const http = require('http');
const https = require('https');

// DON'T JUDGE, THIS WAS MADE FOR A CHALLENGE.

class InternetRandom {
    constructor(url, timeout) {
        if (url && !url.startsWith('http:') && !url.startsWith('https:'))
            throw new Error('Bad URL');

        this.url = url || 'http://speedtest.tele2.net/1000GB.zip';
        this.timeout = timeout || 2000;

        this.client = this.url.startsWith('https') ? https : http;
        this.running = false;
        this.everRan = false;
        this.request = null;
        this.data = [];
    }

    start() {
        if (this.running)
            throw new Error('Already running!');

        this.everRan = true;

        this.running = true;
        this.request = this.client.request(this.url, res => {
            let last = Math.random() * Date.now();

            res.on('data', chunk => {
                this.data.push(this.random(Date.now() - last));
                last = Date.now();
            });

            res.on('end', () => {
                this.running = false;
            });
        });

        this.request.end();
    }

    async read() {
        if (!this.everRan)
            this.start();

        if (this.data.length < 1) {
            if (!this.running) {
                throw new Error('Generator exhausted');
            } else {
                let time = 0;
                while (time < this.timeout) {
                    await this.sleep(100);
                    if (this.data.length > 0)
                        return this.data.shift();
                    time = time + 100;
                }

                throw new Error('Timeout occurred');
            }
        }

        return this.data.shift();
    }

    async stop() {
        this.request.abort();
    }

    isExhausted() {
        return this.data.length < 1 && !this.running && this.everRan;
    }

    // https://codebottle.io/s/14f16d6577
    sleep(ms) {
        return new Promise(resolve => setTimeout(resolve, ms));
    }

    // https://stackoverflow.com/a/19303725/2164304
    random(seed) {
        const x = Math.sin(seed) * 10000;
        return x - Math.floor(x);
    }
}