/**

  * 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;

 import java.net.URL;

 import java.util.Enumeration;

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

  *

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

  */

 class GenJS extends ByteCodeToJavaScript {

     public GenJS(Appendable out) {

         super(out);

     }

     static void compile(Appendable out, String... names) throws IOException {

         compile(out, StringArray.asList(names));

     }

     static void compile(ClassLoader l, Appendable out, String... names) throws IOException {

         compile(l, out, StringArray.asList(names));

     }

     static void compile(Appendable out, StringArray names) throws IOException {

         compile(GenJS.class.getClassLoader(), out, names);

     }

     static void compile(ClassLoader l, Appendable out, StringArray names) throws IOException {

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

     }

     protected void doCompile(ClassLoader l, StringArray names) throws IOException {

         out.append("(function VM(global) {");

         out.append("\n  var 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.getResourceAsStream(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) {

                     out.append(initCode.toArray()[indx]).append("\n");

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

                 }

             }

         }

         out.append(

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

             + "    loadClass : function(name) { return vm[name](true); }\n"

             + "  };\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(ClassLoader l, String name) throws IOException {

         Enumeration<URL> en = l.getResources(name + ".class");

         URL u = null;

         while (en.hasMoreElements()) {

             u = en.nextElement();

         }

         if (u == null) {

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

         }

         if (u.toExternalForm().contains("rt.jar!")) {

             throw new IOException("No emulation for " + u);

         }

         return u.openStream();

     }

     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;

     }

 }