From 6edd5abfc5760a1bd88e747ef205f28b76b15344 Mon Sep 17 00:00:00 2001
From: Christina Yang <ychristina011@gmail.com>
Date: Sat, 18 Jan 2025 19:52:03 -0800
Subject: [PATCH] swipe down to dismiss alert

---
 src/components/Alert.tsx       |  1 +
 src/components/PopupBase.tsx   |  3 +++
 src/hooks/useSwipeToDismiss.ts | 32 +++++++++++++++++++++++---------
 3 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/src/components/Alert.tsx b/src/components/Alert.tsx
index a5a645ab644..8d283c3c60e 100644
--- a/src/components/Alert.tsx
+++ b/src/components/Alert.tsx
@@ -70,6 +70,7 @@ const Alert: FC = () => {
             showXOnHover
             onClose={alert.showCloseLink ? onClose : undefined}
             calculatedHeight={popupRef.current?.getBoundingClientRect().height || 50}
+            swipeDownToDismiss
           >
             <div
               data-testid='alert-content'
diff --git a/src/components/PopupBase.tsx b/src/components/PopupBase.tsx
index bec41c64a82..ea83bc72f67 100644
--- a/src/components/PopupBase.tsx
+++ b/src/components/PopupBase.tsx
@@ -27,6 +27,7 @@ export type PopupBaseProps = PropsWithChildren<
     cssRaw?: SystemStyleObject
     circledCloseButton?: boolean
     showXOnHover?: boolean
+    swipeDownToDismiss?: boolean
   } & Omit<React.HTMLAttributes<HTMLDivElement>, 'className'>
 >
 
@@ -44,6 +45,7 @@ const PopupBase = React.forwardRef<HTMLDivElement, PopupBaseProps>(
       calculatedHeight,
       circledCloseButton,
       showXOnHover,
+      swipeDownToDismiss,
       ...props
     },
     ref,
@@ -61,6 +63,7 @@ const PopupBase = React.forwardRef<HTMLDivElement, PopupBaseProps>(
       onDismissEnd: () => {
         dispatch(alert(null))
       },
+      swipeDown: swipeDownToDismiss,
     })
 
     const combinedRefs = useCombinedRefs(isTouch ? [useSwipeToDismissProps.ref, ref] : [ref])
diff --git a/src/hooks/useSwipeToDismiss.ts b/src/hooks/useSwipeToDismiss.ts
index 323c4594fb2..c1333367ead 100644
--- a/src/hooks/useSwipeToDismiss.ts
+++ b/src/hooks/useSwipeToDismiss.ts
@@ -5,6 +5,7 @@ const defaultOptions = {
   dx: 0,
   snapbackDuration: 0.1,
   snapbackEasing: 'ease-out',
+  swipeDown: false,
 }
 
 /** Custom hook to manage swipe to dismiss alerts. */
@@ -28,10 +29,13 @@ const useSwipeToDismiss = (
 
     // easing function to animate the element back into place after releasing
     snapbackEasing?: string
+
+    // whether to swipe down to dismiss (true) or swipe up (false)
+    swipeDown?: boolean
   } = {},
 ) => {
   // initialize default options
-  const { dismissThreshold, dx, onDismiss, onDismissEnd, snapbackDuration, snapbackEasing } = {
+  const { dismissThreshold, dx, onDismiss, onDismissEnd, snapbackDuration, snapbackEasing, swipeDown } = {
     ...defaultOptions,
     ...options,
   }
@@ -74,12 +78,16 @@ const useSwipeToDismiss = (
       // check for dismiss threshold
       // if specified as a percentage of height, use percentage of element height
       const isPercentageOfHeight = typeof dismissThreshold === 'string' && dismissThreshold.endsWith('%')
-      const dismissThresholdPx = isPercentageOfHeight
-        ? (-parseFloat(dismissThreshold as string) * height) / 100
-        : -parseFloat(dismissThreshold as string)
+      const thresholdValue = isPercentageOfHeight
+        ? (parseFloat(dismissThreshold as string) * height) / 100
+        : parseFloat(dismissThreshold as string)
+
+      // Check threshold based on swipe direction
+      const dismissThresholdPx = swipeDown ? thresholdValue : -thresholdValue
+      const shouldDismiss = swipeDown ? dy > dismissThresholdPx : dy < -dismissThresholdPx
 
-      if (dy < dismissThresholdPx) {
-        setDY(-height * 2)
+      if (shouldDismiss) {
+        setDY(swipeDown ? height * 2 : -height * 2)
         onDismiss?.()
         setTimeout(() => {
           onDismissEnd?.()
@@ -98,11 +106,17 @@ const useSwipeToDismiss = (
       const y = e.touches?.[0].pageY
       const dy = y - y0
 
-      // resist dragging down by taking the square root of positive dy
-      const dyResistant = dy < 0 ? dy : Math.sqrt(dy)
+      // Apply resistance in the non-dismissal direction
+      const dyResistant = swipeDown
+        ? dy < 0
+          ? Math.sqrt(-dy) * -1
+          : dy // resist upward motion when swipeDown
+        : dy > 0
+          ? Math.sqrt(dy)
+          : dy // resist dragging down by taking square root of positive dy
       setDY(dyResistant)
     },
-    [y0],
+    [y0, swipeDown],
   )
 
   return {