/*
 * 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.juick.User;
import com.juick.model.AnonymousUser;
import com.juick.model.CommandResult;
import com.juick.server.util.HttpForbiddenException;
import com.juick.server.util.HttpNotFoundException;
import com.juick.service.MessagesService;
import com.juick.service.UserService;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.math.NumberUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.PingMessage;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.ConcurrentWebSocketSessionDecorator;
import org.springframework.web.socket.handler.TextWebSocketHandler;
import org.springframework.web.util.UriComponents;
import org.springframework.web.util.UriComponentsBuilder;

import javax.annotation.Nonnull;
import javax.inject.Inject;
import java.io.IOException;
import java.net.URI;
import java.time.Instant;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * Created by vitalyster on 28.06.2016.
 */
@Component
public class WebsocketManager extends TextWebSocketHandler {
    private static final Logger logger = LoggerFactory.getLogger(WebsocketManager.class);

    private final List<UserSession> clients = new CopyOnWriteArrayList<>();

    @Inject
    private UserService userService;
    @Inject
    private MessagesService messagesService;
    @Inject
    private CommandsManager commandsManager;


    @Override
    public void afterConnectionEstablished(WebSocketSession session) {

        UserSession userSession = new UserSession(session);
        URI hLocation = session.getUri();

        // Auth
        UriComponents uriComponents = UriComponentsBuilder.fromUri(hLocation).build();
        List<String> hash = uriComponents.getQueryParams().get("hash");
        if (hash != null && hash.get(0).length() == 16) {
            userSession.visitor = userService.getUserByHash(hash.get(0));
        } else {
            logger.debug("wrong hash for {} from {}", userSession.visitor.getUid(), userSession);
        }

        if (hLocation.getPath().equals("/ws/")) {
            logger.debug("user {} connected", userSession.visitor.getUid());
        } else if (hLocation.getPath().equals("/ws/_all")) {
            logger.debug("user {} connected to legacy _all ({})", userSession.visitor.getUid(), hLocation.getPath());
            userSession.legacy = true;
            userSession.allMessages = true;
        } else if (hLocation.getPath().equals("/ws/_replies")) {
            logger.debug("user {} connected to legacy _replies ({})", userSession.visitor.getUid(), hLocation.getPath());
            userSession.legacy = true;
            userSession.allReplies = true;
        } else if (hLocation.getPath().matches("^/ws/(\\d)+$")) {
            int MID = NumberUtils.toInt(hLocation.getPath().substring(4), 0);
            if (MID > 0) {
                if (messagesService.canViewThread(MID, userSession.visitor.getUid())) {
                    logger.debug("user {} connected to legacy thread ({}) from {}", userSession.visitor.getUid(), MID, userSession);
                    userSession.legacy = true;
                    userSession.MID = MID;
                } else {
                    throw new HttpForbiddenException();
                }
            }
        } else {
            throw new HttpNotFoundException();
        }
        clients.add(userSession);
        logger.debug("{} clients connected", clients.size());
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) {
        logger.debug("session closed with status {}: {}", status.getCode(), status.getReason());
        clients.removeIf(c -> c.getDelegate().getId().equals(session.getId()));
        logger.debug("{} clients connected", clients.size());
    }

    @Scheduled(fixedRate = 30000)
    public void ping() {
        clients.forEach(c -> {
            try {
                if (c.isOpen()) {
                    c.sendMessage(new PingMessage());
                }
            } catch (IOException e) {
                logger.error("WebSocket PING exception", e);
            }
        });
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        UserSession ws = clients.stream().filter(c -> c.getDelegate().equals(session))
                .findFirst().orElseThrow(IllegalStateException::new);
        if (!ws.visitor.isAnonymous()) {
            String command = message.getPayload().trim();
            if (StringUtils.isNotEmpty(command)) {
                CommandResult result = commandsManager.processCommand(ws.visitor, command, URI.create(""));
                ws.sendMessage(new TextMessage(result.getText()));
            }
        } else {
            ws.sendMessage(new TextMessage("Authorization required"));
        }
    }

    public List<UserSession> getClients() {
        return clients;
    }

    class UserSession extends ConcurrentWebSocketSessionDecorator {
        User visitor;
        int MID;
        boolean allMessages;
        boolean allReplies;
        Instant tsConnected;
        Instant tsLastData;
        boolean legacy;

        UserSession(WebSocketSession session) {
            super(session, 60000, 65536);
            this.visitor = AnonymousUser.INSTANCE;
            tsConnected = tsLastData = Instant.now();
        }

        @Nonnull
        @Override
        public String toString() {
            HttpHeaders headers = getHandshakeHeaders();
            return headers.getOrDefault("X-Real-IP",
                    Collections.singletonList(getRemoteAddress().toString())).get(0);
        }
    }
}