/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * 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 the University of Southampton 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.
 */
package org.openimaj.citation;

import java.lang.reflect.Method;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.Set;

import org.openimaj.citation.annotation.Reference;
import org.openimaj.citation.annotation.References;

/**
 * Listener that registers instances of {@link Reference} annotations.
 * 
 * @author Jonathon Hare (jsh2@ecs.soton.ac.uk)
 */
public class ReferenceListener {
        private static Set<Reference> references = new LinkedHashSet<Reference>();

        static {
                addOpenIMAJReference();
        }

        private static synchronized void addOpenIMAJReference() {
                try {
                        final Class<?> clz = ReferenceListener.class.getClassLoader().loadClass("org.openimaj.OpenIMAJ");
                        addReference(clz);
                } catch (final ClassNotFoundException e) {
                        // assume that core-citation is being used outside OpenIMAJ
                        // and that thus you don't want/need an OI reference.
                }
        }

        /**
         * Register the given {@link Reference}
         * 
         * @param r
         *            the {@link Reference}
         */
        public static synchronized void addReference(Reference r) {
                references.add(r);
        }

        /**
         * Register the any {@link Reference} or {@link References} from the given
         * class.
         * 
         * @param clz
         *            the class
         */
        public static void addReference(Class<?> clz) {
                final Reference ann = clz.getAnnotation(Reference.class);

                if (ann != null)
                        addReference(ann);

                final References ann2 = clz.getAnnotation(References.class);
                if (ann2 != null)
                        for (final Reference r : ann2.references())
                                addReference(r);

                processPackage(clz);
        }

        private static void processPackage(Class<?> clz) {
                Package base = clz.getPackage();

                while (base != null) {
                        if (base.isAnnotationPresent(Reference.class))
                                addReference(base.getAnnotation(Reference.class));

                        if (base.isAnnotationPresent(References.class))
                                for (final Reference r : base.getAnnotation(References.class).references())
                                        addReference(r);

                        final String name = base.getName();
                        final int dot = name.lastIndexOf(".");

                        if (dot < 0)
                                break;

                        base = Package.getPackage(name.substring(0, dot));
                }
        }

        /**
         * Register the any {@link Reference} or {@link References} from the given
         * method.
         * 
         * @param clz
         *            the class
         * @param methodName
         * @param signature
         */
        public static void addReference(Class<?> clz, String methodName, String signature) {
                for (final Method m : clz.getDeclaredMethods()) {
                        if (m.getName().equals(methodName) && m.toString().endsWith(signature)) {
                                final Reference ann = m.getAnnotation(Reference.class);

                                if (ann != null)
                                        addReference(ann);

                                final References ann2 = m.getAnnotation(References.class);
                                if (ann2 != null)
                                        for (final Reference r : ann2.references())
                                                addReference(r);
                        }
                }

                processPackage(clz);
        }

        /**
         * Reset the references held by the listener, returning the current set of
         * references.
         * 
         * @return the current set of references.
         */
        public static synchronized Set<Reference> reset() {
                final Set<Reference> oldRefs = references;
                references = new LinkedHashSet<Reference>();
                addOpenIMAJReference();
                return oldRefs;
        }

        /**
         * Get a copy of the references collected by the listener
         * 
         * @return the references.
         */
        public static synchronized Set<Reference> getReferences() {
                return new LinkedHashSet<Reference>(references);
        }

        /**
         * Register the given {@link Reference}s
         * 
         * @param refs
         *            the {@link Reference}s
         */
        public static void addReferences(Collection<Reference> refs) {
                references.addAll(refs);
        }
}