/*
    * Copyright 2006-2007 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.batch.item.file.mapping;
  
  import java.beans.PropertyEditor;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Properties;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  import org.springframework.batch.item.file.transform.FieldSet;
  import org.springframework.batch.support.DefaultPropertyEditorRegistrar;
  import org.springframework.beans.BeanWrapperImpl;
  import org.springframework.beans.MutablePropertyValues;
  import org.springframework.beans.NotWritablePropertyException;
  import org.springframework.beans.PropertyAccessor;
  import org.springframework.beans.PropertyAccessorUtils;
  import org.springframework.beans.PropertyEditorRegistry;
  import org.springframework.beans.factory.BeanFactory;
  import org.springframework.beans.factory.BeanFactoryAware;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.util.Assert;
  import org.springframework.util.ReflectionUtils;
  import org.springframework.validation.BindException;
  import org.springframework.validation.DataBinder;
  
  /**
   * {@link FieldSetMapper} implementation based on bean property paths. The
   * {@link FieldSet} to be mapped should have field name meta data corresponding
   * to bean property paths in an instance of the desired type. The instance is
   * created and initialized either by referring to to a prototype object by bean
   * name in the enclosing BeanFactory, or by providing a class to instantiate
   * reflectively.<br/>
   * <br/>
   * 
   * Nested property paths, including indexed properties in maps and collections,
   * can be referenced by the {@link FieldSet} names. They will be converted to
   * nested bean properties inside the prototype. The {@link FieldSet} and the
   * prototype are thus tightly coupled by the fields that are available and those
   * that can be initialized. If some of the nested properties are optional (e.g.
   * collection members) they need to be removed by a post processor.<br/>
   * <br/>
   * 
   * To customize the way that {@link FieldSet} values are converted to the
   * desired type for injecting into the prototype there are several choices. You
   * can inject {@link PropertyEditor} instances directly through the
   * {@link #setCustomEditors(Map) customEditors} property, or you can override
   * the {@link #createBinder(Object)} and {@link #initBinder(DataBinder)}
   * methods, or you can provide a custom {@link FieldSet} implementation.<br/>
   * <br/>
   * 
   * Property name matching is "fuzzy" in the sense that it tolerates close
   * matches, as long as the match is unique. For instance:
   * 
   * <ul>
   * <li>Quantity = quantity (field names can be capitalised)</li>
   * <li>ISIN = isin (acronyms can be lower case bean property names, as per Java
   * Beans recommendations)</li>
   * <li>DuckPate = duckPate (capitalisation including camel casing)</li>
   * <li>ITEM_ID = itemId (capitalisation and replacing word boundary with
   * underscore)</li>
   * <li>ORDER.CUSTOMER_ID = order.customerId (nested paths are recursively
   * checked)</li>
   * </ul>
   * 
   * The algorithm used to match a property name is to start with an exact match
   * and then search successively through more distant matches until precisely one
   * match is found. If more than one match is found there will be an error.
   * 
   * @author Dave Syer
   * 
   */
  public class BeanWrapperFieldSetMapper<T> extends DefaultPropertyEditorRegistrar implements FieldSetMapper<T>,
  		BeanFactoryAware, InitializingBean {
  
  	private String name;
  
  	private Class<? extends T> type;
  
  	private BeanFactory beanFactory;
  
  	private ConcurrentMap<DistanceHolder, ConcurrentMap<String, String>> propertiesMatched = new ConcurrentHashMap<DistanceHolder, ConcurrentMap<String, String>>();
 
 	private int distanceLimit = 5;
 
 	private boolean strict = true;
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see
 	 * org.springframework.beans.factory.BeanFactoryAware#setBeanFactory(org
 	 * .springframework.beans.factory.BeanFactory)
 	 */
     @Override
 	public void setBeanFactory(BeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
 	}
 
 	/**
 	 * The maximum difference that can be tolerated in spelling between input
 	 * key names and bean property names. Defaults to 5, but could be set lower
 	 * if the field names match the bean names.
 	 * 
 	 * @param distanceLimit the distance limit to set
 	 */
 	public void setDistanceLimit(int distanceLimit) {
 		this.distanceLimit = distanceLimit;
 	}
 
 	/**
 	 * The bean name (id) for an object that can be populated from the field set
 	 * that will be passed into {@link #mapFieldSet(FieldSet)}. Typically a
 	 * prototype scoped bean so that a new instance is returned for each field
 	 * set mapped.
 	 * 
 	 * Either this property or the type property must be specified, but not
 	 * both.
 	 * 
 	 * @param name the name of a prototype bean in the enclosing BeanFactory
 	 */
 	public void setPrototypeBeanName(String name) {
 		this.name = name;
 	}
 
 	/**
 	 * Public setter for the type of bean to create instead of using a prototype
 	 * bean. An object of this type will be created from its default constructor
 	 * for every call to {@link #mapFieldSet(FieldSet)}.<br/>
 	 * 
 	 * Either this property or the prototype bean name must be specified, but
 	 * not both.
 	 * 
 	 * @param type the type to set
 	 */
 	public void setTargetType(Class<? extends T> type) {
 		this.type = type;
 	}
 
 	/**
 	 * Check that precisely one of type or prototype bean name is specified.
 	 * 
 	 * @throws IllegalStateException if neither is set or both properties are
 	 * set.
 	 * 
 	 * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
 	 */
     @Override
 	public void afterPropertiesSet() throws Exception {
 		Assert.state(name != null || type != null, "Either name or type must be provided.");
 		Assert.state(name == null || type == null, "Both name and type cannot be specified together.");
 	}
 
 	/**
 	 * Map the {@link FieldSet} to an object retrieved from the enclosing Spring
 	 * context, or to a new instance of the required type if no prototype is
 	 * available.
 	 * @throws BindException if there is a type conversion or other error (if
 	 * the {@link DataBinder} from {@link #createBinder(Object)} has errors
 	 * after binding).
 	 * 
 	 * @throws NotWritablePropertyException if the {@link FieldSet} contains a
 	 * field that cannot be mapped to a bean property.
 	 * @see org.springframework.batch.item.file.mapping.FieldSetMapper#mapFieldSet(FieldSet)
 	 */
     @Override
 	public T mapFieldSet(FieldSet fs) throws BindException {
 		T copy = getBean();
 		DataBinder binder = createBinder(copy);
 		binder.bind(new MutablePropertyValues(getBeanProperties(copy, fs.getProperties())));
 		if (binder.getBindingResult().hasErrors()) {
 			throw new BindException(binder.getBindingResult());
 		}
 		return copy;
 	}
 
 	/**
 	 * Create a binder for the target object. The binder will then be used to
 	 * bind the properties form a field set into the target object. This
 	 * implementation creates a new {@link DataBinder} and calls out to
 	 * {@link #initBinder(DataBinder)} and
 	 * {@link #registerCustomEditors(PropertyEditorRegistry)}.
 	 * 
 	 * @param target
 	 * @return a {@link DataBinder} that can be used to bind properties to the
 	 * target.
 	 */
 	protected DataBinder createBinder(Object target) {
 		DataBinder binder = new DataBinder(target);
 		binder.setIgnoreUnknownFields(!this.strict);
 		initBinder(binder);
 		registerCustomEditors(binder);
 		return binder;
 	}
 
 	/**
 	 * Initialize a new binder instance. This hook allows customization of
 	 * binder settings such as the {@link DataBinder#initDirectFieldAccess()
 	 * direct field access}. Called by {@link #createBinder(Object)}.
 	 * <p>
 	 * Note that registration of custom property editors can be done in
 	 * {@link #registerCustomEditors(PropertyEditorRegistry)}.
 	 * </p>
 	 * @param binder new binder instance
 	 * @see #createBinder(Object)
 	 */
 	protected void initBinder(DataBinder binder) {
 	}
 
 	@SuppressWarnings("unchecked")
 	private T getBean() {
 		if (name != null) {
 			return (T) beanFactory.getBean(name);
 		}
 		try {
 			return type.newInstance();
 		}
 		catch (InstantiationException e) {
 			ReflectionUtils.handleReflectionException(e);
 		}
 		catch (IllegalAccessException e) {
 			ReflectionUtils.handleReflectionException(e);
 		}
 		// should not happen
 		throw new IllegalStateException("Internal error: could not create bean instance for mapping.");
 	}
 
 	/**
 	 * @param bean
 	 * @param properties
 	 * @return
 	 */
 	@SuppressWarnings({ "unchecked", "rawtypes" })
 	private Properties getBeanProperties(Object bean, Properties properties) {
 
 		Class<?> cls = bean.getClass();
 
 		// Map from field names to property names
 		DistanceHolder distanceKey = new DistanceHolder(cls, distanceLimit);
 		if (!propertiesMatched.containsKey(distanceKey)) {
 			propertiesMatched.putIfAbsent(distanceKey, new ConcurrentHashMap<String, String>());
 		}
 		Map<String, String> matches = new HashMap<String, String>(propertiesMatched.get(distanceKey));
 
 		Set<String> keys = new HashSet(properties.keySet());
 		for (String key : keys) {
 
 			if (matches.containsKey(key)) {
 				switchPropertyNames(properties, key, matches.get(key));
 				continue;
 			}
 
 			String name = findPropertyName(bean, key);
 
 			if (name != null) {
 				if (matches.containsValue(name)) {
 					throw new NotWritablePropertyException(
 							cls,
 							name,
 							"Duplicate match with distance <= "
 									+ distanceLimit
 									+ " found for this property in input keys: "
 									+ keys
 									+ ". (Consider reducing the distance limit or changing the input key names to get a closer match.)");
 				}
 				matches.put(key, name);
 				switchPropertyNames(properties, key, name);
 			}
 		}
 
 		propertiesMatched.replace(distanceKey, new ConcurrentHashMap<String, String>(matches));
 		return properties;
 	}
 
 	private String findPropertyName(Object bean, String key) {
 
 		if (bean == null) {
 			return null;
 		}
 
 		Class<?> cls = bean.getClass();
 
 		int index = PropertyAccessorUtils.getFirstNestedPropertySeparatorIndex(key);
 		String prefix;
 		String suffix;
 
 		// If the property name is nested recurse down through the properties
 		// looking for a match.
 		if (index > 0) {
 			prefix = key.substring(0, index);
 			suffix = key.substring(index + 1, key.length());
 			String nestedName = findPropertyName(bean, prefix);
 			if (nestedName == null) {
 				return null;
 			}
 
 			Object nestedValue = getPropertyValue(bean, nestedName);
 			String nestedPropertyName = findPropertyName(nestedValue, suffix);
 			return nestedPropertyName == null ? null : nestedName + "." + nestedPropertyName;
 		}
 
 		String name = null;
 		int distance = 0;
 		index = key.indexOf(PropertyAccessor.PROPERTY_KEY_PREFIX_CHAR);
 
 		if (index > 0) {
 			prefix = key.substring(0, index);
 			suffix = key.substring(index);
 		}
 		else {
 			prefix = key;
 			suffix = "";
 		}
 
 		while (name == null && distance <= distanceLimit) {
 			String[] candidates = PropertyMatches.forProperty(prefix, cls, distance).getPossibleMatches();
 			// If we find precisely one match, then use that one...
 			if (candidates.length == 1) {
 				String candidate = candidates[0];
 				if (candidate.equals(prefix)) { // if it's the same don't
 					// replace it...
 					name = key;
 				}
 				else {
 					name = candidate + suffix;
 				}
 			}
 			distance++;
 		}
 		return name;
 	}
 
 	private Object getPropertyValue(Object bean, String nestedName) {
 		BeanWrapperImpl wrapper = new BeanWrapperImpl(bean);
 		wrapper.setAutoGrowNestedPaths(true);
 
 		Object nestedValue = wrapper.getPropertyValue(nestedName);
 		if (nestedValue == null) {
 			try {
 				nestedValue = wrapper.getPropertyType(nestedName).newInstance();
 				wrapper.setPropertyValue(nestedName, nestedValue);
 			}
 			catch (InstantiationException e) {
 				ReflectionUtils.handleReflectionException(e);
 			}
 			catch (IllegalAccessException e) {
 				ReflectionUtils.handleReflectionException(e);
 			}
 		}
 		return nestedValue;
 	}
 
 	private void switchPropertyNames(Properties properties, String oldName, String newName) {
 		String value = properties.getProperty(oldName);
 		properties.remove(oldName);
 		properties.setProperty(newName, value);
 	}
 
 	/**
 	 * Public setter for the 'strict' property. If true, then
 	 * {@link #mapFieldSet(FieldSet)} will fail of the FieldSet contains fields
 	 * that cannot be mapped to the bean.
 	 * 
 	 * @param strict
 	 */
 	public void setStrict(boolean strict) {
 		this.strict = strict;
 	}
 
 	private static class DistanceHolder {
 		private final Class<?> cls;
 
 		private final int distance;
 
 		public DistanceHolder(Class<?> cls, int distance) {
 			this.cls = cls;
 			this.distance = distance;
 
 		}
 
 		@Override
 		public int hashCode() {
 			final int prime = 31;
 			int result = 1;
 			result = prime * result + ((cls == null) ? 0 : cls.hashCode());
 			result = prime * result + distance;
 			return result;
 		}
 
 		@Override
 		public boolean equals(Object obj) {
 			if (this == obj)
 				return true;
 			if (obj == null)
 				return false;
 			if (getClass() != obj.getClass())
 				return false;
 			DistanceHolder other = (DistanceHolder) obj;
 			if (cls == null) {
 				if (other.cls != null)
 					return false;
 			}
 			else if (!cls.equals(other.cls))
 				return false;
 			if (distance != other.distance)
 				return false;
 			return true;
 		}
 	}
 
 }