/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.bcel.generic;

import java.io.DataOutputStream;
import java.io.IOException;

import org.apache.bcel.Const;
import org.apache.bcel.util.ByteSequence;

/**
 * IINC - Increment local variable by constant
 */
public class IINC extends LocalVariableInstruction {

    private boolean wide;
    private int c;

    /**
     * Empty constructor needed for Instruction.readInstruction. Not to be used otherwise.
     */
    IINC() {
    }

    /**
     * Constructs an IINC instruction.
     *
     * @param n index of local variable.
     * @param c increment factor.
     */
    public IINC(final int n, final int c) {
        // Default behavior of LocalVariableInstruction causes error
        super.setOpcode(Const.IINC);
        super.setLength((short) 3);
        setIndex(n); // May set wide as side effect
        setIncrement(c);
    }

    /**
     * Calls corresponding visitor method(s). The order is: Call visitor methods of implemented interfaces first, then call
     * methods according to the class hierarchy in descending order, that is, the most specific visitXXX() call comes last.
     *
     * @param v Visitor object.
     */
    @Override
    public void accept(final Visitor v) {
        v.visitLocalVariableInstruction(this);
        v.visitIINC(this);
    }

    /**
     * Dumps instruction as byte code to stream out.
     *
     * @param out Output stream.
     */
    @Override
    public void dump(final DataOutputStream out) throws IOException {
        if (wide) {
            out.writeByte(Const.WIDE);
        }
        out.writeByte(super.getOpcode());
        if (wide) {
            out.writeShort(super.getIndex());
            out.writeShort(c);
        } else {
            out.writeByte(super.getIndex());
            out.writeByte(c);
        }
    }

    /**
     * Gets the increment factor.
     *
     * @return increment factor.
     */
    public final int getIncrement() {
        return c;
    }

    /**
     * Gets the int type.
     *
     * @return int type.
     */
    @Override
    public Type getType(final ConstantPoolGen cp) {
        return Type.INT;
    }

    /**
     * Reads needed data (for example index) from file.
     */
    @Override
    protected void initFromFile(final ByteSequence bytes, final boolean wide) throws IOException {
        this.wide = wide;
        if (wide) {
            super.setLength(6);
            super.setIndexOnly(bytes.readUnsignedShort());
            c = bytes.readShort();
        } else {
            super.setLength(3);
            super.setIndexOnly(bytes.readUnsignedByte());
            c = bytes.readByte();
        }
    }

    /**
     * Sets increment factor.
     *
     * @param c the increment factor.
     */
    public final void setIncrement(final int c) {
        this.c = c;
        setWide();
    }

    /**
     * Sets index of local variable.
     */
    @Override
    public final void setIndex(final int n) {
        if (n < 0) {
            throw new ClassGenException("Negative index value: " + n);
        }
        super.setIndexOnly(n);
        setWide();
    }

    private void setWide() {
        wide = super.getIndex() > Const.MAX_BYTE;
        if (c > 0) {
            wide = wide || c > Byte.MAX_VALUE;
        } else {
            wide = wide || c < Byte.MIN_VALUE;
        }
        if (wide) {
            super.setLength(6); // wide byte included
        } else {
            super.setLength(3);
        }
    }

    /**
     * Returns mnemonic for instruction.
     *
     * @return mnemonic for instruction.
     */
    @Override
    public String toString(final boolean verbose) {
        return super.toString(verbose) + " " + c;
    }
}
