import {ProxyError} from './policy';
import {renderRelayEndpoint,type RenderConfig} from './render';

export async function wispReady(socket:WebSocket):Promise<boolean>{
 return new Promise(resolve=>{
  let done=false;
  const finish=(ready:boolean)=>{if(done)return;done=true;clearTimeout(timer);try{socket.close(1000,'Readiness check complete');}catch{}resolve(ready);};
  const timer=setTimeout(()=>finish(false),8000);
  socket.binaryType='arraybuffer';
  socket.addEventListener('message',event=>{
   if(!(event.data instanceof ArrayBuffer)||event.data.byteLength!==9)return;
   const packet=new DataView(event.data);
   // Initial Wisp CONTINUE packet for stream zero proves the protocol is ready.
   if(packet.getUint8(0)===3&&packet.getUint32(1,true)===0)finish(true);
  });
  socket.addEventListener('close',()=>finish(false));socket.addEventListener('error',()=>finish(false));
  socket.accept();
 });
}
export async function wakeRender(env:RenderConfig):Promise<Response>{
 const endpoint=renderRelayEndpoint(env);
 if(!endpoint)throw new ProxyError(503,'RENDER_CONFIG','The hosted relay is not configured.');
 const warming=()=>Response.json({ready:false},{status:202,headers:{'cache-control':'no-store'}});
 try{
  const root=new URL('/',endpoint),healthUrl=new URL('/healthz',endpoint);
  // Visiting either URL starts a sleeping Render service. Wait for both requests
  // to settle; never leave an unobserved background request or forward cookies.
  const [rootResult,healthResult]=await Promise.allSettled([
   fetch(root,{signal:AbortSignal.timeout(45000),redirect:'manual'}),
   fetch(healthUrl,{signal:AbortSignal.timeout(45000),redirect:'manual',headers:{Accept:'application/json'}})
  ]);
  if(rootResult.status==='fulfilled')await rootResult.value.body?.cancel();
  if(healthResult.status!=='fulfilled')return warming();
  const response=healthResult.value;
  if(!response.ok){await response.body?.cancel();return warming();}
  const health=await response.json() as {status?:string;service?:string};
  if(health.status!=='ok'||health.service!=='zeyads-relay')return warming();
  const wsResponse=await fetch(new URL('/wisp/',endpoint),{headers:{Upgrade:'websocket','x-relay-token':env.RELAY_SHARED_SECRET!},signal:AbortSignal.timeout(12000),redirect:'manual'});
  if(wsResponse.status!==101||!wsResponse.webSocket){await wsResponse.body?.cancel();return warming();}
  if(!await wispReady(wsResponse.webSocket))return warming();
  return Response.json({ready:true},{headers:{'cache-control':'no-store'}});
 }catch{return warming();}
}