/*
 * JBoss, Home of Professional Open Source
 * Copyright 2008, Red Hat, Inc., and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jboss.weld.util;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;

import org.jboss.weld.logging.UtilLogger;
import org.jboss.weld.resources.spi.ResourceLoader;
import org.jboss.weld.resources.spi.ResourceLoadingException;

/**
 * A base class for utility classes that represent annotations, classes etc
 *
 * @author Pete Muir
 */
public class ApiAbstraction {

    private static final Class<DummyAnnotation> DUMMY_ANNOTATION = DummyAnnotation.class;

    private static final Class<Dummy> DUMMY_CLASS = Dummy.class;

    private ResourceLoader resourceLoader;

    /**
     * "Not found" annotation
     */
    public @interface DummyAnnotation {
    }

    /**
     * "Not found" class
     */
    public interface Dummy {
    }

    /**
     * "Not found" enumeration value.
     */
    public static enum DummyEnum {
        DUMMY_VALUE
    }

    /**
     * Constructor
     *
     * @param resourceLoader The root resource loaderS
     */
    public ApiAbstraction(ResourceLoader resourceLoader) {
        this.resourceLoader = resourceLoader;
    }

    /**
     * Initializes an annotation class
     *
     * @param name The name of the annotation class
     * @return The instance of the annotation. Returns a dummy if the class was
     *         not found
     */
    @SuppressWarnings("unchecked")
    protected Class<? extends Annotation> annotationTypeForName(String name) {
        try {
            return (Class<? extends Annotation>) resourceLoader.classForName(name);
        } catch (ResourceLoadingException cnfe) {
            return DUMMY_ANNOTATION;
        }
    }

    /**
     * Initializes a type
     *
     * @param name The name of the class
     * @return The instance of the class. Returns a dummy if the class was not
     *         found.
     */
    protected Class<?> classForName(String name) {
        try {
            return resourceLoader.classForName(name);
        } catch (ResourceLoadingException cnfe) {
            return DUMMY_CLASS;
        }
    }

    protected Object enumValue(Class<?> clazz, String memberName) {
        Preconditions.checkArgumentNotNull(memberName, "memberName");
        if (!clazz.isEnum()) {
            throw UtilLogger.LOG.classNotEnum(clazz);
        }
        try {
            Field field = clazz.getField(memberName);
            return field.get(null);
        } catch (SecurityException e) {
            return null;
        } catch (NoSuchFieldException e) {
            return null;
        } catch (java.lang.IllegalArgumentException e) {
            return null;
        } catch (IllegalAccessException e) {
            return null;
        }
    }

}