/* One scene owner. Handoffs happen only at a real ended event and a ready first frame. */
(function(){
'use strict';
const stage=document.querySelector('#stage');
if(!stage||document.documentElement.classList.contains('content-reader'))return;
const slots={idle:null,thinking:null,broadcast:null},entries=new Set();
let current=null,target=null,pageActive=true,scheduled=false;
const visible=()=>pageActive&&!document.hidden;
const wanted=()=>[slots.broadcast,slots.thinking,slots.idle].find(d=>d&&!d.failed&&!d.blocked)||null;
function schedule(){if(!scheduled){scheduled=true;queueMicrotask(()=>{scheduled=false;sync();});}}
function clearTimer(d){clearTimeout(d?.timer);if(d)d.timer=0;}
function arm(d){clearTimer(d);if(visible())d.timer=setTimeout(()=>fail(d,new Error('Avatar media stalled')),12000);}
function retained(d){return d===current||Object.values(slots).includes(d);}
function collect(d){
 if(!d||retained(d)||(!d.retired&&d.keep))return;
 clearTimer(d);d.disposed=true;entries.delete(d);
 d.video.pause();for(const [name,fn] of d.listeners)d.video.removeEventListener(name,fn);
 d.dispose?.();
}
function fail(d,error){
 if(d.disposed||d.failed)return;
 d.failed=true;clearTimer(d);d.video.pause();d.onError?.(error);
 if(current===d){current=null;d.onLeave?.();}
 schedule();
}
function play(d){
 if(!d||d.disposed||d.failed||d.blocked||d.playingPromise||!visible())return;
 if(d===current&&d===wanted()&&d.userPaused)return;
 if(!d.video.paused&&!d.video.ended)return;
 d.playingPromise=true;
 Promise.resolve(d.video.play()).then(()=>{
  if(current!==d||!visible()||(d.userPaused&&wanted()===d))d.video.pause();
 }).catch(error=>{
  if(d.disposed||current!==d||!visible()||error.name==='AbortError')return;
  if(error.name==='NotAllowedError'){d.blocked=true;clearTimer(d);if(current===d){current=null;d.preparing=false;d.onLeave?.();}d.onBlocked?.();schedule();}else fail(d,error);
 }).finally(()=>{d.playingPromise=false;});
}
function prepare(d){
 if(!d||d===current||d.preparing||d.failed)return;
 d.preparing=true;d.ready=false;d.video.preload='auto';d.video.autoplay=false;d.video.loop=false;
 d.prepare?.();
 if(d.video.readyState>=1&&d.video.currentTime!==0){try{d.video.currentTime=0;}catch{}}
 arm(d);ready(d);
}
function ready(d){
 if(d.disposed||d===current||!d.preparing||d.failed)return;
 if(d.video.readyState>=1&&d.video.currentTime!==0){if(!d.video.seeking)try{d.video.currentTime=0;}catch{}return;}
 if(d.video.readyState>=2&&!d.video.seeking){d.ready=true;clearTimer(d);schedule();}
}
function notify(){window.dispatchEvent(new CustomEvent('zhiwei-avatar-scene',{detail:{state:current?.slot||'idle',pending:target?.slot||null}}));}
function enter(d){
 if(!d||d!==wanted()||!d.ready||!visible())return;
 const previous=current;
 if(previous){previous.video.pause();clearTimer(previous);previous.onLeave?.();previous.ready=false;previous.preparing=false;
  if(document.fullscreenElement===previous.video)document.exitFullscreen?.().catch(()=>{});
  if(previous.video.webkitDisplayingFullscreen)previous.video.webkitExitFullscreen?.();
 }
 current=d;target=null;d.preparing=false;d.ready=false;d.atEnd=false;d.blocked=false;
 d.video.muted=d.muted;d.onEnter?.();notify();play(d);collect(previous);
}
function ended(d){
 if(d!==current||d.disposed)return;
 d.atEnd=true;clearTimer(d);
 if(wanted()!==d){schedule();return;}
 if(d.onEnded)d.onEnded();
 else{d.atEnd=false;try{d.video.currentTime=0;}catch{}play(d);}
 schedule();
}
function sync(){
 const next=wanted();target=next!==current?next:null;
 for(const d of entries)if(d!==current&&d!==target){clearTimer(d);collect(d);}
 if(!visible()){
  if(current)current.video.pause();
  for(const d of entries)clearTimer(d);
  return;
 }
 if(target){
  prepare(target);
  // Retain the outgoing frame until the incoming first frame is decoded.
  if(!current||current.failed||current.atEnd||current.video.ended){if(target.ready)enter(target);else arm(target);}
  else{
   // A stopped/replaced narration finishes its visual motion silently.
   if(current.slot==='broadcast')current.video.muted=true;
   current.video.loop=false;play(current);
  }
 }else if(current){
  current.video.muted=current.muted;
  if(current.atEnd||current.video.ended){
   if(!current.onEnded){current.atEnd=false;current.video.currentTime=0;play(current);}
  }else play(current);
 }
}
function create(options){
 const d={...options,slot:options.slot,muted:!!options.muted,keep:!!options.keep,ready:false,preparing:false,atEnd:false,failed:false,blocked:false,userPaused:false,listeners:[]};
 const v=d.video;v.loop=false;v.autoplay=false;v.muted=d.muted;
 function on(name,fn){v.addEventListener(name,fn);d.listeners.push([name,fn]);}
 for(const event of ['loadedmetadata','loadeddata','canplay','seeked'])on(event,()=>ready(d));
 on('ended',()=>ended(d));
 on('pause',()=>{if(current===d&&wanted()===d&&visible()&&v.controls&&!v.ended&&!d.failed)d.userPaused=true;});
 on('play',()=>{if(current===d&&wanted()===d&&visible()&&v.controls)d.userPaused=false;});
 on('error',()=>fail(d,v.error||new Error('Avatar media unavailable')));
 on('playing',()=>{
  if(current!==d||!visible()||(d.userPaused&&wanted()===d)){v.pause();return;}
  clearTimer(d);d.onPlaying?.();
 });
 on('timeupdate',()=>{if(current===d)clearTimer(d);});
 for(const event of ['waiting','stalled'])on(event,()=>{if(current===d&&!d.userPaused)arm(d);});
 entries.add(d);return d;
}
function set(slot,d){
 const previous=slots[slot];slots[slot]=d;
 if(d){d.slot=slot;d.userPaused=false;}
 if(previous!==d)collect(previous);
 schedule();
}
function pause(d){if(!d)return;d.userPaused=true;clearTimer(d);if(d===current)d.video.pause();}
function resume(d){if(!d||d.disposed)return;d.userPaused=false;d.blocked=false;if(d===current&&(d.atEnd||d.video.ended)){d.atEnd=false;d.video.currentTime=0;}if(d.failed){d.failed=false;d.video.load();d.preparing=false;}set(d.slot,d);}
function retire(d){if(!d)return;d.retired=true;if(slots[d.slot]===d)slots[d.slot]=null;collect(d);schedule();}
function recover(){
 if(!visible())return;
 let changed=false;
 for(const d of entries)if(d.blocked){d.blocked=false;changed=true;}
 if(changed)schedule();
}
document.addEventListener('visibilitychange',schedule);
window.addEventListener('pagehide',()=>{pageActive=false;sync();});
window.addEventListener('pageshow',()=>{pageActive=true;recover();schedule();});
document.addEventListener('pointerdown',recover,{passive:true});
document.addEventListener('keydown',recover);
window.addEventListener('online',recover);
window.AvatarScene={create,set,pause,resume,retire,recover,getCurrent:()=>current,getPending:()=>target};
})();