/**

  * 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.vm4brwsr;

 import java.io.ByteArrayInputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import org.apidesign.bck2brwsr.core.JavaScriptBody;

 /**

  *

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

  */

 final class VMLazy {

     private final Object loader;

     private final Object[] args;

     private VMLazy(Object loader, Object[] args) {

         this.loader = loader;

         this.args = args;

     }

     static void init() {

     }

     static Object load(Object loader, String name, Object[] arguments, byte[] arr) 

     throws IOException, ClassNotFoundException {

         if (arr == null) {

             throw new ClassNotFoundException(name);

         }

         return new VMLazy(loader, arguments).defineClass(arr, name, false);

     }

     static Object reload(Object loader, String name, Object[] arguments, byte[] arr) 

     throws IOException, ClassNotFoundException {

         return new VMLazy(loader, arguments).defineClass(arr, name, false);

     }

     private Object load(String name, boolean instance)

     throws IOException, ClassNotFoundException {

         String res = name.replace('.', '/') + ".class";

         byte[] arr = ClassPath.loadBytes(res, args, 0);

         if (arr == null) {

             throw new ClassNotFoundException(name);

         }

         return defineClass(arr, name, instance);

     }

     private Object defineClass(byte[] arr, String name, boolean instance) throws IOException {

         StringBuilder out = new StringBuilder(65535);

         out.append("var loader = arguments[0];\n");

         out.append("var vm = loader.vm;\n");

         int prelude = out.length();

         String initCode = new Gen(this, out).compile(new ByteArrayInputStream(arr));

         String code = out.toString().toString();

         String under = name.replace('.', '_');

         Object fn = applyCode(loader, under, code, instance);

         if (!initCode.isEmpty()) {

             out.setLength(prelude);

             out.append(initCode);

             code = out.toString().toString();

             applyCode(loader, null, code, false);

         }            

         return fn;

     }

     @JavaScriptBody(args = {"loader", "name", "script", "instance" }, body =

         "try {\n" +

         "  new Function(script)(loader, name);\n" +

         "} catch (ex) {\n" +

         "  throw 'Cannot compile ' + name + ' ' + ex + ' line: ' + ex.lineNumber + ' script:\\n' + script;\n" +

         "}\n" +

         "return name != null ? vm[name](instance) : null;\n"

     )

     private static native Object applyCode(Object loader, String name, String script, boolean instance);

     private static final class Gen extends ByteCodeToJavaScript {

         private final VMLazy lazy;

         public Gen(VMLazy vm, Appendable out) {

             super(out);

             this.lazy = vm;

         }

         @JavaScriptBody(args = {"n"},

         body =

         "var cls = n.replace__Ljava_lang_String_2CC('/','_').toString();"

         + "\nvar dot = n.replace__Ljava_lang_String_2CC('/','.').toString();"

         + "\nvar lazy = this._lazy();"

         + "\nvar loader = lazy._loader();"

         + "\nvar vm = loader.vm;"

         + "\nif (vm[cls]) return false;"

         + "\nvm[cls] = function() {"

         + "\n  var instance = arguments.length == 0 || arguments[0] === true;"

         + "\n  return lazy.load__Ljava_lang_Object_2Ljava_lang_String_2Z(dot, instance);"

         + "\n};"

         + "\nreturn true;")

         @Override

         protected boolean requireReference(String internalClassName) {

             throw new UnsupportedOperationException();

         }

         @Override

         protected void requireScript(String resourcePath) throws IOException {

             if (!resourcePath.startsWith("/")) {

                 resourcePath = "/" + resourcePath;

             }

             String code = readCode(resourcePath);

             applyCode(lazy.loader, null, code, false);

         }

         private String readCode(String resourcePath) throws IOException {

             InputStream is = getClass().getResourceAsStream(resourcePath);

             StringBuilder sb = new StringBuilder();

             for (;;) {

                 int ch = is.read();

                 if (ch == -1) {

                     break;

                 }

                 sb.append((char)ch);

             }

             return sb.toString();

         }

         @Override

         String assignClass(String className) {

             return "vm[arguments[1]]=";

         }

         @Override

         String accessClass(String classOperation) {

             return "vm." + classOperation;

         }

     }

 }