/*-
 * ============LICENSE_START=======================================================
 * onap
 * ================================================================================
 * Copyright (C) 2016 - 2017 ONAP
 * ================================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ============LICENSE_END=========================================================
 */

package org.onap.ccsdk.sli.core.sli.provider;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Optional;
import java.util.Properties;
import java.util.Vector;

import org.onap.ccsdk.sli.core.dblib.DblibConfigurationException;
import org.onap.ccsdk.sli.core.sli.ConfigurationException;
import org.onap.ccsdk.sli.core.sli.provider.base.SvcLogicPropertiesProvider;
import org.onap.ccsdk.sli.core.utils.JREFileResolver;
import org.onap.ccsdk.sli.core.utils.KarafRootFileResolver;
import org.onap.ccsdk.sli.core.utils.PropertiesFileResolver;
import org.onap.ccsdk.sli.core.utils.common.CoreDefaultFileResolver;
import org.onap.ccsdk.sli.core.utils.common.SdncConfigEnvVarFileResolver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Responsible for determining the properties file to use and instantiating the
 * <code>DBResourceManager</code> Service. The priority for properties file
 * resolution is as follows:
 *
 * <ol>
 * <li>A directory identified by the system environment variable
 * <code>SDNC_CONFIG_DIR</code></li>
 * <li>The default directory <code>DEFAULT_DBLIB_PROP_DIR</code></li>
 * <li>A directory identified by the JRE argument
 * <code>dblib.properties</code></li>
 * <li>A <code>dblib.properties</code> file located in the karaf root
 * directory</li>
 * </ol>
 */
public class SvcLogicPropertiesProviderImpl implements SvcLogicPropertiesProvider {

	private static final Logger LOG = LoggerFactory.getLogger(SvcLogicPropertiesProviderImpl.class);

	/**
	 * The name of the properties file for database configuration
	 */
	private static final String SVCLOGIC_PROP_FILE_NAME = "svclogic.properties";

	/**
	 * A prioritized list of strategies for resolving dblib properties files.
	 */
	private Vector<PropertiesFileResolver> sliPropertiesFileResolvers = new Vector<>();

	/**
	 * The configuration properties for the db connection.
	 */
	private Properties properties;

	/**
	 * Set up the prioritized list of strategies for resolving dblib properties
	 * files.
	 */
	public SvcLogicPropertiesProviderImpl() {
		sliPropertiesFileResolvers
				.add(new SdncConfigEnvVarFileResolver("Using property file (1) from environment variable"));
		sliPropertiesFileResolvers.add(new CoreDefaultFileResolver("Using property file (2) from default directory"));

		sliPropertiesFileResolvers.add(
				new JREFileResolver("Using property file (3) from JRE argument", SvcLogicPropertiesProviderImpl.class));
		sliPropertiesFileResolvers.add(new KarafRootFileResolver("Using property file (4) from karaf root", this));

		// determines properties file as according to the priority described in the
		// class header comment
		final File propertiesFile = determinePropertiesFile(this);
		if (propertiesFile != null) {
			try (FileInputStream fileInputStream = new FileInputStream(propertiesFile)) {
				properties = new Properties();
				properties.load(fileInputStream);
			} catch (final IOException e) {
				LOG.error("Failed to load properties for file: {}", propertiesFile.toString(),
						new ConfigurationException("Failed to load properties for file: " + propertiesFile.toString(),
								e));
			}
		} else {
			// Try to read properties as resource

			InputStream propStr = getClass().getResourceAsStream("/" + SVCLOGIC_PROP_FILE_NAME);
			if (propStr != null) {
				properties = new Properties();
				try {
					properties.load(propStr);
					propStr.close();
				} catch (IOException e) {
					properties = null;
				}
			}

		}

		if (properties == null) {
			reportFailure("Missing configuration properties resource(3)", new ConfigurationException(
					"Missing configuration properties resource(3): " + SVCLOGIC_PROP_FILE_NAME));
		}
	}

	/**
	 * Extract svclogic config properties.
	 *
	 * @return the svclogic config properties
	 */
	public Properties getProperties() {
		return properties;
	}

	/**
	 * Reports the method chosen for properties resolution to the
	 * <code>Logger</code>.
	 *
	 * @param message
	 *            Some user friendly message
	 * @param fileOptional
	 *            The file location of the chosen properties file
	 * @return the file location of the chosen properties file
	 */
	private static File reportSuccess(final String message, final Optional<File> fileOptional) {
		if (fileOptional.isPresent()) {
			final File file = fileOptional.get();
			LOG.info("{} {}", message, file.getPath());
			return file;
		}
		return null;
	}

	/**
	 * Reports fatal errors. This is the case in which no properties file could be
	 * found.
	 *
	 * @param message
	 *            An appropriate fatal error message
	 * @param configurationException
	 *            An exception describing what went wrong during resolution
	 */
	private static void reportFailure(final String message, final ConfigurationException configurationException) {

		LOG.error("{}", message, configurationException);
	}

	/**
	 * Determines the dblib properties file to use based on the following priority:
	 * <ol>
	 * <li>A directory identified by the system environment variable
	 * <code>SDNC_CONFIG_DIR</code></li>
	 * <li>The default directory <code>DEFAULT_DBLIB_PROP_DIR</code></li>
	 * <li>A directory identified by the JRE argument
	 * <code>dblib.properties</code></li>
	 * <li>A <code>dblib.properties</code> file located in the karaf root
	 * directory</li>
	 * </ol>
	 */
	File determinePropertiesFile(final SvcLogicPropertiesProviderImpl resourceProvider) {

		for (final PropertiesFileResolver sliPropertiesFileResolver : sliPropertiesFileResolvers) {
			final Optional<File> fileOptional = sliPropertiesFileResolver.resolveFile(SVCLOGIC_PROP_FILE_NAME);
			if (fileOptional.isPresent()) {
				return reportSuccess(sliPropertiesFileResolver.getSuccessfulResolutionMessage(), fileOptional);
			}
		}

		return null;
	}
}