document.addEventListener('DOMContentLoaded', function(){
  const stage = document.getElementById('stage');
  const touches = new Map(); // id -> {el,x,y}
  let selecting = false;
  let selectionDone = false;
  let selectionTimer = null;

  function createFinger(t){
    const id = (t.identifier !== undefined && t.identifier !== null) ? String(t.identifier) : ('m'+Date.now());
    const el = document.createElement('div');
    el.className = 'finger';
    el.setAttribute('data-id', id);
    const label = document.createElement('div');
    label.className = 'label';
    label.textContent = '1';
    el.appendChild(label);
    el.style.left = t.clientX + 'px';
    el.style.top = t.clientY + 'px';
    stage.appendChild(el);
    touches.set(id, {el: el, x: t.clientX, y: t.clientY});
    updateLabels();
    return id;
  }

  function updateFinger(t){
    const id = (t.identifier !== undefined && t.identifier !== null) ? String(t.identifier) : 'm';
    const entry = touches.get(id);
    if(entry){ entry.x = t.clientX; entry.y = t.clientY; entry.el.style.left = t.clientX + 'px'; entry.el.style.top = t.clientY + 'px'; }
  }

  function removeFingerById(id){
    const key = String(id);
    const entry = touches.get(key);
    if(entry){ entry.el.remove(); touches.delete(key); updateLabels(); }
  }

  function updateLabels(){
    let i=1;
    for(const entry of touches.values()){
      const lbl = entry.el.querySelector('.label');
      if(lbl) lbl.textContent = String(i++);
    }
  }

  function computeOrderedItems(){
    const arr = Array.from(touches.entries()).map(([id,entry])=>({id,el:entry.el,x:entry.x,y:entry.y}));
    const cx = arr.reduce((s,a)=>s+a.x,0)/arr.length;
    const cy = arr.reduce((s,a)=>s+a.y,0)/arr.length;
    arr.forEach(a=>{
      const ang = Math.atan2(a.y-cy,a.x-cx) * 180/Math.PI; // -180..180
      a.angle = (ang+360)%360; // 0..360
      a.dist = Math.hypot(a.x-cx,a.y-cy);
    });
    arr.sort((a,b)=>a.angle-b.angle);
    return {items:arr, center:{x:cx,y:cy}};
  }

  function startSelectionIfNeeded(){
    if(selecting || selectionDone) return;
    if(touches.size < 1) return; // require at least 1 finger
    selecting = true;

    const {items} = computeOrderedItems();
    const els = items.map(i=>i.el);
    const n = els.length;

    // If only one finger, immediately mark it as winner (short visual)
    if(n === 1){
      const el = els[0];
      el.classList.add('winner','pulse');
      selecting = false;
      selectionDone = true;
      return;
    }

    const rotations = Math.floor(Math.random()*3)+3; // 3-5 rotations
    const winnerIndex = Math.floor(Math.random()*n);
    const totalSteps = rotations * n + winnerIndex;

    let cumulative = 0;
    let current = 0;
    for(let step=0; step<=totalSteps; step++){
      const t = step/totalSteps;
      const delay = 40 + Math.pow(t,2)*520; // ease-out timing
      cumulative += delay;
      const idx = current % n;
      setTimeout(()=>{
        els.forEach((el,i)=>{
          if(i===idx) el.classList.add('highlight'); else el.classList.remove('highlight');
        });
      }, cumulative);
      current++;
    }

    setTimeout(()=>{
      els.forEach((el,i)=>{
        if(i===winnerIndex){ el.classList.remove('highlight'); el.classList.add('winner','pulse'); }
        else { el.classList.remove('highlight'); el.classList.add('lost'); }
      });
      selecting = false;
      selectionDone = true;
    }, cumulative + 80);
  }

  function cancelSelection(){
    clearTimeout(selectionTimer);
    selectionTimer = null;
    selecting = false;
    selectionDone = false;
    for(const entry of touches.values()){ entry.el.classList.remove('highlight','lost','winner','pulse'); entry.el.style.opacity = '1'; }
  }

  function resetWhenAllUp(){
    if(touches.size===0){
      setTimeout(()=>{
        selecting=false; selectionDone=false;
        const nodes = Array.from(stage.querySelectorAll('.finger'));
        nodes.forEach(node=>node.remove());
        touches.clear();
      },160);
    }
  }

  // Touch handlers
  stage.addEventListener('touchstart', function(e){
    e.preventDefault();
    const changed = Array.from(e.changedTouches || []);
    changed.forEach(t=>createFinger(t));
    if(!selectionDone){
      clearTimeout(selectionTimer);
      selectionTimer = setTimeout(startSelectionIfNeeded, 700);
    }
  }, {passive:false});
  stage.addEventListener('touchmove', function(e){
    e.preventDefault();
    const changed = Array.from(e.changedTouches || []);
    changed.forEach(t=>updateFinger(t));
  }, {passive:false});
  stage.addEventListener('touchend', function(e){
    e.preventDefault();
    const changed = Array.from(e.changedTouches || []);
    changed.forEach(t=>removeFingerById(t.identifier));
    if(!selectionDone) cancelSelection();
    if(touches.size===0) resetWhenAllUp();
  }, {passive:false});
  stage.addEventListener('touchcancel', function(e){
    e.preventDefault();
    const changed = Array.from(e.changedTouches || []);
    changed.forEach(t=>removeFingerById(t.identifier));
    if(!selectionDone) cancelSelection();
    if(touches.size===0) resetWhenAllUp();
  }, {passive:false});

  // Support mouse for desktop testing
  let mouseDown = false;
  const mouseId = 'mouse';
  stage.addEventListener('mousedown', function(e){
    mouseDown = true;
    createFinger({identifier:mouseId, clientX:e.clientX, clientY:e.clientY});
    cancelSelection();
    startSelectionIfNeeded();
  });
  window.addEventListener('mousemove', function(e){ if(!mouseDown) return; updateFinger({identifier:mouseId, clientX:e.clientX, clientY:e.clientY}); });
  window.addEventListener('mouseup', function(e){ if(!mouseDown) return; mouseDown=false; removeFingerById(mouseId); if(!selectionDone) cancelSelection(); if(touches.size===0) resetWhenAllUp(); });

});