/*
 * ============LICENSE_START==========================================
 * ONAP Portal SDK
 * ===================================================================
 * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
 * ===================================================================
 *
 * Unless otherwise specified, all software contained herein is licensed
 * under the Apache License, Version 2.0 (the "License");
 * you may not use this software 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.
 *
 * Unless otherwise specified, all documentation contained herein is licensed
 * under the Creative Commons License, Attribution 4.0 Intl. (the "License");
 * you may not use this documentation except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *             https://creativecommons.org/licenses/by/4.0/
 *
 * Unless required by applicable law or agreed to in writing, documentation
 * 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============================================
 *
 * 
 */
/*
 * Copyright 2014-2017 the original author or authors.
 *
 * 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.
 */

package org.onap.portalapp.music.conf;

import java.io.Serializable;
import java.time.Duration;
import java.time.Instant;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.UUID;

import org.onap.music.eelf.logging.EELFLoggerDelegate;
import org.onap.music.exceptions.MusicLockingException;
import org.onap.music.exceptions.MusicServiceException;
import org.onap.portalapp.music.service.MusicService;
import org.onap.portalapp.music.util.MusicProperties;
import org.onap.portalapp.music.util.MusicUtil;
import org.springframework.session.MapSession;
import org.springframework.session.Session;

/**
 * <p>
 * A {@link Session} implementation that is backed by a {@link java.util.Map}. The
 * defaults for the properties are:
 * </p>
 * <ul>
 * <li>id - a secure random generated id</li>
 * <li>creationTime - the moment the {@link MapSession} was instantiated</li>
 * <li>lastAccessedTime - the moment the {@link MapSession} was instantiated</li>
 * <li>maxInactiveInterval - 30 minutes</li>
 * </ul>
 *
 * <p>
 * This implementation has no synchronization, so it is best to use the copy constructor
 * when working on multiple threads.
 * </p>
 *
 * @author SRIDHAR REDDY M
 * @since 1.0
 */
public final class MusicSession implements Session, Serializable  {
	/**
	 * Default {@link #setMaxInactiveInterval(Duration)} (30 minutes).
	 */
	public static final int DEFAULT_MAX_INACTIVE_INTERVAL_SECONDS = MusicProperties.getProperty(MusicProperties.SESSION_MAX_INACTIVE_INTERVAL_SECONDS)==null ? 1800 :Integer.valueOf(MusicProperties.getProperty(MusicProperties.SESSION_MAX_INACTIVE_INTERVAL_SECONDS)) ;
	private static final EELFLoggerDelegate logger = EELFLoggerDelegate.getLogger(MusicSession.class);

	private String id;
	private String originalId;
	private Map<String, Object> sessionAttrs = new HashMap<>();
	private Instant creationTime = Instant.now();
	private Instant lastAccessedTime = this.creationTime;
	private Map<String,Integer> cachingMap = new HashMap<>();
	private boolean musicCache = MusicUtil.isCached();
	/**
	 * Defaults to 30 minutes.
	 */
	private Duration maxInactiveInterval = Duration.ofSeconds(DEFAULT_MAX_INACTIVE_INTERVAL_SECONDS);

	/**
	 * Creates a new instance with a secure randomly generated identifier.
	 */
	public MusicSession() {
		this(generateId());
	}


	/**
	 * Creates a new instance with the specified id. This is preferred to the default
	 * constructor when the id is known to prevent unnecessary consumption on entropy
	 * which can be slow.
	 *
	 * @param id the identifier to use
	 */
	public MusicSession(String id) {
		this.id = id;
		this.originalId = id;
	}

	/**
	 * Creates a new instance from the provided {@link Session}.
	 *
	 * @param session the {@link Session} to initialize this {@link Session} with. Cannot
	 * be null.
	 */
	public MusicSession(Session session) {
		if (session == null) {
			throw new IllegalArgumentException("session cannot be null");
		}
		this.id = session.getId();
		this.originalId = this.id;
		this.sessionAttrs = new HashMap<>(
				session.getAttributeNames().size());
		for (String attrName : session.getAttributeNames()) {
			Object attrValue = session.getAttribute(attrName);
			if (attrValue != null) {
				this.sessionAttrs.put(attrName, attrValue);
			}
		}
		this.creationTime = session.getCreationTime();
		this.lastAccessedTime = session.getLastAccessedTime();
		this.maxInactiveInterval = session.getMaxInactiveInterval();
	}

	@Override
	public void setLastAccessedTime(Instant lastAccessedTime) {
		logger.debug(EELFLoggerDelegate.debugLogger, "setLastAccessedTime: start");
		try{
			MusicService.setAttribute(MusicProperties.LAST_ACCESS_TIME, this.lastAccessedTime, this.id);
		}catch(Exception e){
			logger.error(EELFLoggerDelegate.errorLogger, "setLastAccessedTime failed with id " + this.id, e);
		}
		this.lastAccessedTime = lastAccessedTime;
	}

	@Override
	public Instant getCreationTime() {
		Instant creationTime = null;
		logger.debug(EELFLoggerDelegate.debugLogger, "getCreationTime: start");
		if(musicCache)
			creationTime = this.creationTime;
		else{
			try {
				String creationTimeStr = MusicService.getAttribute( MusicProperties.CREATION_TIME, this.id);
				if(creationTimeStr!=null)
					creationTime = Instant.parse(creationTimeStr); 
				else
					creationTime = Instant.now();
			} catch (Exception e) {
				logger.error(EELFLoggerDelegate.errorLogger, "getCreationTime failed with id " + this.id, e);
			}
		}
		return creationTime;
	}

	@Override
	public String getId() {
		return this.id;
	}

	String getOriginalId() {
		return this.originalId;
	}

	void setOriginalId(String originalId) {
		this.originalId = originalId;
	}

	@Override
	public String changeSessionId() {
		String changedId = generateId();
		setId(changedId);
		return changedId;
	}

	@Override
	public Instant getLastAccessedTime() {
		Instant lastAccessedTime = null;
		logger.debug(EELFLoggerDelegate.debugLogger, "getLastAccessedTime: start");
		if(musicCache)
			lastAccessedTime = this.lastAccessedTime;
		else{
			try {
				String lastAccessedTimeStr = MusicService.getAttribute( MusicProperties.LAST_ACCESS_TIME, this.id);
				if(lastAccessedTimeStr!=null)
					lastAccessedTime = Instant.parse(lastAccessedTimeStr); 
				else
					lastAccessedTime = this.creationTime;
			} catch (Exception e) {
				logger.error(EELFLoggerDelegate.errorLogger, "getLastAccessedTime failed with id "+this.id, e);
			}
		}
		return lastAccessedTime;
	}

	@Override
	public void setMaxInactiveInterval(Duration interval) {
		logger.debug(EELFLoggerDelegate.debugLogger, "setMaxInactiveInterval: start");
		this.maxInactiveInterval = interval;
		try{
			MusicService.setAttribute(MusicProperties.MAX_INACTIVE_INTERVAL, this.maxInactiveInterval, this.id);
		}catch(Exception e){
			logger.error(EELFLoggerDelegate.errorLogger, "setMaxInactiveInterval failed with id " + this.id, e);
		}
	}

	@Override
	public Duration getMaxInactiveInterval() {
		logger.debug(EELFLoggerDelegate.debugLogger, "getMaxInactiveInterval: start");
		Duration maxInactiveInterval = null;
		if(musicCache)
			maxInactiveInterval = this.maxInactiveInterval;
		else{	
			try {
				String maxInactiveIntervalStr = MusicService.getAttribute( MusicProperties.MAX_INACTIVE_INTERVAL, this.id);
				if(maxInactiveIntervalStr!=null)
					maxInactiveInterval = Duration.parse(maxInactiveIntervalStr);
				else
					maxInactiveInterval = Duration.ofSeconds(DEFAULT_MAX_INACTIVE_INTERVAL_SECONDS);
			} catch (Exception e) {
				logger.error(EELFLoggerDelegate.errorLogger, "getMaxInactiveInterval failed with id " + this.id, e);
			}
		}
		return maxInactiveInterval==null? Duration.ofSeconds(DEFAULT_MAX_INACTIVE_INTERVAL_SECONDS):maxInactiveInterval;
	}

	@Override
	public boolean isExpired() {
		return isExpired(Instant.now());
	}

	boolean isExpired(Instant now) {
		logger.debug(EELFLoggerDelegate.debugLogger, "isExpired: start");
		boolean isExpired = false;
		Duration maxInactiveInterval = null;
		Instant lastAccessedTime = null;
		try {
			if(musicCache){
				maxInactiveInterval = this.maxInactiveInterval;
				lastAccessedTime = this.lastAccessedTime;
			}else{
				maxInactiveInterval = getMaxInactiveInterval();
				lastAccessedTime = getLastAccessedTime();
			}
			if (maxInactiveInterval.isNegative()) {
				return false;
			}
			isExpired = now.minus(maxInactiveInterval).compareTo(lastAccessedTime) >= 0;
			if(isExpired){
				MusicService.removeSession(this.id);
			}
		} catch (MusicLockingException e) {
			logger.error(EELFLoggerDelegate.errorLogger, "isExpired locking failed with id:" + id, e);
		} catch (MusicServiceException e) {
			logger.error(EELFLoggerDelegate.errorLogger, "isExpired failed with id:" + id, e);
		}
		return isExpired;
	}

	@Override
	@SuppressWarnings("unchecked")
	public <T> T getAttribute(String attributeName) {
		if(musicCache){
			return (T) this.sessionAttrs.get(attributeName);
		}else{
			try {
				return MusicService.getAttribute( attributeName, this.id);
			} catch (Exception e) {
				logger.error(EELFLoggerDelegate.errorLogger, " getAttribute failed with id:" + this.id + " attribute name "+ attributeName , e);
				return null;
			}	
		}

	}

	@Override
	public Set<String> getAttributeNames() {
		return this.sessionAttrs.keySet();
	}

	@Override
	public void setAttribute(String attributeName, Object attributeValue) {
		if (attributeValue == null) {
			removeAttribute(attributeName);
		}else {
			this.sessionAttrs.put(attributeName, attributeValue);
			try{
				MusicService.setAttribute(attributeName , attributeValue, this.id);
			}catch(Exception e){
				logger.error(EELFLoggerDelegate.errorLogger, " setAttribute failed id:" + this.id + " attribute name "+ attributeName , e);
			}
		}
	}

	@Override
	public void removeAttribute(String attributeName) {
		this.sessionAttrs.remove(attributeName);
		try{
			MusicService.removeAttribute(attributeName, this.id);
		}catch(MusicLockingException e){
			logger.error(EELFLoggerDelegate.errorLogger, " removeAttribute locking failed id:" + this.id + " attribute name "+ attributeName , e);
		}catch(MusicServiceException e){
			logger.error(EELFLoggerDelegate.errorLogger, " removeAttribute failed id:" + this.id + " attribute name "+ attributeName , e);
		}
		
	}

	/**
	 * Sets the time that this {@link Session} was created. The default is when the
	 * {@link Session} was instantiated.
	 * @param creationTime the time that this {@link Session} was created.
	 */
	public void setCreationTime(Instant creationTime) {
		//MusicService musicService = new MusicService();
		this.creationTime = creationTime;
		try{
			MusicService.setAttribute(MusicProperties.CREATION_TIME, creationTime, this.id);
		}catch(Exception e){
			logger.error(EELFLoggerDelegate.errorLogger, " setCreationTime failed id:" + this.id + " creationTime  "+ creationTime , e);
		}

	}

	/**
	 * Sets the identifier for this {@link Session}. The id should be a secure random
	 * generated value to prevent malicious users from guessing this value. The default is
	 * a secure random generated identifier.
	 *
	 * @param id the identifier for this session.
	 */
	public void setId(String id) {
		this.id = id;
	}

	@Override
	public boolean equals(Object obj) {
		return obj instanceof Session && this.id.equals(((Session) obj).getId());
	}

	@Override
	public int hashCode() {
		return this.id.hashCode();
	}

	private static String generateId() {
		return UUID.randomUUID().toString();
	}

	private static final long serialVersionUID = 7160779239673823561L;
}