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/*

 *  $Id: SpecHelper.java,v 1.1 2006/06/14 07:29:07 cesar Exp $

 *  IzPack

 *  Copyright (C) 2004 Klaus Bartz

 *

 *  File :               SpecHelper.java

 *  Description :        Helper for XML specifications.

 *  Author's email :     klaus.bartz@coi.de

 *  Author's Website :   http://www.coi.de/

 *

 *  This program is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU General Public License

 *  as published by the Free Software Foundation; either version 2

 *  of the License, or any later version.

 *

 *  This program 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 General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

 */

package com.izforge.izpack.util;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.File;

import java.io.InputStream;

import java.util.Iterator;

import java.util.Vector;

import com.izforge.izpack.installer.InstallerException;

import com.izforge.izpack.installer.ResourceManager;

import com.izforge.izpack.installer.VariableSubstitutor;

import net.n3.nanoxml.NonValidator;

import net.n3.nanoxml.StdXMLBuilder;

import net.n3.nanoxml.StdXMLParser;

import net.n3.nanoxml.StdXMLReader;

import net.n3.nanoxml.XMLElement;

/**

 * This class contains some helper methods to simplify handling of 

 * xml specification files. 

 *

 * @author  Klaus Bartz

 *

 */

public class SpecHelper 

{

  private String specFilename;

  private XMLElement spec;

  private boolean _haveSpec;

  public static final String YES = "yes";

  public static final String NO = "no";

  private static final String PACK_KEY  = "pack";

  private static final String PACK_NAME = "name";

  /**

   *  The default constructor.

   */

  public SpecHelper()

  {

    super();

  }

   /*--------------------------------------------------------------------------*/

  /**

   * Reads the XML specification given by the file name. The result is

   * stored in spec.

   *

   * @exception Exception for any problems in reading the specification

   */

  /*--------------------------------------------------------------------------*/

   public void readSpec (String specFileName) throws Exception

   {

     readSpec( specFileName, null );

   }

   /*--------------------------------------------------------------------------*/

   /**

    * Reads the XML specification given by the file name. The result is

    * stored in spec.

    *

    * @exception Exception for any problems in reading the specification

    */

   /*--------------------------------------------------------------------------*/

    public void readSpec (String specFileName, VariableSubstitutor substitutor) throws Exception

    {

      // open an input stream

      InputStream input = null;

      try

      {

        input = getResource (specFileName);

      }

      catch (Exception exception)

      {

        _haveSpec = false;

        return;

      }

      if (input == null)

      {

        _haveSpec = false;

        return;

      }

      readSpec( input, substitutor );

      // close the stream

      input.close ();

      this.specFilename = specFileName;

    }

    /*--------------------------------------------------------------------------*/

    /**

     * Reads the XML specification given by the input stream. The result is

     * stored in spec.

     *

     * @exception Exception for any problems in reading the specification

     */

    /*--------------------------------------------------------------------------*/

     public void readSpec (InputStream input) throws Exception

     {

       readSpec( input, null );

     }

   /*--------------------------------------------------------------------------*/

   /**

    * Reads the XML specification given by the input stream. The result is

    * stored in spec.

    *

    * @exception Exception for any problems in reading the specification

    */

   /*--------------------------------------------------------------------------*/

    public void readSpec (InputStream input, VariableSubstitutor substitutor) throws Exception

    {

      // first try to substitute the variables

      if (substitutor != null)

      {

        input = substituteVariables( input, substitutor );

      }

      // initialize the parser

      StdXMLParser parser = new StdXMLParser ();

      parser.setBuilder   (new StdXMLBuilder ());

      parser.setValidator (new NonValidator ());

      parser.setReader    (new StdXMLReader (input));

      // get the data

      spec = (XMLElement) parser.parse ();

      _haveSpec = true;

    }

   /**

   *  Gets the stream to a resource.

   *

   * @param  res            The resource id.

   * @return                The resource value, null if not found

   */

  public InputStream getResource(String res)

  {

    try

    {

      //System.out.println ("retrieving resource " + res);

      return ResourceManager.getInstance().getInputStream(res);

    } catch (Exception e)

    { // Cannot catch ResourceNotFoundException because it is not public.

      return null;

    }

  }

  /**

   * Returns a XML element which represents the pack for the given name.

   * @param packDestName name of the pack which should be returned

   * @return a XML element which represents the pack for the given name

   */

  public XMLElement getPackForName(String packDestName )

  {

    Vector packs = getSpec().getChildrenNamed(PACK_KEY);

    Iterator iter = null;

    if( packs == null )

      return(null);

    iter = packs.iterator();

    while (iter.hasNext())

    {

      XMLElement pack = (XMLElement) iter.next();

      String packName = pack.getAttribute(PACK_NAME); 

      if( packName.equals(packDestName))

        return( pack );

    }

    return(null);

  }

  /**

   * Create parse error with consistent messages. Includes file name and line #

   * of parent. It is an error for 'parent' to be null.

   *

   * @param parent  The element in which the error occured

   * @param message Brief message explaining error

   */

  public void parseError(XMLElement parent, String message)

    throws InstallerException

  {

    throw new InstallerException(

      specFilename + ":" + parent.getLineNr() + ": " + message);

  }

  /**

   * Returns true if a specification exist, else false.

   * @return true if a specification exist, else false

   */

  public boolean haveSpec()

  {

    return _haveSpec;

  }

  /**

   * Returns the specification.

   * @return the specification

   */

  public XMLElement getSpec()

  {

    return spec;

  }

  /**

   * Sets the specifaction to the given XML element.

   * @param element

   */

  public void setSpec(XMLElement element)

  {

    spec = element;

  }

  /**

   * Returns a Vector with all leafs of the tree which is described

   * with childdef.

   * 

   * @param root the XMLElement which is the current root for the search

   * @param childdef a String array which describes the tree; the last element

   * contains the leaf name

   * @return a Vector of XMLElements of all leafs founded under root

   */

        public Vector getAllSubChildren( XMLElement root, String [] childdef)

  {

    return( getSubChildren( root, childdef, 0 ));

  }

  /**

   * Returns a Vector with all leafs of the tree which is described

   * with childdef beginning at the given depth.

   * 

   * @param root the XMLElement which is the current root for the search

   * @param childdef a String array which describes the tree; the last element

   * contains the leaf name

   * @param depth depth to start in childdef

   * @return a Vector of XMLElements of all leafs founded under root

   */

  private Vector getSubChildren( XMLElement root, String [] childdef, int depth)

  {

    Vector retval = null;

    Vector retval2 = null;

    Vector children = root != null ? root.getChildrenNamed(childdef[depth]) : null;

    if( children == null )

      return( null );

    if( depth < childdef.length - 1)

    {

      Iterator iter = children.iterator();

      while( iter.hasNext() )

      {

        retval2 = getSubChildren((XMLElement) iter.next(), childdef, depth + 1 );

        if( retval2 != null)

        {

          if( retval == null )

            retval = new Vector();

          retval.addAll(retval2);

        }

      }

    }

    else

      return( children);

    return( retval);

  }

  /**

   * Creates an temp file in to the substitutor the

   * substituted contents of input writes; close it and

   * (re)open it as FileInputStream.

   * The file will be deleted on exit.

   * @param input the opened input stream which contents should be substituted

   * @param substitutor substitutor which should substitute the contents of input

   * @return a file input stream of the created temporary file

   * @throws Exception

   */

  public InputStream substituteVariables( InputStream input, VariableSubstitutor substitutor)

    throws Exception

  {

    File tempFile = File.createTempFile("izpacksubs", "");

    FileOutputStream fos = null;

    tempFile.deleteOnExit();

    try

    {

      fos = new FileOutputStream( tempFile );

      substitutor.substitute(input,fos,null,null);

    }

    finally

    {

      if( fos != null )

        fos.close();

    }

    return new FileInputStream( tempFile );

  }

  /**

   * Returns whether the value to the given attribute is

   * "yes" or not. If the attribute does not exist, or the

   * value is not "yes" and not "no", the default value is

   * returned.

   * @param element the XML element which contains the attribute

   * @param attribute the name of the attribute

   * @param defaultValue the default value

   * @return whether the value to the given attribute is

   * "yes" or not

   */

  public boolean isAttributeYes( XMLElement element,

    String attribute, boolean defaultValue )

  {

    String value =

      element.getAttribute(attribute, (defaultValue ? YES : NO));

    if (value.equalsIgnoreCase(YES))

      return true;

    if (value.equalsIgnoreCase(NO))

      return false;

    return defaultValue;

  }

  /**

   * Returns the attribute for the given attribute name.

   * If no attribute exist, an InstallerException with

   * a detail message is thrown.

   * @param element XML element which should contain the attribute

   * @param attrName key of the attribute

   * @return the attribute as string 

   * @throws Exception

   */

  public String getRequiredAttribute(XMLElement element,String attrName ) 

    throws InstallerException

  {

    String attr = element.getAttribute(attrName);

    if( attr == null )

    {

      parseError(element, "<" + element.getName() + 

        "> requires attribute '" + attrName + "'.");

    }

    return( attr );

  }

}