[Statsig] Track posting, end reached (#3206)

* Track post create

* Track feed endReached

src/lib/statsig/events.ts

@@ -2,6 +2,18 @@ export type LogEvents = {
   init: {
     initMs: number
   }
+  'feed:endReached': {
+    feedType: string
+    itemCount: number
+  }
+  'post:create': {
+    imageCount: number
+    isReply: boolean
+    hasLink: boolean
+    hasQuote: boolean
+    langs: string
+    logContext: 'Composer'
+  }
   'post:like': {
     logContext: 'FeedItem' | 'PostThreadItem' | 'Post'
   }

src/view/com/composer/Composer.tsx

@@ -65,6 +65,7 @@ import {logger} from '#/logger'
 import {ComposerReplyTo} from 'view/com/composer/ComposerReplyTo'
 import * as Prompt from '#/components/Prompt'
 import {useDialogStateControlContext} from 'state/dialogs'
+import {logEvent} from '#/lib/statsig/statsig'
 
 type Props = ComposerOpts
 export const ComposePost = observer(function ComposePost({
@@ -255,6 +256,16 @@ export const ComposePost = observer(function ComposePost({
       setIsProcessing(false)
       return
     } finally {
+      if (postUri) {
+        logEvent('post:create', {
+          imageCount: gallery.size,
+          isReply: replyTo != null,
+          hasLink: extLink != null,
+          hasQuote: quote != null,
+          langs: langPrefs.postLanguage,
+          logContext: 'Composer',
+        })
+      }
       track('Create Post', {
         imageCount: gallery.size,
       })

src/view/com/posts/Feed.tsx

@@ -33,6 +33,7 @@ import {useLingui} from '@lingui/react'
 import {DiscoverFallbackHeader} from './DiscoverFallbackHeader'
 import {FALLBACK_MARKER_POST} from '#/lib/api/feed/home'
 import {useInitialNumToRender} from 'lib/hooks/useInitialNumToRender'
+import {logEvent} from '#/lib/statsig/statsig'
 
 const LOADING_ITEM = {_reactKey: '__loading__'}
 const EMPTY_FEED_ITEM = {_reactKey: '__empty__'}
@@ -223,16 +224,29 @@ let Feed = ({
     setIsPTRing(false)
   }, [refetch, track, setIsPTRing, onHasNew])
 
+  const feedType = feed.split('|')[0]
   const onEndReached = React.useCallback(async () => {
     if (isFetching || !hasNextPage || isError) return
 
+    logEvent('feed:endReached', {
+      feedType: feedType,
+      itemCount: feedItems.length,
+    })
     track('Feed:onEndReached')
     try {
       await fetchNextPage()
     } catch (err) {
       logger.error('Failed to load more posts', {message: err})
     }
-  }, [isFetching, hasNextPage, isError, fetchNextPage, track])
+  }, [
+    isFetching,
+    hasNextPage,
+    isError,
+    fetchNextPage,
+    track,
+    feedType,
+    feedItems.length,
+  ])
 
   const onPressTryAgain = React.useCallback(() => {
     refetch()