/**

  * 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 org.apidesign.javap.RuntimeConstants;

 import org.apidesign.javap.TypeArray;

 public final class LocalsMapper {

     private final TypeArray argTypeRecords;

     private final TypeArray localTypeRecords;

     public LocalsMapper(final TypeArray stackMapArgs) {

         final TypeArray initTypeRecords = new TypeArray();

         updateRecords(initTypeRecords, stackMapArgs);

         argTypeRecords = initTypeRecords;

         localTypeRecords = new TypeArray(initTypeRecords);

     }

     public void outputArguments(final Appendable out) throws IOException {

         final int argRecordCount = argTypeRecords.getSize();

         if (argRecordCount > 0) {

             Variable variable = getVariable(argTypeRecords, 0);

             out.append(variable);

             int i = variable.isCategory2() ? 2 : 1;

             while (i < argRecordCount) {

                 variable = getVariable(argTypeRecords, i);

                 out.append(", ");

                 out.append(variable);

                 i += variable.isCategory2() ? 2 : 1;

             }

         }

     }

     public void syncWithFrameLocals(final TypeArray frameLocals) {

         updateRecords(localTypeRecords, frameLocals);

     }

     public Variable setI(final int index) {

         return setT(index, VarType.INTEGER);

     }

     public Variable setL(final int index) {

         return setT(index, VarType.LONG);

     }

     public Variable setF(final int index) {

         return setT(index, VarType.FLOAT);

     }

     public Variable setD(final int index) {

         return setT(index, VarType.DOUBLE);

     }

     public Variable setA(final int index) {

         return setT(index, VarType.REFERENCE);

     }

     public Variable setT(final int index, final int type) {

         updateRecord(localTypeRecords, index, type);

         return Variable.getLocalVariable(type, index);

     }

     public Variable getI(final int index) {

         return getT(index, VarType.INTEGER);

     }

     public Variable getL(final int index) {

         return getT(index, VarType.LONG);

     }

     public Variable getF(final int index) {

         return getT(index, VarType.FLOAT);

     }

     public Variable getD(final int index) {

         return getT(index, VarType.DOUBLE);

     }

     public Variable getA(final int index) {

         return getT(index, VarType.REFERENCE);

     }

     public Variable getT(final int index, final int type) {

         final int oldRecordValue = localTypeRecords.get(index);

         if ((oldRecordValue & 0xff) != type) {

             throw new IllegalStateException("Type mismatch");

         }

         return Variable.getLocalVariable(type, index);

     }

     private static void updateRecords(final TypeArray typeRecords,

                                       final TypeArray stackMapTypes) {

         final int srcSize = stackMapTypes.getSize();

         for (int i = 0, dstIndex = 0; i < srcSize; ++i) {

             final int smType = stackMapTypes.get(i);

             if (smType == RuntimeConstants.ITEM_Bogus) {

                 ++dstIndex;

                 continue;

             }

             final int varType = VarType.fromStackMapType(smType);

             updateRecord(typeRecords, dstIndex, varType);

             dstIndex += VarType.isCategory2(varType) ? 2 : 1;

         }

     }

     private static void updateRecord(final TypeArray typeRecords,

                                      final int index, final int type) {

         if (typeRecords.getSize() < (index + 1)) {

             typeRecords.setSize(index + 1);

         }

         final int oldRecordValue = typeRecords.get(index);

         final int usedTypesMask =

                 (oldRecordValue >> 8) | (1 << type);

         typeRecords.set(index, (usedTypesMask << 8) | type);

     }

     private static Variable getVariable(final TypeArray typeRecords,

                                         final int index) {

         return Variable.getLocalVariable(typeRecords.get(index) & 0xff, index);

     }

 }