package com.forsrc.utils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;

import javax.sql.DataSource;

public class JdbcUtils {

    private DataSource dataSource;
    private int fetchSize = 1000;

    public JdbcUtils(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    public JdbcUtils(DataSource dataSource, int fetchSize) {
        this.dataSource = dataSource;
        this.fetchSize = fetchSize;
    }

    public void exec(final String sql, final Object[] params, final Handler handler) throws Exception {
        Connection connection = dataSource.getConnection();
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            statement = connection.prepareStatement(sql);
            statement.setFetchSize(fetchSize);
            if (params != null) {
                for (int i = 0; i < params.length; i++) {
                    statement.setObject(i + 1, params[i]);
                }
            }

            resultSet = statement.executeQuery();
            handler.handle(resultSet);
        } catch (SQLException e) {
            throw e;
        } finally {
            if (resultSet != null) {
                try {
                    resultSet.close();
                } catch (SQLException e) {
                }
            }
            if (statement != null) {
                try {
                    statement.close();
                } catch (SQLException e) {
                }
            }
            if (connection != null) {
                try {
                    connection.close();
                } catch (SQLException e) {
                }
            }
        }

    }

    public void exec(final String sql, final Object[] params, final DataHandler handler) throws Exception {
        exec(sql, params, new Handler() {

            @Override
            public void handle(ResultSet resultSet) throws Exception {
                ResultSetMetaData rsm = resultSet.getMetaData();
                final int columnCount = rsm.getColumnCount();
                String[] columnName = new String[columnCount];
                for (int i = 0; i < columnCount; i++) {
                    columnName[i] = rsm.getColumnName(i + 1);
                }
                int row = 1;
                Map<String, Object> data = null;
                while (resultSet.next()) {
                    data = new HashMap<>(columnCount);
                    for (int i = 0; i < columnCount; i++) {
                        data.put(columnName[i], resultSet.getObject(i + 1));
                    }
                    handler.handle(row++, data);
                }
            }

        });

    }

    public static interface Handler {
        public void handle(ResultSet resultSet) throws Exception;
    }

    public static interface DataHandler {
        public void handle(int row, Map<String, Object> data) throws Exception;
    }
}