package cc.fascinated.bat.service;

import cc.fascinated.bat.common.TimerUtils;
import cc.fascinated.bat.event.EventListener;
import cc.fascinated.bat.model.BatGuild;
import cc.fascinated.bat.model.BatUser;
import com.mongodb.client.model.Filters;
import lombok.Getter;
import lombok.NonNull;
import lombok.extern.log4j.Log4j2;
import net.dv8tion.jda.api.entities.User;
import net.dv8tion.jda.api.events.guild.member.GuildMemberJoinEvent;
import net.dv8tion.jda.api.events.user.update.UserUpdateGlobalNameEvent;
import net.jodah.expiringmap.ExpirationPolicy;
import net.jodah.expiringmap.ExpiringMap;
import org.bson.Document;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.DependsOn;
import org.springframework.stereotype.Service;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

/**
 * @author Fascinated (fascinated7)
 */
@Service
@Log4j2(topic = "User Service")
@Getter
@DependsOn({"discordService", "mongoService"})
public class UserService implements EventListener {
    private static final long SAVE_INTERVAL = TimeUnit.MINUTES.toMillis(5);

    /**
     * The cached users
     */
    private final Map<String, BatUser> users = ExpiringMap.builder()
            .expiration(1, TimeUnit.HOURS)
            .expirationPolicy(ExpirationPolicy.ACCESSED) // Expire after not being accessed for 1 hour
            .expirationListener((key, cachedUser) -> {
                BatUser user = (BatUser) cachedUser;
                log.info("Removed user \"{}\" - \"{}\" from cache", user.getName(), user.getId());
                user.save();
            })
            .build();

    @Autowired
    public UserService() {
        TimerUtils.scheduleRepeating(() -> {
            long before = System.currentTimeMillis();
            for (BatUser user : users.values()) {
                user.save();
            }
            log.info("Saved {} users in {}ms", users.size(), System.currentTimeMillis() - before);
        }, SAVE_INTERVAL, SAVE_INTERVAL);
    }

    /**
     * Gets a user by its ID
     *
     * @param id The ID of the user
     * @return The user
     */
    public BatUser getUser(@NonNull String id, User user) {
        long before = System.currentTimeMillis();
        // User is cached
        if (users.containsKey(id)) {
            return users.get(id);
        }
        // User is not cached
        Document document = MongoService.INSTANCE.getUsersCollection().find(Filters.eq("_id", id)).first();
        if (document != null) {
            BatUser batUser = new BatUser(id, user, document);
            users.put(id, batUser);
            return batUser;
        }
        // New user
        BatUser batUser = new BatUser(id, user, new Document());
        users.put(id, batUser);
        log.info("Created user \"{}\" - \"{}\" in {}ms", batUser.getName(), batUser.getId(), System.currentTimeMillis() - before);
        return batUser;
    }

    /**
     * Gets a user by its ID
     *
     * @param id The ID of the user
     * @return The user
     */
    public BatUser getUser(@NonNull String id) {
        User user = DiscordService.JDA.retrieveUserById(id).complete();
        if (user == null || user.isBot()) {
            return null;
        }
        return getUser(id, null);
    }

    @Override
    public void onShutdown() {
        log.info("Saving all users before shutdown...");
        for (BatUser user : users.values()) {
            user.save();
        }
        log.info("Saved all users.");
    }

    @Override
    public void onGuildMemberJoin(@NonNull BatGuild guild, @NonNull BatUser user, @NonNull GuildMemberJoinEvent event) {
        user.setGlobalName(event.getUser().getGlobalName()); // Ensure the user's name is up-to-date
    }

    @Override
    public void onUserUpdateGlobalName(@NonNull BatUser user, String oldName, String newName, @NonNull UserUpdateGlobalNameEvent event) {
        user.setGlobalName(newName);
    }
}