/**
 * ============LICENSE_START=======================================================
 * org.onap.aai
 * ================================================================================
 * Copyright © 2017-2018 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.aai.logging;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.onap.aai.exceptions.AAIException;
import org.slf4j.MDC;

import com.att.eelf.configuration.EELFLogger;
import com.att.eelf.configuration.EELFManager;

public class LoggingContext {

	public enum StatusCode {
		COMPLETE,
		ERROR
	}

	private static final EELFLogger LOGGER = EELFManager.getInstance().getLogger(LoggingContext.class);

	private static final String PREVIOUS_CONTEXTS_KEY = "_PREVIOUS_CONTEXTS";
	
	//Response codes from Logging Guidelines
	public static final String SUCCESS = "0";
	public static final String PERMISSION_ERROR = "100";
	public static final String AVAILABILITY_TIMEOUT_ERROR = "200";
	public static final String DATA_ERROR = "200";
	public static final String SCHEMA_ERROR = "400";
	public static final String BUSINESS_PROCESS_ERROR = "500";
	public static final String UNKNOWN_ERROR = "900";
	
	public static final Map<String, String> responseMap = new HashMap();
	 
    static {
        responseMap.put(SUCCESS, "Success");
        responseMap.put(UNKNOWN_ERROR, "Unknown error");
    }
	// Specific Log Event Fields
	public static enum LoggingField {
		START_TIME("startTime"),
		REQUEST_ID("requestId"),
		SERVICE_INSTANCE_ID("serviceInstanceId"),
		SERVER_NAME("serverName"),
		SERVICE_NAME("serviceName"),
		PARTNER_NAME("partnerName"),
		STATUS_CODE("statusCode"),
		RESPONSE_CODE("responseCode"),
		RESPONSE_DESCRIPTION("responseDescription"),
		INSTANCE_UUID("instanceUUID"),
		SEVERITY("severity"),
		SERVER_IP_ADDRESS("serverIpAddress"),
		ELAPSED_TIME("elapsedTime"),
		SERVER("server"),
		CLIENT_IP_ADDRESS("clientIpAddress"),
		UNUSED("unused"),
		PROCESS_KEY("processKey"),
		CUSTOM_FIELD_1("customField1"),
		CUSTOM_FIELD_2("customField2"),
		CUSTOM_FIELD_3("customField3"),
		CUSTOM_FIELD_4("customField4"),
		
		// Specific Metric Log Event Fields
		TARGET_ENTITY("targetEntity"),
		TARGET_SERVICE_NAME("targetServiceName"),
		//A&AI Specific Log Event Fields
		COMPONENT("component"),
		STOP_WATCH_START("stopWatchStart");

		private final String text;

		private LoggingField(final String text) {
			this.text = text;
		}

		public String toString() {
			return text;
		}
	}


	public static void init() {
		LoggingContext.clear();
		LoggingContext.startTime();
		LoggingContext.server();
		LoggingContext.serverIpAddress();
	}

	public static void startTime() {
		MDC.put(LoggingField.START_TIME.toString(), LogFormatTools.getCurrentDateTime());
	}

	public static UUID requestId() {
		final String sUuid = MDC.get(LoggingField.REQUEST_ID.toString());

		if (sUuid == null) return null;

		return UUID.fromString(sUuid);
	}

	public static void requestId(UUID requestId) {
		MDC.put(LoggingField.REQUEST_ID.toString(), requestId.toString());
	}

	public static void requestId(String requestId) {
		try {
			if (requestId.contains(":")) {
				String[] uuidParts = requestId.split(":");
				requestId = uuidParts[0];
			}
			MDC.put(LoggingField.REQUEST_ID.toString(), UUID.fromString(requestId).toString());
		} catch (IllegalArgumentException e) {
			final UUID generatedRequestUuid = UUID.randomUUID();
			MDC.put(LoggingField.REQUEST_ID.toString(), generatedRequestUuid.toString());
			LoggingContext.save();
			// set response code to 0 since we don't know what the outcome of this request is yet
			String responseCode = LoggingContext.DATA_ERROR;
			LoggingContext.responseCode(responseCode);
			LoggingContext.responseDescription("Unable to use UUID " + requestId + " (Not formatted properly) ");
			LoggingContext.statusCode(StatusCode.ERROR);
			
			LOGGER.warn("Using generated UUID=" + generatedRequestUuid);
			LoggingContext.restore();

		}
	}

	public static void serviceInstanceId(String serviceInstanceId) {
		MDC.put(LoggingField.SERVICE_INSTANCE_ID.toString(), serviceInstanceId);
	}

	public static void serverName(String serverName) {
		MDC.put(LoggingField.SERVER_NAME.toString(), serverName);
	}

	public static void serviceName(String serviceName) {
		MDC.put(LoggingField.SERVICE_NAME.toString(), serviceName);
	}

	public static void partnerName(String partnerName) {
		MDC.put(LoggingField.PARTNER_NAME.toString(), partnerName);
	}

	public static void statusCode(StatusCode statusCode) {
		MDC.put(LoggingField.STATUS_CODE.toString(), statusCode.toString());
	}

	public static String responseCode() {
		return (String) MDC.get(LoggingField.RESPONSE_CODE.toString());
	}

	public static void responseCode(String responseCode) {
		MDC.put(LoggingField.RESPONSE_CODE.toString(), responseCode);
	}

	public static void responseDescription(String responseDescription) {
		MDC.put(LoggingField.RESPONSE_DESCRIPTION.toString(), responseDescription);
	}

	public static Object instanceUuid() {
		return UUID.fromString(MDC.get(LoggingField.INSTANCE_UUID.toString()));
	}

	public static void instanceUuid(UUID instanceUuid) {
		MDC.put(LoggingField.INSTANCE_UUID.toString(), instanceUuid.toString());
	}

	public static void severity(int severity) {
		MDC.put(LoggingField.SEVERITY.toString(), String.valueOf(severity));
	}

	public static void successStatusFields() {
		responseCode(SUCCESS);
		statusCode(StatusCode.COMPLETE);
		responseDescription("Success");
	}
	private static void serverIpAddress() {
		try {
			MDC.put(LoggingField.SERVER_IP_ADDRESS.toString(), InetAddress.getLocalHost().getHostAddress());
		} catch (UnknownHostException e) {
			LOGGER.warn("Unable to resolve server IP address - will not be displayed in logged events");
		}
	}

	public static void elapsedTime(long elapsedTime, TimeUnit timeUnit) {
		MDC.put(LoggingField.ELAPSED_TIME.toString(), String.valueOf(TimeUnit.MILLISECONDS.convert(elapsedTime, timeUnit)));
	}

	private static void server() {
		try {
			MDC.put(LoggingField.SERVER.toString(),  InetAddress.getLocalHost().getCanonicalHostName());
		} catch (UnknownHostException e) {
			LOGGER.warn("Unable to resolve server IP address - hostname will not be displayed in logged events");
		}
	}

	public static void clientIpAddress(InetAddress clientIpAddress) {
		MDC.put(LoggingField.CLIENT_IP_ADDRESS.toString(), clientIpAddress.getHostAddress());
	}

	public static void clientIpAddress(String clientIpAddress) {
		try {
			MDC.put(LoggingField.CLIENT_IP_ADDRESS.toString(), InetAddress.getByName(clientIpAddress).getHostAddress());
		} catch (UnknownHostException e) {
			//Ignore, will not be thrown since InetAddress.getByName(String) only
			//checks the validity of the passed in string
		}
	}

	public static void unused(String unused) {
		LOGGER.warn("Using field '" + LoggingField.UNUSED + "' (seems like this should go unused...)");
		MDC.put(LoggingField.UNUSED.toString(), unused);
	}

	public static void processKey(String processKey) {
		MDC.put(LoggingField.PROCESS_KEY.toString(), processKey);
	}

	public static String customField1() {
		return MDC.get(LoggingField.CUSTOM_FIELD_1.toString());
	}

	public static void customField1(String customField1) {
		MDC.put(LoggingField.CUSTOM_FIELD_1.toString(), customField1);
	}

	public static void customField2(String customField2) {
		MDC.put(LoggingField.CUSTOM_FIELD_2.toString(), customField2);
	}

	public static void customField3(String customField3) {
		MDC.put(LoggingField.CUSTOM_FIELD_3.toString(), customField3);
	}

	public static void customField4(String customField4) {
		MDC.put(LoggingField.CUSTOM_FIELD_4.toString(), customField4);
	}

	public static void component(String component) {
		MDC.put(LoggingField.COMPONENT.toString(), component);
	}

	public static void targetEntity(String targetEntity) {
		MDC.put(LoggingField.TARGET_ENTITY.toString(), targetEntity);
	}

	public static void targetServiceName(String targetServiceName) {
		MDC.put(LoggingField.TARGET_SERVICE_NAME.toString(), targetServiceName);
	}

	public static boolean isStopWatchStarted() {
		final String rawStopWatchStart = MDC.get(LoggingField.STOP_WATCH_START.toString());
		if (rawStopWatchStart == null) {
			return false;
		}
		return true;
	}
	public static void stopWatchStart() {
		MDC.put(LoggingField.STOP_WATCH_START.toString(), String.valueOf(System.nanoTime()));
	}

	public static double stopWatchStop() {
		final long stopWatchEnd = System.nanoTime();
		final String rawStopWatchStart = MDC.get(LoggingField.STOP_WATCH_START.toString());

		if (rawStopWatchStart == null) throw new StopWatchNotStartedException();

		final Long stopWatchStart = Long.valueOf(rawStopWatchStart);

		MDC.remove(LoggingField.STOP_WATCH_START.toString());

		final double elapsedTimeMillis = (stopWatchEnd - stopWatchStart) / 1000.0 / 1000.0;

		LoggingContext.elapsedTime((long) elapsedTimeMillis, TimeUnit.MILLISECONDS);

		return elapsedTimeMillis;
	}

	public static void put(String key, String value) {
		MDC.put(key, value);
	}

	public static void clear() {
		MDC.clear();
	}

	public static void remove(String key) {
		MDC.remove(key);
	}

	public static void save() {
		final JSONObject context = new JSONObject();

		for (LoggingField field : LoggingField.values()) {
			if (field == LoggingField.ELAPSED_TIME) continue;

			try {
				context.put(field.toString(), MDC.get(field.toString()));
			} catch (JSONException e) {
				//Ignore - only occurs when the key is null (which can't happen)
				//			or the value is invalid (everything is converted to a string
				//			before it get put() to the MDC)
			}
		}

		final String rawJsonArray = MDC.get(PREVIOUS_CONTEXTS_KEY);

		if (rawJsonArray == null) {
			final JSONArray stack = new JSONArray()
											.put(context);

			MDC.put(PREVIOUS_CONTEXTS_KEY, stack.toString());
		} else {
			try {
				final JSONArray stack = new JSONArray(rawJsonArray)
												.put(context);

				MDC.put(PREVIOUS_CONTEXTS_KEY, stack.toString());
			} catch (JSONException e) {
				//Ignore
			}
		}
	}

	public static void restore() {
		
		final String rawPreviousContexts = MDC.get(PREVIOUS_CONTEXTS_KEY);
	
		if (rawPreviousContexts == null) {
			throw new LoggingContextNotExistsException();
		}

		try {
			final JSONArray previousContexts = new JSONArray(rawPreviousContexts);
			final JSONObject previousContext = previousContexts.getJSONObject(previousContexts.length() - 1);

			@SuppressWarnings("unchecked")
			final Iterator<String> keys = previousContext.keys();
			boolean foundElapsedTime = false;
			while (keys.hasNext()) {
				final String key = keys.next();
				if (LoggingField.ELAPSED_TIME.toString().equals(key)) {
					foundElapsedTime = true;
				}
				try {
					MDC.put(key, previousContext.getString(key));
				} catch (JSONException e) {
					//Ignore, only occurs when the key is null (cannot happen)
					//			or the value is invalid (they are all strings)
				}
			}
			if ( !foundElapsedTime ) {
				MDC.remove(LoggingField.ELAPSED_TIME.toString());
			}
			MDC.put(PREVIOUS_CONTEXTS_KEY, removeLast(previousContexts).toString());
		} catch (JSONException e) {
			//Ignore, the previousContext is serialized from a JSONObject
		}
	}
	public static void restoreIfPossible() {
		try {
			restore();
		}
		catch (LoggingContextNotExistsException e) {
			//Ignore
		}
	}

	/**
	 * AJSC declares an ancient version of org.json:json in one of the parent POMs of this project.
	 * I tried to update our version of that library in our POM, but it's ignored because of the way
	 * AJSC has organized their <dependencies>.  Had they put it into the <dependencyManagement> section,
	 * this method would not be necessary.
	 */
	private static JSONArray removeLast(JSONArray previousContexts) {
		final JSONArray result = new JSONArray();

		for (int i = 0; i < previousContexts.length() - 1; i++) {
			try {
				result.put(previousContexts.getJSONObject(i));
			} catch (JSONException e) {
				//Ignore - not possible
			}
		}

		return result;
	}

	public static Map<String, String> getCopy() {
		final Map<String, String> copy = new HashMap<String, String> ();

		for (LoggingField field : LoggingField.values()) {
			final String value = MDC.get(field.toString());

			if (value != null) copy.put(field.toString(), value);
		}

		return copy;
	}
}