import {
	CacheType,
	ChatInputCommandInteraction,
	Client,
	EmbedBuilder,
	GatewayIntentBits,
	Guild,
	Interaction,
	REST,
	Routes,
	SlashCommandBooleanOption,
	SlashCommandBuilder,
	SlashCommandRoleOption,
	SlashCommandStringOption,
	SlashCommandSubcommandBuilder,
} from "npm:discord.js@14.14.1";
import { RuleSet } from "./rules.ts";
import { channel, log_from, SimpleResult, split_promise, try_ } 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 rules;
	private assoc_channel;

	public constructor(bot_token: string, rules: RuleSet) {
		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.rules = rules;
		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 this.try_fetch_member(guild, user_id);
		if (member === undefined) return;
		const role = await guild.roles.fetch(role_id);
		if (role === null) return console.error("Role", role_id, "not found in guild", guild_id);
		log(`Assigning to user '${member.displayName}' role '${role.name}'.`);
		await try_(
			() => member.roles.add(role_id),
			() => log(`FAILED Assignation to user '${member.displayName}' role '${role.name}'.`),
		);
	}

	public async update_user_name(user_id: string, must_contain: string, default_suffix: string) {
		for (const guild of this.bot.guilds.cache.values()) {
			const user = await this.try_fetch_member(guild, user_id);
			if (user === undefined) continue;
			const name = user.displayName;
			if (to_comparable(name).includes(to_comparable(must_contain))) continue;
			const DISCORD_MAX_NAME_LENGTH = 35;
			const generated_name_prefix = name.slice(0, DISCORD_MAX_NAME_LENGTH - default_suffix.length);
			const generated_name = generated_name_prefix + default_suffix;
			log(`Setting name of '${name}' to '${generated_name}'.`);
			await try_(() => user.setNickname(generated_name), () => log(`FAILED Setting name of '${name}'.`));
		}
	}

	private async try_fetch_member(guild: Guild, user_id: string) {
		try {
			return await guild.members.fetch({ user: user_id });
		} catch (_) {
			return undefined;
		}
	}

	/**
	 * 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 assoc_cmd = new SlashCommandBuilder()
			.setName("associate")
			.setDescription("Associates a cri account to your discord account.")
			.addStringOption(
				new SlashCommandStringOption()
					.setName("cri_email")
					.setDescription("par exemple, claude.nougaro@epita.fr")
					.setRequired(true),
			).toJSON();

		const rule_cmd = new SlashCommandBuilder()
			.setName("rule")
			.setDescription("Gestion des règles d'associations groupes cri / rôles.")
			.setDefaultMemberPermissions(0x0000000000000008n)
			.addSubcommand(
				new SlashCommandSubcommandBuilder()
					.setName("list")
					.setDescription("Liste les règles d'association."),
			)
			.addSubcommand(
				new SlashCommandSubcommandBuilder()
					.setName("add")
					.setDescription("Ajoute une règle d'association.")
					.addStringOption(
						new SlashCommandStringOption()
							.setName("group")
							.setDescription("Groupe CRI à associer.")
							.setRequired(true),
					)
					.addRoleOption(
						new SlashCommandRoleOption()
							.setName("role")
							.setDescription("Role à assigner.")
							.setRequired(true),
					)
					.addBooleanOption(
						new SlashCommandBooleanOption()
							.setName("incl_historical")
							.setDescription("Assigner le rôle aux membres qui ont été membre du groupe, mais qui ne le sont plus.")
							.setRequired(true),
					),
			)
			.addSubcommand(
				new SlashCommandSubcommandBuilder()
					.setName("remove")
					.setDescription("Retire une règle d'association.")
					.addStringOption(
						new SlashCommandStringOption()
							.setName("group")
							.setDescription("Groupe CRI à retirer.")
							.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: [assoc_cmd, rule_cmd] },
			);
		}
	}

	private async handle_interaction(interaction: Interaction<CacheType>) {
		if (!interaction.isChatInputCommand()) return;
		if (interaction.commandName === "associate") await this.handle_command_associate(interaction);
		if (interaction.commandName === "rule") {
			const subcommand = interaction.options.getSubcommand();
			if (subcommand === "list") await this.handle_command_rule_list(interaction);
			if (subcommand === "add") await this.handle_command_rule_add(interaction);
			if (subcommand === "remove") await this.handle_command_rule_remove(interaction);
		}
	}

	private async handle_command_associate(interaction: ChatInputCommandInteraction<CacheType>) {
		const email = interaction.options.getString("cri_email")!;
		if (!email.endsWith("@epita.fr")) {
			await interaction.reply(message_command_response_assoc_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_assoc_pending(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_assoc_success());
		else interaction.editReply(message_command_response_assoc_error(result));
	}

	private async handle_command_rule_list(interaction: ChatInputCommandInteraction<CacheType>) {
		const guild_id = interaction.guildId;
		if (guild_id === null) {
			await interaction.reply(
				message_command_response_list_error("Cette commande peut être exécutée uniquement sur un serveur."),
			);
			return;
		}
		const rules = [] as GuildRule[];
		for (const { group_id, role_id, include_historical } of this.rules.roles_for_guild(guild_id)) {
			const role = await interaction.guild!.roles.fetch(role_id);
			const role_name = role?.name ?? "<DELETED>";
			rules.push({ group_id, role_name, include_historical });
		}
		await interaction.reply(message_command_response_rule_list_success(rules));
	}

	private async handle_command_rule_add(interaction: ChatInputCommandInteraction<CacheType>) {
		const guild_id = interaction.guildId;
		if (guild_id === null) {
			await interaction.reply(
				message_command_response_list_error("Cette commande peut être exécutée uniquement sur un serveur."),
			);
			return;
		}
		const group_id = interaction.options.getString("group", true);
		const role = interaction.options.getRole("role", true);
		const include_historical = interaction.options.getBoolean("incl_historical", true);
		// TODO : test if role exists
		const role_id = role.id;
		const role_name = role.name;
		await this.rules.append_rule(group_id, { guild_id, role_id }, include_historical);
		await interaction.reply(message_command_response_rule_add_success({ group_id, role_name, include_historical }));
	}

	private async handle_command_rule_remove(interaction: ChatInputCommandInteraction<CacheType>) {
		const guild_id = interaction.guildId;
		if (guild_id === null) {
			await interaction.reply(
				message_command_response_list_error("Cette commande peut être exécutée uniquement sur un serveur."),
			);
			return;
		}
		const group_id = interaction.options.getString("group", true);
		const removed = await this.rules.remove_rules(group_id, guild_id);
		const rules = [] as GuildRule[];
		for (const { group_id, target_role: { role_id }, include_historical } of removed) {
			const role = await interaction.guild!.roles.fetch(role_id);
			const role_name = role?.name ?? "<DELETED>";
			rules.push({ group_id, role_name, include_historical });
		}
		await interaction.reply(message_command_response_rule_remove_success(rules));
	}
}

function message_command_response_assoc_pending(email: string) {
	const embed = new EmbedBuilder()
		.setTitle("`🟡`| Association")
		.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_assoc_error(msg: string) {
	const embed = new EmbedBuilder()
		.setTitle("`❌`| Association")
		.setDescription(`Échec de l'association :\n\`${msg}\``);
	return { embeds: [embed] };
}

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

function message_command_response_list_error(msg: string) {
	const embed = new EmbedBuilder()
		.setTitle("`❌`| Liste des règles")
		.setDescription(`Échec :\n\`${msg}\``);
	return { embeds: [embed] };
}

type GuildRule = { group_id: string; role_name: string; include_historical: boolean };
function message_command_response_rule_list_success(rules: GuildRule[]) {
	const embed = new EmbedBuilder()
		.setTitle("`📚️`| Liste des règles")
		.setDescription(`Règles d'associations groupe / rôle.
${rules.map(display_rule).join("\n")}
`);
	return { embeds: [embed] };
}

function message_command_response_rule_add_success(rule: GuildRule) {
	const embed = new EmbedBuilder()
		.setTitle("`✅`| Règle ajouté")
		.setDescription(`Règle d'association ajoutée :
${display_rule(rule)}
`);
	return { embeds: [embed] };
}

function message_command_response_rule_remove_success(rules: GuildRule[]) {
	const embed = new EmbedBuilder()
		.setTitle("`✅`| Règle ajouté")
		.setDescription(`Règle d'association retirées :
${rules.map(display_rule).join("\n")}
`);
	return { embeds: [embed] };
}

function to_comparable(input: string) {
	return input
		.toLowerCase()
		.normalize("NFD") // normalize accents
		.replace(/\p{Diacritic}/gu, ""); // remotes accents
}

function display_rule(rule: GuildRule) {
	if (rule.include_historical) return `- \`${rule.group_id}\` [H] → \`@${rule.role_name}\``;
	else return `- \`${rule.group_id}\` → \`@${rule.role_name}\``;
}