main.js

import nodeFetch from "node-fetch";
import fetchCookie from "fetch-cookie";
import { spawn } from "child_process";
import fs from "fs";
import config from "./config.js";

const COURSES_URL = "https://api.frontendmasters.com/v1/kabuki/courses";

const headers = {
  Origin: "https://frontendmasters.com",
  Referer: "https://frontendmasters.com/",
};

const videoQualities = {
  2160: "index_2160p_Q10_20mbps",
  1440: "index_1440p_Q10_9mbps",
  1080: "index_1080_Q10_7mbps",
  720: "index_720_Q8_5mbps",
  360: "index_360_Q8_2mbps",
};

const main = async () => {
  const { FEM_AUTH_MOD, COURSE_URL, QUALITY } = config;

  const quality = videoQualities[QUALITY];

  const jar = new fetchCookie.toughCookie.CookieJar();
  await jar.setCookie(
    `fem_auth_mod=${FEM_AUTH_MOD}; Path=/; Domain=frontendmasters.com; HttpOnly; Secure`,
    "https://frontendmasters.com",
  );
  const fetch = fetchCookie(nodeFetch, jar);

  const courseType = COURSE_URL.replace(/\/+$/gm, "").split("/").at(-1);

  const res = await fetch(`${COURSES_URL}/${courseType}`, { headers });
  const data = await res.json();
  const title = data.title;

  if (!fs.existsSync(title)) {
    fs.mkdirSync(title);
  }

  const lessons = Object.entries(data.lessonData).map(([k, v]) => ({
    hash: k,
    title: v.title,
    index: v.index,
  }));

  for (const lesson of lessons) {
    const res = await fetch(
      `https://api.frontendmasters.com/v1/kabuki/video/${lesson.hash}/source?f=m3u8`,
      { headers },
    );
    const { url } = await res.json();
    const finalUrl = [...url.split("/").slice(0, -1), `${quality}.m3u8`].join(
      "/",
    );

    headers["Cookie"] = await jar.getCookieString(finalUrl);

    const joinedHeaders = Object.entries(headers)
      .map(([k, v]) => `${k}: ${v}`)
      .join("\n");

    const proc = spawn("ffmpeg", [
      "-y",
      "-headers",
      joinedHeaders,
      "-i",
      finalUrl,
      "-map",
      "0",
      "-c",
      "copy",
      `${title}/${lesson.index}_${lesson.title}.mp4`,
    ]);
    proc.stdout.on("data", function (data) {
      console.log(data);
    });

    proc.stderr.setEncoding("utf8");
    proc.stderr.on("data", function (data) {
      console.log(data);
    });
  }
};

await main();