EDIT

// $Id$

/**

* Copyright (C) 2007 EDIT

* European Distributed Institute of Taxonomy 

* http://www.e-taxonomy.eu

* 

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.persistence.dao;

import java.lang.reflect.Method;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.apache.log4j.Logger;

import org.springframework.stereotype.Component;

/**

 * @author n.hoffmann

 * @created Mar 11, 2010

 * @version 1.0

 */

@Component

public class MethodCacheImpl implements IMethodCache {

//	MethodUtils

	private Map<MethodDescriptor, Method> methodMap = new HashMap<MethodDescriptor, Method>();

	/*

	 * (non-Javadoc)

	 * @see eu.etaxonomy.cdm.persistence.dao.IMethodCache#getMethod(java.lang.Class, java.lang.String, java.lang.Class)

	 */

	public Method getMethod(Class clazz, String methodName, Class parameterType) {

		MethodDescriptor methodDescriptor = new MethodDescriptor(clazz, methodName, new Class[]{parameterType}); 

		if(methodMap.containsKey(methodDescriptor)){

			return methodMap.get(methodDescriptor);

		}

		Method method = getMethodInternal(clazz, methodName, parameterType);

		if(method != null){

			method.setAccessible(true);

		}

		// we also put null methods into the map to benefit from caching

		put(methodDescriptor, method);

		return method; 

	}

	/**

	 * Checks class hierarchy of the given class for a method that fits to the given name and parameter type

	 * 

	 * @param clazz

	 * @param methodName

	 * @param parameterType

	 * @return

	 */

	private Method getMethodInternal(Class clazz, String methodName,

			Class parameterType){

		// stop recursing when there are no more superclasses

		if(clazz == null){

			return null;

		}

		Method method = null;

		for(Class includedType : getIncludedTypes(parameterType, new ArrayList<Class>())){

			try {

				method = clazz.getDeclaredMethod(methodName, includedType);

			}catch (NoSuchMethodException e) {

				;

			} 

		}

		// if we have a method return it

		if(method != null){

			return method;

		}

		// recurse into superclass if no method was found

		return getMethodInternal(clazz.getSuperclass(), methodName, parameterType);

	}

	/**

	 * Create a list containing the type and all supertypes of a given type

	 * 

	 * @param clazz

	 * @param classList

	 * @return

	 */

	private List<Class> getIncludedTypes(Class clazz, List<Class> classList){

		if(clazz == null){

			return classList;

		}

		classList.add(clazz);

		Class[] interfaces = clazz.getInterfaces();

		if(interfaces != null){

			classList.addAll(Arrays.asList(interfaces));

		}

		return getIncludedTypes(clazz.getSuperclass(), classList);

	}

	/**

	 * Fill the cache

	 * 

	 * @param methodDescriptor

	 * @param method

	 */

	private void put(MethodDescriptor methodDescriptor, Method method) {

		methodMap.put(methodDescriptor, method);

	}

	/**

	 * 

	 * @author n.hoffmann

	 * @created Mar 11, 2010

	 * @version 1.0

	 */

	private static class MethodDescriptor{

		private static final Logger logger = Logger

				.getLogger(MethodDescriptor.class);

		/** An empty class array */

	    private static final Class[] emptyClassArray = new Class[0];

		private Class clazz;

	    private String methodName;

	    private Class[] parameterTypes;

	    private int hashCode;

	    /**

	     * The sole constructor.

	     *

	     * @param clazz  the class to reflect, must not be null

	     * @param methodName  the method name to obtain

	     * @param paramTypes the array of classes representing the paramater types

	     * @param exact whether the match has to be exact.

	     */

	    public MethodDescriptor(Class clazz, String methodName, Class[] paramTypes) {

	        if (clazz == null) {

	            throw new IllegalArgumentException("Class cannot be null");

	        }

	        if (methodName == null) {

	            throw new IllegalArgumentException("Method Name cannot be null");

	        }

	        if (paramTypes == null) {

	            paramTypes = emptyClassArray;

	        }

	        this.clazz = clazz;

	        this.methodName = methodName;

	        this.parameterTypes = paramTypes;

	        this.hashCode = methodName.length();

	    }

	    /**

	     * Checks for equality.

	     * @param object object to be tested for equality

	     * @return true, if the object describes the same Method.

	     */

	    public boolean equals(Object object) {

	        if (!(object instanceof MethodDescriptor)) {

	            return false;

	        }

	        MethodDescriptor methodDescriptor = (MethodDescriptor)object;

	        return (

	            methodName.equals(methodDescriptor.methodName) &&

	            clazz.equals(methodDescriptor.clazz) &&

	            java.util.Arrays.equals(parameterTypes, methodDescriptor.parameterTypes)

	        );

	    }

	    /**

	     * Returns the string length of method name. I.e. if the

	     * hashcodes are different, the objects are different. If the

	     * hashcodes are the same, need to use the equals method to

	     * determine equality.

	     * @return the string length of method name.

	     */

	    public int hashCode() {

	        return hashCode;

	    }		

	}	

}