/* teach - start: beeldgrootte, contrast, sessie-herstel */
/* =========================================================
   init
==========================================================*/
/* display size: scale the whole app up for pupils who need it (device setting) */
let ZOOM = 100;
const btnZoomIn = document.getElementById("btnZoomIn");
const btnZoomOut = document.getElementById("btnZoomOut");
const zoomPct = document.getElementById("zoomPct");
function setZoom(z){
  ZOOM = Math.max(100, Math.min(200, Math.round(z/10)*10));
  document.body.style.zoom = ZOOM/100;
  zoomPct.textContent = ZOOM+"%";
  zoomPct.classList.toggle("on", ZOOM!==100);
  btnZoomIn.title = btnZoomOut.title = zoomPct.title = T("zoomUI");
  btnZoomIn.disabled = ZOOM>=200;
  btnZoomOut.disabled = ZOOM<=100;
  try{ localStorage.setItem("teach.zoom", ZOOM); }catch(e){}
}
btnZoomIn.addEventListener("click", ()=>setZoom(ZOOM+10));
btnZoomOut.addEventListener("click", ()=>setZoom(ZOOM-10));
zoomPct.addEventListener("click", ()=>setZoom(100));   /* tap the % to reset */
document.addEventListener("langchange", ()=>{ btnZoomIn.title = btnZoomOut.title = zoomPct.title = T("zoomUI"); });
try{ const z = +localStorage.getItem("teach.zoom"); if(z>100) setZoom(z); else setZoom(100); }catch(e){ setZoom(100); }

/* high-contrast accessibility mode (device setting, persists) */
const btnHC = document.getElementById("btnHC");
function setHC(on){
  document.body.classList.toggle("hc", on);
  btnHC.classList.toggle("on", on);
  btnHC.title = T("a11y");
  try{ localStorage.setItem("teach.hc", on ? "1" : ""); }catch(e){}
}
btnHC.addEventListener("click", ()=>setHC(!document.body.classList.contains("hc")));
document.addEventListener("langchange", ()=>{ btnHC.title = T("a11y"); });
try{ if(localStorage.getItem("teach.hc")==="1") setHC(true); }catch(e){}

applyI18n();
updateEmptyHint();
/* restore session (same browser tab session only) */
(function(){
  let name = null;
  try{ name = sessionStorage.getItem("teach.session"); }catch(e){}
  const users = loadUsers();
  if(name && users[name]){
    currentUser = { name, data: users[name].data };
    THEMES = themesFromData(currentUser.data);
    GENERAL_EXTRA = generalExtraFromData(currentUser.data);
    updateUserUI();
    BS = boardsFromData(currentUser.data);
    loadCurrentSlot();
  }else{
    updateBoardsUI();
  }
})();