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import React, {MutableRefObject} from 'react'
import {observer} from 'mobx-react-lite'
import {
ActivityIndicator,
View,
StyleProp,
StyleSheet,
ViewStyle,
} from 'react-native'
import {CenteredView, FlatList} from '../util/Views'
import {PostFeedLoadingPlaceholder} from '../util/LoadingPlaceholder'
import {EmptyState} from '../util/EmptyState'
import {ErrorMessage} from '../util/error/ErrorMessage'
import {FeedModel} from 'state/models/feed-view'
import {FeedItem} from './FeedItem'
import {OnScrollCb} from 'lib/hooks/useOnMainScroll'
import {s} from 'lib/styles'
import {useAnalytics} from 'lib/analytics'
const EMPTY_FEED_ITEM = {_reactKey: '__empty__'}
const ERROR_FEED_ITEM = {_reactKey: '__error__'}
export const Feed = observer(function Feed({
feed,
style,
scrollElRef,
onPressTryAgain,
onScroll,
testID,
headerOffset = 0,
}: {
feed: FeedModel
style?: StyleProp<ViewStyle>
scrollElRef?: MutableRefObject<FlatList<any> | null>
onPressTryAgain?: () => void
onScroll?: OnScrollCb
testID?: string
headerOffset?: number
}) {
const {track} = useAnalytics()
const [isRefreshing, setIsRefreshing] = React.useState(false)
const data = React.useMemo(() => {
let feedItems: any[] = []
if (feed.hasLoaded) {
if (feed.hasError) {
feedItems = feedItems.concat([ERROR_FEED_ITEM])
}
if (feed.isEmpty) {
feedItems = feedItems.concat([EMPTY_FEED_ITEM])
} else {
feedItems = feedItems.concat(feed.feed)
}
}
return feedItems
}, [feed.hasError, feed.hasLoaded, feed.isEmpty, feed.feed])
// events
// =
const onRefresh = React.useCallback(async () => {
track('Feed:onRefresh')
setIsRefreshing(true)
try {
await feed.refresh()
} catch (err) {
feed.rootStore.log.error('Failed to refresh posts feed', err)
}
setIsRefreshing(false)
}, [feed, track, setIsRefreshing])
const onEndReached = React.useCallback(async () => {
track('Feed:onEndReached')
try {
await feed.loadMore()
} catch (err) {
feed.rootStore.log.error('Failed to load more posts', err)
}
}, [feed, track])
// rendering
// =
// TODO optimize renderItem or FeedItem, we're getting this notice from RN: -prf
// VirtualizedList: You have a large list that is slow to update - make sure your
// renderItem function renders components that follow React performance best practices
// like PureComponent, shouldComponentUpdate, etc
const renderItem = React.useCallback(
({item}: {item: any}) => {
if (item === EMPTY_FEED_ITEM) {
return (
<EmptyState
icon="bars"
message="This feed is empty!"
style={styles.emptyState}
/>
)
} else if (item === ERROR_FEED_ITEM) {
return (
<ErrorMessage
message={feed.error}
onPressTryAgain={onPressTryAgain}
/>
)
}
return <FeedItem item={item} />
},
[feed, onPressTryAgain],
)
const FeedFooter = React.useCallback(
() =>
feed.isLoading ? (
<View style={styles.feedFooter}>
<ActivityIndicator />
</View>
) : (
<View />
),
[feed],
)
return (
<View testID={testID} style={style}>
{feed.isLoading && data.length === 0 && (
<CenteredView style={{paddingTop: headerOffset}}>
<PostFeedLoadingPlaceholder />
</CenteredView>
)}
{data.length > 0 && (
<FlatList
ref={scrollElRef}
data={data}
keyExtractor={item => item._reactKey}
renderItem={renderItem}
ListFooterComponent={FeedFooter}
refreshing={isRefreshing}
contentContainerStyle={s.contentContainer}
onScroll={onScroll}
onRefresh={onRefresh}
onEndReached={onEndReached}
removeClippedSubviews={true}
contentInset={{top: headerOffset}}
contentOffset={{x: 0, y: headerOffset * -1}}
progressViewOffset={headerOffset}
/>
)}
</View>
)
})
const styles = StyleSheet.create({
feedFooter: {paddingTop: 20},
emptyState: {paddingVertical: 40},
})
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