/**
 * ─────────────────────────────────────────────
 *  SPB Drive — Personal Cloud Drive
 * ─────────────────────────────────────────────
 *  Author  : Simon-Pierre Boucher
 *  Contact : contact@spboucher.ai
 *  File    : src/preview/office.mjs
 *  Purpose : LibreOffice headless → PDF conversion, queued + cached by sha
 *  License : MIT © Simon-Pierre Boucher
 * ─────────────────────────────────────────────
 */

import { execFile } from 'node:child_process';
import { existsSync } from 'node:fs';
import { mkdtemp, readdir, rename, rm, symlink } from 'node:fs/promises';
import os from 'node:os';
import path from 'node:path';
import { promisify } from 'node:util';
import { config } from '../config.mjs';
import { blobPath } from '../storage/blobs.mjs';
import { enqueue, jobStatus } from './queue.mjs';
import { hasBin } from './thumbs.mjs';

const execFileP = promisify(execFile);
const OFFICE_TIMEOUT = 5 * 60_000;

export const OFFICE_EXTS = new Set(['doc', 'docx', 'xls', 'xlsx', 'ppt', 'pptx', 'odt', 'ods', 'odp', 'rtf']);

const officePdf = (sha) => path.join(config.cacheDir, 'office', `${sha}.pdf`);

/** Locate the LibreOffice binary (macOS app bundle or PATH). */
export async function sofficeBin() {
  const mac = '/Applications/LibreOffice.app/Contents/MacOS/soffice';
  if (existsSync(mac)) return mac;
  if (await hasBin('soffice')) return 'soffice';
  if (await hasBin('libreoffice')) return 'libreoffice';
  return null;
}

/** Conversion status: ready / processing / queued / unavailable / none. */
export function officeState(sha) {
  if (existsSync(officePdf(sha))) return { state: 'ready', path: officePdf(sha) };
  const job = jobStatus(`office:${sha}`);
  if (job?.status === 'running') return { state: 'processing' };
  if (job?.status === 'queued') return { state: 'queued' };
  if (job?.status === 'error') return { state: 'unavailable' };
  return { state: 'none' };
}

/**
 * Convert an office document blob to PDF (queued, cached).
 * @param {string} ext original extension so soffice picks the right filter
 * @returns {Promise<string|null>} pdf path, or null when LibreOffice is absent
 */
export async function convertToPdf(sha, ext) {
  const out = officePdf(sha);
  if (existsSync(out)) return out;
  const bin = await sofficeBin();
  if (!bin) return null;

  return enqueue(`office:${sha}`, async () => {
    if (existsSync(out)) return out;
    const workDir = await mkdtemp(path.join(os.tmpdir(), 'spbdrive-office-'));
    try {
      // soffice needs a real extension to choose an import filter.
      const input = path.join(workDir, `doc.${ext}`);
      await symlink(blobPath(sha), input);
      await execFileP(
        bin,
        ['--headless', '--norestore', `-env:UserInstallation=file://${workDir}/lo-profile`,
          '--convert-to', 'pdf', '--outdir', workDir, input],
        { timeout: OFFICE_TIMEOUT },
      );
      const produced = (await readdir(workDir)).find((f) => f.endsWith('.pdf'));
      if (!produced) throw new Error('LibreOffice produced no PDF');
      await rename(path.join(workDir, produced), out);
      return out;
    } finally {
      await rm(workDir, { recursive: true, force: true });
    }
  });
}