/*
 * FindBugs - Find Bugs in Java programs
 * Copyright (C) 2003-2007 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.ba.jsr305;

import java.util.LinkedList;
import java.util.List;

import javax.annotation.CheckForNull;

import edu.umd.cs.findbugs.classfile.analysis.AnnotatedObject;

/**
 * The result of looking up a TypeQualifierAnnotation. Because type qualifiers
 * are inherited, a full result of looking resolving a TypeQualifierAnnotation
 * may include annotations on one or more supertypes. Potentially, the supertype
 * annotations may conflict with each other, and/or conflict with the annotation
 * on the annotated entity. This object makes it possible to report such
 * conflicts, while still providing a convenient interface for getting the
 * "effective" TypeQualifierAnnotation.
 *
 * @author David Hovemeyer
 */
public class TypeQualifierAnnotationLookupResult {
    /**
     * Partial result of looking up a TypeQualifierAnnotation.
     */
    public static class PartialResult {
        private final AnnotatedObject annotatedObject;

        private final TypeQualifierAnnotation typeQualifierAnnotation;

        PartialResult(AnnotatedObject annotatedObject, TypeQualifierAnnotation typeQualifierAnnotation) {
            this.annotatedObject = annotatedObject;
            this.typeQualifierAnnotation = typeQualifierAnnotation;
        }

        /**
         * @return Returns the annotatedObject.
         */
        public AnnotatedObject getAnnotatedObject() {
            return annotatedObject;
        }

        /**
         * @return Returns the typeQualifierAnnotation.
         */
        public TypeQualifierAnnotation getTypeQualifierAnnotation() {
            return typeQualifierAnnotation;
        }

        /*
         * (non-Javadoc)
         *
         * @see java.lang.Object#toString()
         */
        @Override
        public String toString() {
            return annotatedObject + ":" + typeQualifierAnnotation;
        }
    }

    private final List<PartialResult> partialResultList;

    TypeQualifierAnnotationLookupResult() {
        this.partialResultList = new LinkedList<PartialResult>();
    }

    void addPartialResult(PartialResult partialResult) {
        partialResultList.add(partialResult);
    }

    /**
     * Get the effective TypeQualifierAnnotation.
     *
     * @return the effective TypeQualifierAnnotation, or null if no effective
     *         TypeQualifierAnnotation can be found
     */
    public @CheckForNull
    TypeQualifierAnnotation getEffectiveTypeQualifierAnnotation() {
        boolean firstPartialResult = true;
        TypeQualifierAnnotation effective = null;

        for (PartialResult partialResult : partialResultList) {
            if (firstPartialResult) {
                effective = partialResult.getTypeQualifierAnnotation();
                firstPartialResult = false;
            } else {
                effective = combine(effective, partialResult.getTypeQualifierAnnotation());
            }
        }

        return effective;
    }

    /**
     * Subclasses must override this method to combine TypeQualifierAnnotations
     * found in multiple superclasses.
     *
     * @param a
     *            a TypeQualifierAnnotation
     * @param b
     *            another TypeQualifierAnnotation
     * @return combined TypeQualifierAnnotation compatible with both input
     *         TypeQualifierAnnotations, or null if no such
     *         TypeQualifierAnnotation exists
     */
    protected TypeQualifierAnnotation combine(TypeQualifierAnnotation a, TypeQualifierAnnotation b) {
        return null;
    }

    /*
     * (non-Javadoc)
     *
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return partialResultList.toString();
    }
}
