package org.gcube.dataanalysis.databases.utils;

import java.io.File;
import java.io.FileInputStream;
import java.math.BigInteger;
import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
import java.util.LinkedHashMap;

import org.dom4j.Document;
import org.dom4j.Node;
import org.dom4j.io.SAXReader;
import org.gcube.contentmanagement.lexicalmatcher.utils.AnalysisLogger;
import org.hibernate.SessionFactory;

/** Class that allows to performs some operations on a database */
public class DatabaseOperations {

	private String DBType = ""; // database's type

	// private static final String QueryPostgres =
	// "select count(*) from \"%1$s\" limit 1";
	private static final String QueryPostgres = "select count(*) from (select * from \"%1$s\" limit 1) as a";
	private static final String QueryMysql = "select count(*) from (select * from `%1$s` limit 1) as a";
	// private static final String QueryMysql =
	// "select count(*) from `%1$s` limit 1";

	// private static final String Query = "select * from %1$s limit 1";
	// private static final String countQuery = "select count(*) from %1$s";
	// private static final String explainQuery = "explain select * from %1$s";
	private static final String explainQueryPostgres = "explain select * from \"%1$s\"";
	private static final String explainQueryMysql = "explain select * from `%1$s`";

	private static final String MYSQL = "MySQL";
	private static final String POSTGRES = "Postgres";

	// Method that recover the schema's name of the database.
	public String getDBSchema(String configurationFile) throws Exception {

		File fl = new File(configurationFile);
		FileInputStream stream = new FileInputStream(fl);

		SAXReader saxReader = new SAXReader();
		Document document = saxReader.read(stream);

		List<Node> nodes = document
				.selectNodes("//hibernate-configuration/session-factory/property");

		Iterator<Node> nodesIterator = nodes.iterator();

		String dbschema = "";
		while (nodesIterator.hasNext()) {

			Node currentnode = nodesIterator.next();
			String element = currentnode.valueOf("@name");
			if (element.equals("connection.url")) {
				String url = currentnode.getText();
				dbschema = url.substring(url.lastIndexOf("/") + 1);
				if (dbschema.indexOf('?') > 0)
					dbschema = dbschema.substring(0, dbschema.indexOf('?'));
				AnalysisLogger.getLogger().debug(
						"DatabaseOperations->recovering the database's name: "
								+ dbschema);

				// DBType="MySQL";

				// break;
			}

			if (element.equals("connection.schemaname")) {
				String url = currentnode.getText();
				dbschema = url.substring(url.lastIndexOf("/") + 1);
				if (dbschema.indexOf('?') > 0)
					dbschema = dbschema.substring(0, dbschema.indexOf('?'));
				AnalysisLogger.getLogger().debug(
						"DatabaseOperations->recovering the schema's name: "
								+ dbschema);
				DBType = POSTGRES;
				// break;

			}

			if (DBType.equals("")) {

				DBType = MYSQL;

			}

		}

		// close stream
		stream.close();

		return dbschema;
	}

	// Method that returns the database's type
	public String getDBType() {

		return DBType;

	}
	
	// Method that calculate the estimated number of rows
		public long calculateElements(ConnectionManager connection,
				String dbType, String tablename, SessionFactory session)
				throws Exception {

			long count = 0;

			String countingQuery = null;

			if (dbType.equals(POSTGRES)) {

				countingQuery = String.format(QueryPostgres, tablename);

			}
			if (dbType.equals(MYSQL)) {

				countingQuery = String.format(QueryMysql, tablename);

			}

			AnalysisLogger.getLogger().debug(
					"DatabaseOperations->calculating rows' number with the query: "
							+ countingQuery);

			List<Object> result;

			// try {
			// result = DatabaseFactory.executeSQLQuery(countingQuery, session);

			result = connection.executeQuery(countingQuery, session);

			// if ((result != null) && (result.size() > 0)) {
			if (result != null) {
				
				Object element = result.get(0);
				
				ArrayList<Object> listvalues = new ArrayList<Object>(((LinkedHashMap<String, Object>) element).values());
				
				

				// System.out.println("Dimension: " + result.size());

//				Integer numElem = Integer.valueOf(result.get(0).toString());
				
//				Long numElemvalue = Long.valueOf(result.get(0).toString());
				
				Long numElemvalue = Long.valueOf(listvalues.get(0).toString());
				
				long numElem  = numElemvalue.longValue();

				// if (numElem.intValue() == 0){ throw new
				// Exception("The table has not rows");}

				if (numElem > 0) {

					AnalysisLogger
							.getLogger()
							.debug("DatabaseOperations->the database has at least a row.Calculating rows' number through an estimation");

					String explain = null;

					if (dbType.equals(POSTGRES)) {

						explain = String.format(explainQueryPostgres, tablename);

					}
					if (dbType.equals(MYSQL)) {

						explain = String.format(explainQueryMysql, tablename);

					}

					// call query with explain function

					AnalysisLogger.getLogger().debug(
							"DatabaseOperations->calculating rows' number with the query: "
									+ explain);

					List<Object> resultinfo;

					// resultinfo = DatabaseFactory.executeSQLQuery(explain,
					// session);

					resultinfo = connection.executeQuery(explain, session);

					// recovery result

					if (dbType.equals(MYSQL)) {

//						Object[] resultArray = (Object[]) (resultinfo.get(0));
						
						Object elem = resultinfo.get(0);
						
						ArrayList<Object> values = new ArrayList<Object>(
								((LinkedHashMap<String, Object>) elem).values());
						
//                      //print check
//						AnalysisLogger.getLogger().debug(
//								"DatabaseOperations->VALUE: " + values);
						
						BigInteger value = (BigInteger) values.get(8);

//						BigInteger value = (BigInteger) resultArray[8];
						
						count = value.longValue();
						
						

					}

					if (dbType.equals(POSTGRES)) {

						String var = resultinfo.get(0).toString();

						int beginindex = var.indexOf("rows");

						int lastindex = var.indexOf("width");

						var = var.substring(beginindex + 5, lastindex - 1);
						
						Long value = Long.valueOf(var);

						count = value.longValue();

					}

				}

			}

			// } catch (Exception e) {
			// TODO Auto-generated catch block
			// e.printStackTrace();
			// }

			AnalysisLogger.getLogger().debug(
					"DatabaseOperations->rows' number calculated: " + count);

			return count;

		}

}