/**

  * 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.IOException;

 import java.io.InputStream;

 /** Generator of JavaScript from bytecode of classes on classpath of the VM.

  *

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

  */

 class VM extends ByteCodeToJavaScript {

     public VM(Appendable out) {

         super(out);

     }

     static {

         // uses VMLazy to load dynamic classes

         boolean assertsOn = false;

         assert assertsOn = true;

         if (assertsOn) {

             VMLazy.init();

             Zips.init();

         }

     }

     @Override

     boolean debug(String msg) throws IOException {

         return false;

     }

     static void compile(Bck2Brwsr.Resources l, Appendable out, StringArray names) throws IOException {

         new VM(out).doCompile(l, names);

     }

     protected void doCompile(Bck2Brwsr.Resources l, StringArray names) throws IOException {

         out.append("(function VM(global) {var fillInVMSkeleton = function(vm) {");

         StringArray processed = new StringArray();

         StringArray initCode = new StringArray();

         for (String baseClass : names.toArray()) {

             references.add(baseClass);

             for (;;) {

                 String name = null;

                 for (String n : references.toArray()) {

                     if (processed.contains(n)) {

                         continue;

                     }

                     name = n;

                 }

                 if (name == null) {

                     break;

                 }

                 InputStream is = loadClass(l, name);

                 if (is == null) {

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

                 }

                 try {

                     String ic = compile(is);

                     processed.add(name);

                     initCode.add(ic == null ? "" : ic);

                 } catch (RuntimeException ex) {

                     if (out instanceof CharSequence) {

                         CharSequence seq = (CharSequence)out;

                         int lastBlock = seq.length();

                         while (lastBlock-- > 0) {

                             if (seq.charAt(lastBlock) == '{') {

                                 break;

                             }

                         }

                         throw new IOException("Error while compiling " + name + "\n" 

                             + seq.subSequence(lastBlock + 1, seq.length()), ex

                         );

                     } else {

                         throw new IOException("Error while compiling " + name + "\n" 

                             + out, ex

                         );

                     }

                 }

             }

             for (String resource : scripts.toArray()) {

                 while (resource.startsWith("/")) {

                     resource = resource.substring(1);

                 }

                 InputStream emul = l.get(resource);

                 if (emul == null) {

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

                 }

                 readResource(emul, out);

             }

             scripts = new StringArray();

             StringArray toInit = StringArray.asList(references.toArray());

             toInit.reverse();

             for (String ic : toInit.toArray()) {

                 int indx = processed.indexOf(ic);

                 if (indx >= 0) {

                     final String theCode = initCode.toArray()[indx];

                     if (!theCode.isEmpty()) {

                         out.append(theCode).append("\n");

                     }

                     initCode.toArray()[indx] = "";

                 }

             }

         }

         out.append(

               "  return vm;\n"

             + "  };\n"

             + "  global.bck2brwsr = function() {\n"

             + "    var args = Array.prototype.slice.apply(arguments);\n"

             + "    var vm = fillInVMSkeleton({});\n"

             + "    var loader = {};\n"

             + "    loader.vm = vm;\n"

             + "    loader.loadClass = function(name) {\n"

             + "      var attr = name.replace__Ljava_lang_String_2CC('.','_');\n"

             + "      var fn = vm[attr];\n"

             + "      if (fn) return fn(false);\n"

             + "      return vm.org_apidesign_vm4brwsr_VMLazy(false).\n"

             + "        load__Ljava_lang_Object_2Ljava_lang_Object_2Ljava_lang_String_2_3Ljava_lang_Object_2(loader, name, args);\n"

             + "    }\n"

             + "    if (vm.loadClass) {\n"

             + "      throw 'Cannot initialize the bck2brwsr VM twice!';\n"

             + "    }\n"

             + "    vm.loadClass = loader.loadClass;\n"

             + "    vm.loadBytes = function(name) {\n"

             + "      return vm.org_apidesign_vm4brwsr_VMLazy(false).\n"

             + "        loadBytes___3BLjava_lang_Object_2Ljava_lang_String_2_3Ljava_lang_Object_2(loader, name, args);\n"

             + "    }\n"

             + "    vm.java_lang_reflect_Array(false);\n"

             + "    vm.org_apidesign_vm4brwsr_VMLazy(false).\n"

             + "      loadBytes___3BLjava_lang_Object_2Ljava_lang_String_2_3Ljava_lang_Object_2(loader, null, args);\n"

             + "    return loader;\n"

             + "  };\n");

         out.append("}(this));");

     }

     private static void readResource(InputStream emul, Appendable out) throws IOException {

         try {

             int state = 0;

             for (;;) {

                 int ch = emul.read();

                 if (ch == -1) {

                     break;

                 }

                 if (ch < 0 || ch > 255) {

                     throw new IOException("Invalid char in emulation " + ch);

                 }

                 switch (state) {

                     case 0: 

                         if (ch == '/') {

                             state = 1;

                         } else {

                             out.append((char)ch);

                         }

                         break;

                     case 1:

                         if (ch == '*') {

                             state = 2;

                         } else {

                             out.append('/').append((char)ch);

                             state = 0;

                         }

                         break;

                     case 2:

                         if (ch == '*') {

                             state = 3;

                         }

                         break;

                     case 3:

                         if (ch == '/') {

                             state = 0;

                         } else {

                             state = 2;

                         }

                         break;

                 }

             }

         } finally {

             emul.close();

         }

     }

     private static InputStream loadClass(Bck2Brwsr.Resources l, String name) throws IOException {

         return l.get(name + ".class"); // NOI18N

     }

     static String toString(String name) throws IOException {

         StringBuilder sb = new StringBuilder();

 //        compile(sb, name);

         return sb.toString().toString();

     }

     private StringArray scripts = new StringArray();

     private StringArray references = new StringArray();

     @Override

     protected boolean requireReference(String cn) {

         if (references.contains(cn)) {

             return false;

         }

         references.add(cn);

         return true;

     }

     @Override

     protected void requireScript(String resourcePath) {

         scripts.add(resourcePath);

     }

     @Override

     String assignClass(String className) {

         return "vm." + className + " = ";

     }

     @Override

     String accessClass(String className) {

         return "vm." + className;

     }

 }