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/*
 * #%L
 * fujion
 * %%
 * Copyright (C) 2008 - 2017 Regenstrief Institute, Inc.
 * %%
 * 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.
 *
 * #L%
 */
package org.fujion.annotation;

import java.lang.reflect.Method;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.fujion.ancillary.ComponentRegistry;
import org.fujion.component.BaseComponent;

/**
 * Utility class for scanning class and method annotations and building component definitions from
 * them.
 */
public class ComponentScanner extends AbstractClassScanner {
    
    private static final Log log = LogFactory.getLog(ComponentScanner.class);
    
    private static final ComponentScanner instance = new ComponentScanner();
    
    /**
     * Returns a singleton instance of the component scanner.
     *
     * @return Singleton instance of the component scanner.
     */
    public static ComponentScanner getInstance() {
        return instance;
    }
    
    private ComponentScanner() {
        super(BaseComponent.class, Component.class);
    }
    
    /**
     * Creates and registers a component definition for a class by scanning the class and its
     * superclasses for method annotations.
     *
     * @param clazz Class to scan.
     */
    @Override
    protected void doScanClass(Class clazz) {
        if (log.isDebugEnabled()) {
            log.debug("Processing @Component annotation for class " + clazz);
        }

        ComponentDefinition def = new ComponentDefinition(clazz);
        scanMethods(def, clazz, false);
        scanMethods(def, def.getFactoryClass(), true);
        ComponentRegistry.getInstance().register(def);
    }
    
    /**
     * Scans a class for method annotations, adding them to the component definition as they are
     * found.
     *
     * @param def Component definition for the class.
     * @param clazz The class to be scanned.
     * @param factoryMethods If true, scan for factory methods. Otherwise, component methods.
     */
    private void scanMethods(ComponentDefinition def, Class clazz, boolean factoryMethods) {
        if (clazz == Object.class) {
            return;
        }
        
        for (Method method : clazz.getDeclaredMethods()) {
            method.setAccessible(true);
            
            if (method.isSynthetic() || method.isBridge()) {
                continue;
            }
            
            if (factoryMethods) {
                def._addFactoryParameter(method);
            } else {
                def._addSetter(method);
                def._addGetter(method);
            }
        }
        
        scanMethods(def, clazz.getSuperclass(), factoryMethods);
    }
    
}