Post view client event (#9408)

* Adds post:view client event tracking in feeds

* Add post:view event on the post page itself

* Don't send post:view to statsig for now

* convert to non reactive callback to reduce rerenders

---------

Co-authored-by: Samuel Newman <mozzius@protonmail.com>

src/screens/PostThread/index.tsx

@@ -1,10 +1,11 @@
-import {useCallback, useMemo, useRef, useState} from 'react'
+import {useCallback, useEffect, useMemo, useRef, useState} from 'react'
 import {useWindowDimensions, View} from 'react-native'
 import Animated, {useAnimatedStyle} from 'react-native-reanimated'
 import {Trans} from '@lingui/macro'
 
 import {useInitialNumToRender} from '#/lib/hooks/useInitialNumToRender'
 import {useOpenComposer} from '#/lib/hooks/useOpenComposer'
+import {logger} from '#/logger'
 import {useFeedFeedback} from '#/state/feed-feedback'
 import {type ThreadViewOption} from '#/state/queries/preferences/useThreadPreferences'
 import {
@@ -73,6 +74,29 @@ export function PostThread({uri}: {uri: string}) {
     return {hasParents}
   }, [thread.data.items])
 
+  // Track post:view event when anchor post is viewed
+  const seenPostUriRef = useRef<string | null>(null)
+  useEffect(() => {
+    if (
+      anchor?.type === 'threadPost' &&
+      anchor.value.post.uri !== seenPostUriRef.current
+    ) {
+      const post = anchor.value.post
+      seenPostUriRef.current = post.uri
+
+      logger.metric(
+        'post:view',
+        {
+          uri: post.uri,
+          authorDid: post.author.did,
+          logContext: 'Post',
+          feedDescriptor: feedFeedback.feedDescriptor,
+        },
+        {statsig: false},
+      )
+    }
+  }, [anchor, feedFeedback.feedDescriptor])
+
   const {openComposer} = useOpenComposer()
   const optimisticOnPostReply = useCallback(
     (payload: OnPostSuccessData) => {