/*
 * Copyright (C) 2008-2017, Juick
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.juick.server;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.juick.Message;
import com.juick.User;
import com.juick.model.AnonymousUser;
import com.juick.service.MessagesService;
import com.juick.service.SubscriptionService;
import com.juick.service.UserService;
import com.juick.service.component.LikeEvent;
import com.juick.service.component.MessageEvent;
import com.juick.service.component.MessageReadEvent;
import com.juick.service.component.NotificationListener;
import com.juick.service.component.PingEvent;
import com.juick.service.component.SubscribeEvent;
import com.juick.service.component.TopEvent;
import com.juick.util.MessageUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
import org.springframework.web.socket.TextMessage;

import javax.annotation.PostConstruct;
import javax.inject.Inject;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.stream.Collectors;

/**
 * @author Ugnich Anton
 */
@Component
public class ServerManager implements NotificationListener {
    private static Logger logger = LoggerFactory.getLogger(ServerManager.class);

    @Inject
    private ObjectMapper jsonMapper;
    @Inject
    private MessagesService messagesService;
    @Inject
    private WebsocketManager wsHandler;
    @Inject
    private SubscriptionService subscriptionService;
    @Inject
    private UserService userService;
    private CopyOnWriteArrayList<EventSession> sessions = new CopyOnWriteArrayList<>();

    @Value("${service_user:juick}")
    private String serviceUsername;

    private User serviceUser;

    @PostConstruct
    public void init() {
        serviceUser = userService.getUserByName(serviceUsername);
    }


    private void onJuickPM(final User to, final com.juick.Message jmsg) {
        try {
            String json = jsonMapper.writeValueAsString(jmsg);
            synchronized (wsHandler.getClients()) {
                wsHandler.getClients().stream().filter(c ->
                        (!c.legacy && c.visitor.getUid() == to.getUid()) || c.visitor.equals(serviceUser))
                        .forEach(c -> {
                            try {
                                logger.debug("sending pm to {}", c.visitor.getUid());
                                c.sendMessage(new TextMessage(json));
                            } catch (IOException e) {
                                logger.warn("ws error", e);
                            }
                        });
            }
        } catch (JsonProcessingException e) {
            logger.warn("Invalid JSON", e);
        }
        messageEvent(jmsg, Arrays.asList(to, serviceUser));
    }

    private void onJuickMessagePost(final com.juick.Message jmsg, List<User> subscribedUsers) {
        try {
            String json = jsonMapper.writeValueAsString(jmsg);
            List<Integer> uids = subscribedUsers
                    .stream().map(User::getUid).collect(Collectors.toList());
            synchronized (wsHandler.getClients()) {
                wsHandler.getClients().stream().filter(c ->
                        (!c.legacy && c.visitor.isAnonymous()) // anonymous users
                                || c.visitor.equals(serviceUser) // services
                                || (!c.legacy && uids.contains(c.visitor.getUid()))) // subscriptions
                        .forEach(c -> {
                            try {
                                logger.debug("sending message to {}", c.visitor.getUid());
                                c.sendMessage(new TextMessage(json));
                            } catch (IOException e) {
                                logger.warn("ws error", e);
                            }
                        });
                wsHandler.getClients().stream().filter(c ->
                        c.legacy && c.allMessages) // legacy all posts
                        .forEach(c -> {
                            try {
                                logger.debug("sending message to legacy client {}", c.visitor.getUid());
                                c.sendMessage(new TextMessage(json));
                            } catch (IOException e) {
                                logger.warn("ws error", e);
                            }
                        });
            }
        } catch (JsonProcessingException e) {
            logger.warn("Invalid JSON", e);
        }
        messageEvent(jmsg, subscribedUsers);
        messageEvent(jmsg, Collections.singletonList(AnonymousUser.INSTANCE));
    }

    private void onJuickMessageReply(final com.juick.Message jmsg, final List<User> subscribedUsers) {
        try {

            String json = jsonMapper.writeValueAsString(jmsg);
            com.juick.Message op = messagesService.getMessage(jmsg.getMid());
            List<Integer> threadUsers =
                    subscribedUsers
                            .stream().map(User::getUid).collect(Collectors.toList());
            synchronized (wsHandler.getClients()) {
                wsHandler.getClients().stream().filter(c ->
                        (!c.legacy && c.visitor.isAnonymous()) // anonymous users
                                || c.visitor.equals(serviceUser) // services
                                || (!c.legacy && threadUsers.contains(c.visitor.getUid()))) // subscriptions
                        .forEach(c -> {
                            try {
                                logger.debug("sending reply to {}", c.visitor.getUid());
                                c.sendMessage(new TextMessage(json));
                            } catch (IOException e) {
                                logger.warn("ws error", e);
                            }
                        });
                wsHandler.getClients().stream().filter(c ->
                        (c.legacy && c.allReplies) || (c.legacy && c.MID == jmsg.getMid())) // legacy replies
                        .forEach(c -> {
                            try {
                                logger.debug("sending reply to legacy client {}", c.visitor.getUid());
                                c.sendMessage(new TextMessage(json));
                            } catch (IOException e) {
                                logger.warn("ws error", e);
                            }
                        });
            }
        } catch (JsonProcessingException e) {
            logger.warn("Invalid JSON", e);
        }
        messageEvent(jmsg, subscribedUsers);
        messageEvent(jmsg, Collections.singletonList(AnonymousUser.INSTANCE));
    }

    @Override
    public void processMessageEvent(MessageEvent event) {
        com.juick.Message jmsg = event.getMessage();
        List<User> subscribedUsers = event.getUsers();
        if (jmsg.isService()) {
            readEvent(jmsg, Collections.singletonList(serviceUser));
            return;
        }
        if (MessageUtils.isPM(jmsg)) {
            onJuickPM(jmsg.getTo(), jmsg);
        } else if (!MessageUtils.isReply(jmsg)) {
            // to get full message with attachment, etc.
            onJuickMessagePost(messagesService.getMessage(jmsg.getMid()), subscribedUsers);
        } else {
            // to get quote and attachment
            Message op = messagesService.getMessage(jmsg.getMid());
            com.juick.Message reply = messagesService.getReply(jmsg.getMid(), jmsg.getRid());
            subscriptionService.getUsersSubscribedToComments(op, reply, true).stream()
                    .filter(u -> userService.isReplyToBL(u, reply))
                    .forEach(b -> messagesService.setLastReadComment(b, reply.getMid(), reply.getRid()));
            onJuickMessageReply(reply, subscribedUsers);
        }
        messageEvent(jmsg, Collections.singletonList(serviceUser));
    }

    @Override
    public void processSubscribeEvent(SubscribeEvent subscribeEvent) {

    }

    @Override
    public void processLikeEvent(LikeEvent likeEvent) {

    }

    @Override
    public void processPingEvent(PingEvent pingEvent) {

    }

    @Override
    public void processMessageReadEvent(MessageReadEvent messageReadEvent) {
        User user = messageReadEvent.getUser();
        Message source = messageReadEvent.getMessage();

        logger.info("Message read event from {} for {}", user.getName(), source.getMid());
        Message serviceMessage = new Message();
        serviceMessage.setService(true);
        serviceMessage.setUser(user);
        serviceMessage.setMid(source.getMid());
        serviceMessage.setUnread(false);
        wsHandler.getClients().stream().filter(c ->
                (!c.legacy && c.visitor == user) || c.visitor.equals(serviceUser)
        ).forEach(u -> {
            try {
                u.sendMessage(new TextMessage(jsonMapper.writeValueAsString(serviceMessage)));
            } catch (IOException e) {
                logger.error("JSON error", e);
            }
        });
        readEvent(serviceMessage, Collections.singletonList(serviceUser));
    }

    @Override
    public void processTopEvent(TopEvent topEvent) {
        User topUser = topEvent.getMessage().getUser();
        topEvent(topEvent.getMessage(), Arrays.asList(topUser, serviceUser));
    }

    public void topEvent(Message msg, List<User> subscribers){
        sendSseEvent(msg, "top", subscribers);
    }

    public void readEvent(Message msg, List<User> subscribers){
        sendSseEvent(msg, "read", subscribers);
    }

    public void messageEvent(Message msg, List<User> subscribers){
        sendSseEvent(msg, "msg", subscribers);
    }

    private void sendSseEvent(Message msg, String name, List<User> subscribers) {
        List<EventSession> deadEmitters = new ArrayList<>();
        this.sessions.stream().filter(s -> subscribers.contains(s.user)).forEach(session -> {
            try {
                SseEmitter.SseEventBuilder builder = SseEmitter.event()
                        .name(name)
                        .data(msg);
                session.getEmitter().send(builder);
            } catch (Exception e) {
                deadEmitters.add(session);
            }
        });
        this.sessions.removeAll(deadEmitters);
    }

    public static class EventSession {
        private User user;
        private SseEmitter emitter;

        public EventSession(User user, SseEmitter sseEmitter) {
            this.user = user;
            this.emitter = sseEmitter;
        }

        public User getUser() {
            return user;
        }

        public SseEmitter getEmitter() {
            return emitter;
        }
    }

    public CopyOnWriteArrayList<EventSession> getSessions() {
        return sessions;
    }
}