Allow deleting reminders

structures/remind/TimerManager.js

@@ -0,0 +1,41 @@
+module.exports = class TimerManager {
+	constructor(client) {
+		Object.defineProperty(this, 'client', { value: client });
+
+		this.timeouts = new Map();
+	}
+
+	async fetchAll() {
+		const timers = await this.client.redis.hgetall('timer');
+		for (let data of Object.values(timers)) {
+			data = JSON.parse(data);
+			await this.setTimer(data.channelID, new Date(data.time) - new Date(), data.userID, data.title, false);
+		}
+		return this;
+	}
+
+	async setTimer(channelID, time, userID, title, updateRedis = true) {
+		const data = { time: new Date(Date.now() + time).toISOString(), channelID, userID, title };
+		const timeout = setTimeout(async () => {
+			try {
+				const channel = await this.client.channels.fetch(channelID);
+				await channel.send(`🕰️ <@${userID}>, you wanted me to remind you of: **"${title}"**.`);
+			} finally {
+				await this.client.redis.hdel('timer', `${channelID}-${userID}`);
+			}
+		}, time);
+		if (updateRedis) await this.client.redis.hset('timer', { [`${channelID}-${userID}`]: JSON.stringify(data) });
+		this.timeouts.set(`${channelID}-${userID}`, timeout);
+		return timeout;
+	}
+
+	deleteTimer(channelID, userID) {
+		clearTimeout(this.timeouts.get(`${channelID}-${userID}`));
+		this.timeouts.delete(`${channelID}-${userID}`);
+		return this.client.redis.hdel('timer', `${channelID}-${userID}`);
+	}
+
+	exists(channelID, userID) {
+		return this.client.redis.hexists('timer', `${channelID}-${userID}`);
+	}
+};