/* Shared finger-following track for skin choices and report detail panels. */
window.SwipeTrack = (function () {
  'use strict';
  function create(viewport, track, options) {
    var target = options.gestureTarget || viewport, index = 0;
    var drag = { id: null, horizontal: false, vertical: false }, suppressUntil = 0;
    function release() {
      var id = drag.id;
      drag.id = null; drag.horizontal = drag.vertical = false;
      viewport.classList.remove('dragging'); track.classList.remove('dragging');
      try { if (id != null && target.hasPointerCapture(id)) target.releasePointerCapture(id); } catch (_) {}
    }
    function go(next, instant) {
      index = Math.max(0, Math.min(options.count - 1, next));
      release();
      if (instant) track.style.transition = 'none';
      track.style.transform = 'translateX(-' + index * 100 + '%)';
      if (instant) { void track.offsetWidth; track.style.transition = ''; }
    }
    function cancel() { go(index, true); if (options.onCancel) options.onCancel(index); }
    function lockDirection(dx, dy) {
      if (drag.vertical) return false;
      if (drag.horizontal) return true;
      var threshold = options.startThreshold || 8, ratio = options.directionRatio || 1;
      if (Math.max(Math.abs(dx), Math.abs(dy)) <= threshold) return false;
      // Touch and pointer events must share the same decision, regardless of
      // which event stream the browser dispatches first.
      if (Math.abs(dy) * ratio >= Math.abs(dx)) { drag.vertical = true; return false; }
      drag.horizontal = true;
      if (options.onStart) options.onStart(index);
      viewport.classList.add('dragging'); track.classList.add('dragging');
      try { target.setPointerCapture(drag.id); } catch (_) {}
      return true;
    }
    target.addEventListener('pointerdown', function (e) {
      if (drag.id != null || e.isPrimary === false || e.button !== 0 || !viewport.clientWidth) return;
      suppressUntil = 0; // A fresh tap is intentional, not the preceding drag's click.
      if (options.gestureSelector && (!e.target.closest || !e.target.closest(options.gestureSelector))) return;
      drag.id = e.pointerId; drag.startX = e.clientX; drag.startY = e.clientY;
      drag.offset = track.getBoundingClientRect().left - viewport.getBoundingClientRect().left;
      drag.width = viewport.clientWidth; drag.lastX = e.clientX; drag.lastAt = e.timeStamp; drag.velocity = 0;
      drag.horizontal = drag.vertical = false;
      // Capture only after direction lock: an ordinary image tap must still zoom.
    });
    target.addEventListener('pointermove', function (e) {
      if (e.pointerId !== drag.id || drag.vertical) return;
      var dx = e.clientX - drag.startX, dy = e.clientY - drag.startY;
      if (!lockDirection(dx, dy)) return;
      if (e.cancelable) e.preventDefault();
      var elapsed = e.timeStamp - drag.lastAt;
      if (elapsed > 0) drag.velocity = (e.clientX - drag.lastX) / elapsed;
      drag.lastX = e.clientX; drag.lastAt = e.timeStamp;
      var offset = drag.offset + dx, min = -(options.count - 1) * drag.width;
      var edgeLimit = options.maxOverscroll == null ? Infinity : options.maxOverscroll;
      if (offset > 0) offset = Math.min(edgeLimit, offset * .25);
      else if (offset < min) offset = min - Math.min(edgeLimit, (min - offset) * .25);
      track.style.transform = 'translate3d(' + offset + 'px,0,0)';
      if (options.onMove) options.onMove(Math.max(0, Math.min(options.count - 1, -offset / drag.width)));
    });
    if (options.preventNativeHorizontalPan) {
      // preventDefault on pointermove does not stop native viewport panning.
      // Cancel only the single-touch horizontal gesture before the browser
      // starts scrolling and sends pointercancel. Vertical/text/multi-touch
      // gestures keep their native behavior; taps still open image zoom.
      target.addEventListener('touchmove', function (e) {
        if (drag.id == null || e.touches.length !== 1) return;
        var touch = e.touches[0];
        if (lockDirection(touch.clientX - drag.startX, touch.clientY - drag.startY) && e.cancelable) e.preventDefault();
      }, { passive: false });
    }
    window.addEventListener('pointerup', function (e) {
      if (e.pointerId !== drag.id) return;
      var horizontal = drag.horizontal, dx = e.clientX - drag.startX, next = index;
      if (horizontal) {
        var start = Math.round(-drag.offset / drag.width);
        next = start;
        var speed = e.timeStamp - drag.lastAt > 100 ? 0 : drag.velocity;
        if (Math.abs(dx) >= Math.min(50, drag.width * .2) || (Math.abs(dx) > 12 && Math.abs(speed) > .4)) {
          next = Math.round(-(drag.offset + dx) / drag.width);
          if (next === start) next += (Math.abs(speed) > .4 ? speed : dx) < 0 ? 1 : -1;
        }
        suppressUntil = Date.now() + 350;
      }
      go(next);
      if (horizontal && options.onSelect) options.onSelect(index);
    });
    window.addEventListener('pointercancel', function (e) { if (e.pointerId === drag.id) cancel(); });
    target.addEventListener('lostpointercapture', function (e) {
      // Touch starts with implicit capture on an image/button. Its bubbled loss
      // when we take horizontal capture is not a cancellation of this track.
      if (e.target === target && e.pointerId === drag.id) cancel();
    });
    target.addEventListener('dragstart', function (e) { e.preventDefault(); });
    target.addEventListener('click', function (e) {
      if (Date.now() < suppressUntil) { e.preventDefault(); e.stopPropagation(); }
    }, true);
    window.addEventListener('resize', cancel);
    go(0, true);
    return { go: go, cancel: cancel, isDragging: function () { return drag.horizontal; } };
  }
  return { create: create };
})();