const REMINDER_EMOTE = '🔔';
const REMINDER_LEAD_SECONDS = 1 * 60 * 60;

module.exports = {
    timeout: 60000,
    immediate: true,
    name: 'VRC.TL Event Reminders',
    async tick(client, timer) {
        try {
            const db = await client.localDB;
            const nowUnix = Math.floor(Date.now() / 1000);

            const dueReminders = db.prepare(`
                SELECT id, message_id, channel_id, event_name, event_start
                FROM vrctl_event_reminders
                WHERE reminder_sent = 0 AND event_start - ? <= ?
            `).all(REMINDER_LEAD_SECONDS, nowUnix);

            for (const reminder of dueReminders) {
                const markSent = db.prepare(`UPDATE vrctl_event_reminders SET reminder_sent = 1 WHERE id = ?`);

                if (reminder.event_start <= nowUnix) {
                    // Event already started (e.g. bot was down) - don't send a stale reminder.
                    markSent.run(reminder.id);
                    continue;
                }

                try {
                    const channel = await client.channels.fetch(reminder.channel_id);
                    const message = await channel.messages.fetch(reminder.message_id);
                    const reaction = message.reactions.cache.get(REMINDER_EMOTE);

                    const users = reaction ? await reaction.users.fetch() : new Map();
                    const mentions = [...users.values()]
                        .filter(user => !user.bot)
                        .map(user => `<@${user.id}>`);

                    if (mentions.length > 0) {
                        await channel.send({
                            content: `⏰ **${reminder.event_name}** starts <t:${reminder.event_start}:R>! ${mentions.join(' ')}`,
                            reply: { messageReference: reminder.message_id },
                            allowedMentions: { parse: [], users: mentions.map(m => m.slice(2, -1)) }
                        });
                    }

                    markSent.run(reminder.id);
                } catch (error) {
                    console.error(`[TIMER] Failed to send vrc.tl reminder for message ${reminder.message_id}:`, error);
                }
            }
        } catch (error) {
            console.error('[TIMER] VRC.TL Event Reminders error:', error);
        }
    },
};