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

 // checkstyle: Checks Java source code for adherence to a set of rules.

 // Copyright (C) 2001-2014  Oliver Burn

 //

 // 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 2.1 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; if not, write to the Free Software

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

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

 package com.puppycrawl.tools.checkstyle;

 import com.puppycrawl.tools.checkstyle.api.Utils;

 import com.google.common.collect.Sets;

 import com.puppycrawl.tools.checkstyle.api.AbstractLoader;

 import com.puppycrawl.tools.checkstyle.api.CheckstyleException;

 import com.puppycrawl.tools.checkstyle.api.FastStack;

 import java.io.BufferedInputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.URL;

 import java.util.Enumeration;

 import java.util.Set;

 import javax.xml.parsers.ParserConfigurationException;

 import org.xml.sax.Attributes;

 import org.xml.sax.InputSource;

 import org.xml.sax.SAXException;

 /**

  * Loads a list of package names from a package name XML file.

  * @author Rick Giles

  * @version 4-Dec-2002

  */

 public final class PackageNamesLoader

     extends AbstractLoader

 {

     /** the public ID for the configuration dtd */

     private static final String DTD_PUBLIC_ID =

         "-//Puppy Crawl//DTD Package Names 1.0//EN";

     /** the resource for the configuration dtd */

     private static final String DTD_RESOURCE_NAME =

         "com/puppycrawl/tools/checkstyle/packages_1_0.dtd";

     /** Name of default checkstyle package names resource file.

      * The file must be in the classpath.

      */

     private static final String CHECKSTYLE_PACKAGES =

         "checkstyle_packages.xml";

     /** The temporary stack of package name parts */

     private final FastStack<String> mPackageStack = FastStack.newInstance();

     /** The fully qualified package names. */

     private final Set<String> mPackageNames = Sets.newLinkedHashSet();

     /**

      * Creates a new <code>PackageNamesLoader</code> instance.

      * @throws ParserConfigurationException if an error occurs

      * @throws SAXException if an error occurs

      */

     private PackageNamesLoader()

         throws ParserConfigurationException, SAXException

     {

         super(DTD_PUBLIC_ID, DTD_RESOURCE_NAME);

     }

     /**

      * Returns the set of fully qualified package names this

      * this loader processed.

      * @return the set of package names

      */

     private Set<String> getPackageNames()

     {

         return mPackageNames;

     }

     @Override

     public void startElement(String aNamespaceURI,

                              String aLocalName,

                              String aQName,

                              Attributes aAtts)

         throws SAXException

     {

         if ("package".equals(aQName)) {

             //push package name

             final String name = aAtts.getValue("name");

             if (name == null) {

                 throw new SAXException("missing package name");

             }

             mPackageStack.push(name);

         }

     }

     /**

      * Creates a full package name from the package names on the stack.

      * @return the full name of the current package.

      */

     private String getPackageName()

     {

         final StringBuffer buf = new StringBuffer();

         for (String subPackage : mPackageStack) {

             buf.append(subPackage);

             if (!subPackage.endsWith(".")) {

                 buf.append(".");

             }

         }

         return buf.toString();

     }

     @Override

     public void endElement(String aNamespaceURI,

                            String aLocalName,

                            String aQName)

     {

         if ("package".equals(aQName)) {

             mPackageNames.add(getPackageName());

             mPackageStack.pop();

         }

     }

     /**

      * Returns the set of package names, compiled from all

      * checkstyle_packages.xml files found on the given classloaders

      * classpath.

      * @param aClassLoader the class loader for loading the

      *          checkstyle_packages.xml files.

      * @return the set of package names.

      * @throws CheckstyleException if an error occurs.

      */

     public static Set<String> getPackageNames(ClassLoader aClassLoader)

         throws CheckstyleException

     {

         Enumeration<URL> packageFiles = null;

         try {

             packageFiles = aClassLoader.getResources(CHECKSTYLE_PACKAGES);

         }

         catch (IOException e) {

             throw new CheckstyleException(

                     "unable to get package file resources", e);

         }

         //create the loader outside the loop to prevent PackageObjectFactory

         //being created anew for each file

         final PackageNamesLoader namesLoader = newPackageNamesLoader();

         while ((null != packageFiles) && packageFiles.hasMoreElements()) {

             final URL aPackageFile = packageFiles.nextElement();

             InputStream stream = null;

             try {

                 stream = new BufferedInputStream(aPackageFile.openStream());

                 final InputSource source = new InputSource(stream);

                 loadPackageNamesSource(source, "default package names",

                     namesLoader);

             }

             catch (IOException e) {

                 throw new CheckstyleException(

                         "unable to open " + aPackageFile, e);

             }

             finally {

                 Utils.closeQuietly(stream);

             }

         }

         return namesLoader.getPackageNames();

     }

     /**

      * Creates a PackageNamesLoader instance.

      * @return the PackageNamesLoader

      * @throws CheckstyleException if the creation failed

      */

     private static PackageNamesLoader newPackageNamesLoader()

         throws CheckstyleException

     {

         try {

             return new PackageNamesLoader();

         }

         catch (final ParserConfigurationException e) {

             throw new CheckstyleException(

                     "unable to create PackageNamesLoader ", e);

         }

         catch (final SAXException e) {

             throw new CheckstyleException(

                     "unable to create PackageNamesLoader - "

                     + e.getMessage(), e);

         }

     }

     /**

      * Returns the list of package names in a specified source.

      * @param aSource the source for the list.

      * @param aSourceName the name of the source.

      * @param aNameLoader the PackageNamesLoader instance

      * @throws CheckstyleException if an error occurs.

      */

     private static void loadPackageNamesSource(

             InputSource aSource, String aSourceName,

             PackageNamesLoader aNameLoader)

         throws CheckstyleException

     {

         try {

             aNameLoader.parseInputSource(aSource);

         }

         catch (final SAXException e) {

             throw new CheckstyleException("unable to parse "

                     + aSourceName + " - " + e.getMessage(), e);

         }

         catch (final IOException e) {

             throw new CheckstyleException("unable to read " + aSourceName, e);

         }

     }

 }