@codecademy/gamut

Index: package/dist/DatePicker/DatePickerCalendar/utils/dateSelect.js
===================================================================
--- package/dist/DatePicker/DatePickerCalendar/utils/dateSelect.js
+++ package/dist/DatePicker/DatePickerCalendar/utils/dateSelect.js
@@ -0,0 +1,175 @@
+import { getOrderedCalendarEndpoints, isDateDisabled, isDateInRange, isSameDay } from '../Calendar/utils/dateGrid';
+export const isRangeProps = props => props.mode === 'range';
+/** True if any disabled day falls within [startDate, endDate] (inclusive, by calendar day). */
+export const rangeContainsDisabled = ({
+  startDate,
+  endDate,
+  shouldDisableDate
+}) => {
+  const {
+    low,
+    high
+  } = getOrderedCalendarEndpoints({
+    startDate,
+    endDate
+  });
+  if (isDateDisabled({
+    date: low,
+    shouldDisableDate
+  }) || isDateDisabled({
+    date: high,
+    shouldDisableDate
+  })) {
+    return true;
+  }
+  let date = new Date(low.getFullYear(), low.getMonth(), low.getDate() + 1);
+  while (isDateInRange({
+    date,
+    startDate,
+    endDate
+  })) {
+    if (isDateDisabled({
+      date,
+      shouldDisableDate
+    })) {
+      return true;
+    }
+    date = new Date(date.getFullYear(), date.getMonth(), date.getDate() + 1);
+  }
+  return false;
+};
+export const handleDateSelectSingle = ({
+  date,
+  selectedDate,
+  onSelection
+}) => {
+  // If clicked date is the same as Start Date: Clear Start Date
+  if (isSameDay(date, selectedDate)) {
+    onSelection(null);
+    return;
+  }
+  // If clicked date is not the same as Start Date: Set Start Date to clicked date
+  onSelection(date);
+};
+/** @returns whether a full startDate+endDate range was committed (calendar may close). */
+export const applyRangeOrNewStart = ({
+  startDate,
+  endDate,
+  clickedDate,
+  shouldDisableDate,
+  onRangeSelection
+}) => {
+  // if range contains disabled dates, set start date to clicked date and end date to null
+  if (rangeContainsDisabled({
+    startDate,
+    endDate,
+    shouldDisableDate
+  })) {
+    onRangeSelection(clickedDate, null);
+    return false;
+  }
+  onRangeSelection(startDate, endDate);
+  return true;
+};
+/** @returns whether the calendar should close (full range selected and committed). */
+export const handleDateSelectRange = ({
+  date,
+  activeRangePart,
+  startDate,
+  endDate,
+  onRangeSelection,
+  shouldDisableDate
+}) => {
+  // Range mode: field targeting (start or end input was focused)
+  if (activeRangePart === 'start') {
+    if (isSameDay(date, startDate)) {
+      onRangeSelection(null, endDate);
+      return false;
+    }
+    const newEndDate = endDate !== null && date.getTime() <= endDate.getTime() ? endDate : null;
+    if (newEndDate !== null) {
+      return applyRangeOrNewStart({
+        startDate: date,
+        endDate: newEndDate,
+        clickedDate: date,
+        shouldDisableDate,
+        onRangeSelection
+      });
+    }
+    onRangeSelection(date, newEndDate);
+    return false;
+  }
+  if (activeRangePart === 'end') {
+    if (isSameDay(date, endDate)) {
+      onRangeSelection(startDate, null);
+      return false;
+    }
+    const newStartDate = startDate !== null && date.getTime() >= startDate.getTime() ? startDate : null;
+    if (newStartDate !== null) {
+      return applyRangeOrNewStart({
+        startDate: newStartDate,
+        endDate: date,
+        clickedDate: date,
+        shouldDisableDate,
+        onRangeSelection
+      });
+    }
+    onRangeSelection(newStartDate, date);
+    return false;
+  }
+
+  // Range selection mode (no field focused: calendar drives both)
+  if (startDate && endDate) {
+    // if start date is end date and is clicked, clears everything
+    if (isSameDay(startDate, endDate) && isSameDay(date, startDate)) {
+      onRangeSelection(null, null);
+      return false;
+    }
+    // if clicked on start date, end date becomes start date
+    if (isSameDay(date, startDate)) {
+      onRangeSelection(endDate, null);
+      return false;
+    }
+    // if clicked on end date, clears end date and start remains
+    if (isSameDay(date, endDate)) {
+      onRangeSelection(startDate, null);
+      return false;
+    }
+    // If clicked date > Start: Updates End Date to new date (Start remains)
+    if (date.getTime() > startDate.getTime()) {
+      return applyRangeOrNewStart({
+        startDate,
+        endDate: date,
+        clickedDate: date,
+        shouldDisableDate,
+        onRangeSelection
+      });
+    }
+    // If clicked date < Start: Updates Start Date to new date (End remains) - extends range to the left
+    return applyRangeOrNewStart({
+      startDate: date,
+      endDate,
+      clickedDate: date,
+      shouldDisableDate,
+      onRangeSelection
+    });
+  }
+  // Start is Set, End is Empty
+  if (startDate && !endDate) {
+    // If clicked date < Start: Restarts selection with clicked date as new Start
+    if (date.getTime() < startDate.getTime()) {
+      onRangeSelection(date, null);
+      return false;
+    }
+    // If clicked date > Start: Sets it as End Date (if range valid)
+    return applyRangeOrNewStart({
+      startDate,
+      endDate: date,
+      clickedDate: date,
+      shouldDisableDate,
+      onRangeSelection
+    });
+  }
+  onRangeSelection(date, null);
+  return false;
+};
\ No newline at end of file