package appproperties;

import java.io.File;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Singleton that will contain the real application root so that
 * it can contain code to load properties files or be subclassed
 * to be used as an application wide configuration holder.<br />
 * 
 * <pre>
 *  class AppRoot {
 *      public static void main(String... args) {
 * 
 *          AppProperties props = AppProperties.getInstance();
 * 
 *          String applicationRoot = null;
 *          applicationRoot = props.getApplicationRoot();
 *      
 *          System.out.println(applicationRoot);
 *      }
 *  }
 * </pre>
 * 
 * @author noname
 */
public class AppProperties {

    private static final String CLASS_NAME = "AppProperties.class";
    private static final Class CLASS_REF = AppProperties.class;
    private static AppProperties me;
    private String applicationRoot;

    private AppProperties() {
    }

    /**
     * Get instance
     * @return instance
     */
    public static AppProperties getInstance() {
        if (me == null) {
            me = new AppProperties();
            me.setApplicationRoot(me.parsePath());
        }
        return me;
    }

    public String getApplicationRoot() {
        return applicationRoot;
    }

    public void setApplicationRoot(String applicationRoot) {
        this.applicationRoot = applicationRoot;
    }

    /**
     * Get the real location on dist where this application
     * is installed.
     * 
     * @return
     */
    private String parsePath() {

        String path = null;
        String thisPackage = null;

        /**
         * Get packag name, if it's directly in the root
         * of the classpath then it's empty
         */
        try {
            thisPackage = File.separator + CLASS_REF.getPackage().getName() + File.separator;
        } catch (NullPointerException npe) {
            // No packag
            thisPackage = "";
        }

        /**
         * Get unparsed path
         */
        try {
            // If it is being run from the class directly
            path = "file:" + new File(new URI(CLASS_REF.getResource(CLASS_NAME).toString())).toString();
        } catch (Exception ex) {
            try {
                // if it is begin run from a jar
                path = new URI(CLASS_REF.getResource(CLASS_NAME).toString()).toString();
            } catch (URISyntaxException ex1) {
                throw new RuntimeException("Failed to get application root.\nApplication may not work correctly.");
            }
        }

        /**
         * Parse path
         */
        int start = 0;
        int end = 0;
        if (path.startsWith("file:")) {
            start = 5;
            end = path.indexOf(thisPackage);
        } else if (path.startsWith("jar:file:")) {
            start = 9;
            Pattern p = Pattern.compile("([^" + File.separator + ".]+\\.jar!)");
            Matcher m = p.matcher(path);
            while (m.find()) {
                end = m.start();
            }
        }
        // real path
        path = path.substring(start, end);

        return path;
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        throw new CloneNotSupportedException();
    }
}