/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2003-2008 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.classfile.Method;

import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.NonReportingDetector;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.XFactory;
import edu.umd.cs.findbugs.ba.XMethod;
import edu.umd.cs.findbugs.ba.ch.InterproceduralCallGraph;
import edu.umd.cs.findbugs.ba.ch.InterproceduralCallGraphVertex;
import edu.umd.cs.findbugs.ba.jsr305.Analysis;
import edu.umd.cs.findbugs.classfile.Global;
import edu.umd.cs.findbugs.classfile.MethodDescriptor;

/**
 * Build the interprocedural call graph.
 *
 * NOTE: at the present time, this facility is only used
 * to find relevant type qualifiers.
 * It could become a more general-purpose facility if
 * there were a need.
 *
 * @author David Hovemeyer
 */
public class BuildInterproceduralCallGraph extends BytecodeScanningDetector implements NonReportingDetector {

	private final InterproceduralCallGraph callGraph;
	private InterproceduralCallGraphVertex currentVertex;

	/**
	 * Constructor.
	 *
	 * @param bugReporter the BugReporter to use
	 */
	public BuildInterproceduralCallGraph(BugReporter bugReporter) {
		if (!Analysis.FIND_EFFECTIVE_RELEVANT_QUALIFIERS) {
			return;
		}
		callGraph = new InterproceduralCallGraph();
	}

	/* (non-Javadoc)
	 * @see edu.umd.cs.findbugs.BytecodeScanningDetector#visitClassContext(edu.umd.cs.findbugs.ba.ClassContext)
	 */
	@Override
	public void visitClassContext(ClassContext classContext) {
		if (!Analysis.FIND_EFFECTIVE_RELEVANT_QUALIFIERS) {
			return;
		}
		super.visitClassContext(classContext);
	}

	/* (non-Javadoc)
	 * @see edu.umd.cs.findbugs.visitclass.BetterVisitor#visitMethod(org.apache.bcel.classfile.Method)
	 */
	@Override
	public void visitMethod(Method obj) {
		currentVertex = findVertex(getXMethod());
		super.visitMethod(obj);
	}

	/* (non-Javadoc)
	 * @see edu.umd.cs.findbugs.visitclass.DismantleBytecode#sawOpcode(int)
	 */
	@Override
	public void sawOpcode(int seen) {
		switch (seen) {
		case Constants.INVOKESTATIC:
		case Constants.INVOKEVIRTUAL:
		case Constants.INVOKEINTERFACE:
		case Constants.INVOKESPECIAL:
			MethodDescriptor called = getMethodDescriptorOperand();
			XMethod calledXMethod = XFactory.createXMethod(called);
			InterproceduralCallGraphVertex calledVertex = findVertex(calledXMethod);
			callGraph.createEdge(currentVertex, calledVertex);
		}
	}

	/**
	 * Find the InterproceduralCallGraphVertex for given XMethod.
	 *
	 * @param xmethod an XMethod
	 * @return the XMethod's InterproceduralCallGraphVertex
	 */
	private InterproceduralCallGraphVertex findVertex(XMethod xmethod) {
		InterproceduralCallGraphVertex vertex;
		vertex = callGraph.lookupVertex(xmethod.getMethodDescriptor());
		if (vertex == null) {
			vertex = new InterproceduralCallGraphVertex();
			vertex.setXmethod(xmethod);
			callGraph.addVertex(vertex);
		}
		return vertex;
	}

	/* (non-Javadoc)
	 * @see edu.umd.cs.findbugs.BytecodeScanningDetector#report()
	 */
	@Override
	public void report() {
		if (!Analysis.FIND_EFFECTIVE_RELEVANT_QUALIFIERS) {
			return;
		}
		Global.getAnalysisCache().eagerlyPutDatabase(InterproceduralCallGraph.class, callGraph);
	}
}
