package fedora.server.utilities.rebuild.cli;

import java.io.File;

import java.lang.reflect.Method;

import java.net.URL;
import java.net.URLClassLoader;


/**
 * A proxy for various command-line entry-points.
 * It addresses the following problems with Mavenized builds:
 * Java 5 doesn't support wildcard classpath entries.
 * Windows has a length limitation for command arguments that prevents building a classpath.
 * The endorsed standards override allows specification of a directory, but classes loaded
 * thus cannot use calls to .getClassLoader() to load resources.
 *
 * @see fedora.server.utilities.rebuild.Rebuild
 * @see java.lang.Class#getClassLoader()
 *
 * @author Benjamin Armintor
 */
public class CLILoader
        extends URLClassLoader {
    public CLILoader(URL [] paths){
        super(paths);
    }

    public CLILoader(URL[] paths , ClassLoader parent) {
        super(paths, parent);
    }

    /**
     * {@link CLILoader#main(String[])} assumes access to a system property
     *  ("fedora.web.inf.lib") that refers to a directory containing all the
     *  jar libraries needed to invoke the main class.
     * Usage:
     *  args[0]: <name of main class to be invoked>
     *  args[1:n] : remaining arguments to be passed to class indicated in args[0]
     */
    public static void main(String[] args) {
        try {
            if (args.length == 0){
                System.err.println("No main class specified.");
                System.err.println("usage: CLILoader <fedora main class> <options>");
                System.exit(1);
            }

            String webInfLib = System.getProperty("fedora.web.inf.lib");
            if (webInfLib == null){
                System.err.println("fedora.web.inf.lib not defined");
                System.exit(1);
            }
            File webInfLibDir = new File(webInfLib);
            if (!webInfLibDir.exists()){
                System.err.println("path specified by fedora.web.inf.lib doesn't exist");
                System.exit(1);
            }
            if (!webInfLibDir.isDirectory()){
                System.err.println("path specified by fedora.web.inf.lib not a directory");
                System.exit(1);
            }
            String [] paths = webInfLibDir.list();
            URL[] urls = new URL[paths.length];
            for (int i = 0; i < paths.length; i++){
                urls[i] = new File(webInfLibDir,paths[i]).toURI().toURL();
            }
            CLILoader loader = new CLILoader(urls);
            Thread.currentThread().setContextClassLoader(loader); // necessary to find XML API libraries
            Class<?> rebuild = loader.findClass(args[0]);
            Method main = rebuild.getMethod("main",new Class<?>[]{String[].class});
            String [] modArgs = new String[args.length - 1];
            if (args.length > 1){
                System.arraycopy(args, 1, modArgs, 0, modArgs.length);
            }
            main.invoke(rebuild,new Object[]{modArgs});
        }
        catch (Exception e){
            System.err.println("Error executing main class: " + e.toString());
            e.printStackTrace();
            System.exit(1);
        }
    }

}