import fs from 'fs';
import path from 'path';

import {
	AutocompleteInteraction,
	BaseInteraction,
	ChatInputCommandInteraction,
	GuildMember,
	Interaction,
	Message,
	MessageFlags,
	PermissionFlagsBits,
	REST,
	Routes,
	SlashCommandOptionsOnlyBuilder,
	VoiceState
} from 'discord.js';
import { Logger } from './utils/log';
import { config } from './utils/config';
import { Bot } from './bot';
import { isModule } from './utils/misc';

export interface Command {
	name?: string;
	builder?: SlashCommandOptionsOnlyBuilder;
	requiresAdmin?: boolean;
	ownerOnly?: boolean;

	guild_keys?: Record<string, unknown>;
	user_keys?: Record<string, unknown>;

	execute?: (interaction: ChatInputCommandInteraction) => Promise<void>;
	autocomplete?: (interaction: AutocompleteInteraction) => Promise<void>;
	messageListener?: (msg: Message) => Promise<void>;
	voiceStateListener?: (
		prevState: VoiceState,
		newState: VoiceState
	) => Promise<void>;
}

export interface CommandCategoryInfo {
	name: string;
	description: string;
}

export interface CommandCategory {
	info: CommandCategoryInfo;
	commands: Command[];
}

export class CommandManager {
	private readonly folderPath: string;
	private readonly log: Logger;

	private initialized: boolean = false;
	private categories: Array<CommandCategory> = [];

	/*
		public
	*/
	public constructor(cmdFolder: string) {
		this.folderPath = path.resolve(__dirname, cmdFolder);
		this.log = new Logger('Command manager');
	}

	public async init(): Promise<void> {
		if (this.initialized)
			throw new Error('CommandManager was already initialized');
		this.initialized = true;
		await this.populateCommands();
		this.registerSlashCommands();

		const bot = Bot.get;

		bot.on('interactionCreate', (interaction: Interaction) => {
			this.onInteraction(interaction);
		});
		bot.on('messageCreate', (message: Message) => {
			this.onMessage(message);
		});
		bot.on('voiceStateUpdate', (oldState: VoiceState, newState: VoiceState) => {
			this.onVoiceStateUpdate(oldState, newState);
		});
	}

	public getCategories(): Array<CommandCategory> {
		return this.categories;
	}

	public get(commandName: string): Command | null {
		return this.getAll().find((cmd) => cmd.name === commandName) || null;
	}

	public getAll(): Command[] {
		return this.categories.flatMap((cat) => cat.commands);
	}

	public getAllInteractable(): Command[] {
		return this.getAll().filter((cmd) => !!cmd.name);
	}

	public getGuildKeys(): Record<string, unknown> {
		return this.mergeKeys('guild_keys');
	}

	public getUserKeys(): Record<string, unknown> {
		return this.mergeKeys('user_keys');
	}

	private mergeKeys(
		keyType: 'guild_keys' | 'user_keys'
	): Record<string, unknown> {
		return this.getAll()
			.flatMap((cmd) => (cmd[keyType] ? [cmd[keyType]] : []))
			.reduce((acc, val) => Object.assign(acc, val), {});
	}

	/*
		internal
	*/
	private async populateCommands() {
		if (!fs.existsSync(this.folderPath))
			throw new Error(`Command directory not found: ${this.folderPath}`);

		const categoryFolders = fs.readdirSync(this.folderPath);

		for (const categoryFolder of categoryFolders) {
			const catPath = path.join(this.folderPath, categoryFolder);
			await this.processCategory(catPath, categoryFolder);
		}
	}

	private async processCategory(
		catPath: string,
		folderName: string
	): Promise<void> {
		try {
			const stat = fs.statSync(catPath);
			if (!stat.isDirectory()) {
				this.log.warning(
					'Skipping non-directory entry found on cmd folder (%s)',
					folderName
				);
				return;
			}

			const catInfo = await this.loadCatInfo(catPath);
			const commands = await this.loadCatCommands(catPath);

			if (catInfo == undefined) {
				this.log.warning('Folder %s was missing info, ignoring', folderName);
				return;
			}

			this.categories.push({
				info: catInfo,
				commands: commands
			});
		} catch (err) {
			this.log.error('Error processing category %s: %s', folderName, err);
		}
	}

	private async loadCatInfo(
		catPath: string
	): Promise<CommandCategoryInfo | undefined> {
		try {
			const extensions = ['js', 'mjs', 'cjs', 'ts'];

			for (const ext of extensions) {
				const descriptorPath = path.join(catPath, `_category.${ext}`);
				if (!fs.existsSync(descriptorPath)) continue;

				const module = await import(`file://${descriptorPath}`);
				return (
					module.default?.default ||
					module.default ||
					(module as CommandCategoryInfo)
				);
			}

			throw new Error('Missing categoryinfo.json');
		} catch (err) {
			this.log.error('Error loading category info at %s: %s', catPath, err);
			return undefined;
		}
	}

	private async loadCatCommands(catPath: string): Promise<Array<Command>> {
		const promises = fs
			.readdirSync(catPath)
			.filter((file) => isModule(file))
			.map(
				async (file) => await this.attemptLoadCommand(path.join(catPath, file))
			);
		return (await Promise.all(promises)).filter((cmd): cmd is Command => !!cmd);
	}

	/*
		cmd parsing
	*/
	private async attemptLoadCommand(filePath: string): Promise<Command | null> {
		try {
			const module = await import(`file://${filePath}`);
			const command =
				module.default?.default || module.default || (module as Command);
			return command;
		} catch (error) {
			this.log.error(
				`Error loading command ${path.basename(filePath)}: ${error}`
			);
			return null;
		}
	}

	/*
		misc functions
	*/
	private async registerSlashCommands(): Promise<void> {
		this.log.info('Registering slash commands...');

		try {
			const cmdJSONList = this.getAll()
				.filter((cmd) => cmd.builder !== undefined)
				.map((cmd) => cmd.builder?.toJSON())
				.filter((cmd) => cmd !== undefined);

			const rest = new REST({ version: '10' }).setToken(config.token as string);
			await rest.put(Routes.applicationCommands(config.client_id), {
				body: cmdJSONList
			});

			this.log.info('Registered %i commands', cmdJSONList.length);
		} catch (err) {
			this.log.warning(
				'Error occurred while registering slash commands: %s',
				err
			);
		}
	}

	/*
		interaction handling
	*/
	private async executeCommandInteraction(
		interaction: ChatInputCommandInteraction
	): Promise<void> {
		const cmdName = interaction.commandName;
		const command = this.get(cmdName);
		if (!command)
			return this.log.error(
				'Attempted to execute non-existing command (%s)',
				cmdName
			);

		if (command.requiresAdmin) {
			const member = interaction.member as GuildMember;
			if (!member.permissions.has(PermissionFlagsBits.Administrator) && member.id != config.owner_id) {
				await interaction.reply({
					content:
						"You don't have the permissions required to execute this command.",
					flags: MessageFlags.Ephemeral
				});
				return;
			}
		}

		if (command.ownerOnly) {
			const member = interaction.member as GuildMember;
			if (member.id != config.owner_id) {
				await interaction.reply({
					content: 'This command is restricted.',
					flags: MessageFlags.Ephemeral
				});
				return;
			}
		}

		if (command.execute) {
			try {
				await command.execute(interaction);
			} catch (error) {
				this.log.error(
					'Error occurred while executing command %s: %s',
					cmdName,
					error
				);
			}
		} else this.log.error('Command is missing execute method: %s', cmdName);
	}

	private async autocompleteCommandInteraction(
		interaction: AutocompleteInteraction
	): Promise<void> {
		const cmdName = interaction.commandName;
		const command = this.get(cmdName);

		if (!command)
			return this.log.error(
				'Attempted to execute unexisting command (%s)',
				cmdName
			);

		if (command.autocomplete) {
			try {
				await command.autocomplete(interaction);
			} catch (error) {
				this.log.error(
					'Error occurred while autocompleting command %s: %s',
					cmdName,
					error
				);
			}
		} else
			this.log.error('Command is missing autocomplete method: %s', cmdName);
	}

	/*
		event listeners
	*/
	private async onInteraction(interaction: BaseInteraction): Promise<void> {
		/*
			cmd execution
		*/
		if (interaction.isChatInputCommand())
			return this.executeCommandInteraction(interaction);

		if (interaction.isAutocomplete())
			return this.autocompleteCommandInteraction(interaction);

		return;
	}

	private async onMessage(message: Message<boolean>): Promise<void> {
		if (message.author.bot) return;

		for (const cmd of this.getAll())
			if (cmd.messageListener) await cmd.messageListener(message);
	}

	private async onVoiceStateUpdate(
		oldState: VoiceState,
		newState: VoiceState
	): Promise<void> {
		for (const cmd of this.getAll())
			if (cmd.voiceStateListener)
				await cmd.voiceStateListener(oldState, newState);
	}
}