/*
 * Copyright 2002-2004 the original author or authors.
 * 
 * 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.springframework.beans;

import java.beans.PropertyDescriptor;
import java.beans.PropertyEditor;
import java.util.Map;

/**
 * The central interface of Spring's low-level JavaBeans infrastructure.
 * Typically not directly used by application code but rather implicitly
 * via a BeanFactory or a DataBinder.
 *
 * <p>To be implemented by classes that can manipulate Java beans.
 * Implementing classes have the ability to get and set property values
 * (individually or in bulk), get property descriptors and query the
 * readability and writability of properties.
 *
 * <p>This interface supports <b>nested properties</b> enabling the setting
 * of properties on subproperties to an unlimited depth.
 *
 * <p>If a property update causes an exception, a PropertyVetoException will be
 * thrown. Bulk updates continue after exceptions are encountered, throwing an
 * exception wrapping <b>all</b> exceptions encountered during the update.
 *
 * <p>BeanWrapper implementations can be used repeatedly, with their "target"
 * or wrapped object changed.
 * 
 * @author Rod Johnson
 * @since 13 April 2001
 * @version $Id: BeanWrapper.java,v 1.15 2004/06/03 00:08:26 jhoeller Exp $
 * @see org.springframework.beans.factory.BeanFactory
 * @see org.springframework.validation.DataBinder
 */
public interface BeanWrapper {

	/**
	 * Path separator for nested properties.
	 * Follows normal Java conventions: getFoo().getBar() would be "foo.bar".
	 */
	String NESTED_PROPERTY_SEPARATOR = ".";

	/**
	 * Marker that indicates the start of a property key for an
	 * indexed or mapped property like "person.addresses[0]".
	 */
	String PROPERTY_KEY_PREFIX = "[";

	/**
	 * Marker that indicates the end of a property key for an
	 * indexed or mapped property like "person.addresses[0]".
	 */
	String PROPERTY_KEY_SUFFIX = "]";


	/**
	 * Change the wrapped object. Implementations are required
	 * to allow the type of the wrapped object to change.
	 * @param obj wrapped object that we are manipulating
	 */
	void setWrappedInstance(Object obj);

	/**
	 * Return the bean wrapped by this object (cannot be null).
	 * @return the bean wrapped by this object
	 */
	Object getWrappedInstance();

	/**
	 * Convenience method to return the class of the wrapped object.
	 * @return the class of the wrapped object
	 */
	Class getWrappedClass();

	/**
	 * Register the given custom property editor for all properties of the
	 * given type.
	 * @param requiredType type of the property
	 * @param propertyEditor editor to register
	 */
	void registerCustomEditor(Class requiredType, PropertyEditor propertyEditor);

	/**
	 * Register the given custom property editor for the given type and
	 * property, or for all properties of the given type.
	 * @param requiredType type of the property, can be null if a property is
	 * given but should be specified in any case for consistency checking
	 * @param propertyPath path of the property (name or nested path), or
	 * null if registering an editor for all properties of the given type
	 * @param propertyEditor editor to register
	 */
	void registerCustomEditor(Class requiredType, String propertyPath, PropertyEditor propertyEditor);

	/**
	 * Find a custom property editor for the given type and property.
	 * @param requiredType type of the property, can be null if a property is
	 * given but should be specified in any case for consistency checking
	 * @param propertyPath path of the property (name or nested path), or
	 * null if looking for an editor for all properties of the given type
	 * @return the registered editor, or null if none
	 */
	PropertyEditor findCustomEditor(Class requiredType, String propertyPath);


	/**
	 * Get the value of a property.
	 * @param propertyName name of the property to get the value of
	 * @return the value of the property.
	 * @throws FatalBeanException if there is no such property, if the property
	 * isn't readable, or if the property getter throws an exception.
	 */
	Object getPropertyValue(String propertyName) throws BeansException;

	/**
	 * Set a property value. This method is provided for convenience only.
	 * The setPropertyValue(PropertyValue) method is more powerful.
	 * @param propertyName name of the property to set value of
	 * @param value the new value
	 */
	void setPropertyValue(String propertyName, Object value) throws BeansException;

	/**
	 * Update a property value.
	 * <b>This is the preferred way to update an individual property.</b>
	 * @param pv object containing new property value
	 */
	void setPropertyValue(PropertyValue pv) throws BeansException;

	/**
	 * Perform a bulk update from a Map.
	 * <p>Bulk updates from PropertyValues are more powerful: This method is
	 * provided for convenience. Behaviour will be identical to that of
	 * the setPropertyValues(PropertyValues) method.
	 * @param map Map to take properties from. Contains property value objects,
	 * keyed by property name
	 */
	void setPropertyValues(Map map) throws BeansException;

	/**
	 * The preferred way to perform a bulk update.
	 * <p>Note that performing a bulk update differs from performing a single update,
	 * in that an implementation of this class will continue to update properties
	 * if a <b>recoverable</b> error (such as a vetoed property change or a type mismatch,
	 * but <b>not</b> an invalid fieldname or the like) is encountered, throwing a
	 * PropertyAccessExceptionsException containing all the individual errors.
	 * This exception can be examined later to see all binding errors.
	 * Properties that were successfully updated stay changed.
	 * <p>Does not allow unknown fields.
	 * Equivalent to setPropertyValues(pvs, false, null).
	 * @param pvs PropertyValues to set on the target object
	 */
	void setPropertyValues(PropertyValues pvs) throws BeansException;

	/**
	 * Perform a bulk update with full control over behavior.
	 * Note that performing a bulk update differs from performing a single update,
	 * in that an implementation of this class will continue to update properties
	 * if a <b>recoverable</b> error (such as a vetoed property change or a type mismatch,
	 * but <b>not</b> an invalid fieldname or the like) is encountered, throwing a
	 * PropertyAccessExceptionsException containing all the individual errors.
	 * This exception can be examined later to see all binding errors.
	 * Properties that were successfully updated stay changed.
	 * <p>Does not allow unknown fields.
	 * @param pvs PropertyValues to set on the target object
	 * @param ignoreUnknown should we ignore unknown values (not found in the bean)
	 */
	void setPropertyValues(PropertyValues pvs, boolean ignoreUnknown)
	    throws BeansException;


	/**
	 * Get the PropertyDescriptors identified on this object
	 * (standard JavaBeans introspection).
	 * @return the PropertyDescriptors identified on this object
	 */
	PropertyDescriptor[] getPropertyDescriptors() throws BeansException;

	/**
	 * Get the property descriptor for a particular property.
	 * @param propertyName property to check status for
	 * @return the property descriptor for the particular property
	 * @throws InvalidPropertyException if there is no such property
	 */
	PropertyDescriptor getPropertyDescriptor(String propertyName) throws BeansException;

	/**
	 * Determine the property type for a particular property, either checking
	 * the property descriptor or checking the value in case of an indexed or
	 * mapped element.
	 * @param propertyName property to check status for
	 * @return the property type for the particular property, or null if not
	 * determinable (can only happen with an indexed or mapped element)
	 * @throws InvalidPropertyException if there is no such property
	 */
	Class getPropertyType(String propertyName) throws BeansException;

	/**
	 * Return whether this property is readable.
	 * Returns false if the property doesn't exist.
	 * @param propertyName property to check status for
	 * @return whether this property is readable
	 */
	boolean isReadableProperty(String propertyName) throws BeansException;

	/**
	 * Return whether this property is writable.
	 * Returns false if the property doesn't exist.
	 * @param propertyName property to check status for
	 * @return whether this property is writable
	 */
	boolean isWritableProperty(String propertyName) throws BeansException;

}