/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2004, 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.Constants;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.GETSTATIC;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.ObjectType;

import edu.umd.cs.findbugs.ba.Location;
import edu.umd.cs.findbugs.ba.RepositoryLookupFailureCallback;

/**
 * Stream factory for streams created by loading a value from a static field.
 * This is mainly to handle System.in, System.out, and System.err.
 */
public class StaticFieldLoadStreamFactory implements StreamFactory {
    public String streamBaseClass;

    public String className;

    public String fieldName;

    public String fieldSig;

    /**
     * Constructor. Created Stream objects will be marked as uninteresting.
     *
     * @param streamBaseClass
     *            the base class of the stream objects created by the factory
     * @param className
     *            name of the class containing the static field
     * @param fieldName
     *            name of the static field
     * @param fieldSig
     *            signature of the static field
     */
    public StaticFieldLoadStreamFactory(String streamBaseClass, String className, String fieldName, String fieldSig) {
        this.streamBaseClass = streamBaseClass;
        this.className = className;
        this.fieldName = fieldName;
        this.fieldSig = fieldSig;
    }

    @Override
    public Stream createStream(Location location, ObjectType type, ConstantPoolGen cpg,
            RepositoryLookupFailureCallback lookupFailureCallback) {

        Instruction ins = location.getHandle().getInstruction();
        if (ins.getOpcode() != Constants.GETSTATIC) {
            return null;
        }

        GETSTATIC getstatic = (GETSTATIC) ins;
        if (!className.equals(getstatic.getClassName(cpg)) || !fieldName.equals(getstatic.getName(cpg))
                || !fieldSig.equals(getstatic.getSignature(cpg))) {
            return null;
        }

        return new Stream(location, type.getClassName(), streamBaseClass).setIgnoreImplicitExceptions(true).setIsOpenOnCreation(
                true);
    }
}

