/*-
 * ============LICENSE_START=======================================================
 * ONAP-PAP-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.pap.xacml.restAuth;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Base64;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Properties;

import org.onap.policy.common.logging.eelf.MessageCodes;
import org.onap.policy.common.logging.eelf.PolicyLogger;
import org.onap.policy.common.logging.flexlogger.FlexLogger;
import org.onap.policy.common.logging.flexlogger.Logger;
import org.onap.policy.pap.xacml.rest.XACMLPapServlet;
import org.onap.policy.xacml.api.XACMLErrorConstants;

public class CheckPDP {

	private static Path pdpPath = null;
	private static Properties pdpProp = null;
	private static Long oldModified = null;
	private static Long newModified = null;
	private static HashMap<String, String> pdpMap = null;
	private static final Logger logger = FlexLogger.getLogger(CheckPDP.class);

	public static boolean validateID(String id) {
		// ReadFile
		try {
			readFile();
		} catch (Exception e) {
			PolicyLogger.error(MessageCodes.ERROR_SYSTEM_ERROR, e, "CheckPDP", "Exception reading file");
			return false;
		}
		// Check ID
		if (pdpMap.containsKey(id)) {
			return true;
		}
		return false;
	}

	private static void readFile() throws Exception {
		String pdpFile = XACMLPapServlet.getPDPFile();
		if (pdpFile == null) {
			PolicyLogger.error(MessageCodes.ERROR_SYSTEM_ERROR + "PDP File name is undefined");
			throw new Exception(XACMLErrorConstants.ERROR_SYSTEM_ERROR +"PDP File name not Valid : " + pdpFile);
		}
		if (pdpPath == null) {
			pdpPath = Paths.get(pdpFile);
			if (Files.notExists(pdpPath)) {
				PolicyLogger.error(MessageCodes.ERROR_SYSTEM_ERROR + "File doesn't exist in the specified Path");
				throw new Exception(XACMLErrorConstants.ERROR_SYSTEM_ERROR +"File doesn't exist in the specified Path : "+ pdpPath.toString());
			} 
			if (pdpPath.toString().endsWith(".properties")) {
				readProps();
			} else {
				PolicyLogger.error(MessageCodes.ERROR_SYSTEM_ERROR + "Not a .properties file");
				throw new Exception(XACMLErrorConstants.ERROR_SYSTEM_ERROR +"Not a .properties file");
			}
		}
		// Check if File is updated recently
		else {
			newModified = pdpPath.toFile().lastModified();
			if (newModified != oldModified) {
				// File has been updated.
				readProps();
			}
		}
	}

	@SuppressWarnings({ "rawtypes", "unchecked" })
	private static void readProps() throws Exception {
		InputStream in;
		pdpProp = new Properties();
		try {
			in = new FileInputStream(pdpPath.toFile());
			oldModified = pdpPath.toFile().lastModified();
			pdpProp.load(in);
		} catch (IOException e) {
			PolicyLogger.error(MessageCodes.ERROR_SYSTEM_ERROR, e, "CheckPDP", "Cannot load the Properties file");
			throw new Exception("Cannot Load the Properties file", e);
		}
		// Read the Properties and Load the PDPs and encoding.
		pdpMap = new HashMap<>();
		// Check the Keys for PDP_URLs
		Collection<Object> unsorted = pdpProp.keySet();
		List<String> sorted = new ArrayList(unsorted);
		Collections.sort(sorted);
		for (String propKey : sorted) {
			if (propKey.startsWith("PDP_URL")) {
				String check_val = pdpProp.getProperty(propKey);
				if (check_val == null) {
					throw new Exception("Properties file doesn't have the PDP_URL parameter");
				}
				if (check_val.contains(";")) {
					List<String> pdp_default = new ArrayList<>(Arrays.asList(check_val.split("\\s*;\\s*")));
					int pdpCount = 0;
					while (pdpCount < pdp_default.size()) {
						String pdpVal = pdp_default.get(pdpCount);
						readPDPParam(pdpVal);
						pdpCount++;
					}
				} else {
					readPDPParam(check_val);
				}
			}
		}
		if (pdpMap == null || pdpMap.isEmpty()) {
			logger.debug(XACMLErrorConstants.ERROR_SYSTEM_ERROR + "Cannot Proceed without PDP_URLs");
			throw new Exception(XACMLErrorConstants.ERROR_SYSTEM_ERROR +"Cannot Proceed without PDP_URLs");
		}
	}

	private static void readPDPParam(String pdpVal) throws Exception{
		if(pdpVal.contains(",")){
			List<String> pdpValues = new ArrayList<>(Arrays.asList(pdpVal.split("\\s*,\\s*")));
			if(pdpValues.size()==3){
				// 1:2 will be UserID:Password
				String userID = pdpValues.get(1);
				String pass = pdpValues.get(2);
				Base64.Encoder encoder = Base64.getEncoder();
				// 0 - PDPURL
				pdpMap.put(pdpValues.get(0), encoder.encodeToString((userID+":"+pass).getBytes(StandardCharsets.UTF_8)));
			}else{
				PolicyLogger.error(MessageCodes.ERROR_PERMISSIONS + "No Credentials to send Request");
				throw new Exception(XACMLErrorConstants.ERROR_PERMISSIONS + "No enough Credentials to send Request. " + pdpValues);
			}
		}else{
			PolicyLogger.error(MessageCodes.ERROR_PERMISSIONS + "No Credentials to send Request: " + pdpVal);
			throw new Exception(XACMLErrorConstants.ERROR_PERMISSIONS +"No enough Credentials to send Request.");
		}
	}
	
	public static String getEncoding(String pdpID){
		try {
			readFile();
		} catch (Exception e) {
			PolicyLogger.error(MessageCodes.ERROR_SYSTEM_ERROR, e, "CheckPDP", "Exeption reading Properties file");
		}
		String encoding = null;
		if(pdpMap!=null && (!pdpMap.isEmpty())){
			try{
				encoding = pdpMap.get(pdpID);
			} catch(Exception e){
				PolicyLogger.error(MessageCodes.ERROR_SYSTEM_ERROR, e, "CheckPDP", "Exception encoding");
			}
			return encoding;
		}else{
			return null;
		}
	}

}