/**
 * util.ts
 * Common helper functions
 */

import { Collection, GuildManager, GuildTextBasedChannel, Message, MessageReaction, User } from 'discord.js';
import { createWriteStream, existsSync, unlinkSync } from 'fs';
import { get as httpGet } from 'https';
import { Database, open } from 'sqlite';
import { Database as Database3 } from 'sqlite3';
import 'dotenv/config';
import fetch from 'node-fetch';
import { logError, logInfo, logWarn } from '../logging';
import { ScoreboardMessageRow } from '../models';


const reactionEmojis: string[] = process.env.REACTIONS.split(',');
let db: Database = null;


async function openDb() {
    db = await open({
        filename: 'db.sqlite',
        driver: Database3
    })
}

function clearDb() {
    unlinkSync('db.sqlite');
}

function messageLink(message: ScoreboardMessageRow)
{
    return `https://discord.com/channels/${message.guild}/${message.channel}/${message.id}`;
}

function userAvatarPath(user: User)
{
    return `../public/avatars/${user.id}.webp`;
}

async function downloadUserAvatar(user: User)
{
    logInfo(`[bot] Downloading ${user.id}'s avatar...`);
    const file = createWriteStream(userAvatarPath(user));
    return new Promise<void>(resolve => {
        httpGet(user.displayAvatarURL(), res => {
            res.pipe(file);
            file.on('finish', () => {
                file.close();
                logInfo(`[bot] Finished downloading ${user.id}'s avatar.`);
                resolve();
            });
        });
    });
}

async function refreshUserReactionTotalCount(user: User, emoji_idx: number)
{
    const result = await db.get<{sum: number}>(
        `SELECT sum(reaction_${emoji_idx}_count) AS sum FROM messages WHERE author = ?`,
        user.id
    );
    const emojiTotal = result.sum;
    await db.run(
        `INSERT INTO users(id, username, reaction_${emoji_idx}_total) VALUES(?, ?, ?) ON CONFLICT(id) DO
        UPDATE SET reaction_${emoji_idx}_total = ?, username = ? WHERE id = ?`,
        user.id,
        user.displayName,
        emojiTotal,
        emojiTotal,
        user.displayName,
        user.id
    );
    if (!existsSync(userAvatarPath(user))) {
        await downloadUserAvatar(user);
    }
    logInfo(`[bot] Refreshed ${user.id}'s ${reactionEmojis[emoji_idx - 1]} count.`);
}

async function recordReaction(reaction: MessageReaction)
{
    const emojiIdx = reactionEmojis.indexOf(reaction.emoji.name) + 1;
    if (emojiIdx === 0) {
        return;
    }
    try {
        await db.run(
            `INSERT INTO messages(id, guild, channel, author, content, reaction_${emojiIdx}_count) VALUES(?, ?, ?, ?, ?, ?)
            ON CONFLICT(id) DO UPDATE SET reaction_${emojiIdx}_count = ? WHERE id = ?`,
            reaction.message.id,
            reaction.message.guildId,
            reaction.message.channelId,
            reaction.message.author.id,
            reaction.message.content,
            reaction.count,
            reaction.count,
            reaction.message.id
        );
        await refreshUserReactionTotalCount(reaction.message.author, emojiIdx);
        logInfo(`[bot] Recorded ${reaction.emoji.name}x${reaction.count} in database.`);
    } catch (error) {
        logError('[bot] Something went wrong when updating the database:', error);
        return;
    }
}

async function sync(guilds: GuildManager) {
    const guild = await guilds.fetch(process.env.GUILD);
    if (!guild) {
        logError(`[bot] FATAL: guild ${guild.id} not found!`);
        return 1;
    }
    logInfo(`[bot] Entered guild ${guild.id}`);
    const channels = await guild.channels.fetch();
    const textChannels = <Collection<string, GuildTextBasedChannel>> channels.filter(c => c && 'messages' in c && c.isTextBased);
    for (const [id, textChannel] of textChannels) {
        logInfo(`[bot] Found text channel ${id}`);
        const oldestMsg = await db.get<ScoreboardMessageRow>(
            'SELECT * FROM messages WHERE guild = ? AND channel = ? ORDER BY id ASC LIMIT 1',
            guild.id,
            id
        );
        const newestMsg = await db.get<ScoreboardMessageRow>(
            'SELECT * FROM messages WHERE guild = ? AND channel = ? ORDER BY id DESC LIMIT 1',
            guild.id,
            id
        );
        let before: string = oldestMsg && String(oldestMsg.id);
        let after: string = newestMsg && String(newestMsg.id);
        let messagesCount = 0;
        let reactionsCount = 0;
        let newMessagesBefore: Collection<string, Message<true>>;
        let newMessagesAfter: Collection<string, Message<true>>;
        try {
            do {
                newMessagesBefore = await textChannel.messages.fetch({ before, limit: 100 });
                messagesCount += newMessagesBefore.size;

                newMessagesAfter = await textChannel.messages.fetch({ after, limit: 100 });
                messagesCount += newMessagesAfter.size;
                logInfo(`[bot] [${id}] Fetched ${messagesCount} messages (+${newMessagesBefore.size} older, ${newMessagesAfter.size} newer)`);

                const reactions = newMessagesBefore
                    .flatMap<MessageReaction>(m => m.reactions.cache)
                    .concat(newMessagesAfter.flatMap<MessageReaction>(m => m.reactions.cache));
                for (const [_, reaction] of reactions) {
                    await recordReaction(reaction);
                }
                reactionsCount += reactions.size;
                logInfo(`[bot] [${id}] Recorded ${reactionsCount} reactions (+${reactions.size}).`);

                if (newMessagesBefore.size > 0) {
                    before = newMessagesBefore.last().id;
                }
                if (newMessagesAfter.size > 0) {
                    after = newMessagesAfter.first().id;
                }
            } while (newMessagesBefore.size === 100 || newMessagesAfter.size === 100);
            logInfo(`[bot] [${id}] Done.`);
        } catch (err) {
            logWarn(`[bot] [${id}] Failed to fetch messages and reactions: ${err}`);
        }
    }
}

async function requestTTSResponse(txt: string): Promise<Blob>
{
    const queryParams = new URLSearchParams();
    queryParams.append("token", process.env.LLM_TOKEN);
    queryParams.append("text", txt);

    const ttsEndpoint = `${process.env.LLM_HOST}/tts?${queryParams.toString()}`;
    logInfo(`[bot] Requesting TTS response for "${txt}"`);
    const res = await fetch(ttsEndpoint, {
        method: 'POST'
    });
    const resContents = await res.blob();
    return resContents;
}

export { db, clearDb, openDb, reactionEmojis, recordReaction, requestTTSResponse, sync };