package liquibase.resource;

 import java.io.File;

 import java.io.FileInputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import java.net.MalformedURLException;

 import java.net.URL;

 import java.net.URLClassLoader;

 import java.util.ArrayList;

 import java.util.Enumeration;

 import java.util.Iterator;

 import java.util.List;

 import java.util.Vector;

 /**

  * A FileOpener implementation which finds Files in the File System.

  * <p/>

  * FileSystemFileOpeners can use a BaseDirectory to determine where relative paths should be resolved from.

  * 

  * @author <a href="mailto:csuml@yahoo.co.uk>Paul Keeble</a>

  */

 public class FileSystemResourceAccessor implements ResourceAccessor {

     String baseDirectory;

     /**

      * Creates using a Base directory of null, all files will be resolved exactly as they are given.

      */

     public FileSystemResourceAccessor() {

         baseDirectory = null;

     }

     /**

      * Creates using a supplied base directory.

      * 

      * @param base

      *            The path to use to resolve relative paths

      */

     public FileSystemResourceAccessor(String base) {

         if (new File(base).isFile())

             throw new IllegalArgumentException("base must be a directory");

         baseDirectory = base;

     }

     /**

      * Opens a stream on a file, resolving to the baseDirectory if the file is relative.

      */

     @Override

     public InputStream getResourceAsStream(String file) throws IOException {

         File absoluteFile = new File(file);

         File relativeFile = (baseDirectory == null) ? new File(file) : new File(baseDirectory, file);

         if (absoluteFile.exists() && absoluteFile.isFile() && absoluteFile.isAbsolute()) {

             return new FileInputStream(absoluteFile);

         } else if (relativeFile.exists() && relativeFile.isFile()) {

             return new FileInputStream(relativeFile);

         } else {

             return null;

         }

     }

     @Override

     public Enumeration<URL> getResources(String packageName) throws IOException {

         String directoryPath = (new File(packageName).isAbsolute() || baseDirectory == null) ? packageName

                 : baseDirectory + File.separator + packageName;

         File directoryFile = new File(directoryPath);

         if (!directoryFile.exists()) {

             return new Vector<URL>().elements();

         }

         File[] files = directoryFile.listFiles();

         List<URL> results = new ArrayList<URL>();

         for (File f : files) {

             if (!f.isDirectory())

                 results.add(f.toURI().toURL());

         }

         final Iterator<URL> it = results.iterator();

         return new Enumeration<URL>() {

             @Override

             public boolean hasMoreElements() {

                 return it.hasNext();

             }

             @Override

             public URL nextElement() {

                 return it.next();

             }

         };

     }

     @Override

     public ClassLoader toClassLoader() {

         try {

             return new URLClassLoader(new URL[] { new URL("file://" + baseDirectory) });

         } catch (MalformedURLException e) {

             throw new RuntimeException(e);

         }

     }

     @Override

     public String toString() {

         String dir = baseDirectory;

         if (dir == null) {

             dir = new File(".").getAbsolutePath();

         }

         return getClass().getName() + "(" + dir + ")";

     }

 }