1 files changed, 55 insertions, 0 deletions
diff --git a/public/javascripts/scrollSnap.js b/public/javascripts/scrollSnap.js
new file mode 100644
index 0000000..167f0c1
--- /dev/null
+++ b/public/javascripts/scrollSnap.js
@@ -0,0 +1,55 @@
+require('smoothscroll-polyfill').polyfill()
+
+const self = {}
+const schedule = require('./schedule')
+
+self._nodes = {
+  search: document.querySelector('#search'),
+  weekSelector: document.querySelector('#week-selector')
+}
+
+self._timeoutID = null
+
+self._getScrollPosition = function () {
+  return (document.documentElement && document.documentElement.scrollTop) ||
+          document.body.scrollTop
+}
+
+self._handleDoneScrolling = function () {
+  const scrollPosition = self._getScrollPosition()
+  const weekSelectorHeight = self._nodes.weekSelector.clientHeight - self._nodes.search.clientHeight
+  if (scrollPosition < weekSelectorHeight && scrollPosition > 0) {
+    window.scroll({ top: weekSelectorHeight, left: 0, behavior: 'smooth' })
+  }
+}
+
+self._handleScroll = function () {
+  if (self._timeoutID != null) window.clearTimeout(self._timeoutID)
+  self._timeoutID = window.setTimeout(self._handleDoneScrolling, 500)
+
+  const scrollPosition = self._getScrollPosition()
+  const weekSelectorHeight = self._nodes.weekSelector.clientHeight - self._nodes.search.clientHeight
+  if (scrollPosition >= weekSelectorHeight) {
+    document.body.classList.add('week-selector-not-visible')
+  } else {
+    document.body.classList.remove('week-selector-not-visible')
+  }
+}
+
+self._handleWindowResize = function () {
+  const weekSelectorHeight = self._nodes.weekSelector.clientHeight - self._nodes.search.clientHeight
+  const extraPixelsNeeded = weekSelectorHeight - (document.body.clientHeight - window.innerHeight)
+  if (extraPixelsNeeded > 0) {
+    document.body.style.marginBottom = extraPixelsNeeded + 'px'
+  } else {
+    document.body.style.marginBottom = null
+  }
+}
+
+self.startListening = function () {
+  window.addEventListener('scroll', self._handleScroll)
+}
+
+schedule.on('load', self._handleWindowResize)
+window.addEventListener('resize', self._handleWindowResize)
+module.exports = self