import { spawn } from "node:child_process";

export async function get_audio(url: string): Promise<string> {
  const ytDlpBin = process.env.YT_DLP_BIN_PATH! ?? "yt-dlp";
  const dataDir = "./data";

  const idMatch = /[?&]v=([a-zA-Z0-9_-]{11})/.exec(url);
  if (!idMatch) throw new Error("Cannot extract video ID");

  const id = idMatch[1];
  console.log(`ID: ${id}`);

  // ---- run yt-dlp ----
  await new Promise<void>((resolve, reject) => {
    const p = spawn(ytDlpBin, [
      "-x",
      "--audio-format", "opus",
      "--audio-quality", "0",
      "--no-playlist",
      "--paths", dataDir,
      url,
    ]);

    p.stderr.on("data", d => process.stderr.write(d));
    p.on("close", code => code === 0 ? resolve() : reject(new Error("yt-dlp failed")));
  });

  // ---- find the file ----
  return await new Promise<string>((resolve, reject) => {
    const find = spawn("find", [
      dataDir,
      "-type", "f",
      "-iname", `*${id}*.opus`,
      "-exec", "readlink", "-f", "{}", ";",
    ]);

    let out = "";

    find.stdout.on("data", d => out += d.toString());
    find.stderr.on("data", d => process.stderr.write(d));

    find.on("close", code => {
      if (code !== 0 || !out.trim()) {
        reject(new Error("Audio file not found"));
      } else {
        resolve(out.trim());
      }
    });
  });
}