/**

 * 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.io.BufferedReader;

import java.io.Reader;

import java.lang.ref.WeakReference;

import java.net.URL;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collection;

import java.util.List;

import java.util.TooManyListenersException;

import java.util.concurrent.Executor;

import java.util.logging.Level;

import java.util.logging.Logger;

import javafx.application.Platform;

import javafx.beans.value.ChangeListener;

import javafx.scene.web.WebEngine;

import netscape.javascript.JSObject;

import org.netbeans.html.boot.impl.FindResources;

import org.netbeans.html.boot.impl.FnUtils;

import org.netbeans.html.boot.spi.Fn;

/**

 *

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

 */

public final class JVMBridge {

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

    private final WebEngine engine;

    private final ClassLoader cl;

    private final WebPresenter presenter;

    private static ClassLoader[] ldrs;

    private static ChangeListener<Void> onBck2BrwsrLoad;

    JVMBridge(WebEngine eng) {

        this.engine = eng;

        final ClassLoader p = JVMBridge.class.getClassLoader().getParent();

        this.presenter = new WebPresenter();

        this.cl = FnUtils.newLoader(presenter, presenter, p);

    }

    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 {

        Fn.activate(presenter);

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

    }

    private final class WebPresenter implements Fn.Presenter,

    FindResources, Fn.ToJavaScript, Fn.FromJavaScript, Executor, Fn.KeepAlive {

        @Override

        public void findResources(String name, Collection<? super URL> results, boolean oneIsEnough) {

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

                URL u = l.getResource(name);

                if (u != null) {

                    results.add(u);

                }

            }

        }

        @Override

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

            return defineJSFn(code, names, null);

        }

        @Override

        public Fn defineFn(String code, String[] names, boolean[] keepAlive) {

            return defineJSFn(code, names, keepAlive);

        }

        private JSFn defineJSFn(String code, String[] names, boolean[] keepAlive) {

            StringBuilder sb = new StringBuilder();

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

            sb.append("  return function(");

            String sep = "";

            if (names != null) for (String n : names) {

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

                sep = ",";

            }

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

            sb.append(code);

            sb.append("};");

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

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

            return new JSFn(this, x, keepAlive);

        }

        @Override

        public void displayPage(URL page, Runnable onPageLoad) {

            throw new UnsupportedOperationException("Not supported yet.");

        }

        @Override

        public void loadScript(Reader code) throws Exception {

            BufferedReader r = new BufferedReader(code);

            StringBuilder sb = new StringBuilder();

            for (;;) {

                String l = r.readLine();

                if (l == null) {

                    break;

                }

                sb.append(l).append('\n');

            }

            engine.executeScript(sb.toString());

        }

        @Override

        public Object toJava(Object js) {

            if (js instanceof Weak) {

                js = ((Weak)js).get();

            }

            return checkArray(js);

        }

        @Override

        public Object toJavaScript(Object toReturn) {

            if (toReturn instanceof Object[]) {

                return convertArrays((Object[]) toReturn);

            }

            return toReturn;

        }

        @Override

        public void execute(Runnable command) {

            if (Platform.isFxApplicationThread()) {

                command.run();

            } else {

                Platform.runLater(command);

            }

        }

        final JSObject convertArrays(Object[] arr) {

            for (int i = 0; i < arr.length; i++) {

                if (arr[i] instanceof Object[]) {

                    arr[i] = convertArrays((Object[]) arr[i]);

                }

            }

            final JSObject wrapArr = (JSObject) wrapArrFn().call("array", arr); // NOI18N

            return wrapArr;

        }

        private JSObject wrapArrImpl;

        private final JSObject wrapArrFn() {

            if (wrapArrImpl == null) {

                try {

                    wrapArrImpl = (JSObject) defineJSFn("  var k = {};"

                        + "  k.array= function() {"

                        + "    return Array.prototype.slice.call(arguments);"

                        + "  };"

                        + "  return k;", null, null

                    ).invokeImpl(null, false);

                } catch (Exception ex) {

                    throw new IllegalStateException(ex);

                }

            }

            return wrapArrImpl;

        }

        final Object checkArray(Object val) {

            int length = ((Number) arraySizeFn().call("array", val, null)).intValue();

            if (length == -1) {

                return val;

            }

            Object[] arr = new Object[length];

            arraySizeFn().call("array", val, arr);

            return arr;

        }

        private JSObject arraySize;

        private final JSObject arraySizeFn() {

            if (arraySize == null) {

                try {

                    arraySize = (JSObject) defineJSFn("  var k = {};"

                        + "  k.array = function(arr, to) {"

                        + "    if (to === null) {"

                        + "      if (Object.prototype.toString.call(arr) === '[object Array]') return arr.length;"

                        + "      else return -1;"

                        + "    } else {"

                        + "      var l = arr.length;"

                        + "      for (var i = 0; i < l; i++) to[i] = arr[i];"

                        + "      return l;"

                        + "    }"

                        + "  };"

                        + "  return k;", null, null

                    ).invokeImpl(null, false);

                } catch (Exception ex) {

                    throw new IllegalStateException(ex);

                }

            }

            return arraySize;

        }

    }

    private static final class JSFn extends Fn {

        private final JSObject fn;

        private final boolean[] keepAlive;

        private JSFn(WebPresenter cl, JSObject fn, boolean[] keepAlive) {

            super(cl);

            this.fn = fn;

            this.keepAlive = keepAlive;

        }

        @Override

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

            return invokeImpl(thiz, true, args);

        }

        final Object invokeImpl(Object thiz, boolean arrayChecks, Object... args) throws Exception {

            try {

                List<Object> all = new ArrayList<Object>(args.length + 1);

                all.add(thiz == null ? fn : thiz);

                for (int i = 0; i < args.length; i++) {

                    Object conv = args[i];

                    if (arrayChecks) {

                        if (args[i] instanceof Object[]) {

                            Object[] arr = (Object[]) args[i];

                            conv = ((WebPresenter) presenter()).convertArrays(arr);

                        }

                        if (conv != null && keepAlive != null

                            && !keepAlive[i] && !isJSReady(conv)

                            && !conv.getClass().getSimpleName().equals("$JsCallbacks$") // NOI18N

                            ) {

                            conv = new Weak(conv);

                        }

                    }

                    all.add(conv);

                }

                Object ret = fn.call("call", all.toArray()); // NOI18N

                if (ret instanceof Weak) {

                    ret = ((Weak) ret).get();

                }

                if (ret == fn) {

                    return null;

                }

                if (!arrayChecks) {

                    return ret;

                }

                return ((WebPresenter) presenter()).checkArray(ret);

            } catch (Error t) {

                t.printStackTrace();

                throw t;

            } catch (Exception t) {

                t.printStackTrace();

                throw t;

            }

        }

    }

    private static boolean isJSReady(Object obj) {

        if (obj == null) {

            return true;

        }

        if (obj instanceof String) {

            return true;

        }

        if (obj instanceof Number) {

            return true;

        }

        if (obj instanceof JSObject) {

            return true;

        }

        if (obj instanceof Character) {

            return true;

        }

        return false;

    }

    private static final class Weak extends WeakReference<Object> {

        public Weak(Object referent) {

            super(referent);

            assert !(referent instanceof Weak);

        }

    } // end of Weak

}