package org.apidesign.bck2brwsr.mojo;

 import org.apache.maven.plugin.AbstractMojo;

 import java.io.File;

 import java.io.FileWriter;

 import java.lang.reflect.Method;

 import java.net.MalformedURLException;

 import java.net.URL;

 import java.net.URLClassLoader;

 import java.util.ArrayList;

 import java.util.Collection;

 import java.util.List;

 import org.apache.maven.artifact.Artifact;

 import org.apache.maven.plugin.MojoExecutionException;

 import org.apache.maven.plugins.annotations.LifecyclePhase;

 import org.apache.maven.plugins.annotations.Mojo;

 import org.apache.maven.plugins.annotations.Parameter;

 import org.apache.maven.project.MavenProject;

 /** Compiles classes into JavaScript. */

 @Mojo(name="j2js", defaultPhase=LifecyclePhase.PROCESS_CLASSES)

 public class Bck2BrswrMojo extends AbstractMojo {

     public Bck2BrswrMojo() {

     }

     /** Root of the class files */

     @Parameter(defaultValue="${project.build.directory}/classes")

     private File classes;

     /** File to generate. Defaults bootjava.js in the first non-empty 

      package under the classes directory */

     @Parameter

     private File javascript;

     @Parameter(defaultValue="${project}")

     private MavenProject prj;

     @Override

     public void execute() throws MojoExecutionException {

         if (!classes.isDirectory()) {

             throw new MojoExecutionException("Can't find " + classes);

         }

         if (javascript == null) {

             javascript = new File(findNonEmptyFolder(classes), "bootjava.js");

         }

         List<String> arr = new ArrayList<String>();

         collectAllClasses("", classes, arr);

         try {

             URLClassLoader url = buildClassLoader(classes, prj.getDependencyArtifacts());

             Class<?> c = Class.forName("org.apidesign.vm4brwsr.GenJS");

             Method m = c.getDeclaredMethod("compile", ClassLoader.class, Appendable.class, List.class);

             m.setAccessible(true);

             FileWriter w = new FileWriter(javascript);

             m.invoke(null, url, w, arr);

             w.close();

         } catch (Exception ex) {

             throw new MojoExecutionException("Can't compile", ex);

         }

     }

     private static File findNonEmptyFolder(File dir) throws MojoExecutionException {

         if (!dir.isDirectory()) {

             throw new MojoExecutionException("Not a directory " + dir);

         }

         File[] arr = dir.listFiles();

         if (arr.length == 1 && arr[0].isDirectory()) {

             return findNonEmptyFolder(arr[0]);

         }

         return dir;

     }

     private static void collectAllClasses(String prefix, File toCheck, List<String> arr) {

         File[] files = toCheck.listFiles();

         if (files != null) {

             for (File f : files) {

                 collectAllClasses(prefix + f.getName() + "/", f, arr);

             }

         } else if (toCheck.getName().endsWith(".class")) {

             arr.add(prefix.substring(0, prefix.length() - 7));

         }

     }

     private static URLClassLoader buildClassLoader(File root, Collection<Artifact> deps) throws MalformedURLException {

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

         arr.add(root.toURI().toURL());

         for (Artifact a : deps) {

             arr.add(a.getFile().toURI().toURL());

         }

         return new URLClassLoader(arr.toArray(new URL[0]), Bck2BrswrMojo.class.getClassLoader());

     }

 }