document-store-lib-postgresql/src/main/java/org/gcube/documentstore/persistence/PersistencePostgreSQL.java

/**
 * 
 */
package org.gcube.documentstore.persistence;

import java.io.Serializable;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.SortedSet;
import java.util.TreeSet;

import org.gcube.documentstore.records.Record;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author Luca Frosini (ISTI - CNR)
 */
public class PersistencePostgreSQL extends PersistenceBackend {

	private static final Logger logger = LoggerFactory.getLogger(PersistencePostgreSQL.class);

	public static final String DATETIME_PATTERN = "yyyy-MM-dd HH:mm:ss.SSS Z";
	
	public static final String URL_PROPERTY_KEY = "URL";
	public static final String USERNAME_PROPERTY_KEY = "username";
	public static final String PASSWORD_PROPERTY_KEY = "password";

	private String url;
	private String username;
	private String password;

	private Connection connection;
	private Statement statement;

	@Override
	protected void prepareConnection(PersistenceBackendConfiguration configuration) throws Exception {
		logger.trace("prepareConnection()");
		url = configuration.getProperty(URL_PROPERTY_KEY);
		username = configuration.getProperty(USERNAME_PROPERTY_KEY);
		password = configuration.getProperty(PASSWORD_PROPERTY_KEY);
	}

	@Override
	protected void openConnection() throws Exception {
		logger.trace("openConnection()");
		try {
			Class.forName("org.postgresql.Driver");
			connection = DriverManager.getConnection(url, username, password);
			logger.trace("Opened database successfully");
			connection.setAutoCommit(false);
			statement = connection.createStatement();
		} catch (Exception e) {
			throw e;
		}
	}
	
	public void newConnection() throws Exception {
		openConnection();
	}
	
	protected void appendString(StringBuffer values, String string) {
		values.append("'");
		values.append(string);
		values.append("'");
	}
	
	protected void appendValue(StringBuffer values, Serializable serializable) {
		if(serializable instanceof Integer || serializable instanceof Long) {
			values.append(serializable.toString());
			return;
		}
		
		if(serializable instanceof String) {
			appendString(values, serializable.toString());
			return;
		}
		
		if(serializable instanceof Calendar) {
			Calendar calendar = (Calendar) serializable;
			SimpleDateFormat simpleDateFormat = new SimpleDateFormat(DATETIME_PATTERN);
			String date = simpleDateFormat.format(calendar.getTime());
			appendString(values, date);
			return;
		}
		
		if(serializable instanceof Enum) {
			Enum<?> e = (Enum<?>) serializable;
			appendString(values, e.name());
			return;
		}
		
		values.append(serializable.toString());
	}
	
	protected void appendKey(StringBuffer sql, String key) {
		
		int lenght = key.length(); 
        for (int i=0; i<lenght; i++) { 
           Character ch = key.charAt(i); /*traversing String one by one*/
            if (Character.isUpperCase(ch)) { 
                sql.append("_");
            }
            sql.append(Character.toLowerCase(ch));
        }
	}
	
	protected String getSQLInsertCommand(Record record) {
		StringBuffer sql = new StringBuffer();
		sql.append("INSERT INTO ");
		sql.append(record.getRecordType().toLowerCase()); // tableNme == RecordType.toLowerCase()
		boolean first = true;
		SortedSet<String> keys = new TreeSet<>(record.getRequiredFields());
		StringBuffer values = new StringBuffer();
		for(String key : keys) {
			if(first) {
				sql.append(" (");
				values.append(" (");
				first = false;
			}else {
				sql.append(",");
				values.append(",");
			}
			appendKey(sql, key);
			switch (key) {
				case "creationTime": case "startTime": case "endTime":
					Calendar calendar = Calendar.getInstance();
					calendar.setTimeInMillis((long) record.getResourceProperty(key));
					appendValue(values, calendar);
					break;
	
				default:
					appendValue(values, record.getResourceProperty(key));	
					break;
			}		
		}
		sql.append(") VALUES");
		sql.append(values);
		sql.append(");");
		return sql.toString();
	}
	
	@Override
	protected void reallyAccount(Record record) throws Exception {
		logger.trace("reallyAccount()");
		String sqlCommand = getSQLInsertCommand(record);
		statement.executeUpdate(sqlCommand);
	}
	
	public void insert(Record record) throws Exception {
		reallyAccount(record);
	}

	@Override
	protected void clean() throws Exception {
		logger.trace("clean()");
	}

	@Override
	protected void closeConnection() throws Exception {
		logger.trace("closeConnection()");
		statement.close();
		connection.commit();
		connection.close();
	}

	public void commitAndClose() throws Exception {
		closeConnection();
	}
	
	@Override
	public boolean isConnectionActive() throws Exception {
		return connection.isValid(300);
	};

}