/*
 * Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.util.Set;
import java.util.List;

import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.*;
import javax.lang.model.type.*;
import javax.lang.model.util.*;
import static javax.lang.model.SourceVersion.*;
import static javax.lang.model.element.Modifier.*;
import static javax.lang.model.element.ElementKind.*;
import static javax.lang.model.type.TypeKind.*;
import static javax.lang.model.util.ElementFilter.*;
import static javax.tools.Diagnostic.Kind.*;

/**
 * Annotation processor to find methods and constructors that might be
 * improved by conversion to var-args.
 */
@SupportedAnnotationTypes("*")     // Process (examine) everything
@SupportedSourceVersion(RELEASE_6) // Recognize current source version
public class VarArgProc extends AbstractProcessor {
    private Messager messager;
    private ElementScanner6<Void, Void> varArgChecker;

    @Override
    public boolean process(Set<? extends TypeElement> annotations,
            RoundEnvironment roundEnv) {
        if (!roundEnv.processingOver()) {
	    varArgChecker.scan(roundEnv.getRootElements(), null);
        }
        return false; // Allow other processors to examine files too.
    }

    @Override
    public void init(ProcessingEnvironment processingEnv) {
        super.init(processingEnv);
	this.messager  = processingEnv.getMessager();
        varArgChecker = new VarArgCheckScanner();
    }

    private class VarArgCheckScanner extends ElementScanner6<Void, Void> {
	@Override
   	public Void visitExecutable(ExecutableElement e, Void p) {
	    List<? extends VariableElement> parameters = e.getParameters();
	    if (!e.isVarArgs() && !parameters.isEmpty()) {
		VariableElement lastParam = 
		    parameters.get(parameters.size() - 1);
		if (lastParam.asType().getKind() == ARRAY)
		    messager.printMessage(NOTE,
					  "Var-arg candidate",
					  lastParam);
	    }
	    super.visitExecutable(e, p);
	    return null;
	}
    }
}