package org.openslx.satellitedaemon.db;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.List;
import java.util.Properties;

import org.apache.log4j.Logger;
import org.openslx.satellitedaemon.util.Util;

import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

import fi.evident.dalesbred.Database;

/**
 * Class for talking to the DB via the dalesbred jdbc wrapper. Package private,
 * so only the Db* classes can actually communicate with the database.
 * 
 */
class MySQL
{
	private static final Logger log = Logger.getLogger( MySQL.class );
	private static Database db = null;

	/**
	 * Static initializer for setting up the database connection.
	 * This gets called implicitly as soon as the class loader loads
	 * the class. In most cases that happens when the class is being
	 * accessed for the first time during run time.
	 */
	static
	{
		// Load connection info from class (TODO: Make pretty)
		Properties properties = new Properties();
		String propertiesPath = "config/mysql.properties";
		try {
			final BufferedInputStream stream = new BufferedInputStream( new FileInputStream( propertiesPath ) );
			properties.load( stream );
			stream.close();
		} catch ( FileNotFoundException e ) {
			log.fatal( propertiesPath + " not found!" );
			System.exit( 1 );
		} catch ( IOException e ) {
			log.fatal( "Error reading from " + propertiesPath + ": " + e.getMessage() );
			System.exit( 1 );
		} catch ( Exception e ) {
			log.fatal( "Generic error loading mysql properties file." );
			e.printStackTrace();
			System.exit( 1 );
		}
		final String host = properties.getProperty( "host" );
		final String dbname = properties.getProperty( "db" );
		final String user = properties.getProperty( "user" );
		final String password = properties.getProperty( "password" );

		Util.notNullFatal( host, "host not set in mysql properties" );
		Util.notNullFatal( dbname, "db not set in mysql properties" );
		Util.notNullFatal( user, "user not set in mysql properties" );
		Util.notNullFatal( password, "password not set in mysql properties" );

		// Setup db connection
		try {
			MysqlDataSource ds = new MysqlDataSource();
			ds.setServerName( host );
			ds.setDatabaseName( dbname );
			ds.setUser( user );
			ds.setPassword( password );
			db = Database.forDataSource( ds );
		} catch ( Exception e ) {
			log.fatal( "Error initializing mysql data source!" );
			e.printStackTrace();
			System.exit( 1 );
		}
	}

	/**
	 * Get a list of objects of the given class from the database.
	 * The class needs a matching constructor for the query you pass in, i.e. number of
	 * arguments has to be equal to number of columns returned by query.
	 * 
	 * @param clazz The class to instanciate for the result(s)
	 * @param sql The sql query to run
	 * @param args Any number of arguments to the query (using the '?' placeholder)
	 * @return A list containing the rows returned by the query, represented by the given class
	 */
	protected static <T> List<T> findAll( final Class<T> clazz, final String sql, final Object... args )
	{
		return db.findAll( clazz, sql, args );
	}

	/**
	 * Run a query on the database that will return at most one result.
	 * If the query returns a row, it will be used to instanciate the given class. If
	 * it doesn't return a row, null will be returned.
	 * 
	 * @param clazz The class to instanciate for the result (if any)
	 * @param sql The sql query to run
	 * @param args Any number of arguments to the query (using the '?' placeholder)
	 * @return Instance of clazz or null
	 */
	protected static <T> T findUniqueOrNull( final Class<T> clazz, final String sql, final Object... args )
	{
		return db.findUniqueOrNull( clazz, sql, args );
	}

	/**
	 * Run an update on the database, return number of rows affected.
	 * 
	 * @param sql The update/insert query to run
	 * @param args Any number of arguments to the query (using the '?' placeholder)
	 * @return Number of rows affected by query
	 */
	protected static int update( String sql, Object... args )
	{
		return db.update( sql, args );
	}
}