package test;

import java.nio.file.*;
import java.sql.*;
import java.io.*;
import java.util.*;

/**
 * This program tests that the database and the JDBC driver are correctly configured.
 * @version 1.02 2012-06-05
 * @author Cay Horstmann
 */
public class TestDB
{
   public static void main(String args[]) throws IOException
   {
      try
      {
         runTest();
      }
      catch (SQLException ex)
      {
         for (Throwable t : ex)
            t.printStackTrace();
      }
   }

   /**
    * Runs a test by creating a table, adding a value, showing the table contents, and removing 
    * the table.
    */
   public static void runTest() throws SQLException, IOException
   {
      
      try (Connection conn = getConnection();
         Statement stat = conn.createStatement())
      {
         stat.executeUpdate("CREATE TABLE Greetings (Message CHAR(20))");
         stat.executeUpdate("INSERT INTO Greetings VALUES ('Hello, World!')");

         try (ResultSet result = stat.executeQuery("SELECT * FROM Greetings"))
         {
            if (result.next())
               System.out.println(result.getString(1));
         }
         stat.executeUpdate("DROP TABLE Greetings");
      }
   }

   /**
    * Gets a connection from the properties specified in the file database.properties.
    * @return the database connection
    */
   public static Connection getConnection() throws SQLException, IOException
   {
      Properties props = new Properties();
      try (InputStream in = Files.newInputStream(Paths.get("database.properties")))
      {
         props.load(in);
      }
      String drivers = props.getProperty("jdbc.drivers");
      if (drivers != null) System.setProperty("jdbc.drivers", drivers);
      String url = props.getProperty("jdbc.url");
      String username = props.getProperty("jdbc.username");
      String password = props.getProperty("jdbc.password");

      return DriverManager.getConnection(url, username, password);
   }
}