package org.naftulin.configmgr.parsers;
   
   import java.net.URL;
   import java.sql.Connection;
   import java.sql.DriverManager;
   import java.sql.PreparedStatement;
   import java.sql.ResultSet;
   import java.sql.SQLException;
   import java.util.HashMap;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Properties;
  
  import org.apache.log4j.Logger;
  import org.naftulin.configmgr.ConfigurationManagementEntry;
  import org.naftulin.configmgr.ConfigurationManagementEntryImpl;
  import org.naftulin.configmgr.ConfigurationManagerException;
  import org.naftulin.configmgr.ConfigurationType;
  import org.naftulin.configmgr.content.AbstractRecordImpl;
  import org.naftulin.configmgr.content.NameValuePairImpl;
  
  /*
   * 
   */
  public class DbDirectParserImpl implements ConfigEntryParser {
  	private static final Logger log = Logger.getLogger(ConfigEntryParser.class);
  	
  	private static final long serialVersionUID = 1L;
  	private final String driverClass;
  	private final String connectionUrl;
  	private final String sql;
  	private final String user;
  	private final String password;
  	private final String keyColumnName;
  	private final String valueColumnName;
  	private List<NameValuePairImpl> nameValuePairs;
  	
  	 
  
  	public DbDirectParserImpl(final String driverClass, final String connectionUrl, final String sql, 
  			final String user, final String password, final String keyColumnName, 
  			final String valueColumnName, final List<NameValuePairImpl> nameValuePairs) {
  		super();
  		this.driverClass = driverClass;
  		this.connectionUrl = connectionUrl;
  		this.sql = sql;
  		this.user = user;
  		this.password = password;
  		this.keyColumnName = keyColumnName;
  		this.valueColumnName = valueColumnName;
  		this.nameValuePairs = nameValuePairs;
  	}
  
  	/***
  	 * Returns configuratoin management entry that contains a Map with key-value pairs read from the database based on the sql specified. 
  	 * The steps are: first database connection is established by loading the database driver and connecting to the database using database URL
  	 * and user/ password if provided with any other connection specific properties if provided in configuration description. 
  	 * Second sql provided is executed against the database connection and lastly the results are read based on the columns provided in the
  	 * configuration.
  	 * @param key configuration management key
  	 * @param fileUrl file url is null, since database configuration is not file URL based.
  	 * @return Configuration management entry.
  	 */
  	public ConfigurationManagementEntry getConfigurationManagementEntry(
  			final String key, final URL fileUrl) throws ConfigurationManagerException {
  		ConfigurationManagementEntry entry = null;
  		// at this point connect to the database, and get the info
  		validateParameters(key);
  		
  		
  		loadJdbcDriverClass(key);
  		log.info("Driver class " + driverClass + " is loaded.");
  		
  		final Properties props = new Properties();
  		prepareJdbcConnectionProperties(props);
  		
  		Connection c = null;
  		PreparedStatement stmt = null;
  		ResultSet rs = null;
  		try {
  			c = DriverManager.getConnection(connectionUrl, props);
  			log.info("Connected to the database " + connectionUrl + " and sql " + sql);
  			
  			stmt = c.prepareStatement(sql);
  			log.debug("Statment perpared " + sql + " for database " + connectionUrl);
  			
  			rs = stmt.executeQuery();
  			log.debug("Received result set for sql " + sql);
  			
  			entry = createEntryBasedOnResultSet(key, rs);
  			log.info("configuration management entry created for key " + key + " with sql " + sql);
  		} catch (SQLException e) {
  			log.error("Could not connect to the database using driver class: " + driverClass + " url " + connectionUrl + " sql " + sql + " and other parameters from configuration " + key, e);
  			throw new ConfigurationManagerException("Could not connect to the database using driver class: " + driverClass + " url " + connectionUrl + " sql " + sql + " and other parameters from configuration " + key, e);
  		} finally {
  			DBUtils.closeResultSet(rs);
  			DBUtils.closeStatement(stmt);
  			DBUtils.closeConnection(c);
 		}
 		
 		return entry;
 	}
 
 	private ConfigurationManagementEntry createEntryBasedOnResultSet(
 			final String key, final ResultSet rs) throws SQLException {
 		ConfigurationManagementEntry entry;
 		final Map<String, String> configuration = new HashMap<String, String>();
 		String mapKey = null;
 		String mapValue = null;
 		while(rs.next()) {
 			mapKey = rs.getString(keyColumnName);
 			mapValue = rs.getString(valueColumnName);
 			log.debug("getting key " + mapKey + " value " + mapValue + " for sql " + sql);
 			configuration.put(mapKey, mapValue);
 		}
 		final String fileName = "driver : " + driverClass + " connection " + connectionUrl + " sql " + sql + " user " + user;
 		//construct the configuration entry
 		entry = new ConfigurationManagementEntryImpl(key, fileName, configuration, this, ConfigurationType.DB_DIRECT);
 		return entry;
 	}
 
 	private void prepareJdbcConnectionProperties(final Properties props) {
 		if (user != null) { props.put("user", user); }
 		if (password != null) { props.put("password", password); }
 		
 		final Iterator<NameValuePairImpl> it = nameValuePairs.iterator();
 		while(it.hasNext()) {
 			NameValuePairImpl nvp = it.next();
 			props.put(nvp.getName(), nvp.getValue());			
 		}
 	}
 
 	private void loadJdbcDriverClass(final String key) throws ConfigurationManagerException {
 		try {
 			Class.forName(driverClass);
 		} catch(Exception e) {
 			log.error("Could not load driver class: " + driverClass + " for configuration " + key, e);
 			throw new ConfigurationManagerException("Could not load driver class: " + driverClass + " for configuration " + key, e);
 		}
 	}
 
 	private void validateParameters(final String key) throws ConfigurationManagerException {
 		if (key == null) { 
 			throw new ConfigurationManagerException("key is null, please provide the key in you master configuraton file for all the db direct cofigurations");
 		}
 		if (driverClass == null) {
 			throw new ConfigurationManagerException("driverClass is null, please provide driver class in you master configuraton file for external cofiguraton with key =" + key);
 		}
 		if (sql == null) {
 			throw new ConfigurationManagerException("sql is null, please provide sql in you master configuraton file for external cofiguraton with key =" + key);
 		}
 		if (keyColumnName == null) {
 			throw new ConfigurationManagerException("keyColumnName is null, please provide key column name in you master configuraton file for external cofiguraton with key =" + key);
 		}
 		if (valueColumnName == null) {
 			throw new ConfigurationManagerException("valueColumnName is null, please provide valueColumnName in you master configuraton file for external cofiguraton with key =" + key);
 		}
 	}
 
 
 	public String getDriverClass() {
 		return driverClass;
 	}
 
 	public String getKeyColumnName() {
 		return keyColumnName;
 	}
 
 
 	public List<NameValuePairImpl> getNameValuePairs() {
 		return nameValuePairs;
 	}
 
 
 	public String getPassword() {
 		return password;
 	}
 
 
 	public String getSql() {
 		return sql;
 	}
 
 
 	public String getUser() {
 		return user;
 	}
 
 
 	public String getValueColumnName() {
 		return valueColumnName;
 	}
 	
 	public String getConnectionUrl() { 
 		return this.connectionUrl;
 	}
 
 }