package com.exel.dwrp.api.data;

import com.exel.dwrp.api.system.task.DBBlocklistWordReloadTask;
import com.exel.dwrp.api.system.task.DBReloadTask;
import com.exel.dwrp.api.utils.LogUtils;
import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Timer;

/**
 * MySQL Database connection using Hikari as pooling library
 *
 * @author usman
 * @since 24-03-2017
 */
public class DBConnector {

    private static DBConnector instance = null;
    Connection con;
    HikariDataSource ds;

    /**
     * Init timer and configuration
     */
    private DBConnector() {
        try {
            initDBPool();
            con = ds.getConnection();
            if (Constant.db_auto_reload) {
//                Timer timer = new Timer(true);
//                timer.scheduleAtFixedRate(new DBReloadTask(), 10000, Constant.db_auto_reload_timer);
                Timer timer1 = new Timer(true);
                timer1.scheduleAtFixedRate(new DBBlocklistWordReloadTask(), 10000, Constant.db_auto_reload_blockword_timer);
            }
        } catch (Exception e) {
            StringWriter errors = new StringWriter();
            e.printStackTrace(new PrintWriter(errors));
            LogUtils.getInstance().writeLog(DBConnector.class, LogUtils.Level.ERROR, errors.toString());
            System.out.println("<=== System shutdown. ===>");
            System.out.println("<=== Database connection failed.. please check error log. ===>");
            System.exit(0);
        }

    }

    public static DBConnector getInstance() {
        if (instance == null) {
            instance = new DBConnector();
        }
        return instance;
    }

    /**
     * Init database configuration and pooling library
     */
    private void initDBPool() {
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl("jdbc:mysql://" + Constant.db_host + ":" + Constant.db_port + "/" + Constant.db_name);
        config.setUsername(Constant.db_username);
        config.setPassword(Constant.db_password);
        config.setMaximumPoolSize(Constant.db_connection);
        config.addDataSourceProperty("cachePrepStmts", "true");
        config.addDataSourceProperty("prepStmtCacheSize", "500");
        config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048");
        config.addDataSourceProperty("useServerPrepStmts","true");
        config.addDataSourceProperty("useLocalSessionState","true");
        config.addDataSourceProperty("useLocalTransactionState","true");
        config.addDataSourceProperty("rewriteBatchedStatements","true");
        config.addDataSourceProperty("cacheResultSetMetadata","true");
        config.addDataSourceProperty("cacheServerConfiguration","true");
        config.addDataSourceProperty("elideSetAutoCommits","true");
        config.addDataSourceProperty("maintainTimeStats","false");
        config.addDataSourceProperty("autoReconnect","true");
        config.addDataSourceProperty("useSSL","false");
        config.setMaxLifetime(Constant.maxLifetime);
        config.setIdleTimeout(Constant.idleTimeout);
        config.setConnectionTimeout(Constant.connectionTimeout);
        config.setValidationTimeout(Constant.validationTimeout);
        config.setConnectionInitSql("SELECT 1");
        config.setConnectionTestQuery("SELECT 1");
        config.setLeakDetectionThreshold(Constant.leakDetectionThreshold);
        ds = new HikariDataSource(config);
    }

    /**
     * getting statement of database
     * @return Statement variable
     */
    public Statement getStatement() {
        Statement statement = null;
        try {
            if (con.isClosed()) {
                initDBPool();
                con = ds.getConnection();
                statement = con.createStatement();
            }
        } catch (SQLException e) {
            StringWriter errors = new StringWriter();
            e.printStackTrace(new PrintWriter(errors));
            LogUtils.getInstance().writeLog(DBConnector.class, LogUtils.Level.ERROR, errors.toString());
        }
        try {
            statement = con.createStatement();
        } catch (SQLException e) {
            StringWriter errors = new StringWriter();
            e.printStackTrace(new PrintWriter(errors));
            LogUtils.getInstance().writeLog(DBConnector.class, LogUtils.Level.ERROR, errors.toString());
        }
        return statement;
    }
}