package com.smtservlet.mybatis;

import java.io.IOException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.util.Map;

import org.apache.ibatis.builder.xml.XMLMapperBuilder;
import org.apache.ibatis.builder.xml.XMLMapperEntityResolver;
import org.apache.ibatis.executor.ErrorContext;
import org.apache.ibatis.parsing.XPathParser;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.core.io.Resource;

import static org.springframework.util.ObjectUtils.isEmpty;

public class SMTSqlSessionFactoryBean extends SqlSessionFactoryBean 
{
	private Resource[] _mapperLocations;
	
	public void setSMTMapperLocations(Resource[] mapperLocations) 
	{
		this._mapperLocations = mapperLocations;
	}

	
	@Override
	protected SqlSessionFactory buildSqlSessionFactory() throws Exception
	{
		//TestAction app = SMTApp.getBean(TestAction.class);
		// 如果未设置自定义map列表，则直接调用系统类
		if(isEmpty(this._mapperLocations))
			return super.buildSqlSessionFactory();
		
		Field f_sqlSessionFactoryBuilder;
		final SqlSessionFactoryBuilder v_sqlSessionFactoryBuilder;
		
		try
		{
			// 绑定并替换私有字段sqlSessionFactoryBuilder
			f_sqlSessionFactoryBuilder = SqlSessionFactoryBean.class.getDeclaredField("sqlSessionFactoryBuilder");
			f_sqlSessionFactoryBuilder.setAccessible(true);
			v_sqlSessionFactoryBuilder = (SqlSessionFactoryBuilder)f_sqlSessionFactoryBuilder.get(this);
			
			// 将sqlSessionFactoryBuilder重定向到自定义的类中
			f_sqlSessionFactoryBuilder.set(this, new SqlSessionFactoryBuilder()
			{
				@Override
				public SqlSessionFactory build(Configuration configuration)
				{
					// 扫描资源库
					for (Resource mapperLocation : _mapperLocations) {
						if (mapperLocation == null) {
							continue;
						}

						try {
							Constructor<?> c0 = XMLMapperBuilder.class.getDeclaredConstructor(new Class[]{
									XPathParser.class, Configuration.class, String.class, Map.class});
							c0.setAccessible(true);
							
							
							XMLMapperBuilder xmlMapperBuilder = (XMLMapperBuilder) c0.newInstance(
									new XPathParser(mapperLocation.getInputStream(), false, configuration.getVariables(), new XMLMapperEntityResolver()),
									  configuration, mapperLocation.toString(), configuration.getSqlFragments());
							xmlMapperBuilder.parse();
						} catch (Exception e) {
							throw new RuntimeException(
									"Failed to parse mapping resource: '"
											+ mapperLocation + "'", e);
						} finally {
							ErrorContext.instance().reset();
						}
					}
					return v_sqlSessionFactoryBuilder.build(configuration);
				}
			});
		}
		catch(Exception ex)
		{
			throw new IOException(ex);
		}
		
		try
		{
			return super.buildSqlSessionFactory();
		}
		finally
		{
			try 
			{
				// 退出时恢复原先的值
				if(f_sqlSessionFactoryBuilder != null)
					f_sqlSessionFactoryBuilder.set(this, v_sqlSessionFactoryBuilder);
			} 
			catch (Exception e) 
			{
			}
		}
	}
}