ImageArgumentType - discord.js-commando

const { ArgumentType } = require('discord.js-commando');

const fileType = require('file-type');
const fetch = require('node-fetch');


let buffer;

/**
 * ImageArgumentType for discord.js-commando
 * returns a buffer usable for MessageAttachment
 */
class ImageArgumentType extends ArgumentType {
  constructor(client) {
    super(client, 'image');
  }


  async validate(val, msg, arg) {
    const matches = val ? val.match(/^(?:http(s)?:\/\/)\s?[\w.-]+(?:\.[\w\.-]+)+[\w\-\._~:/?#[\]@!\$&'\(\)\*\+,;=.]+$/gi) : null;
    const mime = ['image/jpeg', 'image/jpg', 'image/png'];


    if (val && msg.attachments.size > 0) {
      // const message = await msg.channel.messages.get(msg.author.lastMessageID);
      const attachment = msg.attachments.first();

      buffer = await fetch(attachment.url).then(res => res.buffer())
      const type = fileType(buffer)

      if (type === null) {
        return "You provided an invalid image. Please try again."
      }

      const check = mime.find(n => n === type.mime)
      if (check) return true

    }

    const message = await msg.channel.messages.get(msg.author.lastMessageID);

    if (message.attachments.size > 0) {
      const attachment = message.attachments.first();

      buffer = await fetch(attachment.url).then(res => res.buffer());
      const type = fileType(buffer)

      if (type === null) {
        return "You provided an invalid image. Please try again."
      }

      const check = mime.find(n => n === type.mime)
      if (check) return true


    }

    if (matches) {
      buffer = await fetch(val).then(res => res.buffer())
      const type = fileType(buffer)

      if (type === null) {
        return "You provided an invalid image url. Please try again."
      }

      const check = mime.find(n => n === type.mime)
      if (check) return true

    }

    return false;

  }

  async parse(val, msg) {

    return buffer;

  }

  isEmpty(val, msg, arg) {
    if (msg.attachments.size) return false;
    // if (!match) return !val

    if (Array.isArray(val)) return val.length === 0;
    return !val;
  }

};

module.exports = ImageArgumentType;