
 
     /**
      * This method is responsible for writing the PDF to the response stream.
      * 
      * @param facesContext
      * @param response
      * @param fileName
      * @param dataTable
      */
     public static void generatePDF(FacesContext facesContext,
             HttpServletResponse response, String fileName,
             HtmlDataTable dataTable) throws Exception
     {
         int currentRowIndex;
         Document document = new Document();
         ByteArrayOutputStream byteArrayStream = new ByteArrayOutputStream();
         PdfWriter.getInstance(document, byteArrayStream);
         PdfPTable pdfTable = null;
 
         /*
          * By default if the fileName is not specified, then use the table id.
          */
         if (fileName == null)
         {
             fileName = dataTable.getId();
         }
 
         currentRowIndex = dataTable.getRowIndex();
 
         // generate the PDF table model.
         pdfTable = generatePDFTableModel(facesContext, dataTable);
 
         // open the document and write the generated PDF.
         document.open();
         document.add(pdfTable);
         document.close();
 
         // write the response headers.
         setPDFResponseHeaders(response, byteArrayStream, fileName);
 
         dataTable.setRowIndex(currentRowIndex);
 
     }
 }