Derive shadow like count (#2616)

src/state/cache/post-shadow.ts

@@ -12,9 +12,7 @@ export type {Shadow} from './types'
 
 export interface PostShadow {
   likeUri: string | undefined
-  likeCount: number | undefined
   repostUri: string | undefined
-  repostCount: number | undefined
   isDeleted: boolean
 }
 
@@ -62,11 +60,31 @@ function mergeShadow(
   if (shadow.isDeleted) {
     return POST_TOMBSTONE
   }
+
+  const wasLiked = !!post.viewer?.like
+  const isLiked = !!shadow.likeUri
+  let likeCount = post.likeCount ?? 0
+  if (wasLiked && !isLiked) {
+    likeCount--
+  } else if (!wasLiked && isLiked) {
+    likeCount++
+  }
+  likeCount = Math.max(0, likeCount)
+
+  const wasReposted = !!post.viewer?.repost
+  const isReposted = !!shadow.repostUri
+  let repostCount = post.repostCount ?? 0
+  if (wasReposted && !isReposted) {
+    repostCount--
+  } else if (!wasReposted && isReposted) {
+    repostCount++
+  }
+  repostCount = Math.max(0, repostCount)
+
   return castAsShadow({
     ...post,
-    likeCount: 'likeCount' in shadow ? shadow.likeCount : post.likeCount,
-    repostCount:
-      'repostCount' in shadow ? shadow.repostCount : post.repostCount,
+    likeCount: likeCount,
+    repostCount: repostCount,
     viewer: {
       ...(post.viewer || {}),
       like: 'likeUri' in shadow ? shadow.likeUri : post.viewer?.like,

src/state/queries/post.ts

@@ -59,13 +59,12 @@ export function usePostLikeMutation() {
   return useMutation<
     {uri: string}, // responds with the uri of the like
     Error,
-    {uri: string; cid: string; likeCount: number} // the post's uri, cid, and likes
+    {uri: string; cid: string} // the post's uri and cid
   >({
     mutationFn: post => getAgent().like(post.uri, post.cid),
     onMutate(variables) {
       // optimistically update the post-shadow
       updatePostShadow(variables.uri, {
-        likeCount: variables.likeCount + 1,
         likeUri: 'pending',
       })
     },
@@ -79,7 +78,6 @@ export function usePostLikeMutation() {
     onError(error, variables) {
       // revert the optimistic update
       updatePostShadow(variables.uri, {
-        likeCount: variables.likeCount,
         likeUri: undefined,
       })
     },
@@ -87,11 +85,7 @@ export function usePostLikeMutation() {
 }
 
 export function usePostUnlikeMutation() {
-  return useMutation<
-    void,
-    Error,
-    {postUri: string; likeUri: string; likeCount: number}
-  >({
+  return useMutation<void, Error, {postUri: string; likeUri: string}>({
     mutationFn: async ({likeUri}) => {
       await getAgent().deleteLike(likeUri)
       track('Post:Unlike')
@@ -99,14 +93,12 @@ export function usePostUnlikeMutation() {
     onMutate(variables) {
       // optimistically update the post-shadow
       updatePostShadow(variables.postUri, {
-        likeCount: variables.likeCount - 1,
         likeUri: undefined,
       })
     },
     onError(error, variables) {
       // revert the optimistic update
       updatePostShadow(variables.postUri, {
-        likeCount: variables.likeCount,
         likeUri: variables.likeUri,
       })
     },
@@ -117,13 +109,12 @@ export function usePostRepostMutation() {
   return useMutation<
     {uri: string}, // responds with the uri of the repost
     Error,
-    {uri: string; cid: string; repostCount: number} // the post's uri, cid, and reposts
+    {uri: string; cid: string} // the post's uri and cid
   >({
     mutationFn: post => getAgent().repost(post.uri, post.cid),
     onMutate(variables) {
       // optimistically update the post-shadow
       updatePostShadow(variables.uri, {
-        repostCount: variables.repostCount + 1,
         repostUri: 'pending',
       })
     },
@@ -137,7 +128,6 @@ export function usePostRepostMutation() {
     onError(error, variables) {
       // revert the optimistic update
       updatePostShadow(variables.uri, {
-        repostCount: variables.repostCount,
         repostUri: undefined,
       })
     },
@@ -145,11 +135,7 @@ export function usePostRepostMutation() {
 }
 
 export function usePostUnrepostMutation() {
-  return useMutation<
-    void,
-    Error,
-    {postUri: string; repostUri: string; repostCount: number}
-  >({
+  return useMutation<void, Error, {postUri: string; repostUri: string}>({
     mutationFn: async ({repostUri}) => {
       await getAgent().deleteRepost(repostUri)
       track('Post:Unrepost')
@@ -157,14 +143,12 @@ export function usePostUnrepostMutation() {
     onMutate(variables) {
       // optimistically update the post-shadow
       updatePostShadow(variables.postUri, {
-        repostCount: variables.repostCount - 1,
         repostUri: undefined,
       })
     },
     onError(error, variables) {
       // revert the optimistic update
       updatePostShadow(variables.postUri, {
-        repostCount: variables.repostCount,
         repostUri: variables.repostUri,
       })
     },

src/view/com/util/post-ctrls/PostCtrls.tsx

@@ -73,20 +73,17 @@ let PostCtrls = ({
       postLikeMutation.mutate({
         uri: post.uri,
         cid: post.cid,
-        likeCount: post.likeCount || 0,
       })
     } else {
       postUnlikeMutation.mutate({
         postUri: post.uri,
         likeUri: post.viewer.like,
-        likeCount: post.likeCount || 0,
       })
     }
   }, [
     post.viewer?.like,
     post.uri,
     post.cid,
-    post.likeCount,
     postLikeMutation,
     postUnlikeMutation,
   ])
@@ -98,20 +95,17 @@ let PostCtrls = ({
       postRepostMutation.mutate({
         uri: post.uri,
         cid: post.cid,
-        repostCount: post.repostCount || 0,
       })
     } else {
       postUnrepostMutation.mutate({
         postUri: post.uri,
         repostUri: post.viewer.repost,
-        repostCount: post.repostCount || 0,
       })
     }
   }, [
     post.uri,
     post.cid,
     post.viewer?.repost,
-    post.repostCount,
     closeModal,
     postRepostMutation,
     postUnrepostMutation,