/**

 * 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.launcher;

import java.io.IOException;

import java.io.InputStream;

import java.net.URL;

import java.util.Enumeration;

import java.util.LinkedHashSet;

import java.util.Set;

import java.util.logging.Logger;

import javax.script.Invocable;

import javax.script.ScriptEngine;

import javax.script.ScriptEngineManager;

import javax.script.ScriptException;

import org.apidesign.vm4brwsr.Bck2Brwsr;

/**

 * Tests execution in Java's internal scripting engine.

 */

final class JSLauncher extends Launcher {

    private static final Logger LOG = Logger.getLogger(JSLauncher.class.getName());

    private Set<ClassLoader> loaders = new LinkedHashSet<>();

    private final Res resources = new Res();

    private Invocable code;

    private StringBuilder codeSeq;

    private Object console;

    @Override

    public MethodInvocation addMethod(Class<?> clazz, String method) {

        loaders.add(clazz.getClassLoader());

        MethodInvocation mi = new MethodInvocation(clazz.getName(), method);

        try {

            mi.result(code.invokeMethod(

                console,

                "invoke__Ljava_lang_String_2Ljava_lang_String_2Ljava_lang_String_2",

                mi.className, mi.methodName).toString(), null);

        } catch (ScriptException | NoSuchMethodException ex) {

            mi.result(null, ex);

        }

        return mi;

    }

    public void addClassLoader(ClassLoader url) {

        this.loaders.add(url);

    }

    @Override

    public void initialize() throws IOException {

        try {

            initRhino();

        } catch (Exception ex) {

            if (ex instanceof IOException) {

                throw (IOException)ex;

            }

            if (ex instanceof RuntimeException) {

                throw (RuntimeException)ex;

            }

            throw new IOException(ex);

        }

    }

    private void initRhino() throws IOException, ScriptException, NoSuchMethodException {

        StringBuilder sb = new StringBuilder();

        Bck2Brwsr.generate(sb, new Res());

        ScriptEngineManager sem = new ScriptEngineManager();

        ScriptEngine mach = sem.getEngineByExtension("js");

        sb.append(

              "\nvar vm = new bck2brwsr(org.apidesign.bck2brwsr.launcher.Console.read);"

            + "\nfunction initVM() { return vm; };"

            + "\n");

        Object res = mach.eval(sb.toString());

        if (!(mach instanceof Invocable)) {

            throw new IOException("It is invocable object: " + res);

        }

        code = (Invocable) mach;

        codeSeq = sb;

        Object vm = code.invokeFunction("initVM");

        console = code.invokeMethod(vm, "loadClass", Console.class.getName());

    }

    @Override

    public void shutdown() throws IOException {

    }

    @Override

    public String toString() {

        return codeSeq.toString();

    }

    private class Res implements Bck2Brwsr.Resources {

        @Override

        public InputStream get(String resource) throws IOException {

            for (ClassLoader l : loaders) {

                URL u = null;

                Enumeration<URL> en = l.getResources(resource);

                while (en.hasMoreElements()) {

                    u = en.nextElement();

                }

                if (u != null) {

                    return u.openStream();

                }

            }

            throw new IOException("Can't find " + resource);

        }

    }

}