package org.gcube.dataharvest.dao;

import java.security.Key;
import java.util.List;
import java.util.Properties;

import org.gcube.common.encryption.StringEncrypter;
import org.gcube.common.resources.gcore.ServiceEndpoint;
import org.gcube.common.resources.gcore.ServiceEndpoint.AccessPoint;
import org.gcube.common.resources.gcore.utils.Group;
import org.gcube.dataharvest.AccountingDataHarvesterPlugin;
import org.gcube.resources.discovery.client.api.DiscoveryClient;
import org.gcube.resources.discovery.client.queries.api.SimpleQuery;
import org.gcube.resources.discovery.icclient.ICFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author Luca Frosini (ISTI - CNR)
 */
public class DatabaseParameterRetriever {
	
	private static Logger logger = LoggerFactory.getLogger(DatabaseParameterRetriever.class);
	
	public static final String LOCAL_DB = "LOCAL_DB";
	
	public static final String SERVICE_ENDPOINT_CATEGORY = "Database";
	public static final String SERVICE_ENDPOINT_NAME = "AccountingDashboard";
	
	public static final String DB_URI = "DB_URI";
	public static final String DB_USERNAME = "DB_USERNAME";
	public static final String DB_PASSWORD = "DB_PASSWORD";
	
	public DatabaseParameterRetriever() {
	}
	
	private static String decrypt(String encrypted, Key... key) throws Exception {
		return StringEncrypter.getEncrypter().decrypt(encrypted);
	}
	
	protected void checkParameter(String parameter, String parameterName, boolean localDB) throws DaoException {
		if(parameter == null || parameter.isEmpty()) {
			throw new DaoException("DB " + parameterName + " cannot be null nor empty. Please check your "
					+ (localDB ? "local configuration." : "ServiceEndpoint"));
		}
	}
	
	public DatabaseConnectionData retrieveDatabaseInfo() throws DaoException {
		
		Properties properties = AccountingDataHarvesterPlugin.getProperties().get();
		
		boolean localDB = Boolean.parseBoolean(properties.getProperty(LOCAL_DB, "true"));
		
		String uri = "";
		String username = "";
		String password = "";
		
		if(localDB) {
			logger.debug("Using configuration from local config");
			uri = properties.getProperty(DB_URI);
			username = properties.getProperty(DB_USERNAME);
			password = properties.getProperty(DB_PASSWORD);
		} else {
			try {
				String className = this.getClass().getSimpleName();
				
				SimpleQuery query = ICFactory.queryFor(ServiceEndpoint.class);
				query.addCondition(
						String.format("$resource/Profile/Category/text() eq '%s'", SERVICE_ENDPOINT_CATEGORY));
				query.addCondition(String.format("$resource/Profile/Name/text() eq '%s'", SERVICE_ENDPOINT_NAME));
				query.addCondition(String.format("$resource/Profile/AccessPoint/Interface/Endpoint/@EntryName eq '%s'",
						className));
				
				DiscoveryClient<ServiceEndpoint> client = ICFactory.clientFor(ServiceEndpoint.class);
				List<ServiceEndpoint> serviceEndpoints = client.submit(query);
				if(serviceEndpoints.size()==0) {
					throw new DaoException("No endpoints found to get database connection.");
				}
				
				if(serviceEndpoints.size() > 1) {
					throw new DaoException("More than one endpoint found to get database connection. Not sure which one use.");
				}
				
				Group<AccessPoint> accessPoints = serviceEndpoints.get(0).profile().accessPoints();
				
				for(AccessPoint accessPoint : accessPoints) {
					if(accessPoint.name().compareTo(className) == 0) {
						uri = accessPoint.address();
						username = accessPoint.username();
						
						String encryptedPassword = accessPoint.password();
						password = decrypt(encryptedPassword);
					}
				}
				
			} catch(Exception e) {
				throw new DaoException("Error retrieving database connection", e);
			}
			
		}
		
		checkParameter(uri, "URI", localDB);
		checkParameter(username, "Username", localDB);
		checkParameter(password, "Password", localDB);
		
		return new DatabaseConnectionData(uri, username, password);
	}
}