Refactor to more consistent structure (e.g. "plugins")

plugins/nag/checkin.ts

@@ -0,0 +1,44 @@
+import {
+	type ChatInputCommandInteraction,
+	SlashCommandBuilder,
+} from 'discord.js';
+
+import type {Settings} from '../../plugin';
+import {CheckIn, Nag} from './models';
+
+export default function (_settings: Settings) {
+	return {
+		data: new SlashCommandBuilder()
+			.setName('checkin')
+			.setDescription('Check-in for your daily nag')
+			.addStringOption(option =>
+				option
+					.setName('text')
+					.setDescription('Optional description of what you have achieved'),
+			),
+
+		execute: async (interaction: ChatInputCommandInteraction) => {
+			// TODO For now there is only one nag, but in the future this could be different.
+			// So let's construct it as a loop for now.
+			const result = await Nag.findAll({
+				where: {
+					userId: interaction.user.id,
+				},
+			});
+			if (!result) {
+				await interaction.reply(
+					"Couldn't find any nags for you, what are you checking in for?",
+				);
+				return;
+			}
+			for (const nag of result) {
+				await CheckIn.create({
+					nagId: nag.id,
+					lastCheckIn: new Date(Date.now()),
+				});
+				await interaction.reply('Thanks for checking in!');
+				break;
+			}
+		},
+	};
+}