'use strict';

var instances = require('../instances');
var updateGeometry = require('../update-geometry');
var updateScroll = require('../update-scroll');

function bindClickRailHandler(element, i) {
  function pageOffset(el) {
    return el.getBoundingClientRect();
  }
  var stopPropagation = function (e) { e.stopPropagation(); };

  i.event.bind(i.scrollbarY, 'click', stopPropagation);
  i.event.bind(i.scrollbarYRail, 'click', function (e) {
    var positionTop = e.pageY - window.pageYOffset - pageOffset(i.scrollbarYRail).top;
    var direction = positionTop > i.scrollbarYTop ? 1 : -1;

    updateScroll(element, 'top', element.scrollTop + direction * i.containerHeight);
    updateGeometry(element);

    e.stopPropagation();
  });

  i.event.bind(i.scrollbarX, 'click', stopPropagation);
  i.event.bind(i.scrollbarXRail, 'click', function (e) {
    var positionLeft = e.pageX - window.pageXOffset - pageOffset(i.scrollbarXRail).left;
    var direction = positionLeft > i.scrollbarXLeft ? 1 : -1;

    updateScroll(element, 'left', element.scrollLeft + direction * i.containerWidth);
    updateGeometry(element);

    e.stopPropagation();
  });
}

module.exports = function (element) {
  var i = instances.get(element);
  bindClickRailHandler(element, i);
};