/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2004-2008 University of Maryland
 * Copyright (C) 2008 Google
 *
 * 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 edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.Detector;
import edu.umd.cs.findbugs.Priorities;
import edu.umd.cs.findbugs.ba.AnalysisContext;
import edu.umd.cs.findbugs.ba.CFG;
import edu.umd.cs.findbugs.ba.CFGBuilderException;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
import edu.umd.cs.findbugs.ba.Hierarchy2;
import edu.umd.cs.findbugs.ba.Location;
import edu.umd.cs.findbugs.ba.MethodUnprofitableException;
import edu.umd.cs.findbugs.ba.XClass;
import edu.umd.cs.findbugs.ba.XMethod;
import edu.umd.cs.findbugs.ba.ch.Subtypes2;
import edu.umd.cs.findbugs.ba.type.TypeDataflow;
import edu.umd.cs.findbugs.ba.type.TypeFrame;

import org.apache.bcel.Constants;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.INVOKEINTERFACE;
import org.apache.bcel.generic.INVOKESTATIC;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.InvokeInstruction;

import java.util.Iterator;
import java.util.Set;

public class CallToUnsupportedMethod implements Detector  {

	BugReporter bugReporter;

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

	public void visitClassContext(ClassContext classContext) {
		JavaClass javaClass = classContext.getJavaClass();
		Method[] methodList = javaClass.getMethods();

		for (Method method : methodList) {
			if (method.getCode() == null)
				continue;

			try {
				analyzeMethod(classContext, method);
			} catch (MethodUnprofitableException e) {
				assert true; // move along; nothing to see
			} catch (CFGBuilderException e) {
				String msg = "Detector " + this.getClass().getName()
										+ " caught exception while analyzing " + javaClass.getClassName() + "." + method.getName() + " : " + method.getSignature();
				bugReporter.logError(msg , e);
			} catch (DataflowAnalysisException e) {
				String msg = "Detector " + this.getClass().getName()
										+ " caught exception while analyzing " + javaClass.getClassName() + "." + method.getName() + " : " + method.getSignature();
				bugReporter.logError(msg, e);
			}
		}
	}

	
	/**
     * @param classContext
     * @param method
     */
    private void analyzeMethod(ClassContext classContext, Method method) throws MethodUnprofitableException, CFGBuilderException, DataflowAnalysisException {
    	if (method.isSynthetic() || (method.getAccessFlags() & Constants.ACC_BRIDGE) == Constants.ACC_BRIDGE) return;
		CFG cfg = classContext.getCFG(method);
		TypeDataflow typeDataflow = classContext.getTypeDataflow(method);
		ConstantPoolGen constantPoolGen = classContext.getConstantPoolGen();
		
		locationLoop: for (Iterator<Location> iter = cfg.locationIterator(); iter.hasNext();) {
			Location location = iter.next();
			InstructionHandle handle = location.getHandle();
			Instruction ins = handle.getInstruction();

			// Only consider invoke instructions
			if (!(ins instanceof InvokeInstruction))
				continue;
			if (ins instanceof INVOKEINTERFACE) 
				continue;
			
			InvokeInstruction inv = (InvokeInstruction) ins;
			TypeFrame frame = typeDataflow.getFactAtLocation(location);
			
			String methodName = inv.getMethodName(constantPoolGen);
			if (methodName.toLowerCase().indexOf("unsupported") >= 0) 
				continue;
			String methodSig = inv.getSignature(constantPoolGen);
			if (methodSig.equals("()Ljava/lang/UnsupportedOperationException;"))
				continue;
			
			Set<XMethod> targets;
            try {
	            
				targets = Hierarchy2.resolveMethodCallTargets(inv, frame, constantPoolGen);
            } catch (ClassNotFoundException e) {
	            AnalysisContext.reportMissingClass(e);
	            continue locationLoop;
            }
			if (targets.isEmpty()) 
				continue locationLoop;
			int priority = targets.size() == 1 ? Priorities.HIGH_PRIORITY : Priorities.NORMAL_PRIORITY;
			for(XMethod m : targets) {
				if (!m.isUnsupported()) 
					continue locationLoop;
				XClass xc = AnalysisContext.currentXFactory().getXClass(m.getClassDescriptor());
				if (!(inv instanceof INVOKESTATIC) && !(m.isFinal() || xc.isFinal()))
					priority = Priorities.NORMAL_PRIORITY;
				if (xc == null || xc.isAbstract()) {
					try {
	                    if (!AnalysisContext.currentAnalysisContext().getSubtypes2().hasSubtypes(m.getClassDescriptor()))
	                    	continue locationLoop;
                    } catch (ClassNotFoundException e) {
	                    AnalysisContext.reportMissingClass(e);
	                    continue locationLoop;
                    }
				}
			}
			BugInstance bug = new BugInstance(this, "DMI_UNSUPPORTED_METHOD", priority)
				.addClassAndMethod(classContext.getJavaClass(), method)
				.addCalledMethod(constantPoolGen, inv)
				.addSourceLine(classContext, method, location);
			bugReporter.reportBug(bug);
			
		}
	    
    }

	/* (non-Javadoc)
     * @see edu.umd.cs.findbugs.Detector#report()
     */
    public void report() {
	    // TODO Auto-generated method stub
	    
    }

}
