/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2005 Dave Brosius <dbrosius@users.sourceforge.net>
 * 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 java.util.HashSet;
import java.util.Set;

import org.apache.bcel.Repository;
import org.apache.bcel.classfile.JavaClass;

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 XMLFactoryBypass extends BytecodeScanningDetector  {
	private BugReporter bugReporter;
	private static final Set<String> xmlInterfaces = new HashSet<String>()
	{
		static final long serialVersionUID = -9117982073509840017L;
		{
		add("javax.xml.parsers.DocumentBuilder");
		add("org.w3c.dom.Document");
		add("javax.xml.parsers.SAXParser");
		add("org.xml.sax.XMLReader");
		add("org.xml.sax.XMLFilter");
		add("javax.xml.transform.Transformer");
		add("org.w3c.dom.Attr");
		add("org.w3c.dom.CDATASection");
		add("org.w3c.dom.Comment");
		add("org.w3c.dom.Element");
		add("org.w3c.dom.Text");
		}
	};
	private final Set<String> rejectedXMLClasses = new HashSet<String>();
	private JavaClass curClass;

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

	@Override
	public void visitClassContext(ClassContext classContext) {
		curClass = classContext.getJavaClass();
		super.visitClassContext(classContext);
	}

	@Override
		 public void sawOpcode(int seen) {
		try {
			if (seen == INVOKESPECIAL) {
				String newClsName = getClassConstantOperand();
				if (rejectedXMLClasses.contains(newClsName))
					return;
				rejectedXMLClasses.add(newClsName);

				if (newClsName.startsWith("java/") || newClsName.startsWith("javax/"))
					return;

				if (newClsName.endsWith("Adapter"))
					return;

				if (!getNameConstantOperand().equals("<init>"))
					return;

				String invokerClsName = this.getClassName();
				if (samePackageBase(invokerClsName, newClsName))
					return;

				JavaClass newCls = Repository.lookupClass(getDottedClassConstantOperand());

				JavaClass superCls = curClass.getSuperClass();
				if (superCls.getClassName().equals(newClsName.replace('/', '.')))
					return;

				JavaClass[] infs = newCls.getAllInterfaces();
				for (JavaClass inf : infs) {
					if (xmlInterfaces.contains(inf.getClassName())) {
						bugReporter.reportBug(new BugInstance(this, "XFB_XML_FACTORY_BYPASS", LOW_PRIORITY)
								.addClassAndMethod(this)
								.addSourceLine(this));
						rejectedXMLClasses.remove(newClsName);
					}
				}
			}
		} catch (ClassNotFoundException cnfe) {
			bugReporter.reportMissingClass(cnfe);
		}
	}

	public boolean samePackageBase(String invokerClsName, String newClsName)
	{
		String[] invokerParts = invokerClsName.split("/");
		String[] newClsParts = newClsName.split("/");

		if (newClsParts.length < 3)
			return false;
		if (invokerParts.length < 3)
			return false;

		if (!invokerParts[0].equals(newClsParts[0]))
			return false;

		return invokerParts[1].equals(newClsParts[1]);
	}
}
