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.model.Dependency;

import org.apache.maven.plugin.MojoExecutionException;

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

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());

    }

}