/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2003-2005 University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package edu.umd.cs.findbugs.detect;

import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.Method;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.StatelessDetector;

//   2:   astore_1
//   3:   monitorenter
//   4:   aload_0
//   5:   invokevirtual   #13; //Method java/lang/Object.notify:()V
//   8:   aload_1
//   9:   monitorexit

public class FindNakedNotify extends BytecodeScanningDetector implements StatelessDetector {
    int stage = 0;

    private final BugReporter bugReporter;

    boolean synchronizedMethod;

    private int notifyPC;

    public FindNakedNotify(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
    }

    @Override
    public void visit(Method obj) {
        int flags = obj.getAccessFlags();
        synchronizedMethod = (flags & ACC_SYNCHRONIZED) != 0;
    }

    @Override
    public void visit(Code obj) {
        stage = synchronizedMethod ? 1 : 0;
        super.visit(obj);
        if (synchronizedMethod && stage == 4) {
            bugReporter.reportBug(new BugInstance(this, "NN_NAKED_NOTIFY", NORMAL_PRIORITY).addClassAndMethod(this)
                    .addSourceLine(this, notifyPC));
        }
    }

    @Override
    public void sawOpcode(int seen) {
        switch (stage) {
        case 0:
            if (seen == MONITORENTER) {
                stage = 1;
            }
            break;
        case 1:
            stage = 2;
            break;
        case 2:
            if (seen == INVOKEVIRTUAL
            && ("notify".equals(getNameConstantOperand()) || "notifyAll".equals(getNameConstantOperand()))
            && "()V".equals(getSigConstantOperand())) {
                stage = 3;
                notifyPC = getPC();
            } else {
                stage = 0;
            }
            break;
        case 3:
            stage = 4;
            break;
        case 4:
            if (seen == MONITOREXIT) {
                bugReporter.reportBug(new BugInstance(this, "NN_NAKED_NOTIFY", NORMAL_PRIORITY).addClassAndMethod(this)
                        .addSourceLine(this, notifyPC));
                stage = 5;
            } else {
                stage = 0;
            }
            break;
        case 5:
            break;
        default:
            assert false;
        }

    }
}
