Oasis

import { Argument, Command, Context } from 'oasis';

// define responses
const responses = [
    'It is certain',
    'It is decidedly so',
    'Without a doubt',
    'Yes, definitely',
    'You may rely on it',
    'Most likely',
    'Outlook good',
    'Yes',
];

@Command
class EightBall {
    readonly data = {
        name: `${responses.length}ball`,
        description: 'Ask the magic 8ball a question',
    };

    readonly aliases = ['ball'];

    @Argument('The question', true)
    declare question: string; // it works without 'declare' if you compile down to ES2020

    // get all options
    get options(): unknown[] {
        return [this.question]; // first argument in the command
    }

    async run(ctx: Context) {
        const question = ctx.options.getString(0) ?? ctx.options.getString('question');
        const response = responses[Math.floor(Math.random() * responses.length)];

        if (question) {
            await ctx.respond({ with: `Question: ${question} | Reply: ${response}` });
        }
    }
}

const PREFIX = '->';
const { interactionCreate, messageCreate } = bot.events;

bot.events.interactionCreate = (bot, interaction) => {
    if (interaction.user.toggles.bot) {
        interactionCreate(bot, interaction);
        return;
    }

    const ctx = new Context(PREFIX, bot, undefined, interaction);
    const commandName = ctx.getCommandName();

    if (!commandName) {
        return;
    }

    const [command] = commands.get(commandName) ?? [];

    if (command) {
        command.run(ctx);
    }

    interactionCreate(bot, interaction);
};

bot.events.messageCreate = (bot, message) => {
    if (message.isBot) {
        // forward the event
        messageCreate(bot, message);
        return;
    }

    // make sure to import Context from oasis
    const ctx = new Context(PREFIX, bot, message, undefined);
    const commandName = ctx.getCommandName();

    if (!commandName) {
        return;
    }

    const [command] = commands.get(commandName) ?? commands.get(commandAliases.get(commandName) ?? '') ?? [];

    if (command) {
        command.run(ctx);
    }

    messageCreate(bot, message);
};