/**
 *	2007/11/15
 *	@version 
 *	@author
 */
package com.hb.core.dao.hibernateImp;

import java.io.Serializable;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;

import org.hibernate.metadata.ClassMetadata;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;
import org.springframework.util.Assert;

import com.hb.core.dao.IGenericDao;

/**
 * Hibernate Dao的泛型基類
 * 
 * <pre>
 * 繼承于Spring的HibernateDaoSupport
 * 提供分頁函數和若干便捷查詢方法，并對返回值作了泛型類型轉換
 * </pre>
 */
public class HibernateDaoImp<T> extends HibernateDaoSupport implements IGenericDao<T> {
	/** 最大的ID */
	protected final String DEFAULT_MAX_ID = "00000001";
	protected Class<T> entityClass;// DAO所管理的Entity類型.

	/**
	 * 取得entityClass.JDK1.4不支持泛型的子類可以拋開Class<T> entityClass,重載此函數達到相同效果。
	 */
	protected Class<T> getEntityClass() {
		return entityClass;
	}

	/**
	 * 在構造函數中將泛型T.class賦給entityClass.
	 */
	@SuppressWarnings("unchecked")
	public HibernateDaoImp() {
		entityClass = getSuperClassGenricType(getClass());
	}

	@SuppressWarnings("unchecked")
	public T get(Serializable id) {
		return (T) getHibernateTemplate().get(entityClass, id);
	}

	@SuppressWarnings("unchecked")
	public List<T> getAll() {
		return getHibernateTemplate().loadAll(entityClass);
	}

	@SuppressWarnings("unchecked")
	public String getIdName(Class clazz) {
		Assert.notNull(clazz);
		ClassMetadata meta = getSessionFactory().getClassMetadata(clazz);
		Assert.notNull(meta, "Class " + clazz + " not define in hibernate session factory.");
		String idName = meta.getIdentifierPropertyName();
		Assert.hasText(idName, clazz.getSimpleName() + " has no identifier property define.");
		return idName;
	}

	public void remove(Object o) {
		getHibernateTemplate().delete(o);
	}

	public void removeById(Serializable id) {
		remove(get(id));
	}

	public void save(T instance) {
		getHibernateTemplate().saveOrUpdate(instance);
	}

	@SuppressWarnings("unchecked")
	protected Class getSuperClassGenricType(Class clazz) {
		return (Class) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
		// return getSuperClassGenricType(clazz, 0);
	}

	@SuppressWarnings("unchecked")
	/**
	 * 通過反射,獲得定義Class時聲明的父類的范型參數的類型. 如public BookManager extends GenricManager<Book>
	 * 
	 * @param clazz clazz The class to introspect
	 * @param index the Index of the generic declaration,start from 0.
	 * @return the index generic declaration, or <code>Object.class</code> if
	 *         cannot be determined
	 */
	protected Class getSuperClassGenricType(Class clazz, int index) {
		Type genType = clazz.getGenericSuperclass();

		Type[] params = ((ParameterizedType) genType).getActualTypeArguments();

		if (index >= params.length || index < 0) {
			return Object.class;
		}
		if (!(params[index] instanceof Class)) {
			return Object.class;
		}
		return (Class) params[index];
	}
}