package ru.indvdum.jpa.entities

 import java.lang.reflect.Modifier

 import javax.persistence.EmbeddedId

 import javax.persistence.Entity

 import javax.persistence.Id

 import javax.persistence.Transient

 import org.apache.openjpa.util.OpenJPAId

 import org.codehaus.jackson.map.ObjectMapper

 import ru.indvdum.jpa.dao.JPADataAccessObject;

 /**

  * @author 	indvdum (gotoindvdum@gmail.com)

  * @since 25.12.2011 13:26:57

  *

  */

 abstract class AbstractEntity implements Serializable {

 	@Transient

 	protected ObjectMapper mapper = new ObjectMapper()

 	@Override

 	public String toString() {

 		return getClass().getSimpleName() + '-' + getIdentifierValue()

 	}

 	/**

 	 * JSON-like representation of an object

 	 * 

 	 * @return

 	 */

 	public String toJSON() {

 		return mapper.writeValueAsString(this)

 	}

 	/* 

 	 * HashCode, based on root class name of entity class hierarchy and id value 

 	 * 

 	 * (non-Javadoc)

 	 * @see java.lang.Object#hashCode()

 	 */

 	@Override

 	public int hashCode() {

 		Class clazz = getClass()

 		while (

 			clazz.superclass != null

 			&& !Modifier.isAbstract(clazz.superclass.modifiers)

 			&& clazz.superclass.annotations.find {it instanceof Entity} != null

 		)

 			clazz = clazz.superclass

 		String res = clazz.getName() + ': ' + getIdentifierValue()

 		return res.hashCode()

 	}

 	/* 

 	 * Comparison, based on entities id's

 	 * 

 	 * (non-Javadoc)

 	 * @see java.lang.Object#equals(java.lang.Object)

 	 */

 	@Override

 	public boolean equals(Object obj) {

 		if(obj == null)

 			return false

 		if(!(obj.class.isAssignableFrom(this.class) || this.class.isAssignableFrom(obj.class)))

 			return false

 		def id = getIdentifierValue()

 		def objId = (obj as AbstractEntity).getIdentifierValue()

 		return id == objId || id != null && id != this && id.equals(objId)

 	}

 	/**

 	 * @return The identifier value of an entity.

 	 */

 	@Transient

 	public Object getIdentifierValue() {

 		// an attempt to get id by EntityManagerFactory

 		Object identifier = JPADataAccessObject.emf.getPersistenceUnitUtil().getIdentifier(this)

 		if(identifier instanceof OpenJPAId)

 			return ((OpenJPAId)identifier).getIdObject()

 		def result

 		// an attempt to find id by annotated fields

 		Class clazz = getClass()

 		def self = this

 		Collection fields = clazz.declaredFields

 		while(clazz.superclass != null) {

 			clazz = clazz.superclass

 			fields.addAll(clazz.declaredFields)

 		}

 		fields.grep {

 			!it.synthetic &&

 					!Modifier.isStatic(it.modifiers) &&

 					!Modifier.isTransient(it.modifiers)

 		}.grep {

 			it.annotations.find {

 				it instanceof Id || it instanceof EmbeddedId

 			} != null

 		}.each {

 			boolean isAccessible = it.accessible

 			it.accessible = true

 			result = it.get(self)

 			it.accessible = isAccessible

 		}

 		if(result != null && !(result instanceof Reference && (result as Reference).value == null))

 			return result

 		// an attempt to represent id as a aggregate of all fields

 		// TODO check, why toJSON method don't work

 //		return toJSON()

 		result = '{'

 		fields.grep {

 			!it.synthetic &&

 					!Modifier.isStatic(it.modifiers) &&

 					!Modifier.isTransient(it.modifiers)

 		}.grep {

 			it.annotations.find {

 				it instanceof Transient

 			} == null

 		}.each {

 			boolean isAccessible = it.accessible

 			it.accessible = true

 			result += '"' + it.name + '": "' + it.get(self) + '", '

 			it.accessible = isAccessible

 		}

 		return result

 	}

 	protected def callMethod(method, Object ... args) {

 		"$method"(*args)

 	}

 }