package compbio.cassandra.readers;

import org.apache.log4j.Logger;

import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.exceptions.QueryExecutionException;
import com.datastax.driver.core.exceptions.QueryValidationException;

import compbio.cassandra.CassandraNativeConnector;

/**
 * basic reader of the ProteoCache database. It depends on open
 * CassandraNativeConnector, which should provide an open session to the
 * ProteoCache DB (in the default constructor)
 * 
 * @author as373024
 *
 */
public class CassandraReader {
	protected static long earlestDate = 0;
	protected Session session;
	protected static Logger log = Logger.getLogger(CassandraNativeConnector.class);

	/**
	 * default constructor.
	 */
	public CassandraReader() {
		Session inis = CassandraNativeConnector.getSession();
		setSession(inis);
	}

	public void setSession(Session s) {
		assert s != null;
		session = s;
	}

	/**
	 * Basic query to the DB. The method throws exception if the input command
	 * is not valid or if there is a problem with execution of the command
	 * 
	 * @param command - reading CQL command
	 * @return resulting outout of the command
	 */
	protected ResultSet CassandraQuery(String command) {
		try {
			ResultSet results = session.execute(command);
			return results;
		} catch (QueryExecutionException e) {
			String mess = "ProteoCache Cassandra DB interface: query execution exception...\n   Command: " + command;
			System.out.println(mess);
			log.error(mess);
			log.error(e.getLocalizedMessage(), e.getCause());
			return null;
		} catch (QueryValidationException e) {
			String mess = "CProteoCache Cassandra DB interface: query validation exception...\n   Command: " + command;
			System.out.println(mess);
			log.error(mess);
			log.error(e.getLocalizedMessage(), e.getCause());
			return null;
		}

	}

	/**
	 * finds the earliest date in the database
	 * 
	 * @return the earliest date (long)
	 */
	public static long earliestDate() {
		earlestDate = CassandraNativeConnector.getEarliestDateInDB();
		return earlestDate;
	}

	/**
	 * prepares an example of either job id or IP for the DB
	 * 
	 * @param exampletype
	 *            defines which example you need (an existing job from the DB -
	 *            jobid, an IP - "ip")
	 * @return a string representation of the requested example, if the example
	 *         type is not known empty string is returned
	 */
	public String getExample(String exampletype) {
		if (exampletype.equals("jobid")) {
			return "jp_NzBOJKo";
		} else if (exampletype.equals("ip")) {
			return "127.0.0.1";
		}
		return "";
	}

}