the_big_one/src/main/java/jesse/keeblarcraft/ConfigMgr/SQLConfig.java

package jesse.keeblarcraft.ConfigMgr;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import jesse.keeblarcraft.Utils.CommonStructures.Pair;

public class SQLConfig {
    private static SQLConfig static_inst;
    private String dbName;
    private String dbUser;
    private String dbPass;
    private String dbAddr;
    private Boolean connected = false;
    private Connection conn = null; // Actual connection object

    public static SQLConfig GetInstance() {
        if (static_inst == null) {
            static_inst = new SQLConfig();
        }

        return static_inst;
    }


    public SQLConfig() {
        connected = false;
        try {
            // According to some random online tutorial; this loads the driver!
            Class.forName("com.mysql.cj.jdbc.Driver");
            connected = true;
        } catch (Exception e) {
            System.out.println("Could not find the proper SQL JDBC Drivers. Cannot connect to SQL Config");
            e.printStackTrace();
        }

        if (connected) {
            try {
                dbName = GeneralConfig.GetInstance().GetSQLDatabase();
                dbUser = GeneralConfig.GetInstance().GetSQLUsername();
                dbPass = GeneralConfig.GetInstance().GetSQLPassword();
                dbAddr = "jdbc:mysql://" + GeneralConfig.GetInstance().GetSQLAddress() + "/" + dbName;
                conn = DriverManager.getConnection(dbAddr, dbUser, dbPass);
                Statement stmnt = conn.createStatement();
                String testSql = "SELECT * FROM test_table";
                ResultSet rs = stmnt.executeQuery(testSql);

                System.out.println("Printing out result set from test query");
                while (rs.next()) {
                    System.out.println("[RS]: " + rs.getString("test_name"));
                }
            } catch (SQLException e) {}
        }
    }

    private ResultSet RunCommand(String sqlCommand) {
        ResultSet cmdResult = null;
        if (conn != null) {
            try {
                Statement statement = conn.createStatement();
                cmdResult = statement.executeQuery(sqlCommand);
            } catch (Exception e) {}
        }

        return cmdResult;
    }

    // Re-attempt the connection
    public Boolean Connect() {
        if (conn != null) {
            try {
                conn.close();
            } catch (Exception e) {}
        }

        Boolean success = false;
        try {
            conn = DriverManager.getConnection(dbAddr, dbUser, dbPass);
            success = true;
        } catch (Exception e) {}
        return success;
    }

    public Boolean IsConnected() {
        return conn != null && this.connected;
    }

    private Boolean TableExists(String name) {
        boolean tableExists = false;
        try (ResultSet rs = conn.getMetaData().getTables(null, null, name, null)) {
            while (rs.next()) {
                String tName = rs.getString("TABLE_NAME");
                if (tName != null && tName.equals(name)) {
                    tableExists = true;
                    break;
                }
            }
        } catch (SQLException e) {}
        return tableExists;
    }

    // Might fix heap pollution decay in future with enum types or something. For now we assume the user isn't horrifically stupid and will give a SQL-able type
    public Boolean CreateTable(String tableName, Pair<String, Object>... columnPairs) {
        Boolean success = false;

        if (!TableExists(tableName.toUpperCase())) {
            String sqlCommand = "CREATE TABLE " + tableName.toUpperCase() + "(";
            for (Pair<String, Object> colPair : columnPairs) {
                sqlCommand = sqlCommand + " " + colPair.GetKey() + " " + String.valueOf(colPair.GetValue()) + ",";
            }

            System.out.println("DEBUG STATEMENT, SQL STATEMENT: " + sqlCommand);
            ResultSet rs = RunCommand(sqlCommand);
        }
        return success;
    }
}