/**************************************************************************
/* This class implements a manager for DocumentFactories.
/*
/* Copyright (c) 2003-2004 by Bernhard Bablok (mail@bablokb.de)
/*
/* This library is free software; you can redistribute it and/or modify
/* it under the terms of the GNU Lesser General Public License as published
/* by  the Free Software Foundation; either version 2 of the License or
/* (at your option) any later version.
/*
/* This library is distributed in the hope that it will be useful, but
/* WITHOUT ANY WARRANTY; without even the implied warranty of
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
/* GNU Lesser General Public License for more details.
/*
/* You should have received a copy of the GNU Lesser General Public License
/* along with this library; see the file COPYING.LESSER.  If not, write to
/* the Free Software Foundation Inc., 59 Temple Place - Suite 330,
/* Boston, MA  02111-1307 USA
/**************************************************************************/

package de.bablokb.luala.lib;

import java.io.*;
import java.util.*;

import de.bablokb.luala.lib.*;

/**
   This class implements a manager for DocumentFactories.

   @version $Revision: 1.4 $
   @author  $Author: bablokb $
*/

public class DocumentFactoryManager {

  ////////////////////////////////////////////////////////////////////////////

  /**
     The hashtable of available factories.
  */

  private Hashtable iFactoryTable;

  ////////////////////////////////////////////////////////////////////////////

  /**
     Default-Constructor.
  */

  public DocumentFactoryManager() {
    iFactoryTable = new Hashtable();
    initFactoryTable();
  }

  ////////////////////////////////////////////////////////////////////////////

  /**
     Initialize the factory hashtable.

     <p><strong>TODO</strong>: read info from a properties-file.
  */

  private void initFactoryTable() {
    iFactoryTable.
      put("_unknown",
	  new Entry("_unknown","de.bablokb.luala.lib.StandardDocumentFactory"));
    iFactoryTable.
      put("txt",new Entry("txt","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("java",new Entry("java","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("c",new Entry("c","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("html",new Entry("html","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("htm",new Entry("htm","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("xml",new Entry("xml","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("jsp",new Entry("jsp","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("ps",new Entry("ps","de.bablokb.luala.lib.TextDocumentFactory"));
    iFactoryTable.
      put("pdf",new Entry("pdf","de.bablokb.luala.lib.PDFDocumentFactory"));
  }

  ////////////////////////////////////////////////////////////////////////////

  /**
     Return the factory for a given file.

     @param name The name of the document

     @throws FactoryException if the factory-class is not found or can't be
                              accessed
  */

  public DocumentFactory getFactory(String name) throws FactoryException {
    int lastDot = name.lastIndexOf('.');
    String extension = null;
    Entry entry = null;
    if (lastDot != -1 && lastDot < name.length()) {
      extension = name.substring(lastDot+1).toLowerCase();
      entry = (Entry) iFactoryTable.get(extension);
    }
    if (entry == null)
      entry = guessFactory(name);
    if (entry != null)
      return entry.getFactory();
    else
      return null;
  }

  ////////////////////////////////////////////////////////////////////////////

  /**
     Guess the correct factory. Under unix, try to use the
     external file-command.

     @param name Name of the file.
  */

  private Entry guessFactory(String name) {
    int lastDot = name.lastIndexOf('.');
    if (lastDot == -1 || lastDot == name.length())
      return (Entry) iFactoryTable.get("txt");
    String lowerName = name.toLowerCase();
    if (lowerName.startsWith("makefile") || lowerName.startsWith("copying"))
      return (Entry) iFactoryTable.get("txt");
    return  (Entry) iFactoryTable.get("_unknown");
  }

  ////////////////////////////////////////////////////////////////////////////
  ////////////////////////////////////////////////////////////////////////////

  /**
     An entry in the factory-hashtable.
  */

  class Entry {
    String iExtension, iClassName;
    DocumentFactory iFactory;
    
    Entry(String extension, String className) {
      iExtension = extension;
      iClassName = className;
      iFactory   = null;
    }
    
    DocumentFactory getFactory() throws FactoryException {
      try {
	if (iFactory == null)
	  iFactory = (DocumentFactory) Class.forName(iClassName).newInstance();
	return iFactory;
      } catch (Exception e) {
	throw new FactoryException(e);
      }
    }
  }  
}