1 files changed, 171 insertions, 0 deletions
diff --git a/app/assets/javascripts/fly_out_nav.js b/app/assets/javascripts/fly_out_nav.js
new file mode 100644
index 00000000000..cbc3ad23990
--- /dev/null
+++ b/app/assets/javascripts/fly_out_nav.js
@@ -0,0 +1,171 @@
+import Cookies from 'js-cookie';
+import bp from './breakpoints';
+
+const HIDE_INTERVAL_TIMEOUT = 300;
+const IS_OVER_CLASS = 'is-over';
+const IS_ABOVE_CLASS = 'is-above';
+const IS_SHOWING_FLY_OUT_CLASS = 'is-showing-fly-out';
+let currentOpenMenu = null;
+let menuCornerLocs;
+let timeoutId;
+
+export const mousePos = [];
+
+export const setOpenMenu = (menu = null) => { currentOpenMenu = menu; };
+
+export const slope = (a, b) => (b.y - a.y) / (b.x - a.x);
+
+export const canShowActiveSubItems = (el) => {
+  const isHiddenByMedia = bp.getBreakpointSize() === 'sm' || bp.getBreakpointSize() === 'md';
+
+  if (el.classList.contains('active') && !isHiddenByMedia) {
+    return Cookies.get('sidebar_collapsed') === 'true';
+  }
+
+  return true;
+};
+
+export const canShowSubItems = () => bp.getBreakpointSize() === 'sm' || bp.getBreakpointSize() === 'md' || bp.getBreakpointSize() === 'lg';
+
+export const getHideSubItemsInterval = () => {
+  if (!currentOpenMenu) return 0;
+
+  const currentMousePos = mousePos[mousePos.length - 1];
+  const prevMousePos = mousePos[0];
+  const currentMousePosY = currentMousePos.y;
+  const [menuTop, menuBottom] = menuCornerLocs;
+
+  if (currentMousePosY < menuTop.y ||
+      currentMousePosY > menuBottom.y) return 0;
+
+  if (slope(prevMousePos, menuBottom) < slope(currentMousePos, menuBottom) &&
+    slope(prevMousePos, menuTop) > slope(currentMousePos, menuTop)) {
+    return HIDE_INTERVAL_TIMEOUT;
+  }
+
+  return 0;
+};
+
+export const calculateTop = (boundingRect, outerHeight) => {
+  const windowHeight = window.innerHeight;
+  const bottomOverflow = windowHeight - (boundingRect.top + outerHeight);
+
+  return bottomOverflow < 0 ? (boundingRect.top - outerHeight) + boundingRect.height :
+    boundingRect.top;
+};
+
+export const hideMenu = (el) => {
+  if (!el) return;
+
+  const parentEl = el.parentNode;
+
+  el.style.display = ''; // eslint-disable-line no-param-reassign
+  el.style.transform = ''; // eslint-disable-line no-param-reassign
+  el.classList.remove(IS_ABOVE_CLASS);
+  parentEl.classList.remove(IS_OVER_CLASS);
+  parentEl.classList.remove(IS_SHOWING_FLY_OUT_CLASS);
+
+  setOpenMenu();
+};
+
+export const moveSubItemsToPosition = (el, subItems) => {
+  const boundingRect = el.getBoundingClientRect();
+  const top = calculateTop(boundingRect, subItems.offsetHeight);
+  const isAbove = top < boundingRect.top;
+
+  subItems.classList.add('fly-out-list');
+  subItems.style.transform = `translate3d(0, ${Math.floor(top)}px, 0)`; // eslint-disable-line no-param-reassign
+
+  const subItemsRect = subItems.getBoundingClientRect();
+
+  menuCornerLocs = [
+    {
+      x: subItemsRect.left, // left position of the sub items
+      y: subItemsRect.top, // top position of the sub items
+    },
+    {
+      x: subItemsRect.left, // left position of the sub items
+      y: subItemsRect.top + subItemsRect.height, // bottom position of the sub items
+    },
+  ];
+
+  if (isAbove) {
+    subItems.classList.add(IS_ABOVE_CLASS);
+  }
+};
+
+export const showSubLevelItems = (el) => {
+  const subItems = el.querySelector('.sidebar-sub-level-items');
+
+  if (!canShowSubItems() || !canShowActiveSubItems(el)) return;
+
+  el.classList.add(IS_OVER_CLASS);
+
+  if (!subItems) return;
+
+  subItems.style.display = 'block';
+  el.classList.add(IS_SHOWING_FLY_OUT_CLASS);
+
+  setOpenMenu(subItems);
+  moveSubItemsToPosition(el, subItems);
+};
+
+export const mouseEnterTopItems = (el) => {
+  clearTimeout(timeoutId);
+
+  timeoutId = setTimeout(() => {
+    if (currentOpenMenu) hideMenu(currentOpenMenu);
+
+    showSubLevelItems(el);
+  }, getHideSubItemsInterval());
+};
+
+export const mouseLeaveTopItem = (el) => {
+  const subItems = el.querySelector('.sidebar-sub-level-items');
+
+  if (!canShowSubItems() || !canShowActiveSubItems(el) ||
+      (subItems && subItems === currentOpenMenu)) return;
+
+  el.classList.remove(IS_OVER_CLASS);
+};
+
+export const documentMouseMove = (e) => {
+  mousePos.push({
+    x: e.clientX,
+    y: e.clientY,
+  });
+
+  if (mousePos.length > 6) mousePos.shift();
+};
+
+export default () => {
+  const sidebar = document.querySelector('.sidebar-top-level-items');
+
+  if (!sidebar) return;
+
+  const items = [...sidebar.querySelectorAll('.sidebar-top-level-items > li')];
+
+  sidebar.addEventListener('mouseleave', () => {
+    clearTimeout(timeoutId);
+
+    timeoutId = setTimeout(() => {
+      if (currentOpenMenu) hideMenu(currentOpenMenu);
+    }, getHideSubItemsInterval());
+  });
+
+  items.forEach((el) => {
+    const subItems = el.querySelector('.sidebar-sub-level-items');
+
+    if (subItems) {
+      subItems.addEventListener('mouseleave', () => {
+        clearTimeout(timeoutId);
+        hideMenu(currentOpenMenu);
+      });
+    }
+
+    el.addEventListener('mouseenter', e => mouseEnterTopItems(e.currentTarget));
+    el.addEventListener('mouseleave', e => mouseLeaveTopItem(e.currentTarget));
+  });
+
+  document.addEventListener('mousemove', documentMouseMove);
+};