1 files changed, 121 insertions, 0 deletions
diff --git a/src/lib/custom-animations/CountWheel.web.tsx b/src/lib/custom-animations/CountWheel.web.tsx
new file mode 100644
index 000000000..618dcb1a5
--- /dev/null
+++ b/src/lib/custom-animations/CountWheel.web.tsx
@@ -0,0 +1,121 @@
+import React from 'react'
+import {View} from 'react-native'
+import {useReducedMotion} from 'react-native-reanimated'
+import {i18n} from '@lingui/core'
+
+import {decideShouldRoll} from 'lib/custom-animations/util'
+import {s} from 'lib/styles'
+import {formatCount} from 'view/com/util/numeric/format'
+import {Text} from 'view/com/util/text/Text'
+import {atoms as a, useTheme} from '#/alf'
+
+const animationConfig = {
+  duration: 400,
+  easing: 'cubic-bezier(0.4, 0, 0.2, 1)',
+  fill: 'forwards' as FillMode,
+}
+
+const enteringUpKeyframe = [
+  {opacity: 0, transform: 'translateY(18px)'},
+  {opacity: 1, transform: 'translateY(0)'},
+]
+
+const enteringDownKeyframe = [
+  {opacity: 0, transform: 'translateY(-18px)'},
+  {opacity: 1, transform: 'translateY(0)'},
+]
+
+const exitingUpKeyframe = [
+  {opacity: 1, transform: 'translateY(0)'},
+  {opacity: 0, transform: 'translateY(-18px)'},
+]
+
+const exitingDownKeyframe = [
+  {opacity: 1, transform: 'translateY(0)'},
+  {opacity: 0, transform: 'translateY(18px)'},
+]
+
+export function CountWheel({
+  likeCount,
+  big,
+  isLiked,
+}: {
+  likeCount: number
+  big?: boolean
+  isLiked: boolean
+}) {
+  const t = useTheme()
+  const shouldAnimate = !useReducedMotion()
+  const shouldRoll = decideShouldRoll(isLiked, likeCount)
+
+  const countView = React.useRef<HTMLDivElement>(null)
+  const prevCountView = React.useRef<HTMLDivElement>(null)
+
+  const [prevCount, setPrevCount] = React.useState(likeCount)
+  const prevIsLiked = React.useRef(isLiked)
+  const formattedCount = formatCount(i18n, likeCount)
+  const formattedPrevCount = formatCount(i18n, prevCount)
+
+  React.useEffect(() => {
+    if (isLiked === prevIsLiked.current) {
+      return
+    }
+
+    const newPrevCount = isLiked ? likeCount - 1 : likeCount + 1
+    if (shouldAnimate && shouldRoll) {
+      countView.current?.animate?.(
+        isLiked ? enteringUpKeyframe : enteringDownKeyframe,
+        animationConfig,
+      )
+      prevCountView.current?.animate?.(
+        isLiked ? exitingUpKeyframe : exitingDownKeyframe,
+        animationConfig,
+      )
+      setPrevCount(newPrevCount)
+    }
+    prevIsLiked.current = isLiked
+  }, [isLiked, likeCount, shouldAnimate, shouldRoll])
+
+  if (likeCount < 1) {
+    return null
+  }
+
+  return (
+    <View>
+      <View
+        aria-disabled={true}
+        // @ts-expect-error is div
+        ref={countView}>
+        <Text
+          testID="likeCount"
+          style={[
+            big ? a.text_md : {fontSize: 15},
+            a.user_select_none,
+            isLiked
+              ? [a.font_bold, s.likeColor]
+              : {color: t.palette.contrast_500},
+          ]}>
+          {formattedCount}
+        </Text>
+      </View>
+      {shouldAnimate ? (
+        <View
+          style={{position: 'absolute'}}
+          aria-disabled={true}
+          // @ts-expect-error is div
+          ref={prevCountView}>
+          <Text
+            style={[
+              big ? a.text_md : {fontSize: 15},
+              a.user_select_none,
+              isLiked
+                ? [a.font_bold, s.likeColor]
+                : {color: t.palette.contrast_500},
+            ]}>
+            {formattedPrevCount}
+          </Text>
+        </View>
+      ) : null}
+    </View>
+  )
+}