function calculateMenuPositions()

in modules/closure/select/select.js [1989:2133]
122 lines of code
24 McCabe index (conditional complexity)

    function calculateMenuPositions(scope, element, opts) {
      var
        containerNode = element[0],
        targetNode = opts.target[0].children[0], // target the label
        parentNode = $document[0].body,
        selectNode = opts.selectEl[0],
        contentNode = opts.contentEl[0],
        parentRect = parentNode.getBoundingClientRect(),
        targetRect = targetNode.getBoundingClientRect(),
        shouldOpenAroundTarget = false,
        bounds = {
          left: parentRect.left + SELECT_EDGE_MARGIN,
          top: SELECT_EDGE_MARGIN,
          bottom: parentRect.height - SELECT_EDGE_MARGIN,
          right: parentRect.width - SELECT_EDGE_MARGIN - ($mdUtil.floatingScrollbars() ? 16 : 0)
        },
        spaceAvailable = {
          top: targetRect.top - bounds.top,
          left: targetRect.left - bounds.left,
          right: bounds.right - (targetRect.left + targetRect.width),
          bottom: bounds.bottom - (targetRect.top + targetRect.height)
        },
        maxWidth = parentRect.width - SELECT_EDGE_MARGIN * 2,
        selectedNode = selectNode.querySelector('md-option[selected]'),
        optionNodes = selectNode.getElementsByTagName('md-option'),
        optgroupNodes = selectNode.getElementsByTagName('md-optgroup'),
        isScrollable = calculateScrollable(element, contentNode),
        centeredNode;

      var loading = isPromiseLike(opts.loadingAsync);
      if (!loading) {
        // If a selected node, center around that
        if (selectedNode) {
          centeredNode = selectedNode;
          // If there are option groups, center around the first option group
        } else if (optgroupNodes.length) {
          centeredNode = optgroupNodes[0];
          // Otherwise - if we are not loading async - center around the first optionNode
        } else if (optionNodes.length) {
          centeredNode = optionNodes[0];
          // In case there are no options, center on whatever's in there... (eg progress indicator)
        } else {
          centeredNode = contentNode.firstElementChild || contentNode;
        }
      } else {
        // If loading, center on progress indicator
        centeredNode = contentNode.firstElementChild || contentNode;
      }

      if (contentNode.offsetWidth > maxWidth) {
        contentNode.style['max-width'] = maxWidth + 'px';
      } else {
        contentNode.style.maxWidth = null;
      }
      if (shouldOpenAroundTarget) {
        contentNode.style['min-width'] = targetRect.width + 'px';
      }

      // Remove padding before we compute the position of the menu
      if (isScrollable) {
        selectNode.classList.add('md-overflow');
      }

      var focusedNode = centeredNode;
      if ((focusedNode.tagName || '').toUpperCase() === 'MD-OPTGROUP') {
        focusedNode = optionNodes[0] || contentNode.firstElementChild || contentNode;
        centeredNode = focusedNode;
      }
      // Cache for autoFocus()
      opts.focusedNode = focusedNode;

      // Get the selectMenuRect *after* max-width is possibly set above
      containerNode.style.display = 'block';
      var selectMenuRect = selectNode.getBoundingClientRect();
      var centeredRect = getOffsetRect(centeredNode);

      if (centeredNode) {
        var centeredStyle = $window.getComputedStyle(centeredNode);
        centeredRect.paddingLeft = parseInt(centeredStyle.paddingLeft, 10) || 0;
        centeredRect.paddingRight = parseInt(centeredStyle.paddingRight, 10) || 0;
      }

      if (isScrollable) {
        var scrollBuffer = contentNode.offsetHeight / 2;
        contentNode.scrollTop = centeredRect.top + centeredRect.height / 2 - scrollBuffer;

        if (spaceAvailable.top < scrollBuffer) {
          contentNode.scrollTop = Math.min(
            centeredRect.top,
            contentNode.scrollTop + scrollBuffer - spaceAvailable.top
          );
        } else if (spaceAvailable.bottom < scrollBuffer) {
          contentNode.scrollTop = Math.max(
            centeredRect.top + centeredRect.height - selectMenuRect.height,
            contentNode.scrollTop - scrollBuffer + spaceAvailable.bottom
          );
        }
      }

      var left, top, transformOrigin, minWidth, fontSize;
      if (shouldOpenAroundTarget) {
        left = targetRect.left;
        top = targetRect.top + targetRect.height;
        transformOrigin = '50% 0';
        if (top + selectMenuRect.height > bounds.bottom) {
          top = targetRect.top - selectMenuRect.height;
          transformOrigin = '50% 100%';
        }
      } else {
        left = (targetRect.left + centeredRect.left - centeredRect.paddingLeft);
        top = Math.floor(targetRect.top + targetRect.height / 2 - centeredRect.height / 2 -
            centeredRect.top + contentNode.scrollTop) + 2;

        transformOrigin = (centeredRect.left + targetRect.width / 2) + 'px ' +
          (centeredRect.top + centeredRect.height / 2 - contentNode.scrollTop) + 'px 0px';

        minWidth = Math.min(targetRect.width + centeredRect.paddingLeft + centeredRect.paddingRight, maxWidth);

        fontSize = window.getComputedStyle(targetNode)['font-size'];
      }

      // Keep left and top within the window
      var containerRect = containerNode.getBoundingClientRect();
      var scaleX = Math.round(100 * Math.min(targetRect.width / selectMenuRect.width, 1.0)) / 100;
      var scaleY = Math.round(100 * Math.min(targetRect.height / selectMenuRect.height, 1.0)) / 100;

      return {
        container: {
          element: angular.element(containerNode),
          styles: {
            left: Math.floor(clamp(bounds.left, left, bounds.right - minWidth)),
            top: Math.floor(clamp(bounds.top, top, bounds.bottom - containerRect.height)),
            'min-width': minWidth,
            'font-size': fontSize
          }
        },
        dropDown: {
          element: angular.element(selectNode),
          styles: {
            transformOrigin: transformOrigin,
            transform: !opts.alreadyOpen ? $mdUtil.supplant('scale({0},{1})', [scaleX, scaleY]) : ""
          }
        }
      };
    }