/*

 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.apidesign.javap;

import static org.apidesign.javap.RuntimeConstants.ITEM_Integer;

import static org.apidesign.javap.RuntimeConstants.ITEM_Float;

import static org.apidesign.javap.RuntimeConstants.ITEM_Double;

import static org.apidesign.javap.RuntimeConstants.ITEM_Long;

import static org.apidesign.javap.RuntimeConstants.ITEM_Object;

public final class StackMapIterator {

    private final StackMapTableData[] stackMapTable;

    private final TypeArray argTypes;

    private final TypeArray localTypes;

    private final TypeArray stackTypes;

    private int nextFrameIndex;

    private int lastFrameByteCodeOffset;

    private int byteCodeOffset;

    StackMapIterator(final MethodData methodData) {

        this(methodData.getStackMapTable(),

             methodData.getInternalSig(),

             methodData.isStatic());

    }

    StackMapIterator(final StackMapTableData[] stackMapTable,

                     final String methodSignature,

                     final boolean isStaticMethod) {

        this.stackMapTable = (stackMapTable != null)

                                 ? stackMapTable

                                 : new StackMapTableData[0];

        argTypes = getArgTypes(methodSignature, isStaticMethod);

        localTypes = new TypeArray();

        stackTypes = new TypeArray();

        localTypes.addAll(argTypes);

        lastFrameByteCodeOffset = -1;

        advanceBy(0);

    }

    public String getFrameAsString() {

        return (nextFrameIndex == 0)

                   ? StackMapTableData.toString("INITIAL", 0, null, null)

                   : stackMapTable[nextFrameIndex - 1].toString();

    }

    public int getFrameIndex() {

        return nextFrameIndex;

    }

    public TypeArray getFrameStack() {

        return stackTypes;

    }

    public TypeArray getFrameLocals() {

        return localTypes;

    }

    public TypeArray getArguments() {

        return argTypes;

    }

    public void advanceBy(final int numByteCodes) {

        if (numByteCodes < 0) {

            throw new IllegalStateException("Forward only iterator");

        }

        byteCodeOffset += numByteCodes;

        while ((nextFrameIndex < stackMapTable.length)

                    && ((byteCodeOffset - lastFrameByteCodeOffset)

                            >= (stackMapTable[nextFrameIndex].offsetDelta

                                    + 1))) {

            final StackMapTableData nextFrame = stackMapTable[nextFrameIndex];

            lastFrameByteCodeOffset += nextFrame.offsetDelta + 1;

            nextFrame.applyTo(localTypes, stackTypes);

            ++nextFrameIndex;

        }

    }

    public void advanceTo(final int nextByteCodeOffset) {

        advanceBy(nextByteCodeOffset - byteCodeOffset);

    }

    private static TypeArray getArgTypes(final String methodSignature,

                                         final boolean isStaticMethod) {

        final TypeArray argTypes = new TypeArray();

        if (!isStaticMethod) {

            argTypes.add(ITEM_Object);

        }

        if (methodSignature.charAt(0) != '(') {

            throw new IllegalArgumentException("Invalid method signature");

        }

        final int length = methodSignature.length();

        boolean skipType = false;

        int argType;

        for (int i = 1; i < length; ++i) {

            switch (methodSignature.charAt(i)) {

                case 'B':

                case 'C':

                case 'S':

                case 'Z':

                case 'I':

                    argType = ITEM_Integer;

                    break;

                case 'J':

                    argType = ITEM_Long;

                    break;

                case 'F':

                    argType = ITEM_Float;

                    break;

                case 'D':

                    argType = ITEM_Double;

                    break;

                case 'L': {

                    i = methodSignature.indexOf(';', i + 1);

                    if (i == -1) {

                        throw new IllegalArgumentException(

                                      "Invalid method signature");

                    }

                    argType = ITEM_Object;

                    break;

                }

                case ')':

                    // not interested in the return value type

                    return argTypes;

                case '[':

                    if (!skipType) {

                        argTypes.add(ITEM_Object);

                        skipType = true;

                    }

                    continue;

                default:

                    throw new IllegalArgumentException(

                                  "Invalid method signature");

            }

            if (!skipType) {

                argTypes.add(argType);

            } else {

                skipType = false;

            }

        }

        return argTypes;

    }

}