66 lines
3.6 KiB
JavaScript
66 lines
3.6 KiB
JavaScript
/* Cache the single page-owned app response before it registers the worker. */
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(function (root) {
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'use strict';
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const doc=root.document, manifest=root.Lazy.manifest, key=root.Lazy.url('/app.js');
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let domReady=doc.readyState==='complete', appSawDom=false;
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doc.addEventListener('DOMContentLoaded',()=>{domReady=true;appSawDom=typeof root.boot==='function';},{once:true});
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function execute(node) {
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doc.head.append(node);
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node.remove();
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delete root.Lazy.appResponse;
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// app.js keeps its original DOMContentLoaded listener. Async response
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// consumption can finish after that event; boot exactly once in that case.
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if(domReady)root.boot();
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}
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async function external(url) {
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await new Promise((resolve,reject)=>{
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const node=doc.createElement('script');node.src=url;
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node.onload=()=>{if(domReady&&!appSawDom)root.boot();resolve();};node.onerror=()=>reject(Error('Unable to load player'));
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doc.head.append(node);
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});
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}
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async function verified(response, expected) {
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const bytes=await response.clone().arrayBuffer();
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const digest=new Uint8Array(await root.crypto.subtle.digest('SHA-256',bytes));
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const hex=Array.from(digest,b=>b.toString(16).padStart(2,'0')).join('');
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if(hex.slice(0,10)!==expected)throw Error('Player body hash mismatch');
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return {bytes,digest};
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}
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async function start() {
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if(!manifest.appCache || !root.crypto?.subtle || !root.Lazy.captureApp)return external(key);
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const expected=manifest.files['/app.js'].h;
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let cache;
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try { cache=await root.caches?.open('ytplayer-assets'); } catch {}
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let response=await cache?.match(key);
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if(!response || response.headers.get('X-Asset-Hash')!==expected) {
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try { response=await (root.Lazy.appResponse || root.fetch(key,{credentials:'same-origin'})); } catch {}
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}
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if(!response?.ok || response.headers.get('X-Asset-Hash')!==expected) {
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// Preserve staged N-1 boot after an individual cache eviction. Only the
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// controller can serve this old URL safely; never fetch stale URLs bare.
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const state=cache && await root.AssetSyncCore.state(cache);
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const previousKey=state && root.AssetSyncCore.fallback(manifest,state.previous,'/app.js');
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const previous=previousKey && await cache.match(previousKey);
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const previousHash=state?.previous?.files['/app.js']?.h;
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const contractsMatch=state?.previous && Object.entries(manifest.groups).every(([name,group])=>state.previous.groups[name]?.contract===group.contract);
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if(contractsMatch && root.navigator?.serviceWorker?.controller && previous?.ok && previous.headers.get('X-Asset-Hash')===previousHash) {
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await verified(previous,previousHash);
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delete root.Lazy.appResponse;
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return external(previousKey);
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}
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throw Error('Player asset hash mismatch');
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}
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const {bytes,digest}=await verified(response,expected);
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const permission="'sha256-"+root.btoa(String.fromCharCode(...digest))+"'";
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if(!doc.querySelector('meta[http-equiv="Content-Security-Policy"]').content.includes(permission))throw Error('Player body hash mismatch');
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// CacheStorage may share a full quota with saved music. Never remove data
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// to make room; boot from these verified bytes even if caching is refused.
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try { await cache?.put(key,response); } catch(error) { root.console.warn('[app-cache]',error.message); }
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const node=doc.createElement('script');node.textContent=new root.TextDecoder().decode(bytes);
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execute(node);
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}
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const ready=start();
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root.AppBootstrap={ready};
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ready.catch(error=>root.console.error('[app-cache]',error.message));
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})(typeof window!=='undefined'?window:globalThis);
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