import { readFile } from 'fs/promises';

import { getArg } from './lib/args.js';
import { getUser } from './lib/dl.js';
import { error, log } from './lib/log.js';

const ctx = 'buildDb.js';

const getMany = (processes, threadMax, directory) => new Promise((resolve, reject) => {
  let running = 0;
  let index = 0;

  const get = () => {
    const onFinish = (currentIndex) => {
      log(ctx, `Finished ${processes[currentIndex].user}/media`);
      --running;
      get();
    }

    while (running < threadMax && index < processes.length) {
      ++running;
      let currentIndex = index++;

      let proc = getUser(processes[currentIndex].user, directory);
      proc.stdout.on('data', data => {
        processes[currentIndex].logs.push(data);
      });
      proc.stderr.on('data', _ => onFinish(currentIndex));
      proc.on('close', _ => onFinish(currentIndex));
      proc.on('error', _ => onFinish(currentIndex));
    }

    if (running === 0) {
      resolve();
    }
  }
  get();
});

const buildDb = async () => {
  log(ctx, 'Grabbing db');
  let directory = '', threadMax = 1, db;
  try {
    directory = getArg('path');
  } catch (err) {
    error(ctx, err);
    return;
  }
  try {
    threadMax = getArg('threads');
    log(ctx, `Using ${threadMax} threads`);
  } catch (err) {
    log(ctx, 'Using 1 thread');
  }
  try {
    let file = await readFile(`${directory}/db.json`, { encoding: 'utf8' });
    db = JSON.parse(file);
  } catch (err) {
    error(ctx, err);
    return;
  }

  let processes = db.map(entry => ({
    ...entry,
    logs: [],
  }));

  log(ctx, `Building db using <user>/media for ${processes.length} users`);
  await getMany(processes, threadMax, directory);

  log(ctx, 'Building db using /search');
}

buildDb();