/*-
 * ============LICENSE_START=======================================================
 * ONAP Policy Engine
 * ================================================================================
 * Copyright (C) 2017-2019 AT&T Intellectual Property. All rights reserved.
 * Modified Copyright (C) 2018 Samsung Electronics Co., Ltd.
 * Modifications Copyright (C) 2019 Bell Canada
 * ================================================================================
 * 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.admin;

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

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
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.Map;
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 org.onap.policy.utils.PeCryptoUtils;
import org.onap.policy.xacml.api.XACMLErrorConstants;

/**
 * What is not good about this class is that once a value has been set for pdpProperties path you cannot change it. That
 * may be ok for a highly controlled production environment in which nothing changes, but not a very good
 * implementation.
 *
 * <p>The reset() method has been added to assist with the above problem in order to acquire >80% JUnit code coverage.
 *
 * <p>This static class doesn't really check a PDP, it simply loads a properties file and tried to ensure 
 * that a valid URL exists for a PDP along with user/password.
 */
public class CheckPdpProperties {

    private static Path pdpPath = null;
    private static Long oldModified = null;
    private static HashMap<String, String> pdpMap = null;
    private static final Logger LOGGER = FlexLogger.getLogger(CheckPdpProperties.class);

    private CheckPdpProperties() {
        // default constructor
    }

    public static Map<String, String> getPdpMap() {
        return pdpMap;
    }

    private static void reset() {
        pdpPath = null;
        oldModified = null;
        pdpMap = null;
    }

    /**
     * validateId - validates that the ID is in the properties.
     *
     * @param id Input ID
     * @return true it is in the properties
     */
    public static boolean validateId(String id) {
        // ReadFile
        try {
            readFile();
        } catch (Exception e) {
            LOGGER.error(XACMLErrorConstants.ERROR_SYSTEM_ERROR + e);
            return false;
        }
        if (pdpMap == null) {
            return false;
        }
        // Check ID
        return pdpMap.containsKey(id);
    }

    private static void readFile() {
        String pdpFile;
        try {
            pdpFile = XACMLProperties.getProperty(XACMLRestProperties.PROP_PDP_IDFILE);
        } catch (Exception e) {
            LOGGER.error(XACMLErrorConstants.ERROR_DATA_ISSUE + "Cannot read the PDP ID File" + e);
            return;
        }
        if (pdpFile == null) {
            LOGGER.error(XACMLErrorConstants.ERROR_SYSTEM_ERROR + "PDP File name not Valid : " + pdpFile);
        } else if (pdpPath == null) {
            pdpPath = Paths.get(pdpFile);
            if (!pdpPath.toString().endsWith(".properties") || !pdpPath.toFile().exists()) {
                LOGGER.error(XACMLErrorConstants.ERROR_SYSTEM_ERROR + "File doesn't exist in the specified Path : "
                        + pdpPath.toString());
                CheckPdpProperties.reset();
                return;
            }
            readProps();
        } else { // Check if File is updated recently
            Long newModified = pdpPath.toFile().lastModified();
            if (!newModified.equals(oldModified)) {
                // File has been updated.
                readProps();
            }
        }
    }

    @SuppressWarnings({"unchecked", "rawtypes"})
    private static void readProps() {
        Properties pdpProp;
        pdpProp = new Properties();
        try (InputStream in = new FileInputStream(pdpPath.toFile())) {
            oldModified = pdpPath.toFile().lastModified();
            pdpProp.load(in);
            // 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) {
                loadPdpProperties(propKey, pdpProp);
            }
        } catch (IOException e) {
            LOGGER.error(XACMLErrorConstants.ERROR_SYSTEM_ERROR + e);
        }
        if (pdpMap == null || pdpMap.isEmpty()) {
            LOGGER.debug(XACMLErrorConstants.ERROR_SYSTEM_ERROR + "Cannot Proceed without PDP_URLs");
            CheckPdpProperties.reset();
        }
    }

    private static void loadPdpProperties(String propKey, Properties pdpProp) {
        if (propKey.startsWith("PDP_URL")) {
            String checkVal = pdpProp.getProperty(propKey);
            if (checkVal == null) {
                LOGGER.error("Properties file doesn't have the PDP_URL parameter");
            }
            if (checkVal != null && checkVal.contains(";")) {
                List<String> pdpDefault = new ArrayList<>(Arrays.asList(checkVal.split("\\s*;\\s*")));
                int pdpCount = 0;
                while (pdpCount < pdpDefault.size()) {
                    String pdpVal = pdpDefault.get(pdpCount);
                    readPdpParam(pdpVal);
                    pdpCount++;
                }
            }
        }
    }

    private static void readPdpParam(String pdpVal) {
        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 = PeCryptoUtils.decrypt(pdpValues.get(2));
                Base64.Encoder encoder = Base64.getEncoder();
                // 0 - PDPURL
                pdpMap.put(pdpValues.get(0),
                        encoder.encodeToString((userID + ":" + pass).getBytes(StandardCharsets.UTF_8)));
            } else {
                LOGGER.error(XACMLErrorConstants.ERROR_PERMISSIONS + "No Credentials to send Request: " + pdpValues);
            }
        } else {
            LOGGER.error(XACMLErrorConstants.ERROR_PERMISSIONS + "No Credentials to send Request: " + pdpVal);
        }
    }

    /**
     * getEncoding reads in the PDP properties and returns an encoding
     * for the given pdp.
     * 
     * @param pdpID Input PDP Id
     * @return String encoding
     */
    public static String getEncoding(String pdpID) {
        try {
            readFile();
        } catch (Exception e) {
            LOGGER.error(XACMLErrorConstants.ERROR_SYSTEM_ERROR + e);
        }
        String encoding = null;
        if (pdpMap != null && (!pdpMap.isEmpty())) {
            try {
                encoding = pdpMap.get(pdpID);
            } catch (Exception e) {
                LOGGER.error(XACMLErrorConstants.ERROR_SYSTEM_ERROR + e);
            }
            return encoding;
        } else {
            return null;
        }
    }
}