/* Put a video file on the device itself (Photos / Files / Downloads).
 * Pure helpers + the three ways a browser can do it; the app decides which
 * source (saved copy, server copy, other devices) the bytes come from.
 *   DeviceExport.fileName(title, ext)        → safe "Title.ext"
 *   DeviceExport.canShareFile(file)          → Web Share with files works here
 *   DeviceExport.canPickLocation()           → "Save as…" dialog exists (desktop Chromium)
 *   DeviceExport.share(file, name, title)    → share sheet ("Save Video" → Photos / Files)
 *   DeviceExport.pick(file, name)            → stream into a user-chosen file
 *   DeviceExport.download(urlOrFile, name)   → plain browser download
 */
(function (root) {
  'use strict';
  const BAD = /[\u0000-\u001f\\/:*?"<>|]+/g;

  function fileName(title, ext, fallback) {
    const base = String(title || '').replace(BAD, ' ').replace(/\s+/g, ' ').trim().slice(0, 120)
      || String(fallback || 'video');
    const e = String(ext || 'mp4').replace(/^\./, '').toLowerCase().replace(/[^a-z0-9]/g, '') || 'mp4';
    return `${base}.${e}`;
  }
  const mimeFor = (name) => (/\.(m4a|mp3|aac|opus|ogg|flac|wav)$/i.test(name) ? 'audio/mp4' : /\.webm$/i.test(name) ? 'video/webm' : 'video/mp4');
  const typed = (file, name) => (file.type ? file : new File([file], name, { type: mimeFor(name) }));

  function canShareFile(file) {
    try {
      if (!navigator.canShare || !navigator.share || !file) return false;
      return navigator.canShare({ files: [typed(file, file.name || 'video.mp4')] });
    } catch { return false; }
  }
  const canPickLocation = () => typeof root.showSaveFilePicker === 'function' && !/Android|iPhone|iPad/i.test(navigator.userAgent || '');

  // Resolves 'shared' | 'cancelled'; rejects on a real failure.
  async function share(file, name, title) {
    // new File() over an OPFS file does not copy it — it stays disk-backed.
    const f = new File([file], name, { type: file.type || mimeFor(name) });
    try {
      await navigator.share({ files: [f], title: title || name });
      return 'shared';
    } catch (e) {
      if (e && e.name === 'AbortError') return 'cancelled';
      throw e;
    }
  }

  async function pick(file, name) {
    let handle;
    try {
      handle = await root.showSaveFilePicker({ suggestedName: name, types: [{ description: 'Video', accept: { [mimeFor(name)]: ['.' + name.split('.').pop()] } }] });
    } catch (e) {
      if (e && e.name === 'AbortError') return 'cancelled';
      throw e;
    }
    const w = await handle.createWritable();
    await file.stream().pipeTo(w); // chunked: a multi-GB file is never held in memory
    return 'saved';
  }

  // A File/Blob → object URL; a string → used as the href directly (server copy).
  function download(src, name) {
    const isStr = typeof src === 'string';
    const href = isStr ? src : URL.createObjectURL(src);
    const a = document.createElement('a');
    a.href = href;
    a.download = name;
    a.rel = 'noopener';
    document.body.appendChild(a);
    a.click();
    a.remove();
    if (!isStr) setTimeout(() => URL.revokeObjectURL(href), 10 * 60 * 1000);
    return 'started';
  }

  root.DeviceExport = { fileName, canShareFile, canPickLocation, share, pick, download };
  if (typeof module !== 'undefined' && module.exports) module.exports = root.DeviceExport;
})(typeof window !== 'undefined' ? window : globalThis);