import {
	CacheType,
	Client,
	EmbedBuilder,
	GatewayIntentBits,
	Interaction,
	REST,
	Routes,
	SlashCommandBuilder,
	SlashCommandStringOption,
} from "npm:discord.js@14.14.1";
import { channel, log_from, SimpleResult, split_promise } from "./utils.ts";
const log = log_from(import.meta.url);

/**
 * Wraps a discord bot and implements required actions.
 */
export class EpitlsBot {
	private bot;
	private token;
	private rest;
	private assoc_channel;

	public constructor(bot_token: string) {
		this.token = bot_token;
		const intents = [GatewayIntentBits.Guilds];
		this.bot = new Client({ intents });
		this.bot.on("interactionCreate", (interaction) => this.handle_interaction(interaction));
		this.rest = new REST().setToken(bot_token);
		this.assoc_channel = channel<
			{ cri_login: string; discord_user_id: string; callback: (success: SimpleResult) => void }
		>();
	}

	/**
	 * Connects to discord API server and registers slash commands.\
	 * Needs to be run after construction as it is an asynchronous operation.
	 */
	public async start() {
		const { promise, resolver } = split_promise<void>();
		this.bot.on("ready", () => resolver());
		this.bot.login(this.token);
		await promise;
		await this.register_commands();
	}

	/**
	 * Assigns a discord role to a discord user.
	 */
	public async assign_role(user_id: string, guild_id: string, role_id: string) {
		const guild = await this.bot.guilds.fetch(guild_id);
		const member = await guild.members.fetch({ user: user_id });
		const role = await guild.roles.fetch(role_id);
		if (role === null) return console.error("Role", role_id, "not found in guild", guild_id);
		member.roles.add(role_id);
		log(`Assigned role '${role.name}' to user '${member.displayName}'.`);
	}

	/**
	 * Pull-style API to wait for and receive account association requests.
	 */
	public async *receive_associations() {
		while (true) yield await this.assoc_channel.receive();
	}

	/**
	 * Connected bot name accessor.
	 */
	public bot_name() {
		return this.bot.user?.displayName;
	}

	public async get_username(user_id: string) {
		try {
			const user = await this.bot.users.fetch(user_id);
			return user.displayName;
		} catch (_) {
			return undefined;
		}
	}

	private async register_commands() {
		const cmd = new SlashCommandBuilder()
			.setName("associate")
			.setDescription("Associates a cri account to your discord account.")
			.addStringOption(
				new SlashCommandStringOption()
					.setName("cri_email")
					.setDescription("claude.nougaro@epita.fr")
					.setRequired(true),
			).toJSON();

		for (const guild_id of this.bot.guilds.cache.keys()) {
			await this.rest.put(
				Routes.applicationGuildCommands(this.bot.application!.id, guild_id),
				{ body: [cmd] },
			);
		}
	}

	private async handle_interaction(interaction: Interaction<CacheType>) {
		if (!interaction.isChatInputCommand()) return;
		if (interaction.commandName != "associate") return;
		const email = interaction.options.getString("cri_email")!;
		if (!email.endsWith("@epita.fr")) {
			await interaction.reply(message_command_response_error("invalid cri email " + email));
			return;
		}
		const [cri_login] = email.split("@epita.fr");
		const discord_user_id = interaction.user.id;
		const { promise, resolver } = split_promise<SimpleResult>();

		this.assoc_channel.send({ cri_login, discord_user_id, callback: resolver });
		await interaction.reply(message_command_response_sending_email(email));
		log(`Started verification for discord id '${discord_user_id}' with cri login '${cri_login}'.`);
		const result = await promise;
		if (result === true) interaction.editReply(message_command_response_success());
		else interaction.editReply(message_command_response_error(result));
	}
}

function message_command_response_sending_email(email: string) {
	const embed = new EmbedBuilder()
		.setTitle("`🟡`| Vérification")
		.setDescription(`
Un lien de vérification a été envoyé par e-mail à \`${email}\`.
Le lien expirera dans 5 minutes.
**Il pourraît être arrivé dans \`Courrier indésirable\`.**
`.trim());
	return { embeds: [embed] };
}

function message_command_response_error(msg: string) {
	const embed = new EmbedBuilder()
		.setTitle("`❌`| Vérification")
		.setDescription(`Échec de la vérification :\n\`${msg}\``);
	return { embeds: [embed] };
}

function message_command_response_success() {
	const embed = new EmbedBuilder()
		.setTitle("`✅`| Vérification")
		.setDescription("Votre e-mail CRI a bien été associé à ce compte Discord.");
	return { embeds: [embed] };
}