/**
 * ─────────────────────────────────────────────
 *  SPB Drive — Personal Cloud Drive
 * ─────────────────────────────────────────────
 *  Author  : Simon-Pierre Boucher
 *  Contact : contact@spboucher.ai
 *  File    : src/preview/office-thumb.mjs
 *  Purpose : Thumbnail page 1 of a LibreOffice-converted PDF from cache
 *  License : MIT © Simon-Pierre Boucher
 * ─────────────────────────────────────────────
 */

import { execFile } from 'node:child_process';
import { existsSync } from 'node:fs';
import { rename, rm } from 'node:fs/promises';
import path from 'node:path';
import { promisify } from 'node:util';
import sharp from 'sharp';
import { config } from '../config.mjs';
import { enqueue } from './queue.mjs';
import { hasBin } from './thumbs.mjs';

const execFileP = promisify(execFile);

/** Thumbnail an office doc via its cached converted PDF (webp, cached). */
export async function getThumbFromFile(sha, size = 256) {
  const sz = Number(size) === 512 ? 512 : 256;
  const out = path.join(config.cacheDir, 'thumbs', `${sha}.${sz}.webp`);
  if (existsSync(out)) return out;
  const pdf = path.join(config.cacheDir, 'office', `${sha}.pdf`);
  if (!existsSync(pdf) || !(await hasBin('pdftoppm'))) return null;

  return enqueue(`thumb:${sha}:${sz}`, async () => {
    if (existsSync(out)) return out;
    const tmpBase = `${out}.tmp-${process.pid}`;
    try {
      await execFileP('pdftoppm', ['-png', '-f', '1', '-l', '1', '-scale-to', String(sz), pdf, tmpBase], {
        timeout: 60_000,
      });
      const png = `${tmpBase}-1.png`;
      if (!existsSync(png)) return null;
      await sharp(png).webp({ quality: 80 }).toFile(`${tmpBase}.webp`);
      await rm(png, { force: true });
      await rename(`${tmpBase}.webp`, out);
      return out;
    } catch {
      await rm(`${tmpBase}.webp`, { force: true });
      return null;
    }
  });
}