package com.alibaba.sql;

import java.lang.reflect.InvocationTargetException;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.apache.commons.beanutils.BeanUtils;

public class DAO {

    public void update(String sql, Object...args){

        Connection connection = null;

        PreparedStatement preparedStatement = null;

        try{

            connection = JDBCTools.getConnection();

            preparedStatement = connection.prepareStatement(sql);

            for(int i = 0; i < args.length; i++){

                preparedStatement.setObject(i + 1, args[i]);

            }

            preparedStatement.executeUpdate();

        }catch (Exception e) {

            e.printStackTrace();

        }

        finally{

            JDBCTools.release(null, preparedStatement, connection);

        }

    }

    public <T> T get(Class<T> clazz, String sql, Object...args){

        List<T> list = getForList(clazz, sql, args);

        if(list != null){

            return list.get(0);

        }

        return null;

    }

    public <T> List<T> getForList(Class<T> clazz, String sql, Object...args){

        Connection connection = null;

        PreparedStatement preparedStatement = null;

        ResultSet resultSet = null;

        List<T> list = null;

        try{

            connection = JDBCTools.getConnection();

            preparedStatement = connection.prepareStatement(sql);

            for(int i = 0; i < args.length; i++){

                preparedStatement.setObject(i + 1, args[i]);

            }

            resultSet = preparedStatement.executeQuery();

            List<String> label = getLabel(resultSet);

            List<Map<String, Object>> values = getValues(resultSet, label);

            if(values.size() > 0){

                list = valueTolist(clazz, values);

            }

    }catch(Exception e){

        e.printStackTrace();

    }finally{

        JDBCTools.release(resultSet, preparedStatement, connection);

    }

        return list;

    }

    private <T> List<T> valueTolist(Class<T> clazz, List<Map<String, Object>> values) throws InstantiationException,

            IllegalAccessException, InvocationTargetException {

        List<T> list = new ArrayList<T>();

        for(Map<String, Object> map:values){

            T entity = clazz.newInstance();

            for(Map.Entry<String, Object> entry:map.entrySet()){

                String fieldName = entry.getKey();

                Object fieldValue = entry.getValue();

                BeanUtils.setProperty(entity, fieldName, fieldValue);

            }

            list.add(entity);

        }

        return list;

    }

    private List<Map<String, Object>> getValues(ResultSet resultSet,

            List<String> label) throws SQLException {

        List<Map<String, Object>> values = new ArrayList<Map<String, Object>>();

        while(resultSet.next()){

            Map<String, Object> map = new HashMap<String, Object>();

            for(int i = 0; i < label.size(); i++){

                String fieldName = label.get(i);

                Object fieldValue = resultSet.getObject(fieldName);

                map.put(fieldName, fieldValue);

            }

            values.add(map);

        }

        return values;

    }

    private List<String> getLabel(ResultSet resultSet) throws SQLException {

        ResultSetMetaData rsmd = resultSet.getMetaData();

        List<String> label = new ArrayList<String>();

        for(int i = 0; i< rsmd.getColumnCount(); i++){

            label.add(rsmd.getColumnLabel(i+1));

        }

        return label;

    }

    @SuppressWarnings("unchecked")

    public <E> E getForValue(String sql, Object...args){

        Connection connection = null;

        PreparedStatement preparedStatement = null;

        ResultSet resultSet = null;

        E entity = null;

        try{

            connection = JDBCTools.getConnection();

            preparedStatement = connection.prepareStatement(sql);

            for(int i = 0; i < args.length; i++){

                preparedStatement.setObject(i + 1, args[i]);

            }

            resultSet = preparedStatement.executeQuery();

            if(resultSet.next()){

                entity = (E)resultSet.getObject(1);

            }

        }catch(Exception e){

            e.printStackTrace();

        }finally{

            JDBCTools.release(resultSet, preparedStatement, connection);

        }

        return entity;

    }

}