package org.keel.services.misc;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.StringTokenizer;
import java.util.Vector;

import org.omg.CosNaming.NamingContextPackage.CannotProceed;

/**
 * This is an utility class that allows the conversion of a typical
 * classpath specification to an URL array as needed by the URLClassLoader
 * class.  During the conversion process, this class checks to see that the
 * each component of the classpath is present and accessible.
 * 
 * @version	$Revision: 1.1 $	$Date: Nov 5, 2002 05:51:00 PM $
 * @author Shash Chatterjee
 * Created on Nov 5, 2002
 */
public class URLClassLoaderPath {

	/**
	 * The specified path to convert
	 */
	protected String m_path = null;

	/**
	 * Cosntruct the helper object
	 * @param path The classpath string, formatted
	 * as is normally expected for the java.class.path property
	 * or the CLASSPATH environment variable.
	 */
	public URLClassLoaderPath(String path) {
		m_path = path;
	}

	/**
	 * Set the path string to be converted
	 * @param path The classpath string, formatted
	 * as is normally expected for the java.class.path property
	 * or the CLASSPATH environment variable.
	 */
	public void setPath(String path) {
		m_path = path;
	}

	/**
	 * COnvert the string so that each individual JAR or directory
	 * in the classpath is returned as a URL object
	 * @return URL[] The array of JAR/directory resources
	 * @throws Exception
	 */
	public URL[] getURLArray() throws Exception {

		// Each path component is stored here after processing
		Vector urlVec = new Vector(0);

		// Either set the path using the constructor or
		// use the setPath method.
		if (m_path == null) {
			throw new Exception("Path has not been set");
		}

		//Split up the supplied path using the system-specific 
		// path separator
		StringTokenizer tok =
			new StringTokenizer(m_path, System.getProperty("path.separator"));
			
		//Iterate through each path component and store it in the Vecotr
		// of URLs
		while (tok.hasMoreTokens()) {
			
			// Make sure the file exists and is accessible
			String fileName = tok.nextToken();
			File file = new File(fileName);

			if (file.exists() && file.canRead()) {
				// File exists and is accessible
				try {
					
					//Get the FQN of the file 
					String canonicalPath = file.getCanonicalPath();
					
					//We need to make an URL out of this, replace the
					//system-dependent separators with a "/"
					canonicalPath = canonicalPath.replace('\\', '/');
					
					// If the file is a directory, then tag on the
					// trailing "/" since that is what the
					// standard URLClassLoader uses to designate a directory
					if (file.isDirectory()) {
						canonicalPath += "/";
					}
					
					// Convert the path component into an URL resource
					URL url = new URL("file", null, "/" + canonicalPath);
					
					System.out.println("Adding URL " + url.toString());
					//Add the resource to the vector of URLs
					urlVec.add(url);
					
				} catch (IOException e) {
					throw new Exception ("Cannot create URL for " + fileName, e);
				}
			} else {
				//File does not exist and is not accessible -- throw exception
				throw new Exception("Cannot find or read " + fileName);
			}
		}
		
		// Processed all components, return in array format
		return (URL[])urlVec.toArray(new URL[0]);
	}
}