// import type { ChatInputCommandInteraction } from "discord.js";
import {
	PermissionsBitField,
	SlashCommandBuilder,
	TextChannel,
	type ChatInputCommandInteraction,
	type Client,
} from "discord.js";
import { type Sequelize, Model, INTEGER, TEXT, DATE, BOOLEAN } from "sequelize";
import * as sequelize from "sequelize";
import * as chrono from "chrono-node";

// const REMINDERS_CHANNEL = "1062196593379520593"; // #bot-test-channel
// const REMINDERS_CHANNEL = ""; // #general

interface Settings {
	client: Client; // Main Discord client object
	db: Sequelize; // Database access object
	responseMode: string;
	publicChannel: string; // Channel to use if a reminder is public
	loopIntervalSec?: number; // Loop interval in seconds
}

const data = new SlashCommandBuilder()
	.setName("remind")
	.setDescription("Remind me to do something")
	.addStringOption((option) =>
		option
			.setName("when")
			.setDescription("Short description of when you want the reminder")
			.setRequired(true),
	)
	.addStringOption((option) =>
		option
			.setName("what")
			.setDescription("Short description of what you want to be reminded of")
			.setRequired(true),
	);

class Reminder extends Model {
	declare id: number;
	declare userId: string;
	declare text: string | null;
	declare trigger: Date;
	declare isValid: boolean;
	declare requestChannel: string;
	declare requestMessage: string;
}

class Plugin {
	settings: Settings;
	interval: NodeJS.Timeout;

	constructor(settings: Settings) {
		this.settings = settings;
	}

	getChannel(reminder: Reminder) {
		let channel: TextChannel | null = null;
		const client = this.settings.client;
		const publicChannel = this.settings.publicChannel;
		// if (this.settings.responseMode === "private") {
		// 	channel = getSendableTextChannel(client, reminder.requestChannel);
		// }
		if (this.settings.responseMode === "public" || !channel) {
			channel = getSendableTextChannel(client, publicChannel);
		}
		if (!channel) {
			throw Error("Cannot find valid channel to send reminder on");
		}
		return channel;
	}

	async loop() {
		console.debug("remind.js main loop");
		const results = await Reminder.findAll({
			// NOTE: 'trigger' is the time when the reminder should go off. If trigger -
			// now is positive, trigger is in the future. If trigger - now <=
			// 1.0, then we have less than one minute before the timer should go
			// off.
			where: sequelize.literal(
				"isValid AND (julianday(trigger) - julianday('now')) <= 1.0",
			),
		});
		for (const reminder of results) {
			try {
				const now = new Date(Date.now());
				const delay = reminder.trigger.getTime() - now.getTime();
				console.log(
					`Callback for Reminder ${reminder.get("id")} triggering in ${delay}ms`,
				);
				const channel = this.getChannel(reminder);
				setTimeout(async () => await triggerReminder(channel, reminder), delay);
			} catch (error) {
				console.error(
					`Error while processing Reminder ${reminder.id}: ${error}`,
				);
				console.trace();
			}
		}
	}

	start() {
		this.interval = setInterval(
			this.loop.bind(this),
			1000 * (this.settings.loopIntervalSec ?? 60),
		);
	}

	stop() {
		clearInterval(this.interval);
	}
}

async function initialize(settings: Settings) {
	console.log("Initializing remind.js");

	// Populate Reminder table inside SQLite DB
	Reminder.init(
		{
			id: {
				type: INTEGER,
				primaryKey: true,
				autoIncrement: true,
			},
			userId: {
				type: TEXT,
				allowNull: false,
			},
			text: TEXT,
			trigger: {
				type: DATE,
				allowNull: false,
			},
			isValid: BOOLEAN,
			requestChannel: TEXT,
			requestMessage: TEXT,
		},
		{ sequelize: settings.db },
	);
	await Reminder.sync();

	// Try and determine how the bot will send reminders
	console.debug(`Accessing channel ${settings.publicChannel}`);
	if (!getSendableTextChannel(settings.client, settings.publicChannel)) {
		throw Error(
			"Invalid value for publicChannel; specify a channel the bot can access.",
		);
	}

	// Initialize the 'plugin' object which will store all state required to control the mainloop.
	if (settings.loopIntervalSec == null || settings.loopIntervalSec <= 0) {
		console.log("Setting plugin loop interval to default of 60 seconds");
		settings.loopIntervalSec = 60;
	}
	const plugin = new Plugin(settings);
	plugin.start();
}

function getSendableTextChannel(client: Client, chanId: string) {
	// console.log(`getSendableTextChannel(${client}, ${chanId})`);
	const channel = client.channels.cache.get(chanId);
	if (!client.user) {
		throw Error("Can't check non-existent client");
	}
	if (!channel) {
		throw Error("No such channel is visible to Blitz");
	}
	if (!channel?.isSendable()) {
		throw Error("Channel is not a text channel, or otherwise not Sendable");
	}
	if (!(channel instanceof TextChannel)) {
		throw Error("Channel is not a guild channel");
	}
	const permissions = channel?.permissionsFor(client.user);
	const requiredPerms = new PermissionsBitField([
		PermissionsBitField.Flags.SendMessages,
		PermissionsBitField.Flags.ViewChannel,
	]);
	if (!permissions?.has(requiredPerms)) {
		throw Error("Missing required permissions: SendMessages, ViewChannel");
	}
	return channel;
}

async function triggerReminder(channel: TextChannel, reminder: Reminder) {
	try {
		await channel.send({
			content: `Reminder for <@${reminder.userId}>: ${reminder.text}`,
		});
		reminder.isValid = false;
	} catch (error) {
		console.log(`Error trigggering Reminder ${reminder.id}: ${error}`);
	} finally {
		await reminder.save();
	}
}

async function execute(interaction: ChatInputCommandInteraction) {
	const whenString = interaction.options.getString("when") ?? "now";
	const when = chrono.parseDate(whenString);
	if (!when) {
		await interaction.reply(`Sorry, I don't understand '${when}' as a date`);
		return;
	}
	const reminder = await Reminder.create({
		userId: interaction.user.id,
		text: interaction.options.getString("what"),
		trigger: when, // TODO
		requestMessage: interaction.id,
		requestChannel: interaction.channelId,
		isValid: true,
	});
	reminder.save();
	await interaction.reply(`Ok, I'll remind you at ${when}`);
	console.info(
		`Created Reminder ${reminder.id} to be triggered at ${reminder.trigger}`,
	);
}

export default function (settings: Settings) {
	return {
		data,
		execute,
		initialize: async () => await initialize(settings),
		Reminder,
		settings,
	};
}