115 lines
4.2 KiB
JavaScript
115 lines
4.2 KiB
JavaScript
/* ============================================================================
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* opfs-worker.js — off-main-thread video download → OPFS
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*
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* One dedicated Worker per download (spawned by OPFS.downloadVideo in
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* opfs.js, terminated when finished). The worker does the whole job itself —
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* fetch from /api/download plus streaming writes via createSyncAccessHandle —
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* so a multi-hundred-MB save never allocates buffers or runs stream pumps on
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* the main thread. createSyncAccessHandle is worker-only but has wider
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* support than createWritable (Safari 15.2+ vs 18.2+), which also removes
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* the whole-file ArrayBuffer fallback the main-thread path needs on WebKit.
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*
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* In message: { videoId, url }
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* Out messages:
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* { type: 'unsupported' } → caller falls back to main thread
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* { type: 'progress', received } → bytes written so far
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* { type: 'done', ext } → file stored as <videoId>.<ext>
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* { type: 'error', error } → failed; .part cleaned up
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* ========================================================================== */
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'use strict';
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async function getVideosDir() {
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const root = await navigator.storage.getDirectory();
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return root.getDirectoryHandle('videos', { create: true });
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}
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function extFromContentType(ct) {
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ct = ct || 'video/mp4';
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return ct.includes('webm') ? 'webm' : ct.includes('ogg') ? 'ogg' : 'mp4';
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}
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self.onmessage = async (e) => {
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const { videoId, url } = e.data || {};
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if (
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typeof navigator === 'undefined' ||
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!navigator.storage ||
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typeof navigator.storage.getDirectory !== 'function' ||
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typeof FileSystemFileHandle === 'undefined' ||
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typeof FileSystemFileHandle.prototype.createSyncAccessHandle !== 'function'
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) {
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self.postMessage({ type: 'unsupported' });
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return;
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}
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let dir = null;
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let partName = null;
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try {
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const res = await fetch(url);
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if (!res.ok) {
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let msg = 'HTTP ' + res.status;
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try { msg = (await res.json()).error || msg; } catch { /* non-JSON */ }
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throw new Error(msg);
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}
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const ext = extFromContentType(res.headers.get('content-type'));
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const filename = videoId + '.' + ext;
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partName = filename + '.part';
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dir = await getVideosDir();
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const partHandle = await dir.getFileHandle(partName, { create: true });
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const access = await partHandle.createSyncAccessHandle();
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let offset = 0;
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try {
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const reader = res.body.getReader();
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for (;;) {
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const { done, value } = await reader.read();
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if (done) break;
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access.write(value, { at: offset });
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offset += value.byteLength;
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self.postMessage({ type: 'progress', received: offset });
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}
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access.truncate(offset);
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access.flush();
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} finally {
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access.close();
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}
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// Finalize: .part → permanent name. Prefer the native rename, but treat
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// ANY move() failure as "unavailable" and fall back to a chunked copy —
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// WebKit's move() has a different signature/behavior than Chrome's and
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// throws TypeError ("Not enough arguments") rather than being absent.
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try { await dir.removeEntry(filename); } catch { /* no previous copy */ }
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let renamed = false;
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if (typeof partHandle.move === 'function') {
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try { await partHandle.move(filename); renamed = true; } catch { /* copy below */ }
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}
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if (!renamed) {
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const finalHandle = await dir.getFileHandle(filename, { create: true });
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const out = await finalHandle.createSyncAccessHandle();
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try {
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const file = await partHandle.getFile();
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const CHUNK = 8 * 1024 * 1024;
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let pos = 0;
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while (pos < file.size) {
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const buf = await file.slice(pos, pos + CHUNK).arrayBuffer();
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out.write(new Uint8Array(buf), { at: pos });
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pos += buf.byteLength;
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}
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out.truncate(file.size);
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out.flush();
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} finally {
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out.close();
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}
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await dir.removeEntry(partName);
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}
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self.postMessage({ type: 'done', ext });
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} catch (err) {
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// Never leave a corrupt partial behind
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try { if (dir && partName) await dir.removeEntry(partName); } catch { /* gone */ }
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self.postMessage({ type: 'error', error: err && err.message ? err.message : String(err) });
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}
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};
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