alvarocastro/diamondbot

import { ChatCommand } from '@diamondbot/core';
import fetch from 'node-fetch';
import randomItem from 'random-item';
import VolatileMap from 'volatile-map';

const CACHE_TTL = 600000; // 10 minutes

export default class HistoryCommand extends ChatCommand {
    constructor (options = {}) {
        super(Object.assign({
            name: 'history',
            alias: 'hist',
            description: 'Get a random history event that happened on a day like today'
        }, options));

        this.cache = new VolatileMap(options.cache ?? CACHE_TTL);
    }

    async commandHelp (channel) {
        return await channel.send(`
            > Today in history:
            > \`!${this.name}\` - Get an event that happened today but from another year.
            > \`!${this.name} [year]\` - Get an event that happened today but form that year.
            > \`!${this.name} [month] [day]\` - Get an event that happened that date but form another year.
            > \`!${this.name} [year] [month] [day]\` - Get an event that happened that date.
        `);
    }

    async getEvents (month, day) {
        const key = `${month}_${day}`;

        if (this.cache.has(key)) {
            return this.cache.get(key);
        }

        const response = await fetch(`https://history.muffinlabs.com/date/${month}/${day}`);
        const data = await response.json();
        this.cache.set(key, data);

        return data;
    }

    async exec ({channel}, args) {
        const now = new Date;
        let month;
        let day;
        let year;
        let message;
        let isToday = false;

        // Sanitize input
        if (args.length <= 1) {
            isToday = true;
            month = now.getMonth() + 1;
            day = now.getDate();
            if (args.length === 1) {
                year = Number(args[0]);
            }
        } else if (args.length === 2) {
            month = Number(args[0]);
            day = Number(args[1]);
        } else if (args.length === 3) {
            year = Number(args[0]);
            month = Number(args[1]);
            day = Number(args[2]);
        }

        // Validate input
        const lastDayOfMonth = new Date(year || now.getFullYear(), month, 0);
        if (
            args[0] === 'h' ||
            args[0] === 'help' ||
            args.length > 3 ||
            (year && isNaN(year)) ||
            isNaN(month) ||
            isNaN(day) ||
            day > lastDayOfMonth.getDate() ||
            day <= 0 ||
            month > 12 ||
            month <= 0 ||
            year > now.getFullYear() ||
            year <= 0
        ) {
            return await this.commandHelp(channel);
        }

        const {date, data} = await this.getEvents(month, day);

        if (!data) {
            throw new Error(`Got no response for ${month}/${day}`);
        }

        if (isToday) {
            message = `A day like today but`;
        } else {
            message = `On ${date}`;
        }
        let events = data.Events;
        if (year) {
            year = year.toString();
            events = events.filter(e => e.year === year);
        }

        const event = randomItem(events);
        if (!event) {
            message += ` of ${year}...\nNothing interesting happened ${this.bot.emoji('KEKWait')}`;
        } else {
            year = event.year;
            message += ` of ${year}...\n${event.text}`;
        }
        await channel.send(message);
    }
}