/**

 * 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.util.ArrayList;

import java.util.Collection;

import java.util.List;

import org.apidesign.bck2brwsr.core.ExtraJavaScript;

import org.apidesign.bck2brwsr.core.JavaScriptBody;

import sun.tools.javap.ClassData;

import sun.tools.javap.FieldData;

import sun.tools.javap.MethodData;

import static sun.tools.javap.RuntimeConstants.*;

/** Translator of the code inside class files to JavaScript.

 *

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

 */

public final class ByteCodeToJavaScript {

    private final ClassData jc;

    private final Appendable out;

    private final Collection<? super String> references;

    private ByteCodeToJavaScript(

        ClassData jc, Appendable out, Collection<? super String> references

    ) {

        this.jc = jc;

        this.out = out;

        this.references = references;

    }

    /**

     * Converts a given class file to a JavaScript version.

     *

     * @param classFile input stream with code of the .class file

     * @param out a {@link StringBuilder} or similar to generate the output to

     * @param references a write only collection where the system adds list of

     *   other classes that were referenced and should be loaded in order the

     *   generated JavaScript code works properly. The names are in internal 

     *   JVM form so String is <code>java/lang/String</code>. Can be <code>null</code>

     *   if one is not interested in knowing references

     * @param scripts write only collection with names of resources to read

     * @return the initialization code for this class, if any. Otherwise <code>null</code>

     * 

     * @throws IOException if something goes wrong during read or write or translating

     */

    public static String compile(

        InputStream classFile, Appendable out,

        Collection<? super String> references,

        Collection<? super String> scripts

    ) throws IOException {

        ClassData jc = new ClassData(classFile);

        /*

        final ClassName extraAnn = ClassName.getClassName(ExtraJavaScript.class.getName().replace('.', '/'));

        Annotation a = jc.getAnnotation(extraAnn);

        if (a != null) {

            final ElementValue annVal = a.getComponent("resource").getValue();

            String res = ((PrimitiveElementValue)annVal).getValue().getValue().toString();

            scripts.add(res);

            final AnnotationComponent process = a.getComponent("processByteCode");

            if (process != null && "const=0".equals(process.getValue().toString())) {

                return null;

            }

        }

        */

        ByteCodeToJavaScript compiler = new ByteCodeToJavaScript(

            jc, out, references

        );

        List<String> toInitilize = new ArrayList<String>();

        for (MethodData m : jc.getMethods()) {

            if (m.isStatic()) {

                compiler.generateStaticMethod(m, toInitilize);

            } else {

                compiler.generateInstanceMethod(m);

            }

        }

        for (FieldData v : jc.getFields()) {

            if (v.isStatic()) {

                compiler.generateStaticField(v);

            }

        }

        final String className = className(jc);

        out.append("\nfunction ").append(className);

        out.append("() {");

        for (FieldData v : jc.getFields()) {

            if (!v.isStatic()) {

                out.append("\n  this.fld_").

                    append(v.getName()).append(" = 0;");

            }

        }

        out.append("\n}\n\nfunction ").append(className).append("_proto() {");

        out.append("\n  if (").append(className).

            append(".prototype.$instOf_").append(className).append(") {");

        out.append("\n    return new ").append(className).append(";");

        out.append("\n  }");

        // ClassName sc = jc.getSuperClass();

        String sc = jc.getSuperClassName(); // with _

        if (sc != null) {

            out.append("\n  var p = ").append(className)

               .append(".prototype = ").

                append(sc.replace('/', '_')).append("_proto();");

        } else {

            out.append("\n  var p = ").append(className).append(".prototype;");

        }

        for (MethodData m : jc.getMethods()) {

            if (!m.getName().contains("<init>") && !m.getName().contains("<cinit>")) {

                compiler.generateMethodReference("\n  p.", m);

            }

        }

        out.append("\n  p.$instOf_").append(className).append(" = true;");

        for (String superInterface : jc.getSuperInterfaces()) {

            out.append("\n  p.$instOf_").append(superInterface.replace('/', '_')).append(" = true;");

        }

        out.append("\n  return new ").append(className).append(";");

        out.append("\n}");

        out.append("\n").append(className).append("_proto();");

        StringBuilder sb = new StringBuilder();

        for (String init : toInitilize) {

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

        }

        return sb.toString();

    }

    private void generateStaticMethod(MethodData m, List<String> toInitilize) throws IOException {

        if (javaScriptBody(m, true)) {

            return;

        }

        int[] argsCnt = { -1 };

        final String mn = findMethodName(m, argsCnt);

        out.append("\nfunction ").append(

            className(jc)

        ).append('_').append(mn);

        if (mn.equals("classV")) {

            toInitilize.add(className(jc) + '_' + mn);

        }

        out.append('(');

        String space = "";

        for (int index = 0, i = 0; i < argsCnt[0]; i++) {

            out.append(space);

            out.append("arg").append(String.valueOf(index));

            space = ",";

            final String desc = null;// XXX findDescriptor(args.get(i).getDescriptor());

            if ("D".equals(desc) || "J".equals(desc)) {

                index += 2;

            } else {

                index++;

            }

        }

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

        final byte[] code = m.getCode();

        if (code != null) {

            int len = m.getMaxLocals();

            for (int index = argsCnt[0], i = argsCnt[0]; i < len; i++) {

                out.append("  var ");

                out.append("arg").append(String.valueOf(i)).append(";\n");

            }

            out.append("  var stack = new Array();\n");

            produceCode(code);

        } else {

            out.append("  /* no code found for ").append(m.getInternalSig()).append(" */\n");

        }

        out.append("}");

    }

    private void generateMethodReference(String prefix, MethodData m) throws IOException {

        final String name = findMethodName(m, null);

        out.append(prefix).append(name).append(" = ")

           .append(className(jc))

           .append('_').append(name).append(";");

    }

    private void generateInstanceMethod(MethodData m) throws IOException {

        if (javaScriptBody(m, false)) {

            return;

        }

        int[] argsCnt = { -1 };

        out.append("\nfunction ").append(

            className(jc)

        ).append('_').append(findMethodName(m, argsCnt));

        out.append("(arg0");

        String space = ",";

        for (int index = 1, i = 0; i < argsCnt[0]; i++) {

            out.append(space);

            out.append("arg").append(String.valueOf(index));

            final String desc = null;// XXX findDescriptor(args.get(i).getDescriptor());

            if ("D".equals(desc) || "J".equals(desc)) {

                index += 2;

            } else {

                index++;

            }

        }

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

        final byte[] code = m.getCode();

        if (code != null) {

            int len = m.getMaxLocals();

            for (int index = argsCnt[0], i = argsCnt[0]; i < len; i++) {

                out.append("  var ");

                out.append("arg").append(String.valueOf(i + 1)).append(";\n");

            }

            out.append(";\n  var stack = new Array();\n");

            produceCode(code);

        } else {

            out.append("  /* no code found for ").append(m.getInternalSig()).append(" */\n");

        }

        out.append("}");

    }

    private void produceCode(byte[] byteCodes) throws IOException {

        out.append("\n  var gt = 0;\n  for(;;) switch(gt) {\n");

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

            int prev = i;

            out.append("    case " + i).append(": ");

            final int c = readByte(byteCodes, i);

            switch (c) {

                case opc_aload_0:

                case opc_iload_0:

                case opc_lload_0:

                case opc_fload_0:

                case opc_dload_0:

                    out.append("stack.push(arg0);");

                    break;

                case opc_aload_1:

                case opc_iload_1:

                case opc_lload_1:

                case opc_fload_1:

                case opc_dload_1:

                    out.append("stack.push(arg1);");

                    break;

                case opc_aload_2:

                case opc_iload_2:

                case opc_lload_2:

                case opc_fload_2:

                case opc_dload_2:

                    out.append("stack.push(arg2);");

                    break;

                case opc_aload_3:

                case opc_iload_3:

                case opc_lload_3:

                case opc_fload_3:

                case opc_dload_3:

                    out.append("stack.push(arg3);");

                    break;

                case opc_iload:

                case opc_lload:

                case opc_fload:

                case opc_dload:

                case opc_aload: {

                    final int indx = readByte(byteCodes, ++i);

                    out.append("stack.push(arg").append(indx + ");");

                    break;

                }

                case opc_istore:

                case opc_lstore:

                case opc_fstore:

                case opc_dstore:

                case opc_astore: {

                    final int indx = readByte(byteCodes, ++i);

                    out.append("arg" + indx).append(" = stack.pop();");

                    break;

                }

                case opc_astore_0:

                case opc_istore_0:

                case opc_lstore_0:

                case opc_fstore_0:

                case opc_dstore_0:

                    out.append("arg0 = stack.pop();");

                    break;

                case opc_astore_1:

                case opc_istore_1:

                case opc_lstore_1:

                case opc_fstore_1:

                case opc_dstore_1:

                    out.append("arg1 = stack.pop();");

                    break;

                case opc_astore_2:

                case opc_istore_2:

                case opc_lstore_2:

                case opc_fstore_2:

                case opc_dstore_2:

                    out.append("arg2 = stack.pop();");

                    break;

                case opc_astore_3:

                case opc_istore_3:

                case opc_lstore_3:

                case opc_fstore_3:

                case opc_dstore_3:

                    out.append("arg3 = stack.pop();");

                    break;

                case opc_iadd:

                case opc_ladd:

                case opc_fadd:

                case opc_dadd:

                    out.append("stack.push(stack.pop() + stack.pop());");

                    break;

                case opc_isub:

                case opc_lsub:

                case opc_fsub:

                case opc_dsub:

                    out.append("{ var tmp = stack.pop(); stack.push(stack.pop() - tmp); }");

                    break;

                case opc_imul:

                case opc_lmul:

                case opc_fmul:

                case opc_dmul:

                    out.append("stack.push(stack.pop() * stack.pop());");

                    break;

                case opc_idiv:

                case opc_ldiv:

                    out.append("{ var tmp = stack.pop(); stack.push(Math.floor(stack.pop() / tmp)); }");

                    break;

                case opc_fdiv:

                case opc_ddiv:

                    out.append("{ var tmp = stack.pop(); stack.push(stack.pop() / tmp); }");

                    break;

                case opc_iand:

                case opc_land:

                    out.append("stack.push(stack.pop() & stack.pop());");

                    break;

                case opc_ior:

                case opc_lor:

                    out.append("stack.push(stack.pop() | stack.pop());");

                    break;

                case opc_ixor:

                case opc_lxor:

                    out.append("stack.push(stack.pop() ^ stack.pop());");

                    break;

                case opc_ineg:

                case opc_lneg:

                case opc_fneg:

                case opc_dneg:

                    out.append("stack.push(- stack.pop());");

                    break;

                case opc_ishl:

                case opc_lshl:

                    out.append("{ var v = stack.pop(); stack.push(stack.pop() << v); }");

                    break;

                case opc_ishr:

                case opc_lshr:

                    out.append("{ var v = stack.pop(); stack.push(stack.pop() >> v); }");

                    break;

                case opc_iushr:

                case opc_lushr:

                    out.append("{ var v = stack.pop(); stack.push(stack.pop() >>> v); }");

                    break;

                case opc_iinc: {

                    final int varIndx = readByte(byteCodes, ++i);

                    final int incrBy = byteCodes[++i];

                    if (incrBy == 1) {

                        out.append("arg" + varIndx).append("++;");

                    } else {

                        out.append("arg" + varIndx).append(" += " + incrBy).append(";");

                    }

                    break;

                }

                case opc_return:

                    out.append("return;");

                    break;

                case opc_ireturn:

                case opc_lreturn:

                case opc_freturn:

                case opc_dreturn:

                case opc_areturn:

                    out.append("return stack.pop();");

                    break;

                case opc_i2l:

                case opc_i2f:

                case opc_i2d:

                case opc_l2i:

                    // max int check?

                case opc_l2f:

                case opc_l2d:

                case opc_f2d:

                case opc_d2f:

                    out.append("/* number conversion */");

                    break;

                case opc_f2i:

                case opc_f2l:

                case opc_d2i:

                case opc_d2l:

                    out.append("stack.push(Math.floor(stack.pop()));");

                    break;

                case opc_i2b:

                case opc_i2c:

                case opc_i2s:

                    out.append("/* number conversion */");

                    break;

                case opc_aconst_null:

                    out.append("stack.push(null);");

                    break;

                case opc_iconst_m1:

                    out.append("stack.push(-1);");

                    break;

                case opc_iconst_0:

                case opc_dconst_0:

                case opc_lconst_0:

                case opc_fconst_0:

                    out.append("stack.push(0);");

                    break;

                case opc_iconst_1:

                case opc_lconst_1:

                case opc_fconst_1:

                case opc_dconst_1:

                    out.append("stack.push(1);");

                    break;

                case opc_iconst_2:

                case opc_fconst_2:

                    out.append("stack.push(2);");

                    break;

                case opc_iconst_3:

                    out.append("stack.push(3);");

                    break;

                case opc_iconst_4:

                    out.append("stack.push(4);");

                    break;

                case opc_iconst_5:

                    out.append("stack.push(5);");

                    break;

                case opc_ldc: {

                    int indx = readByte(byteCodes, ++i);

                    String v = encodeConstant(indx);

                    out.append("stack.push(").append(v).append(");");

                    break;

                }

                case opc_ldc_w:

                case opc_ldc2_w: {

                    int indx = readIntArg(byteCodes, i);

                    i += 2;

                    String v = encodeConstant(indx);

                    out.append("stack.push(").append(v).append(");");

                    break;

                }

                case opc_lcmp:

                case opc_fcmpl:

                case opc_fcmpg:

                case opc_dcmpl:

                case opc_dcmpg: {

                    out.append("{ var delta = stack.pop() - stack.pop(); stack.push(delta < 0 ?-1 : (delta == 0 ? 0 : 1)); }");

                    break;

                }

                case opc_if_acmpeq:

                    i = generateIf(byteCodes, i, "===");

                    break;

                case opc_if_acmpne:

                    i = generateIf(byteCodes, i, "!=");

                    break;

                case opc_if_icmpeq: {

                    i = generateIf(byteCodes, i, "==");

                    break;

                }

                case opc_ifeq: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (stack.pop() == 0) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_ifne: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (stack.pop() != 0) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_iflt: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (stack.pop() < 0) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_ifle: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (stack.pop() <= 0) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_ifgt: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (stack.pop() > 0) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_ifge: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (stack.pop() >= 0) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_ifnonnull: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (stack.pop()) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_ifnull: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("if (!stack.pop()) { gt = " + indx);

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

                    i += 2;

                    break;

                }

                case opc_if_icmpne:

                    i = generateIf(byteCodes, i, "!=");

                    break;

                case opc_if_icmplt:

                    i = generateIf(byteCodes, i, ">");

                    break;

                case opc_if_icmple:

                    i = generateIf(byteCodes, i, ">=");

                    break;

                case opc_if_icmpgt:

                    i = generateIf(byteCodes, i, "<");

                    break;

                case opc_if_icmpge:

                    i = generateIf(byteCodes, i, "<=");

                    break;

                case opc_goto: {

                    int indx = i + readIntArg(byteCodes, i);

                    out.append("gt = " + indx).append("; continue;");

                    i += 2;

                    break;

                }

                case opc_lookupswitch: {

                    int table = i / 4 * 4 + 4;

                    int dflt = i + readInt4(byteCodes, table);

                    table += 4;

                    int n = readInt4(byteCodes, table);

                    table += 4;

                    out.append("switch (stack.pop()) {\n");

                    while (n-- > 0) {

                        int cnstnt = readInt4(byteCodes, table);

                        table += 4;

                        int offset = i + readInt4(byteCodes, table);

                        table += 4;

                        out.append("  case " + cnstnt).append(": gt = " + offset).append("; continue;\n");

                    }

                    out.append("  default: gt = " + dflt).append("; continue;\n}");

                    i = table - 1;

                    break;

                }

                case opc_tableswitch: {

                    int table = i / 4 * 4 + 4;

                    int dflt = i + readInt4(byteCodes, table);

                    table += 4;

                    int low = readInt4(byteCodes, table);

                    table += 4;

                    int high = readInt4(byteCodes, table);

                    table += 4;

                    out.append("switch (stack.pop()) {\n");

                    while (low <= high) {

                        int offset = i + readInt4(byteCodes, table);

                        table += 4;

                        out.append("  case " + low).append(": gt = " + offset).append("; continue;\n");

                        low++;

                    }

                    out.append("  default: gt = " + dflt).append("; continue;\n}");

                    i = table - 1;

                    break;

                }

                case opc_invokeinterface: {

                    i = invokeVirtualMethod(byteCodes, i) + 2;

                    break;

                }

                case opc_invokevirtual:

                    i = invokeVirtualMethod(byteCodes, i);

                    break;

                case opc_invokespecial:

                    i = invokeStaticMethod(byteCodes, i, false);

                    break;

                case opc_invokestatic:

                    i = invokeStaticMethod(byteCodes, i, true);

                    break;

                case opc_new: {

                    int indx = readIntArg(byteCodes, i);

                    String ci = jc.getClassName(indx);

                    out.append("stack.push(");

                    out.append("new ").append(ci.replace('/','_'));

                    out.append(");");

                    addReference(ci);

                    i += 2;

                    break;

                }

                case opc_newarray: {

                    int type = byteCodes[i++];

                    out.append("stack.push(new Array(stack.pop()));");

                    break;

                }

                case opc_anewarray: {

                    i += 2; // skip type of array

                    out.append("stack.push(new Array(stack.pop()));");

                    break;

                }

                case opc_multianewarray: {

                    i += 2;

                    int dim = readByte(byteCodes, ++i);

                    out.append("{ var a0 = new Array(stack.pop());");

                    for (int d = 1; d < dim; d++) {

                        out.append("\n  var l" + d).append(" = stack.pop();");

                        out.append("\n  for (var i" + d).append (" = 0; i" + d).

                            append(" < a" + (d - 1)).

                            append(".length; i" + d).append("++) {");

                        out.append("\n    var a" + d).

                            append (" = new Array(l" + d).append(");");

                        out.append("\n    a" + (d - 1)).append("[i" + d).append("] = a" + d).

                            append(";");

                    }

                    for (int d = 1; d < dim; d++) {

                        out.append("\n  }");

                    }

                    out.append("\nstack.push(a0); }");

                    break;

                }

                case opc_arraylength:

                    out.append("stack.push(stack.pop().length);");

                    break;

                case opc_iastore:

                case opc_lastore:

                case opc_fastore:

                case opc_dastore:

                case opc_aastore:

                case opc_bastore:

                case opc_castore:

                case opc_sastore: {

                    out.append("{ var value = stack.pop(); var indx = stack.pop(); stack.pop()[indx] = value; }");

                    break;

                }

                case opc_iaload:

                case opc_laload:

                case opc_faload:

                case opc_daload:

                case opc_aaload:

                case opc_baload:

                case opc_caload:

                case opc_saload: {

                    out.append("{ var indx = stack.pop(); stack.push(stack.pop()[indx]); }");

                    break;

                }

                case opc_pop2:

                    out.append("stack.pop();");

                case opc_pop:

                    out.append("stack.pop();");

                    break;

                case opc_dup:

                    out.append("stack.push(stack[stack.length - 1]);");

                    break;

                case opc_bipush:

                    out.append("stack.push(" + byteCodes[++i] + ");");

                    break;

                case opc_sipush:

                    out.append("stack.push(" + readIntArg(byteCodes, i) + ");");

                    i += 2;

                    break;

                case opc_getfield: {

                    int indx = readIntArg(byteCodes, i);

                    String[] fi = jc.getFieldInfoName(indx);

                    out.append("stack.push(stack.pop().fld_").

                        append(fi[1]).append(");");

                    i += 2;

                    break;

                }

                case opc_getstatic: {

                    int indx = readIntArg(byteCodes, i);

                    String[] fi = jc.getFieldInfoName(indx);

                    out.append("stack.push(").append(fi[0].replace('/', '_'));

                    out.append('_').append(fi[1]).append(");");

                    i += 2;

                    addReference(fi[0]);

                    break;

                }

                case opc_putstatic: {

                    int indx = readIntArg(byteCodes, i);

                    String[] fi = jc.getFieldInfoName(indx);

                    out.append(fi[0].replace('/', '_'));

                    out.append('_').append(fi[1]).append(" = stack.pop();");

                    i += 2;

                    addReference(fi[0]);

                    break;

                }

                case opc_putfield: {

                    int indx = readIntArg(byteCodes, i);

                    String[] fi = jc.getFieldInfoName(indx);

                    out.append("{ var v = stack.pop(); stack.pop().fld_")

                       .append(fi[1]).append(" = v; }");

                    i += 2;

                    break;

                }

                case opc_checkcast: {

                    int indx = readIntArg(byteCodes, i);

                    final String type = jc.getClassName(indx);

                    if (!type.startsWith("[")) {

                        // no way to check arrays right now

                        out.append("if(stack[stack.length - 1].$instOf_")

                           .append(type.replace('/', '_'))

                           .append(" != 1) throw {};"); // XXX proper exception

                    }

                    i += 2;

                    break;

                }

                case opc_instanceof: {

                    int indx = readIntArg(byteCodes, i);

                    final String type = jc.getClassName(indx);

                    out.append("stack.push(stack.pop().$instOf_")

                       .append(type.replace('/', '_'))

                       .append(" ? 1 : 0);");

                    i += 2;

                    break;

                }

                case opc_athrow: {

                    out.append("{ var t = stack.pop(); stack = new Array(1); stack[0] = t; throw t; }");

                    break;

                }

                default: {

                    out.append("throw 'unknown bytecode " + c + "';");

                }

            }

            out.append(" //");

            for (int j = prev; j <= i; j++) {

                out.append(" ");

                final int cc = readByte(byteCodes, j);

                out.append(Integer.toString(cc));

            }

            out.append("\n");

        }

        out.append("  }\n");

    }

    private int generateIf(byte[] byteCodes, int i, final String test) throws IOException {

        int indx = i + readIntArg(byteCodes, i);

        out.append("if (stack.pop() ").append(test).append(" stack.pop()) { gt = " + indx);

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

        return i + 2;

    }

    private int readIntArg(byte[] byteCodes, int offsetInstruction) {

        final int indxHi = byteCodes[offsetInstruction + 1] << 8;

        final int indxLo = byteCodes[offsetInstruction + 2];

        return (indxHi & 0xffffff00) | (indxLo & 0xff);

    }

    private int readInt4(byte[] byteCodes, int offsetInstruction) {

        final int d = byteCodes[offsetInstruction + 0] << 24;

        final int c = byteCodes[offsetInstruction + 1] << 16;

        final int b = byteCodes[offsetInstruction + 2] << 8;

        final int a = byteCodes[offsetInstruction + 3];

        return (d & 0xff000000) | (c & 0xff0000) | (b & 0xff00) | (a & 0xff);

    }

    private int readByte(byte[] byteCodes, int offsetInstruction) {

        return (byteCodes[offsetInstruction] + 256) % 256;

    }

    private static int countArgs(String descriptor, boolean[] hasReturnType, StringBuilder sig) {

        int cnt = 0;

        int i = 0;

        Boolean count = null;

        boolean array = false;

        int firstPos = sig.length();

        while (i < descriptor.length()) {

            char ch = descriptor.charAt(i++);

            switch (ch) {

                case '(':

                    count = true;

                    continue;

                case ')':

                    count = false;

                    continue;

                case 'A':

                    array = true;

                    break;

                case 'B': 

                case 'C': 

                case 'D': 

                case 'F': 

                case 'I': 

                case 'J': 

                case 'S': 

                case 'Z': 

                    if (count) {

                        cnt++;

                        if (array) {

                            sig.append('A');

                        }

                        sig.append(ch);

                    } else {

                        hasReturnType[0] = true;

                        sig.insert(firstPos, ch);

                        if (array) {

                            sig.insert(firstPos, 'A');

                        }

                    }

                    array = false;

                    continue;

                case 'V': 

                    assert !count;

                    hasReturnType[0] = false;

                    sig.insert(firstPos, 'V');

                    continue;

                case 'L':

                    int next = descriptor.indexOf(';', i);

                    if (count) {

                        cnt++;

                        if (array) {

                            sig.append('A');

                        }

                        sig.append(ch);

                        sig.append(descriptor.substring(i, next).replace('/', '_'));

                    } else {

                        sig.insert(firstPos, descriptor.substring(i, next).replace('/', '_'));

                        sig.insert(firstPos, ch);

                        if (array) {

                            sig.insert(firstPos, 'A');

                        }

                        hasReturnType[0] = true;

                    }

                    i = next + 1;

                    continue;

                case '[':

                    //arrays++;

                    continue;

                default:

                    break; // invalid character

            }

        }

        return cnt;

    }

    private void generateStaticField(FieldData v) throws IOException {

        out.append("\nvar ")

           .append(className(jc))

           .append('_').append(v.getName()).append(" = 0;");

    }

    private String findMethodName(MethodData m, int[] cnt) {

        StringBuilder name = new StringBuilder();

        if ("<init>".equals(m.getName())) { // NOI18N

            name.append("cons"); // NOI18N

        } else if ("<clinit>".equals(m.getName())) { // NOI18N

            name.append("class"); // NOI18N

        } else {

            name.append(m.getName());

        } 

        boolean hasReturn[] = { false };

        int argsCnt = countArgs(findDescriptor(m.getInternalSig()), hasReturn, name);

        if (cnt != null) {

            cnt[0] = argsCnt;

        }

        return name.toString();

    }

    private String findMethodName(String[] mi, int[] cnt, boolean[] hasReturn) {

        StringBuilder name = new StringBuilder();

        String descr = mi[2];//mi.getDescriptor();

        String nm= mi[1];

        if ("<init>".equals(nm)) { // NOI18N

            name.append("cons"); // NOI18N

        } else {

            name.append(nm);

        }

        cnt[0] = countArgs(findDescriptor(descr), hasReturn, name);

        return name.toString();

    }

    private int invokeStaticMethod(byte[] byteCodes, int i, boolean isStatic)

    throws IOException {

        int methodIndex = readIntArg(byteCodes, i);

        String[] mi = jc.getFieldInfoName(methodIndex);

        boolean[] hasReturn = { false };

        int[] cnt = { 0 };

        String mn = findMethodName(mi, cnt, hasReturn);

        out.append("{ ");

        for (int j = cnt[0] - 1; j >= 0; j--) {

            out.append("var v" + j).append(" = stack.pop(); ");

        }

        if (hasReturn[0]) {

            out.append("stack.push(");

        }

        final String in = mi[0];

        out.append(in.replace('/', '_'));

        if (isStatic) {

            out.append(".prototype.");

        } else {

            out.append('_');

        }

        out.append(mn);

        out.append('(');

        String sep = "";

        if (!isStatic) {

            out.append("stack.pop()");

            sep = ", ";

        }

        for (int j = 0; j < cnt[0]; j++) {

            out.append(sep);

            out.append("v" + j);

            sep = ", ";

        }

        out.append(")");

        if (hasReturn[0]) {

            out.append(")");

        }

        out.append("; }");

        i += 2;

        addReference(in);

        return i;

    }

    private int invokeVirtualMethod(byte[] byteCodes, int i)

    throws IOException {

        int methodIndex = readIntArg(byteCodes, i);

        String[] mi = jc.getFieldInfoName(methodIndex);

        boolean[] hasReturn = { false };

        int[] cnt = { 0 };

        String mn = findMethodName(mi, cnt, hasReturn);

        out.append("{ ");

        for (int j = cnt[0] - 1; j >= 0; j--) {

            out.append("var v" + j).append(" = stack.pop(); ");

        }

        out.append("var self = stack.pop(); ");

        if (hasReturn[0]) {

            out.append("stack.push(");

        }

        out.append("self.");

        out.append(mn);

        out.append('(');

        out.append("self");

        for (int j = 0; j < cnt[0]; j++) {

            out.append(", ");

            out.append("v" + j);

        }

        out.append(")");

        if (hasReturn[0]) {

            out.append(")");

        }

        out.append("; }");

        i += 2;

        return i;

    }

    private void addReference(String cn) throws IOException {

        if (references != null) {

            if (references.add(cn)) {

                out.append(" /* needs ").append(cn).append(" */");

            }

        }

    }

    private void outType(String d, StringBuilder out) {

        int arr = 0;

        while (d.charAt(0) == '[') {

            out.append('A');

            d = d.substring(1);

        }

        if (d.charAt(0) == 'L') {

            assert d.charAt(d.length() - 1) == ';';

            out.append(d.replace('/', '_').substring(0, d.length() - 1));

        } else {

            out.append(d);

        }

    }

    private String encodeConstant(int entryIndex) {

        String s = jc.stringValue(entryIndex, true);

        return s;

    }

    private String findDescriptor(String d) {

        return d.replace('[', 'A');

    }

    private boolean javaScriptBody(MethodData m, boolean isStatic) throws IOException {

        return false;

        /*