/*
 * fb-contrib - Auxiliary detectors for Java programs
 * Copyright (C) 2005-2017 Dave Brosius
 *
 * 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 com.mebigfatguy.fbcontrib.detect;

import java.util.Set;

import org.apache.bcel.classfile.Code;

import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.UnmodifiableSet;
import com.mebigfatguy.fbcontrib.utils.Values;

import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.ba.ClassContext;

/**
 *
 * looks for calls to Arrays.asList where the parameter is a primitive array. This does not produce a list that holds the primitive boxed value, but a list of
 * one item, the array itself.
 *
 */
public class ConfusingArrayAsList extends BytecodeScanningDetector {

    private static final Set<String> PRIMITIVE_ARRAYS = UnmodifiableSet.create(Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_BYTE,
            Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_CHAR, Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_SHORT,
            Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_INT, Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_LONG,
            Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_FLOAT, Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_DOUBLE,
            Values.SIG_ARRAY_OF_ARRAYS_PREFIX + Values.SIG_PRIMITIVE_BOOLEAN);

    private BugReporter bugReporter;
    private OpcodeStack stack;

    /**
     * constructs a CAAL detector given the reporter to report bugs on
     *
     * @param bugReporter
     *            the sync of bug reports
     */
    public ConfusingArrayAsList(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
    }

    /**
     * implements the visitor to create and teardown the opcode stack
     *
     * @param classContext
     *            the context object of the currently parsed class
     */
    @Override
    public void visitClassContext(ClassContext classContext) {
        try {
            stack = new OpcodeStack();
            super.visitClassContext(classContext);
        } finally {
            stack = null;
        }
    }

    /**
     * implements the visitor to clear the opcode stack
     *
     * @param obj
     *            the currently code block
     */
    @Override
    public void visitCode(Code obj) {
        stack.resetForMethodEntry(this);
        super.visitCode(obj);
    }

    /**
     * implements the visitor to find calls to Arrays.asList with a primitive array
     *
     * @param seen
     *            the currently visitor opcode
     */
    @Override
    public void sawOpcode(int seen) {
        try {
            stack.precomputation(this);

            if (seen == INVOKESTATIC) {
                String clsName = getClassConstantOperand();
                if ("java/util/Arrays".equals(clsName)) {
                    String methodName = getNameConstantOperand();
                    if ("asList".equals(methodName) && (stack.getStackDepth() >= 1)) {
                        OpcodeStack.Item item = stack.getStackItem(0);
                        String sig = item.getSignature();
                        if (PRIMITIVE_ARRAYS.contains(sig)) {
                            Object con = item.getConstant();
                            if (!(con instanceof Integer) || (((Integer) con).intValue() <= 1)) {
                                bugReporter.reportBug(new BugInstance(this, BugType.CAAL_CONFUSING_ARRAY_AS_LIST.name(), NORMAL_PRIORITY).addClass(this)
                                        .addMethod(this).addSourceLine(this));
                            }
                        }
                    }
                }
            }
        } finally {
            stack.sawOpcode(this, seen);
        }
    }
}