cardboardbox/commands/Fun/react.js

const discordEmoji = require('discord-emoji');
const emoji = {};

Object.values(discordEmoji).forEach(value => {
	Object.keys(value).forEach(key => {
		emoji[key] = value[key];
	});
});

const mappings = {
	'a': [':regional_indicator_a:', ':a:'],
	'b': [':regional_indicator_b:', ':b:'],
	'c': [':regional_indicator_c:'],
	'd': [':regional_indicator_d:'],
	'e': [':regional_indicator_e:'],
	'f': [':regional_indicator_f:'],
	'g': [':regional_indicator_g:', ':compression:'],
	'h': [':regional_indicator_h:'],
	'i': [':regional_indicator_i:', ':information_source:'],
	'j': [':regional_indicator_j:'],
	'k': [':regional_indicator_k:'],
	'l': [':regional_indicator_l:'],
	'm': [':regional_indicator_m:', ':m:'],
	'n': [':regional_indicator_n:'],
	'o': [':regional_indicator_o:', ':o2:', ':o:'],
	'p': [':regional_indicator_p:', ':parking:'],
	'q': [':regional_indicator_q:'],
	'r': [':regional_indicator_r:'],
	's': [':regional_indicator_s:'],
	't': [':regional_indicator_t:', ':cross:'],
	'u': [':regional_indicator_u:'],
	'v': [':regional_indicator_v:'],
	'w': [':regional_indicator_w:'],
	'x': [':regional_indicator_x:', ':heavy_multiplication_x:', ':x:', ':negative_squared_cross_mark:'],
	'y': [':regional_indicator_y:'],
	'z': [':regional_indicator_z:'],
	'0': [':zero:'],
	'1': [':one:'],
	'2': [':two:'],
	'3': [':three:'],
	'4': [':four:'],
	'5': [':five:'],
	'6': [':six:'],
	'7': [':seven:'],
	'8': [':eight:'],
	'9': [':nine:'],
	'!': [':exclamation:', ':grey_exclamation:'],
	'?': [':question:', ':grey_question:'],
	'*': [':asterisk:', ':eight_spoked_asterisk:'],
	'#': [':hash:'],
	'$': [':heavy_dollar_sign:']
};

function clone(object) {
	const newObject = {};

	Object.keys(object).forEach(key => {
		if (object[key] instanceof Array) {
			newObject[key] = new Array(...object[key]);
		} else {
			newObject[key] = object[key];
		}
	});

	return newObject;
}

function emojiToUnicode(input) {
	if (/^:regional_indicator_[a-z]:$/.test(input)) {
		return String.fromCharCode(55356) + String.fromCharCode(56806 + input.substr(20, 1).charCodeAt(0) - 97);
	}
	return emoji[input.slice(1, -1)];
}

function react(message, remaining, allowedMappings) {
	if (remaining.length < 1) {
		// We're out of stuff
		return;
	}

	const char = remaining.shift().toLowerCase();

	if (!char) {
		return;
	}

	if (!allowedMappings[char]) {
		// Not a usable char
		return;
	}

	const next = allowedMappings[char].shift();
	if (!next) {
		// We have no more mappings available
		return;
	}

	message.react(emojiToUnicode(next)).then(() => {
		react(message, remaining, allowedMappings);
	});
}

exports.run = async (client, message, args, level) => {
  if (args.length < 1) {
  	await message.reply("you should actually try to tell me what I should react with...")
  	message.delete();
		client.user.lastMessage.delete(5000);
	}

	const fetchOptions = { limit: 1 };
	if (args[1]) {
		if (!/\d{18}/.test(args[1])) {
			await message.reply(`${args[1]} isn't a valid message ID!`);
			message.delete();
			client.user.lastMessage.delete(5000);
		}

		fetchOptions.around = args[1];
	} else {
		fetchOptions.before = message.id;
	}

	message.channel.fetchMessages(fetchOptions).then(messages => {
		if (messages.length < 1) {
			return message.reply("I couldn't find the specified message.");
		}

		const target = messages.first();
		const allowedMappings = clone(mappings);

		// Remove current reactions from allowed emojis
		target.reactions.forEach(reaction => {
			const emoji = reaction.toString();
			for (const key in allowedMappings) {
				const index = allowedMappings[key].indexOf(emoji);
				if (index > -1) {
					allowedMappings[key].splice(index, 1);
				}
			}
		});

		message.delete();

		react(target, args[0].split(''), allowedMappings);
	}).catch(message.error);
};

exports.conf = {
  enabled: true,
  guildOnly: false,
  aliases: [],
  permLevel: "User"
};

exports.help = {
  name: "react",
  category: "Fun",
  description: "Reacts to the last sent message (or another message) with a given text; your response cannot contain spaces.",
  usage: "react <text> [message ID]"
};