/*
 * Copyright 2014-2018 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 de.codecentric.boot.admin.server.notify;

import java.util.HashMap;
import java.util.Map;

import javax.annotation.Nullable;

import org.springframework.context.expression.MapAccessor;
import org.springframework.expression.Expression;
import org.springframework.expression.ParserContext;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.web.client.RestTemplate;
import reactor.core.publisher.Mono;

import de.codecentric.boot.admin.server.domain.entities.Instance;
import de.codecentric.boot.admin.server.domain.entities.InstanceRepository;
import de.codecentric.boot.admin.server.domain.events.InstanceEvent;

/**
 * Notifier submitting events to Telegram.
 */
public class TelegramNotifier extends AbstractStatusChangeNotifier {

	private static final String DEFAULT_MESSAGE = "<strong>#{instance.registration.name}</strong>/#{instance.id} is <strong>#{event.statusInfo.status}</strong>";

	private final SpelExpressionParser parser = new SpelExpressionParser();

	private RestTemplate restTemplate;

	/**
	 * base url for telegram (i.e. https://api.telegram.org)
	 */
	private String apiUrl = "https://api.telegram.org";

	/**
	 * Unique identifier for the target chat or username of the target channel
	 */
	@Nullable
	private String chatId;

	/**
	 * The token identifiying und authorizing your Telegram bot (e.g.
	 * `123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11`)
	 */
	@Nullable
	private String authToken;

	/**
	 * Send Markdown or HTML, if you want Telegram apps to show bold, italic, fixed-width
	 * text or inline URLs in your bot's message.
	 */
	private String parseMode = "HTML";

	/**
	 * If true users will receive a notification with no sound.
	 */
	private boolean disableNotify = false;

	private Expression message;

	public TelegramNotifier(InstanceRepository repository, RestTemplate restTemplate) {
		super(repository);
		this.restTemplate = restTemplate;
		this.message = parser.parseExpression(DEFAULT_MESSAGE, ParserContext.TEMPLATE_EXPRESSION);
	}

	@Override
	protected Mono<Void> doNotify(InstanceEvent event, Instance instance) {
		return Mono
				.fromRunnable(() -> restTemplate.getForObject(buildUrl(), Void.class, createMessage(event, instance)));
	}

	protected String buildUrl() {
		return String.format("%s/bot%s/sendmessage?chat_id={chat_id}&text={text}&parse_mode={parse_mode}"
				+ "&disable_notification={disable_notification}", this.apiUrl, this.authToken);
	}

	private Map<String, Object> createMessage(InstanceEvent event, Instance instance) {
		Map<String, Object> parameters = new HashMap<>();
		parameters.put("chat_id", this.chatId);
		parameters.put("parse_mode", this.parseMode);
		parameters.put("disable_notification", this.disableNotify);
		parameters.put("text", getText(event, instance));
		return parameters;
	}

	@Nullable
	protected String getText(InstanceEvent event, Instance instance) {
		Map<String, Object> root = new HashMap<>();
		root.put("event", event);
		root.put("instance", instance);
		root.put("lastStatus", getLastStatus(event.getInstance()));
		StandardEvaluationContext context = new StandardEvaluationContext(root);
		context.addPropertyAccessor(new MapAccessor());
		return message.getValue(context, String.class);
	}

	public void setRestTemplate(RestTemplate restTemplate) {
		this.restTemplate = restTemplate;
	}

	public String getApiUrl() {
		return apiUrl;
	}

	public void setApiUrl(String apiUrl) {
		this.apiUrl = apiUrl;
	}

	@Nullable
	public String getChatId() {
		return chatId;
	}

	public void setChatId(@Nullable String chatId) {
		this.chatId = chatId;
	}

	@Nullable
	public String getAuthToken() {
		return authToken;
	}

	public void setAuthToken(@Nullable String authToken) {
		this.authToken = authToken;
	}

	public boolean isDisableNotify() {
		return disableNotify;
	}

	public void setDisableNotify(boolean disableNotify) {
		this.disableNotify = disableNotify;
	}

	public String getParseMode() {
		return parseMode;
	}

	public void setParseMode(String parseMode) {
		this.parseMode = parseMode;
	}

	public void setMessage(String message) {
		this.message = parser.parseExpression(message, ParserContext.TEMPLATE_EXPRESSION);
	}

}
