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)

	}

}