const dns = require("dns");
const superagent = require("superagent");

function resolveDNSAsync(domain) {
    return new Promise((res, rej) => {
        if (!/([\--z]+\.)?([\--z]+)\.([A-z]+)/g.test(domain)) return rej("Not a valid domain");

        const options = {
            family: 4,
            hints: dns.ADDRCONFIG | dns.V4MAPPED
        };
        dns.lookup(domain, options, (err, address, family) => {
            if (err) return rej(err);
            res(address);
        });
    });
}

function roundToTwo(num) {
    return +(Math.round(num + "e+2")  + "e-2");
}

module.exports = () => {
    // Code entered here will be run every 5 minutes
    return new Promise(async (res, rej) => {
        let servers = {
            canterlot: [await resolveDNSAsync("canterlot.equestria.dev"), 52937],
            ponyville: [await resolveDNSAsync("ponyville-ipv4.equestria.dev"), 52937],
            bridlewood: [await resolveDNSAsync("bridlewood.equestria.dev"), 52937],
            zephyrheights: [await resolveDNSAsync("zephyrheights-ipv4.equestria.dev"), 52938],
            maretimebay: [await resolveDNSAsync("maretimebay-ipv4.equestria.dev"), 52937]
        }

        let stats = {}

        for (let key in Object.keys(servers)) {
            key = Object.keys(servers)[key];
            let status = {
                online: null,
                cpu: null,
                memory: null,
                os: null,
                uptime: null
            }

            superagent.get(`http://${servers[key][0]}:${servers[key][1]}/json`)
                .timeout({
                    response: 5000,
                })
                .then(data => data = data.body)
                .then(data => {
                    status.online = true;
                    status.cpu = data.cpu;
                    status.cpu.load = Math.floor(data.cpu.load * 100);
                    status.memory = data.memory;
                    status.memory.swap.used = roundToTwo(data.memory.swap.used / 1073741824);
                    status.memory.swap.free = roundToTwo(data.memory.swap.free / 1073741824);
                    status.memory.swap.total = roundToTwo(data.memory.swap.total / 1073741824);
                    status.memory.physical.used = roundToTwo(data.memory.physical.used / 1073741824);
                    status.memory.physical.free = roundToTwo(data.memory.physical.free / 1073741824);
                    status.memory.physical.total = roundToTwo(data.memory.physical.total / 1073741824);
                    status.os = data.os;
                    status.uptime = data.uptime;
                })
                .catch(reason => {
                    if (reason.timeout) {
                        // We timed out.
                        status.online = false;
                    } else {
                        if(reason.code == "ECONNREFUSED") {
                            status.online = false;
                            console.warn(`Server ${key} refused our connection. `)
                        } else {
                            console.error(reason);
                        }
                    }
                })
                .finally(() => {
                    stats[key] = status;

                    if(Object.keys(stats).length == Object.keys(servers).length) {
                        res(stats);
                    }
                });
        }
    });
}