$(document).ready(function () {
  var dropdown = '';
  var menu = '';
  var tag = '';
  var dropdownHeight = 0;
  var menuHeight = 0;
  $('.dropdown-menu').mCustomScrollbar({
    advanced: {
      updateOnContentResize: true
    }
  });

  $('.dropdown-toggle').click(function () {
    // 先收起其他展开的，在展开
    $('.dropdown.open').not($(this).parents('.dropdown')).each(function() {
      $(this).removeClass('open').find('.dropdown-menu').slideUp();
    });
    // 展开点击的
    dropdown = $(this).parents('.dropdown');
    menu = dropdown.find('.dropdown-menu');
    tag = dropdown.find('.tag');

    if (menu.is(":hidden")) {
      // 因此其他
      menu.css({ height: 'auto' })
      menu.show();
      dropdownHeight = dropdown.outerHeight();
      menuHeight = menu.outerHeight();
      menu.hide();
    }

    if (!menu.is(":hidden")) {
      dropdown.removeClass('open');
      menu.slideUp();
    } else {
      menu.slideDown();
      dropdown.addClass('open');
    }
    updateDropdownPosition();


  });

  $(document).click(function (e) {
    if (!$(e.target).closest('.dropdown').length && dropdown) {
      dropdown.removeClass('open');
      menu.slideUp();
    }
  });

  $('.dropdown-menu li').click(function () {
    var selectedText = $(this).text();
    $(this).parents('.dropdown').find('.input-value').val(selectedText);
    // 设置标签
    tag.text(selectedText);
    dropdown.removeClass('open');
    menu.slideUp();
  });

  $(window).resize(function () {
    if (dropdown) {
      updateDropdownPosition();
    }
  });

  $(window).scroll(function () {
    if (dropdown) {
      updateDropdownPosition();
    }
  });

  function updateDropdownPosition() {
    var offset = dropdown.offset();
    var top = offset.top + dropdownHeight;
    var windowHeight = $(window).height();
    var scrollTop = $(window).scrollTop();

    if (top + menuHeight > windowHeight + scrollTop) {
      menu.css({
        top: 'auto',
        bottom: dropdownHeight + 'px'
      });
    } else {
      menu.css({
        top: dropdownHeight + 'px',
        bottom: 'auto'
      });
    }
  }
});