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/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2004-2005 Dave Brosius 
 * Copyright (C) 2004-2005 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.Const;
import org.apache.bcel.Repository;
import org.apache.bcel.classfile.Code;
import org.apache.bcel.classfile.JavaClass;
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.ba.ClassContext;

public class BadAppletConstructor extends BytecodeScanningDetector {
    private final BugReporter bugReporter;

    private final JavaClass appletClass;

    private boolean inConstructor;

    public BadAppletConstructor(BugReporter bugReporter) {
        this.bugReporter = bugReporter;
        JavaClass appletClass = null;
        try {
            appletClass = Repository.lookupClass("java.applet.Applet");
        } catch (ClassNotFoundException cnfe) {
            bugReporter.reportMissingClass(cnfe);
        }
        this.appletClass = appletClass;
    }

    @Override
    public void visitClassContext(ClassContext classContext) {
        if (appletClass == null) {
            return;
        }

        JavaClass cls = classContext.getJavaClass();
        try {
            if (cls.instanceOf(appletClass)) {
                cls.accept(this);
            }
        } catch (ClassNotFoundException cnfe) {
            bugReporter.reportMissingClass(cnfe);
        }
    }

    @Override
    public void visit(Method obj) {
        inConstructor = Const.CONSTRUCTOR_NAME.equals(obj.getName());
    }

    @Override
    public void visit(Code obj) {
        if (inConstructor) {
            super.visit(obj);
        }
    }

    @Override
    public void sawOpcode(int seen) {
        if (seen == Const.INVOKEVIRTUAL) {
            String method = getNameConstantOperand();
            String signature = getSigConstantOperand();
            if ((("getDocumentBase".equals(method) || "getCodeBase".equals(method)) && "()Ljava/net/URL;".equals(signature))
                    || ("getAppletContext".equals(method) && "()Ljava/applet/AppletContext;".equals(signature))
                    || ("getParameter".equals(method) && "(Ljava/lang/String;)Ljava/lang/String;".equals(signature))) {
                bugReporter.reportBug(new BugInstance(this, "BAC_BAD_APPLET_CONSTRUCTOR", NORMAL_PRIORITY)
                        .addClassAndMethod(this).addSourceLine(this));
            }
        }
    }
}