package com.cjs.site.util.db;

import static java.lang.reflect.Proxy.newProxyInstance;
import static org.apache.ibatis.reflection.ExceptionUtil.unwrapThrowable;
import static org.mybatis.spring.SqlSessionUtils.closeSqlSession;
import static org.mybatis.spring.SqlSessionUtils.getSqlSession;
import static org.mybatis.spring.SqlSessionUtils.isSqlSessionTransactional;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.sql.Connection;
import java.util.List;
import java.util.Map;

import org.apache.ibatis.exceptions.PersistenceException;
import org.apache.ibatis.executor.BatchResult;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.MyBatisExceptionTranslator;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.dao.support.PersistenceExceptionTranslator;

/**
 * 继承SqlSessionTemplate 重写相关方法，解决事务中无法动态切换数据源的问题。
 * 事务中Spring会使用第一个Dao方法的datasource，这时候切换数据源是无效的，所以需要通过AOP动态改变SqlSessionFactory。
 * 
 * @author tongyufu
 *
 */
public class RoutingSqlSessionTemplate extends SqlSessionTemplate {

    private final SqlSessionFactory              sqlSessionFactory;
    private final ExecutorType                   executorType;
    private final SqlSession                     sqlSessionProxy;
    private final PersistenceExceptionTranslator exceptionTranslator;

    private Map<Object, SqlSessionFactory>       targetSqlSessionFactorys;
    private SqlSessionFactory                    defaultTargetSqlSessionFactory;

    public void setTargetSqlSessionFactorys(Map<Object, SqlSessionFactory> targetSqlSessionFactorys) {
        this.targetSqlSessionFactorys = targetSqlSessionFactorys;
    }

    public void setDefaultTargetSqlSessionFactory(SqlSessionFactory defaultTargetSqlSessionFactory) {
        this.defaultTargetSqlSessionFactory = defaultTargetSqlSessionFactory;
    }

    public RoutingSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        this(sqlSessionFactory, sqlSessionFactory.getConfiguration().getDefaultExecutorType());
    }

    public RoutingSqlSessionTemplate(SqlSessionFactory sqlSessionFactory,
                                     ExecutorType executorType) {
        this(sqlSessionFactory, executorType, new MyBatisExceptionTranslator(
            sqlSessionFactory.getConfiguration().getEnvironment().getDataSource(), true));
    }

    public RoutingSqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType,
                                     PersistenceExceptionTranslator exceptionTranslator) {
        super(sqlSessionFactory, executorType, exceptionTranslator);
        this.sqlSessionFactory = sqlSessionFactory;
        this.executorType = executorType;
        this.exceptionTranslator = exceptionTranslator;
        this.sqlSessionProxy = (SqlSession) newProxyInstance(
            SqlSessionFactory.class.getClassLoader(), new Class[] { SqlSession.class },
            new SqlSessionInterceptor());
        this.defaultTargetSqlSessionFactory = sqlSessionFactory;
    }

    @Override
    public SqlSessionFactory getSqlSessionFactory() {
        String datasourceKey = RoutingDataSource.getDataSourceKey();
        SqlSessionFactory sqlSessionFactory = targetSqlSessionFactorys.get(datasourceKey);

        if (sqlSessionFactory != null) {
            return sqlSessionFactory;
        }
        if (defaultTargetSqlSessionFactory != null) {
            return defaultTargetSqlSessionFactory;
        }
        return this.sqlSessionFactory;
    }

    @Override
    public Configuration getConfiguration() {
        return this.getSqlSessionFactory().getConfiguration();
    }

    public ExecutorType getExecutorType() {
        return this.executorType;
    }

    public PersistenceExceptionTranslator getPersistenceExceptionTranslator() {
        return this.exceptionTranslator;
    }

    /**
     * {@inheritDoc}
     */
    public <T> T selectOne(String statement) {
        return this.sqlSessionProxy.<T> selectOne(statement);
    }

    /**
     * {@inheritDoc}
     */
    public <T> T selectOne(String statement, Object parameter) {
        return this.sqlSessionProxy.<T> selectOne(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public <K, V> Map<K, V> selectMap(String statement, String mapKey) {
        return this.sqlSessionProxy.<K, V> selectMap(statement, mapKey);
    }

    /**
     * {@inheritDoc}
     */
    public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey) {
        return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey);
    }

    /**
     * {@inheritDoc}
     */
    public <K, V> Map<K, V> selectMap(String statement, Object parameter, String mapKey,
                                      RowBounds rowBounds) {
        return this.sqlSessionProxy.<K, V> selectMap(statement, parameter, mapKey, rowBounds);
    }

    /**
     * {@inheritDoc}
     */
    public <E> List<E> selectList(String statement) {
        return this.sqlSessionProxy.<E> selectList(statement);
    }

    /**
     * {@inheritDoc}
     */
    public <E> List<E> selectList(String statement, Object parameter) {
        return this.sqlSessionProxy.<E> selectList(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public <E> List<E> selectList(String statement, Object parameter, RowBounds rowBounds) {
        return this.sqlSessionProxy.<E> selectList(statement, parameter, rowBounds);
    }

    /**
     * {@inheritDoc}
     */
    public void select(String statement, ResultHandler handler) {
        this.sqlSessionProxy.select(statement, handler);
    }

    /**
     * {@inheritDoc}
     */
    public void select(String statement, Object parameter, ResultHandler handler) {
        this.sqlSessionProxy.select(statement, parameter, handler);
    }

    /**
     * {@inheritDoc}
     */
    public void select(String statement, Object parameter, RowBounds rowBounds,
                       ResultHandler handler) {
        this.sqlSessionProxy.select(statement, parameter, rowBounds, handler);
    }

    /**
     * {@inheritDoc}
     */
    public int insert(String statement) {
        return this.sqlSessionProxy.insert(statement);
    }

    /**
     * {@inheritDoc}
     */
    public int insert(String statement, Object parameter) {
        return this.sqlSessionProxy.insert(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public int update(String statement) {
        return this.sqlSessionProxy.update(statement);
    }

    /**
     * {@inheritDoc}
     */
    public int update(String statement, Object parameter) {
        return this.sqlSessionProxy.update(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public int delete(String statement) {
        return this.sqlSessionProxy.delete(statement);
    }

    /**
     * {@inheritDoc}
     */
    public int delete(String statement, Object parameter) {
        return this.sqlSessionProxy.delete(statement, parameter);
    }

    /**
     * {@inheritDoc}
     */
    public <T> T getMapper(Class<T> type) {
        return getConfiguration().getMapper(type, this);
    }

    /**
     * {@inheritDoc}
     */
    public void commit() {
        throw new UnsupportedOperationException(
            "Manual commit is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void commit(boolean force) {
        throw new UnsupportedOperationException(
            "Manual commit is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void rollback() {
        throw new UnsupportedOperationException(
            "Manual rollback is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void rollback(boolean force) {
        throw new UnsupportedOperationException(
            "Manual rollback is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void close() {
        throw new UnsupportedOperationException(
            "Manual close is not allowed over a Spring managed SqlSession");
    }

    /**
     * {@inheritDoc}
     */
    public void clearCache() {
        this.sqlSessionProxy.clearCache();
    }

    /**
     * {@inheritDoc}
     */
    public Connection getConnection() {
        return this.sqlSessionProxy.getConnection();
    }

    /**
     * {@inheritDoc}
     * 
     * @since 1.0.2
     */
    public List<BatchResult> flushStatements() {
        return this.sqlSessionProxy.flushStatements();
    }

    /**
     * Proxy needed to route MyBatis method calls to the proper SqlSession got
     * from Spring's Transaction Manager It also unwraps exceptions thrown by
     * {@code Method#invoke(Object, Object...)} to pass a
     * {@code PersistenceException} to the
     * {@code PersistenceExceptionTranslator}.
     */
    private class SqlSessionInterceptor implements InvocationHandler {
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            final SqlSession sqlSession = getSqlSession(
                RoutingSqlSessionTemplate.this.getSqlSessionFactory(),
                RoutingSqlSessionTemplate.this.executorType,
                RoutingSqlSessionTemplate.this.exceptionTranslator);
            try {
                Object result = method.invoke(sqlSession, args);
                if (!isSqlSessionTransactional(sqlSession,
                    RoutingSqlSessionTemplate.this.getSqlSessionFactory())) {
                    // force commit even on non-dirty sessions because some
                    // databases require
                    // a commit/rollback before calling close()
                    sqlSession.commit(true);
                }
                return result;
            } catch (Throwable t) {
                Throwable unwrapped = unwrapThrowable(t);
                if (RoutingSqlSessionTemplate.this.exceptionTranslator != null
                    && unwrapped instanceof PersistenceException) {
                    Throwable translated = RoutingSqlSessionTemplate.this.exceptionTranslator
                        .translateExceptionIfPossible((PersistenceException) unwrapped);
                    if (translated != null) {
                        unwrapped = translated;
                    }
                }
                throw unwrapped;
            } finally {
                closeSqlSession(sqlSession, RoutingSqlSessionTemplate.this.getSqlSessionFactory());
            }
        }
    }

}