1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
|
import {useEffect, useState, useMemo, useCallback} from 'react'
import EventEmitter from 'eventemitter3'
import {AppBskyFeedDefs} from '@atproto/api'
import {batchedUpdates} from '#/lib/batchedUpdates'
import {Shadow, castAsShadow} from './types'
export type {Shadow} from './types'
const emitter = new EventEmitter()
export interface PostShadow {
likeUri: string | undefined
likeCount: number | undefined
repostUri: string | undefined
repostCount: number | undefined
isDeleted: boolean
}
export const POST_TOMBSTONE = Symbol('PostTombstone')
interface CacheEntry {
ts: number
value: PostShadow
}
const firstSeenMap = new WeakMap<AppBskyFeedDefs.PostView, number>()
function getFirstSeenTS(post: AppBskyFeedDefs.PostView): number {
let timeStamp = firstSeenMap.get(post)
if (timeStamp !== undefined) {
return timeStamp
}
timeStamp = Date.now()
firstSeenMap.set(post, timeStamp)
return timeStamp
}
export function usePostShadow(
post: AppBskyFeedDefs.PostView,
): Shadow<AppBskyFeedDefs.PostView> | typeof POST_TOMBSTONE {
const postSeenTS = getFirstSeenTS(post)
const [state, setState] = useState<CacheEntry>(() => ({
ts: postSeenTS,
value: fromPost(post),
}))
const [prevPost, setPrevPost] = useState(post)
if (post !== prevPost) {
// if we got a new prop, assume it's fresher
// than whatever shadow state we accumulated
setPrevPost(post)
setState({
ts: postSeenTS,
value: fromPost(post),
})
}
const onUpdate = useCallback(
(value: Partial<PostShadow>) => {
setState(s => ({ts: Date.now(), value: {...s.value, ...value}}))
},
[setState],
)
// react to shadow updates
useEffect(() => {
emitter.addListener(post.uri, onUpdate)
return () => {
emitter.removeListener(post.uri, onUpdate)
}
}, [post.uri, onUpdate])
return useMemo(() => {
return state.ts > postSeenTS
? mergeShadow(post, state.value)
: castAsShadow(post)
}, [post, state, postSeenTS])
}
export function updatePostShadow(uri: string, value: Partial<PostShadow>) {
batchedUpdates(() => {
emitter.emit(uri, value)
})
}
function fromPost(post: AppBskyFeedDefs.PostView): PostShadow {
return {
likeUri: post.viewer?.like,
likeCount: post.likeCount,
repostUri: post.viewer?.repost,
repostCount: post.repostCount,
isDeleted: false,
}
}
function mergeShadow(
post: AppBskyFeedDefs.PostView,
shadow: PostShadow,
): Shadow<AppBskyFeedDefs.PostView> | typeof POST_TOMBSTONE {
if (shadow.isDeleted) {
return POST_TOMBSTONE
}
return castAsShadow({
...post,
likeCount: shadow.likeCount,
repostCount: shadow.repostCount,
viewer: {
...(post.viewer || {}),
like: shadow.likeUri,
repost: shadow.repostUri,
},
})
}
|
