/*-
 * ============LICENSE_START=======================================================
 * ONAP-PDP-REST
 * ================================================================================
 * Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
 * ================================================================================
 * 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.policy.pdp.rest;

import java.net.URI;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.NoSuchElementException;
import java.util.Properties;

import org.onap.policy.common.logging.flexlogger.FlexLogger;
import org.onap.policy.common.logging.flexlogger.Logger;
import org.onap.policy.rest.XACMLRestProperties;

import com.att.research.xacml.util.XACMLProperties;

public class PapUrlResolver {
	private static final Logger LOGGER = FlexLogger.getLogger(PapUrlResolver.class);
	//how long to keep a pap failed before making it un-failed, in milli-seconds
	private static final long FAIL_TIMEOUT = 18000000;
	
	//thread locks
	public static final Object propertyLock = new Object();
	
	//keeping this here for backward compatibility
	public static String extractIdFromUrl(String url){
		return extractQuery(url);
	}
	public static String extractQuery(String url){
		try{
			return URI.create(url).getQuery();
		} catch(Exception e){
			LOGGER.error("Exception occured while extracting query. So, empty string is returned"+e);
			return "";
		}
	}
	public static String modifyUrl(String idUrl, String serverUrl){
		URI one = URI.create(idUrl);
		String host = one.getPath()+one.getQuery();
		URI two = URI.create(serverUrl);
		two.resolve(host);
		return two.toString();
	}

	//get an instance of a new PapUrlResolver, using XACMLProperties to get the url lists
	public static PapUrlResolver getInstance(){
		return new PapUrlResolver(null,null,null,true);
	}
	
	//get an instance of a new PapUrlResolver, using the provides strings for the url lists
	public static PapUrlResolver getInstance(String urlList, String failedList, String succeededList){
		return new PapUrlResolver(urlList, failedList, succeededList,false);
	}

	//keeps track of our current location in the list of urls, allows for iterating
	private int pointer;
	
	//should the XACML property lists be updated after anything changes or should we wait for the update
	//method to be called.
	private boolean autoUpdateProperties;
	
	//this list keeps the sorted, priority of PAP URLs
	private PapUrlNode[] sortedUrlNodes;
	//this list keeps the original list of nodes so that they can be entered into the property list correctly
	private PapUrlNode[] originalUrlNodes;
	
	//private constructor to make an instance of a PapUrlResolver, called by static method getInstance.
	//If the list property strings are not defined, we get the values from XACMLProperties.
	//The instance acts as an iterator, with hasNext and next methods, but does not implement Iterable,
	//because it is used for a difference purpose.
	private PapUrlResolver(String urlList, String failedList, String succeededList, boolean autoUpdateProperties){	
		this.autoUpdateProperties = autoUpdateProperties;
		String papUrlLists = urlList;
		String papUrlFailedList = failedList;
		String papUrlSuccessList = succeededList;
		if(papUrlLists == null){
			papUrlLists = XACMLProperties.getProperty(XACMLRestProperties.PROP_PAP_URLS);
			if(papUrlLists == null){
				papUrlLists = XACMLProperties.getProperty(XACMLRestProperties.PROP_PAP_URL);
			}
			papUrlFailedList = XACMLProperties.getProperty(XACMLRestProperties.PROP_PAP_FAILED_URLS);
			papUrlSuccessList = XACMLProperties.getProperty(XACMLRestProperties.PROP_PAP_SUCCEEDED_URLS);
		}
		
		String[] urls = papUrlLists.split(",");
		if(urls.length == 0){		
			//log error
		}
		String[] failed = emptyOrSplit(papUrlFailedList,urls.length);
		String[] succeeded = emptyOrSplit(papUrlSuccessList,urls.length);
		
		sortedUrlNodes = new PapUrlNode[urls.length];
		for(int i=0;i<urls.length;i++){
		
			String userId = null;
			String pass = null;
			userId = XACMLProperties.getProperty(urls[i]+"."+XACMLRestProperties.PROP_PAP_USERID);					
			pass = XACMLProperties.getProperty(urls[i]+"."+XACMLRestProperties.PROP_PAP_PASS);
			if(userId == null || pass == null){
				userId = XACMLProperties.getProperty(XACMLRestProperties.PROP_PAP_USERID);
				pass = XACMLProperties.getProperty(XACMLRestProperties.PROP_PAP_PASS);
			}
			if(userId == null || pass == null){
				userId = "";
				pass = "";
			}
			PapUrlNode newNode = new PapUrlNode(urls[i],userId,pass);
			newNode.setFailedTime(failed[i]);
			newNode.setSucceededTime(succeeded[i]);
			if(sortedUrlNodes[i] == null){
				sortedUrlNodes[i] = newNode;
			}
		}
		originalUrlNodes = sortedUrlNodes.clone();
		sort(sortedUrlNodes);
		pointer = 0;
	}
	
	
	//either split a list by commas, or fill an array to the expected length, if the property list is not long enough
	private String[] emptyOrSplit(String list,int expectedLength){
		String[] ret;
		if(list == null){
			ret = new String[expectedLength];
			for(int i=0;i<expectedLength;i++){
				ret[i] = "-1";
			}
		} else {
			ret = list.split(",");
			if(ret.length != expectedLength){
				ret = emptyOrSplit(null,expectedLength);
			}
		}
		return ret;
	}
	
	private void sort(PapUrlNode[] array){
		
		//O(n^2) double-loop most likely the best in this case, since number of records will be VERY small
		for(int i=0;i<array.length;i++){
			for(int j=i;j<array.length;j++){
				if(array[j].compareTo(array[i])<0){
					PapUrlNode temp = array[i];
					array[i] = array[j];
					array[j] = temp;
				}
			}
		}
	}
	
	//returns whether this PapUrlResolver object has more PAP urls that can be tried
	public boolean hasMoreUrls(){
		return pointer < sortedUrlNodes.length;
	}
	
	//sets the current PAP url as being failed
	//this will set the failed time to now and remove any succeeded time
	public void failed(){
		LOGGER.error("PAP Server FAILED: "+sortedUrlNodes[pointer].getUrl());

		sortedUrlNodes[pointer].setFailedTime(new Date());
		sortedUrlNodes[pointer].setSucceededTime(null);
		propertiesUpdated();
	}
	
	//sets the current PAP url as being working
	//this will set the succeeded time to now and remove any failed time
	//Also, this will cause hasMoreUrls to return false, since a working one has been found
	
	public void succeeded(){
		registered();
		pointer = sortedUrlNodes.length;
	}
	public void registered(){
		sortedUrlNodes[pointer].setFailedTime(null);
		sortedUrlNodes[pointer].setSucceededTime(new Date());
		LOGGER.info("PAP server SUCCEEDED "+sortedUrlNodes[pointer].getUrl());
		propertiesUpdated();
	}
	
	//returns a properties object with the properties that pertain to PAP urls
	public Properties getProperties(){
		String failedPropertyString = "";
		String succeededPropertyString = "";
		String urlPropertyString = "";
		for(int i=0;i<originalUrlNodes.length;i++){
			failedPropertyString = failedPropertyString.concat(",").concat(originalUrlNodes[i].getFailedTime());
			succeededPropertyString = succeededPropertyString.concat(",").concat(originalUrlNodes[i].getSucceededTime());
			urlPropertyString = urlPropertyString.concat(",").concat(originalUrlNodes[i].getUrl());
		}
		Properties prop = new Properties();
		failedPropertyString = failedPropertyString.substring(1);
		succeededPropertyString = succeededPropertyString.substring(1);
		urlPropertyString = urlPropertyString.substring(1);
		prop.setProperty(XACMLRestProperties.PROP_PAP_FAILED_URLS,failedPropertyString);
		prop.setProperty(XACMLRestProperties.PROP_PAP_URLS,urlPropertyString);
		prop.setProperty(XACMLRestProperties.PROP_PAP_SUCCEEDED_URLS,succeededPropertyString);
		return prop;
	}
	
	//saves the updates urls to the correct properties
	private void propertiesUpdated(){
		if(!autoUpdateProperties){
			return;
		}
		Properties prop = getProperties();

		LOGGER.debug("Failed PAP Url List: "+prop.getProperty(XACMLRestProperties.PROP_PAP_FAILED_URLS));
		LOGGER.debug("Succeeded PAP Url List: "+prop.getProperty(XACMLRestProperties.PROP_PAP_SUCCEEDED_URLS));
		XACMLProperties.setProperty(XACMLRestProperties.PROP_PAP_FAILED_URLS,prop.getProperty(XACMLRestProperties.PROP_PAP_FAILED_URLS));
		XACMLProperties.setProperty(XACMLRestProperties.PROP_PAP_SUCCEEDED_URLS,prop.getProperty(XACMLRestProperties.PROP_PAP_SUCCEEDED_URLS));
	}
	
	//iterates to the next available PAP url, according to the priority order
	public void getNext(){
		pointer++;
	}
	
	//returns the url of the current PAP server that we are iterating over
	//will append the provided policy id to the url
	public String getUrl(String query){
		if(sortedUrlNodes[pointer]== null){
			throw new NoSuchElementException();
		} else {
			return sortedUrlNodes[pointer].getUrl().concat("?").concat(query);
		}
	}
	
	//returns the url of the current PAP server that we are iterating over
	//Just returns the url, with no id appended to it
	public String getUrl(){
		if(sortedUrlNodes[pointer]== null){
			throw new NoSuchElementException();
		} else {	
			
			return sortedUrlNodes[pointer].getUrl();
		}
	}
	public String getUserId(){
		if(sortedUrlNodes[pointer]== null){
			throw new NoSuchElementException();
		} else {	
			
			return sortedUrlNodes[pointer].getUserId();
		}
	}
	public String getPass(){
		if(sortedUrlNodes[pointer]== null){
			throw new NoSuchElementException();
		} else {	
			
			return sortedUrlNodes[pointer].getPass();
		}
	}

	
	//This is the class to hold the details of a single PAP URL
	//including: the url itself, the last time it failed, and the last time it succeeded
	//It also includes the custom comparer which can compare based on failed and succeeded times, and takes into account
	//the timeout on failures.
	private class PapUrlNode implements Comparable<PapUrlNode> {
		private String papUrl;
		private Date failedTime;
		private Date succeededTime;
		private String userId;
		private String pass;
		
		public PapUrlNode(String url,String userId,String pass){
			this.papUrl = url;
			failedTime = null;
			this.succeededTime = null;
			this.userId = userId;
			this.pass = pass;
			
		}
		public String getUserId(){
			return this.userId;
		}
		public String getPass(){
			return this.pass;
		}
		
		public void setFailedTime(Object time){
			Date failedTimeAsDate = setHandler(time);
			if(failedTimeAsDate == null){
				this.failedTime = null;
			} else {
				long timeDifference = new Date().getTime() - failedTimeAsDate.getTime();
				if(timeDifference < FAIL_TIMEOUT){
					this.failedTime = failedTimeAsDate;
				} else {
					this.failedTime = null;
				}
			}
		}
		
		//set the time that this url succeeded at
		public void setSucceededTime(Object time){
			this.succeededTime = setHandler(time);
		}
		
		//parses string into a date or a null date, if the url never failed/succeeded (since -1 will be in the property)
		private Date setHandler(Object time){
			if(time instanceof String){
				if("-1".equals((String)time)){
					return null;
				}
				try {
					DateFormat df = new SimpleDateFormat();
					return df.parse((String)time);
				} catch (ParseException e) {					
					return null;
				}
			}
			if(time instanceof Date){
				return (Date)time;
			}
			return null;
		}
		
		
		public String getFailedTime(){
			return formatTime(this.failedTime);
		}
		
		public String getSucceededTime(){
			return formatTime(this.succeededTime);
		}
		
		//formats a Date into a string or a -1 if there is not date (-1 is used in properties for no date)
		private String formatTime(Date d){
			if(d == null){
				return "-1";
			}
			DateFormat df = new SimpleDateFormat();
			return df.format(d);
		}
		
		public String getUrl(){
			return papUrl;
		}
		
		@Override
		public int compareTo(PapUrlNode other){
			if(this.failedTime == null && other.failedTime != null){
				return -1;
			}
			if(this.failedTime != null && other.failedTime == null){
				return 1;
			}
			if(this.failedTime != null){
				return this.failedTime.compareTo(other.failedTime);
			}
			return 0;
		}
	}
}