/**

 * 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.fximpl;

import java.net.URL;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Enumeration;

import java.util.List;

import java.util.TooManyListenersException;

import javafx.beans.value.ChangeListener;

import javafx.scene.web.WebEngine;

import netscape.javascript.JSObject;

/**

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

public final class JVMBridge {

    private final WebEngine engine;

    private final WebClassLoader cl;

    private static ClassLoader[] ldrs;

    private static ChangeListener<Void> onBck2BrwsrLoad;

    JVMBridge(WebEngine eng) {

        this.engine = eng;

        this.cl = new WebClassLoader(JVMBridge.class.getClassLoader().getParent());

    }

    public static void registerClassLoaders(ClassLoader[] loaders) {

        ldrs = loaders.clone();

    }

    public static void addBck2BrwsrLoad(ChangeListener<Void> l) throws TooManyListenersException {

        if (onBck2BrwsrLoad != null) {

            throw new TooManyListenersException();

        }

        onBck2BrwsrLoad = l;

    }

    public static void onBck2BrwsrLoad() {

        ChangeListener<Void> l = onBck2BrwsrLoad;

        if (l != null) {

            l.changed(null, null, null);

        }

    }

    public Class<?> loadClass(String name) throws ClassNotFoundException {

        return Class.forName(name, true, cl);

    }

    private final class WebClassLoader extends JsClassLoader {

        public WebClassLoader(ClassLoader parent) {

            super(parent);

        }

        @Override

        protected URL findResource(String name) {

            if (ldrs != null) for (ClassLoader l : ldrs) {

                URL u = l.getResource(name);

                if (u != null) {

                    return u;

                }

            }

            return null;

        }

        @Override

        protected Enumeration<URL> findResources(String name) {

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

            if (ldrs != null) {

                for (ClassLoader l : ldrs) {

                    URL u = l.getResource(name);

                    if (u != null) {

                        arr.add(u);

                    }

                }

            }

            return Collections.enumeration(arr);

        }

        @Override

        protected Fn defineFn(String code, String... names) {

            StringBuilder sb = new StringBuilder();

            sb.append("(function() {");

            sb.append("  var x = {};");

            sb.append("  x.fn = function(");

            String sep = "";

            for (String n : names) {

                sb.append(sep).append(n);

                sep = ",";

            }

            sb.append(") {\n");

            sb.append(code);

            sb.append("};");

            sb.append("return x;");

            sb.append("})()");

            JSObject x = (JSObject) engine.executeScript(sb.toString());

            return new JSFn(x);

        }

    }

    private static final class JSFn extends Fn {

        private final JSObject fn;

        public JSFn(JSObject fn) {

            this.fn = fn;

        }

        @Override

        public Object invoke(Object... args) throws Exception {

            try {

                return fn.call("fn", args); // NOI18N

            } catch (Error t) {

                t.printStackTrace();

                throw t;

            } catch (Exception t) {

                t.printStackTrace();

                throw t;

            }

        }

    }

}