Use an sqlite3 database for timer feature

There were some other small edits as well, mostly formatting or better
logging in certain functions

util/timer/checkTimer.js

@@ -1,15 +1,37 @@
 const sendTimerReminder = require('./sendTimerReminder')
 const fs = require('fs')
-module.exports = function (client) {
+const sqlite3 = require('sqlite3').verbose();
+module.exports = async function (client) {
 	const checkTimer = require('./checkTimer')
+	const db = new sqlite3.Database('data/database.db')
+	let currentUnixTime = Math.floor(new Date() / 1000);
+	await new Promise((resolve, reject) => {
+		db.get(
+			`SELECT * FROM timers WHERE reminderTime <= ? AND hasPassed = ?`,
+			[currentUnixTime, false],
+			function (error, timer) {
+				if (error) {
+					console.error(error);
+					reject(error);
+				} else {
+					if (timer !== undefined) {
+						db.run(`UPDATE timers SET hasPassed = ? WHERE ID = ?`, [true, timer.ID],
+							function (error) {
+								if (error) {
+									console.error(`Error while updating ${timer.ID} setPassed to true`, error);
+									reject(error);
+								} else {
+									console.log(`Updated ${timer.ID}, set hasPassed to true.`);
+								}
+							})
+						sendTimerReminder(client, timer);
+					}
 
-	for(let i = 0; i < client.timers.length; i++){
-		if(parseInt(client.timers[i].reminderDate) <= Math.floor(new Date() / 1000)){
-			sendTimerReminder(client, client.timers[i]);
-			client.timers.splice(i, 1);
-			i--
-			fs.writeFileSync('data/timers.json', JSON.stringify(client.timers, null, 4))
-		}
-	}
+					db.close();
+					resolve();
+				}
+			}
+		);
+	})
 	setTimeout(checkTimer, 1000, client);
 }