[Statsig] Instrument feed display (#3455)

* [Statsig] Instrument feed display

* Back out leftover change

4 files changed, 71 insertions, 15 deletions

diff --git a/src/lib/statsig/events.ts b/src/lib/statsig/events.ts
index 73e9876ac..3d650b8b7 100644
--- a/src/lib/statsig/events.ts
+++ b/src/lib/statsig/events.ts
@@ -44,6 +44,12 @@ export type LogEvents = {
   }
   'onboarding:moderation:nextPressed': {}
   'onboarding:finished:nextPressed': {}
+  'home:feedDisplayed': {
+    feedUrl: string
+    feedType: string
+    index: number
+    reason: 'focus' | 'tabbar-click' | 'pager-swipe' | 'desktop-sidebar-click'
+  }
   'feed:endReached': {
     feedUrl: string
     feedType: string
diff --git a/src/view/com/pager/Pager.tsx b/src/view/com/pager/Pager.tsx
index 06ec2e450..26070fb88 100644
--- a/src/view/com/pager/Pager.tsx
+++ b/src/view/com/pager/Pager.tsx
@@ -1,17 +1,22 @@
 import React, {forwardRef} from 'react'
 import {Animated, View} from 'react-native'
 import PagerView, {
-  PagerViewOnPageSelectedEvent,
   PagerViewOnPageScrollEvent,
+  PagerViewOnPageSelectedEvent,
   PageScrollStateChangedNativeEvent,
 } from 'react-native-pager-view'
+
+import {LogEvents} from '#/lib/statsig/events'
 import {s} from 'lib/styles'
 
 export type PageSelectedEvent = PagerViewOnPageSelectedEvent
 const AnimatedPagerView = Animated.createAnimatedComponent(PagerView)
 
 export interface PagerRef {
-  setPage: (index: number) => void
+  setPage: (
+    index: number,
+    reason: LogEvents['home:feedDisplayed']['reason'],
+  ) => void
 }
 
 export interface RenderTabBarFnProps {
@@ -25,7 +30,10 @@ interface Props {
   initialPage?: number
   renderTabBar: RenderTabBarFn
   onPageSelected?: (index: number) => void
-  onPageSelecting?: (index: number) => void
+  onPageSelecting?: (
+    index: number,
+    reason: LogEvents['home:feedDisplayed']['reason'],
+  ) => void
   onPageScrollStateChanged?: (
     scrollState: 'idle' | 'dragging' | 'settling',
   ) => void
@@ -51,7 +59,13 @@ export const Pager = forwardRef<PagerRef, React.PropsWithChildren<Props>>(
     const pagerView = React.useRef<PagerView>(null)
 
     React.useImperativeHandle(ref, () => ({
-      setPage: (index: number) => pagerView.current?.setPage(index),
+      setPage: (
+        index: number,
+        reason: LogEvents['home:feedDisplayed']['reason'],
+      ) => {
+        pagerView.current?.setPage(index)
+        onPageSelecting?.(index, reason)
+      },
     }))
 
     const onPageSelectedInner = React.useCallback(
@@ -79,14 +93,14 @@ export const Pager = forwardRef<PagerRef, React.PropsWithChildren<Props>>(
         // -prf
         if (scrollState.current === 'settling') {
           if (lastDirection.current === -1 && offset < lastOffset.current) {
-            onPageSelecting?.(position)
+            onPageSelecting?.(position, 'pager-swipe')
             setSelectedPage(position)
             lastDirection.current = 0
           } else if (
             lastDirection.current === 1 &&
             offset > lastOffset.current
           ) {
-            onPageSelecting?.(position + 1)
+            onPageSelecting?.(position + 1, 'pager-swipe')
             setSelectedPage(position + 1)
             lastDirection.current = 0
           }
@@ -113,7 +127,7 @@ export const Pager = forwardRef<PagerRef, React.PropsWithChildren<Props>>(
     const onTabBarSelect = React.useCallback(
       (index: number) => {
         pagerView.current?.setPage(index)
-        onPageSelecting?.(index)
+        onPageSelecting?.(index, 'tabbar-click')
       },
       [pagerView, onPageSelecting],
     )
diff --git a/src/view/com/pager/Pager.web.tsx b/src/view/com/pager/Pager.web.tsx
index 42982ef7f..abba12b2c 100644
--- a/src/view/com/pager/Pager.web.tsx
+++ b/src/view/com/pager/Pager.web.tsx
@@ -1,6 +1,8 @@
 import React from 'react'
-import {flushSync} from 'react-dom'
 import {View} from 'react-native'
+import {flushSync} from 'react-dom'
+
+import {LogEvents} from '#/lib/statsig/events'
 import {s} from 'lib/styles'
 
 export interface RenderTabBarFnProps {
@@ -14,7 +16,10 @@ interface Props {
   initialPage?: number
   renderTabBar: RenderTabBarFn
   onPageSelected?: (index: number) => void
-  onPageSelecting?: (index: number) => void
+  onPageSelecting?: (
+    index: number,
+    reason: LogEvents['home:feedDisplayed']['reason'],
+  ) => void
 }
 export const Pager = React.forwardRef(function PagerImpl(
   {
@@ -31,11 +36,16 @@ export const Pager = React.forwardRef(function PagerImpl(
   const anchorRef = React.useRef(null)
 
   React.useImperativeHandle(ref, () => ({
-    setPage: (index: number) => onTabBarSelect(index),
+    setPage: (
+      index: number,
+      reason: LogEvents['home:feedDisplayed']['reason'],
+    ) => {
+      onTabBarSelect(index, reason)
+    },
   }))
 
   const onTabBarSelect = React.useCallback(
-    (index: number) => {
+    (index: number, reason: LogEvents['home:feedDisplayed']['reason']) => {
       const scrollY = window.scrollY
       // We want to determine if the tabbar is already "sticking" at the top (in which
       // case we should preserve and restore scroll), or if it is somewhere below in the
@@ -54,7 +64,7 @@ export const Pager = React.forwardRef(function PagerImpl(
       flushSync(() => {
         setSelectedPage(index)
         onPageSelected?.(index)
-        onPageSelecting?.(index)
+        onPageSelecting?.(index, reason)
       })
       if (isSticking) {
         const restoredScrollY = scrollYs.current[index]
@@ -73,7 +83,7 @@ export const Pager = React.forwardRef(function PagerImpl(
       {renderTabBar({
         selectedPage,
         tabBarAnchor: <View ref={anchorRef} />,
-        onSelect: onTabBarSelect,
+        onSelect: e => onTabBarSelect(e, 'tabbar-click'),
       })}
       {React.Children.map(children, (child, i) => (
         <View style={selectedPage === i ? s.flex1 : s.hidden} key={`page-${i}`}>
diff --git a/src/view/screens/Home.tsx b/src/view/screens/Home.tsx
index e6ba0395c..39bdac669 100644
--- a/src/view/screens/Home.tsx
+++ b/src/view/screens/Home.tsx
@@ -2,8 +2,9 @@ import React from 'react'
 import {ActivityIndicator, AppState, StyleSheet, View} from 'react-native'
 import {useFocusEffect} from '@react-navigation/native'
 
+import {useNonReactiveCallback} from '#/lib/hooks/useNonReactiveCallback'
 import {useSetTitle} from '#/lib/hooks/useSetTitle'
-import {useGate} from '#/lib/statsig/statsig'
+import {logEvent, LogEvents, useGate} from '#/lib/statsig/statsig'
 import {emitSoftReset} from '#/state/events'
 import {FeedSourceInfo, usePinnedFeedsInfos} from '#/state/queries/feed'
 import {FeedDescriptor, FeedParams} from '#/state/queries/post-feed'
@@ -79,7 +80,7 @@ function HomeScreenReady({
     // This is supposed to only happen on the web when you use the right nav.
     if (selectedIndex !== lastPagerReportedIndexRef.current) {
       lastPagerReportedIndexRef.current = selectedIndex
-      pagerRef.current?.setPage(selectedIndex)
+      pagerRef.current?.setPage(selectedIndex, 'desktop-sidebar-click')
     }
   }, [selectedIndex])
 
@@ -96,6 +97,17 @@ function HomeScreenReady({
     }, [setDrawerSwipeDisabled, selectedIndex, setMinimalShellMode]),
   )
 
+  useFocusEffect(
+    useNonReactiveCallback(() => {
+      logEvent('home:feedDisplayed', {
+        index: selectedIndex,
+        feedType: selectedFeed.split('|')[0],
+        feedUrl: selectedFeed,
+        reason: 'focus',
+      })
+    }),
+  )
+
   const disableMinShellOnForegrounding = useGate(
     'disable_min_shell_on_foregrounding',
   )
@@ -123,6 +135,19 @@ function HomeScreenReady({
     [setDrawerSwipeDisabled, setSelectedFeed, setMinimalShellMode, allFeeds],
   )
 
+  const onPageSelecting = React.useCallback(
+    (index: number, reason: LogEvents['home:feedDisplayed']['reason']) => {
+      const feed = allFeeds[index]
+      logEvent('home:feedDisplayed', {
+        index,
+        feedType: feed.split('|')[0],
+        feedUrl: feed,
+        reason,
+      })
+    },
+    [allFeeds],
+  )
+
   const onPressSelected = React.useCallback(() => {
     emitSoftReset()
   }, [])
@@ -175,6 +200,7 @@ function HomeScreenReady({
       ref={pagerRef}
       testID="homeScreen"
       initialPage={selectedIndex}
+      onPageSelecting={onPageSelecting}
       onPageSelected={onPageSelected}
       onPageScrollStateChanged={onPageScrollStateChanged}
       renderTabBar={renderTabBar}>