/**
 * bot.ts
 * Scans the chat for reactions and updates the leaderboard database.
 */

import {
    Client,
    Events,
    GatewayIntentBits,
    MessageReaction,
    PartialMessageReaction,
    Partials,
    TextChannel,
    User
} from 'discord.js';
import {
    db,
    logInfo,
    logError,
    openDb,
    reactionEmojis,
    recordReaction,
    sync
} from './util';


const client = new Client({
    intents: [GatewayIntentBits.Guilds, GatewayIntentBits.GuildMessages, GatewayIntentBits.GuildMessageReactions],
    partials: [Partials.Message, Partials.Channel, Partials.Reaction],
});

client.once(Events.ClientReady, async () => {
    logInfo('[bot] Ready.');
    for (let i = 0; i < reactionEmojis.length; ++i)
        logInfo(`[bot] config: reaction_${i + 1} = ${reactionEmojis[i]}`);
});


async function onMessageReactionChanged(reaction: MessageReaction | PartialMessageReaction, user: User)
{
    // When a reaction is received, check if the structure is partial
    if (reaction.partial) {
        // If the message this reaction belongs to was removed, the fetching might result in an API error which should be handled
        try {
            await reaction.fetch();
        } catch (error) {
            logError('[bot] Something went wrong when fetching the reaction:', error);
            // Return as `reaction.message.author` may be undefined/null
            return;
        }
    }
    if (reaction.message.partial) {
        // If the message this reaction belongs to was removed, the fetching might result in an API error which should be handled
        try {
            await reaction.message.fetch();
        } catch (error) {
            logError('[bot] Something went wrong when fetching the message:', error);
            // Return as `reaction.message.author` may be undefined/null
            return;
        }
    }

    // Now the message has been cached and is fully available
    logInfo(`[bot] ${reaction.message.author.id}'s message reaction count changed: ${reaction.emoji.name}x${reaction.count}`);
    await recordReaction(<MessageReaction> reaction);
}

async function fetchMotd()
{
    const res = await fetch(process.env.MOTD_HREF);
    const xml = await res.text();
    const parser = new DOMParser();
    const doc = parser.parseFromString(xml, 'text/html');
    return doc.querySelector(process.env.MOTD_QUERY).textContent;
}

async function scheduleRandomMessage(firstTime = false)
{
    if (!firstTime) {
        const channel = <TextChannel> await client.channels.fetch(process.env.MOTD_CHANNEL);
        const randomMessage = await fetchMotd();
        await channel.send(randomMessage);
        logInfo(`[bot] Sent MOTD: ${randomMessage}`);
    }
    // wait between 2-8 hours
    const timeoutMins = Math.random() * 360 + 120;
    const scheduledTime = new Date();
    scheduledTime.setMinutes(scheduledTime.getMinutes() + timeoutMins);
    logInfo(`[bot] Next MOTD: ${scheduledTime}`);
    setTimeout(scheduleRandomMessage, timeoutMins * 60 * 1000);
}

client.on(Events.MessageReactionAdd, onMessageReactionChanged);
client.on(Events.MessageReactionRemove, onMessageReactionChanged);

async function startup() {
    logInfo("[db] Opening...");
    await openDb();
    logInfo("[db] Migrating...");
    await db.migrate();
    logInfo("[db] Ready.");
    logInfo("[bot] Logging in...");
    await client.login(process.env.TOKEN);
    await sync(client.guilds);
    if (process.env.ENABLE_MOTD) {
        await scheduleRandomMessage(true);
    }
}

startup();