/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 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 edu.umd.cs.findbugs.BugAccumulator;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;

public class BadUseOfReturnValue extends BytecodeScanningDetector {

    BugAccumulator bugAccumulator;

    public BadUseOfReturnValue(BugReporter bugReporter) {
        this.bugAccumulator = new BugAccumulator(bugReporter);
    }

    boolean readLineOnTOS = false;

    boolean stringIndexOfOnTOS = false;

    @Override
    public void visit(Code obj) {
        stringIndexOfOnTOS = false;
        readLineOnTOS = false;
        super.visit(obj);
        bugAccumulator.reportAccumulatedBugs();
    }

    @Override
    public void sawOpcode(int seen) {
        if (seen == INVOKEVIRTUAL && "indexOf".equals(getNameConstantOperand())
                && "java/lang/String".equals(getClassConstantOperand())
                && "(Ljava/lang/String;)I".equals(getSigConstantOperand())) {
            stringIndexOfOnTOS = true;
        } else if (stringIndexOfOnTOS) {
            if (seen == IFLE || seen == IFGT) {
                bugAccumulator.accumulateBug(
                        new BugInstance(this, "RV_CHECK_FOR_POSITIVE_INDEXOF", LOW_PRIORITY).addClassAndMethod(this), this);
            }
            stringIndexOfOnTOS = false;
        }

        if (seen == INVOKEVIRTUAL && "readLine".equals(getNameConstantOperand())
                && "()Ljava/lang/String;".equals(getSigConstantOperand()) && getClassConstantOperand().startsWith("java/io")
                && !"java/io/LineNumberReader".equals(getClassConstantOperand())) {
            readLineOnTOS = true;
        } else if (readLineOnTOS) {
            if (seen == IFNULL || seen == IFNONNULL) {
                bugAccumulator.accumulateBug(
                        new BugInstance(this, "RV_DONT_JUST_NULL_CHECK_READLINE", NORMAL_PRIORITY).addClassAndMethod(this), this);
            }

            readLineOnTOS = false;
        }
    }

}
