/**

 * Back 2 Browser Bytecode Translator

 * Copyright (C) 2012 Jaroslav Tulach <jaroslav.tulach@apidesign.org>

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, version 2 of the License.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. Look for COPYING file in the top folder.

 * If not, see http://opensource.org/licenses/GPL-2.0.

 */

package org.apidesign.bck2brwsr.mojo;

import org.apache.maven.plugin.AbstractMojo;

import java.io.File;

import java.io.FileWriter;

import java.io.IOException;

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;

import org.apidesign.vm4brwsr.Bck2Brwsr;

/** Compiles classes into JavaScript. */

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

public class Java2JavaScript extends AbstractMojo {

    public Java2JavaScript() {

    }

    /** 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>();

        long newest = collectAllClasses("", classes, arr);

        if (javascript.lastModified() > newest) {

            return;

        }

        try {

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

            FileWriter w = new FileWriter(javascript);

            Bck2Brwsr.generate(w, url, arr.toArray(new String[0]));

            w.close();

        } catch (IOException 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 long collectAllClasses(String prefix, File toCheck, List<String> arr) {

        File[] files = toCheck.listFiles();

        if (files != null) {

            long newest = 0L;

            for (File f : files) {

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

                if (newest < lastModified) {

                    newest = lastModified;

                }

            }

            return newest;

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

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

            return toCheck.lastModified();

        } else {

            return 0L;

        }

    }

    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]), Java2JavaScript.class.getClassLoader());

    }

}