/* Live klasdashboard: rendert actieve en recente leersessies en houdt de
   weergave via Server-Sent Events actueel. Een 30-secondencontrole is alleen
   een vangnet voor tijdelijk weggevallen mobiele/proxyverbindingen. */
"use strict";

function liveSessionTime(value){
  const seconds=Math.max(0,Math.round((Date.now()-new Date(value).getTime())/1000));
  if(seconds<60)return T("amLiveJustNow");
  const minutes=Math.floor(seconds/60);
  if(minutes<60)return T("amLiveMinutes").replace("{count}",minutes);
  const hours=Math.floor(minutes/60);
  return T("amLiveHours").replace("{count}",hours);
}

function updateLiveConnectionState(host,state){
  const badge=host.querySelector(".live-connection");
  if(!badge)return;
  badge.className="live-connection "+state;
  badge.textContent=T(state==="connected"?"amLiveConnected":"amLiveReconnecting");
}

function renderLiveSessionOverview(host,data,onPupil){
  const section=document.createElement("section");
  section.className="live-session-overview";
  const head=document.createElement("div");
  head.className="live-session-head";
  const title=document.createElement("strong");
  title.textContent=T("amLiveSessions");
  const connection=document.createElement("span");
  connection.className="live-connection connecting";
  connection.textContent=T("amLiveReconnecting");
  head.append(title,connection);
  section.appendChild(head);

  const sessions=data.sessions||[];
  const active=sessions.filter(session=>session.status==="live");
  const recent=sessions.filter(session=>session.status!=="live").slice(0,20);
  const renderGroup=(label,items,emptyKey)=>{
    const group=document.createElement("div");
    group.className="live-session-group";
    const groupHead=document.createElement("div");
    groupHead.className="live-session-group-head";
    const groupTitle=document.createElement("strong");
    groupTitle.textContent=label;
    const count=document.createElement("span");
    count.textContent=String(items.length);
    groupHead.append(groupTitle,count);
    group.appendChild(groupHead);
    if(!items.length){
      const empty=document.createElement("div");
      empty.className="guestnote";
      empty.textContent=T(emptyKey);
      group.appendChild(empty);
      section.appendChild(group);
      return;
    }
    const grid=document.createElement("div");
    grid.className="live-session-grid";
    items.forEach(session=>{
      const card=document.createElement("button");
      card.type="button";
      const justStarted=session.status==="live"
        && new Date(data.serverTime||Date.now()).getTime()-new Date(session.startedAt).getTime()<60000;
      card.className="live-session-card "+(session.status==="live"?"live":"recent");
      const status=document.createElement("span");
      status.className="live-session-status";
      status.textContent=T(justStarted?"amLiveNew":session.status==="live"?"amLiveWorking":"amLiveEnded");
      const name=document.createElement("strong");
      name.className="live-session-name";
      name.textContent=session.pupilName;
      const widget=document.createElement("span");
      widget.className="live-session-widget";
      widget.textContent=(T("wg_"+session.widgetType)||session.widgetType)+" · "+T(session.mode==="kijken"?"amModeWatch":"amModeWork");
      const time=document.createElement("span");
      time.className="live-session-time";
      time.textContent=T(session.status==="live"?"amLiveStarted":"amLiveLastSeen")+" "+
        liveSessionTime(session.status==="live"?session.startedAt:session.lastSeenAt);
      card.append(status,name,widget,time);
      if(session.progressCount){
        const score=document.createElement("span");
        score.className="live-session-score";
        score.textContent=T("amLiveUpdates").replace("{count}",session.progressCount);
        if(session.attempts)score.textContent+=" · "+T("amLiveScore")
          .replace("{correct}",session.correct).replace("{attempts}",session.attempts);
        card.appendChild(score);
      }
      card.addEventListener("click",()=>onPupil(session.pupilId));
      grid.appendChild(card);
    });
    group.appendChild(grid);
    section.appendChild(group);
  };
  renderGroup(T("amLiveNow"),active,"amLiveNone");
  renderGroup(T("amLiveRecent"),recent,"amLiveRecentNone");
  host.appendChild(section);
}

function connectLiveClassDashboard(classId,onChange,isActive,onState){
  let source=null;
  let stopped=false;
  let reloadTimer=null;
  const queueReload=()=>{
    clearTimeout(reloadTimer);
    reloadTimer=setTimeout(()=>{if(!stopped&&isActive())onChange();},180);
  };
  if(typeof EventSource!=="undefined"){
    source=new EventSource("/api/progress/live/class/"+encodeURIComponent(classId)+"/stream");
    source.onopen=()=>onState("connected");
    source.onerror=()=>onState("reconnecting");
    source.addEventListener("sessions",queueReload);
  }
  const fallback=setInterval(()=>{
    if(!isActive()){stop();return;}
    onChange();
  },30000);
  function stop(){
    if(stopped)return;
    stopped=true;
    clearInterval(fallback);
    clearTimeout(reloadTimer);
    if(source)source.close();
  }
  return stop;
}