/* Receiving a message is not evidence of seeing it. No receipts are cached on disk. */
document.querySelectorAll('[data-conversation-workspace][data-read-url]').forEach(workspace=>{
  const scroller=workspace.querySelector('[data-conversation]');
  if(!scroller)return;
  const acknowledged=new Set(),tracked=new Set();
  let running=false,timer=0,controller=null;
  const cookie=name=>document.cookie.split('; ').find(row=>row.startsWith(`${name}=`))?.split('=').slice(1).join('=')||'';
  const visibleIds=()=>{
    if(document.visibilityState!=='visible' || workspace.dataset.accessDenied)return [];
    const bounds=scroller.getBoundingClientRect();
    const viewport=window.visualViewport;
    const viewTop=viewport?.offsetTop||0,viewLeft=viewport?.offsetLeft||0;
    const top=Math.max(bounds.top,viewTop),bottom=Math.min(bounds.bottom,viewTop+(viewport?.height||innerHeight));
    const left=Math.max(bounds.left,viewLeft),right=Math.min(bounds.right,viewLeft+(viewport?.width||innerWidth));
    return [...scroller.querySelectorAll('[data-message-id]')].filter(message=>{
      if(acknowledged.has(message.dataset.messageId) || message.hasAttribute('data-message-deleted'))return false;
      const box=message.getBoundingClientRect();
      const height=Math.min(box.bottom,bottom)-Math.max(box.top,top);
      if(box.height<=0 || box.width<=0 || height<Math.min(48,box.height) || Math.min(box.right,right)<=Math.max(box.left,left))return false;
      const x=(Math.max(box.left,left)+Math.min(box.right,right))/2;
      const y=(Math.max(box.top,top)+Math.min(box.bottom,bottom))/2;
      return message.contains(document.elementFromPoint(x,y));
    }).slice(0,100).map(message=>message.dataset.messageId);
  };
  const schedule=()=>{
    clearTimeout(timer);
    timer=setTimeout(send,250);
  };
  const denyAccess=()=>{
    workspace.dataset.accessDenied='true';
    delete workspace.dataset.pollUrl;
    controller?.abort();clearTimeout(timer);
    scroller.querySelectorAll('[data-load-older]').forEach(button=>window.htmx?.trigger(button,'htmx:abort'));
    scroller.querySelectorAll('[data-message],.date-divider,.conversation-empty,[data-load-older]').forEach(item=>item.remove());
    const notice=document.createElement('p');
    notice.className='conversation-empty';notice.textContent='دسترسی به این مکاتبات لغو شده است.';
    scroller.append(notice);
    const composer=workspace.querySelector('[data-composer-shell]');if(composer)composer.hidden=true;
    const jump=workspace.querySelector('[data-jump-latest]');if(jump)jump.hidden=true;
  };
  async function send(){
    if(running)return;
    const ids=visibleIds();if(!ids.length)return;
    running=true;controller=new AbortController();
    try{
      const response=await fetch(workspace.dataset.readUrl,{method:'POST',credentials:'same-origin',cache:'no-store',signal:controller.signal,
        headers:{'Content-Type':'application/json','X-CSRFToken':decodeURIComponent(cookie('csrftoken'))},body:JSON.stringify({message_ids:ids})});
      if(response.redirected || [401,403,404].includes(response.status)){workspace.dispatchEvent(new Event('conversation:access-denied'));return}
      if(!response.ok)throw new Error(`HTTP ${response.status}`);
      const data=await response.json();
      if(workspace.dataset.accessDenied)return;
      (data.read_ids||[]).forEach(id=>acknowledged.add(id));
      if(typeof data.unread_shares==='number')document.querySelectorAll('[data-share-unread-count]').forEach(badge=>{
        badge.textContent=String(data.unread_shares);badge.hidden=!data.unread_shares;
      });
    }catch(error){if(error.name!=='AbortError')console.error('Message read acknowledgement failed',error)}
    finally{running=false;controller=null;if(visibleIds().length)timer=setTimeout(send,3000)}
  }
  const observer=new IntersectionObserver(schedule,{root:scroller,threshold:[0,0.1,0.5,1]});
  const observeMessages=()=>{
    tracked.forEach(message=>{if(!scroller.contains(message)){observer.unobserve(message);tracked.delete(message)}});
    scroller.querySelectorAll('[data-message-id]').forEach(message=>{if(!tracked.has(message)){tracked.add(message);observer.observe(message)}});
    schedule();
  };
  new MutationObserver(observeMessages).observe(scroller,{childList:true,subtree:true});
  scroller.addEventListener('scroll',schedule,{passive:true});
  new ResizeObserver(schedule).observe(scroller);
  document.addEventListener('click',schedule);
  document.addEventListener('keydown',schedule);
  window.addEventListener('resize',schedule);
  window.visualViewport?.addEventListener('resize',schedule);
  document.addEventListener('visibilitychange',schedule);
  window.addEventListener('pageshow',schedule);
  workspace.addEventListener('conversation:access-denied',denyAccess);
  window.addEventListener('pagehide',()=>{clearTimeout(timer);controller?.abort()});
  observeMessages();
});