/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2004-2006 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.CodeException;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.Priorities;
import edu.umd.cs.findbugs.ba.XField;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;

public class SynchronizingOnContentsOfFieldToProtectField extends OpcodeStackDetector {

	final BugReporter bugReporter;

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

	@Override
	public void visit(Code code) {
		// System.out.println(getMethodName());

		state = 0;
		countDown = 0;
		super.visit(code); // make callbacks to sawOpcode for all opcodes
		syncField = field = putField = null;
		pendingBug  = null;

	}
	
	 int state = 0;

	XField field, putField;
	XField syncField;
	int putPC;
	BugInstance pendingBug;
	int countDown = 0;

	@Override
	public void sawOpcode(int seen) {
//		System.out.println(state + " " + getPC() + " " + OPCODE_NAMES[seen]);
		if (countDown == 2 && seen == GOTO) {
			CodeException tryBlock = getSurroundingTryBlock(getPC());
			if (tryBlock != null && tryBlock.getEndPC() == getPC())
				pendingBug.lowerPriority();
		}
		if (countDown > 0) {
			countDown--;
			if (countDown == 0) {
				if (seen == MONITOREXIT)
					pendingBug.lowerPriority();
				
				bugReporter.reportBug(pendingBug);
				pendingBug = null;
			}
		}
		if (seen == PUTFIELD) {
			
			if (syncField != null && getPrevOpcode(1) != ALOAD_0 && syncField.equals(getXFieldOperand())) {
				OpcodeStack.Item value = stack.getStackItem(0);
				int priority = Priorities.HIGH_PRIORITY;
				 if (value.isNull())
					 priority = Priorities.NORMAL_PRIORITY;
	            pendingBug = new BugInstance(this, "ML_SYNC_ON_FIELD_TO_GUARD_CHANGING_THAT_FIELD", priority).addClassAndMethod(this)
				        .addField(syncField).addSourceLine(this);
	            countDown = 2;
	            
            }
			
		}
		if (seen == MONITOREXIT) {
			pendingBug = null;
			countDown = 0;
		}
		
		if (seen==MONITORENTER)
			syncField = null;
		
		switch (state) {
		case 0:
			if (seen == ALOAD_0)
				state = 1;
			break;
		case 1:
			if (seen == GETFIELD) {
				state = 2;
				field = getXFieldOperand();
			} else
				state = 0;
			break;
		case 2:
			if (seen == DUP)
				state = 3;
			else
				state = 0;
			break;
		case 3:
			if (isRegisterStore())
				state = 4;
			else
				state = 0;
			break;
		case 4:
			if (seen == MONITORENTER) {
				state = 0;
				syncField = field;
			} else
				state = 0;
			break;
		
		}

	}

}

@@ -1656,19 +1656,8 @@
 ld =
- putField =
  nul
@@ -1722,18 +1722,8 @@
 ield
-, putField
 ;%0A%09X
@@ -1743,20 +1743,8 @@
 ld;%0A
-%09int putPC;%0A
 %09Bug

fix findbugs warnings