/**
 * @author : 최정우
 * @since : 2022.10.21
 * @dscription : Mysql DB Connection Pool 생성 관리 모듈 입니다. (private와 public object 환경 구성)
 */
 const MysqlConnection = (function () {

    //Mysql DB Connection 라이브러리 모듈
    const mysql = require('mysql');

    //Connection Pool 객체 - private object(변수)
    const connectionPool = mysql.createPool({
        host: 'localhost',
        user: 'root',
        password: '1234',
        database: 'test',
        ssl: false,
        port: 3306,
        max: 10,
    });

    return {
        getConnectionPool: function () {
            return connectionPool;
        },
        queryExcute: function (sql, params) {
            const result = new Promise((resolve, reject) => {
                connectionPool.getConnection(function (connectionError, connection) {
                    if (!connectionError) {
                        try {
                            connection.query(sql, params, function (queryError, rows, columns) {
                                if (!queryError) {
                                    resolve({'rows': rows, 'columns': columns});
                                } else {
                                    reject(queryError);
                                }
                            })
                        } catch (proccessError) {
                            reject(proccessError);
                        } finally {
                            connection.release(); 
                        }
                    } else {
                        reject(connectionError);
                    }
                })

                /* connectionPool.getConnection().then(async (connection) => {
                    let queryResult = await connection.query(sql);
                    resolve(queryResult);
                    connection.release();
                }).catch((error) => {
                    reject(error);
                }); */
            })
            return result;
        },
    }

})();

module.exports = MysqlConnection;