Fix fixed footer experiment (#4969)

* Split minimal shell mode into headerMode and footerMode

For now, we'll always write them in sync. When we read them, we'll use headerMode as source of truth. This will let us keep footerMode independent in a future commit.

* Remove fixed_bottom_bar special cases during calculation

This isn't the right time to determine special behavior. Instead we'll adjust footerMode itself conditionally on the gate.

* Copy-paste setMode into MainScrollProvider

This lets us fork the implementation later just for this case.

* Gate footer adjustment in MainScrollProvider

This is the final piece. Normal calls to setMode() keep setting both header and footer, but MainScrollProvider adjusts the footer conditionally.

1 files changed, 18 insertions, 27 deletions

diff --git a/src/lib/hooks/useMinimalShellTransform.ts b/src/lib/hooks/useMinimalShellTransform.ts
index 17fe058e9..678776755 100644
--- a/src/lib/hooks/useMinimalShellTransform.ts
+++ b/src/lib/hooks/useMinimalShellTransform.ts
@@ -2,21 +2,24 @@ import {interpolate, useAnimatedStyle} from 'react-native-reanimated'
 
 import {useMinimalShellMode} from '#/state/shell/minimal-mode'
 import {useShellLayout} from '#/state/shell/shell-layout'
-import {useGate} from '../statsig/statsig'
 
 // Keep these separated so that we only pay for useAnimatedStyle that gets used.
 
 export function useMinimalShellHeaderTransform() {
-  const mode = useMinimalShellMode()
+  const {headerMode} = useMinimalShellMode()
   const {headerHeight} = useShellLayout()
 
   const headerTransform = useAnimatedStyle(() => {
     return {
-      pointerEvents: mode.value === 0 ? 'auto' : 'none',
-      opacity: Math.pow(1 - mode.value, 2),
+      pointerEvents: headerMode.value === 0 ? 'auto' : 'none',
+      opacity: Math.pow(1 - headerMode.value, 2),
       transform: [
         {
-          translateY: interpolate(mode.value, [0, 1], [0, -headerHeight.value]),
+          translateY: interpolate(
+            headerMode.value,
+            [0, 1],
+            [0, -headerHeight.value],
+          ),
         },
       ],
     }
@@ -26,21 +29,20 @@ export function useMinimalShellHeaderTransform() {
 }
 
 export function useMinimalShellFooterTransform() {
-  const mode = useMinimalShellMode()
+  const {footerMode} = useMinimalShellMode()
   const {footerHeight} = useShellLayout()
-  const gate = useGate()
-  const isFixedBottomBar = gate('fixed_bottom_bar')
 
   const footerTransform = useAnimatedStyle(() => {
-    if (isFixedBottomBar) {
-      return {}
-    }
     return {
-      pointerEvents: mode.value === 0 ? 'auto' : 'none',
-      opacity: Math.pow(1 - mode.value, 2),
+      pointerEvents: footerMode.value === 0 ? 'auto' : 'none',
+      opacity: Math.pow(1 - footerMode.value, 2),
       transform: [
         {
-          translateY: interpolate(mode.value, [0, 1], [0, footerHeight.value]),
+          translateY: interpolate(
+            footerMode.value,
+            [0, 1],
+            [0, footerHeight.value],
+          ),
         },
       ],
     }
@@ -50,24 +52,13 @@ export function useMinimalShellFooterTransform() {
 }
 
 export function useMinimalShellFabTransform() {
-  const mode = useMinimalShellMode()
-  const gate = useGate()
-  const isFixedBottomBar = gate('fixed_bottom_bar')
+  const {footerMode} = useMinimalShellMode()
 
   const fabTransform = useAnimatedStyle(() => {
-    if (isFixedBottomBar) {
-      return {
-        transform: [
-          {
-            translateY: -44,
-          },
-        ],
-      }
-    }
     return {
       transform: [
         {
-          translateY: interpolate(mode.value, [0, 1], [-44, 0]),
+          translateY: interpolate(footerMode.value, [0, 1], [-44, 0]),
         },
       ],
     }