140 lines
3.6 KiB
TypeScript
140 lines
3.6 KiB
TypeScript
import type { mastodon } from 'masto'
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import type { Ref } from 'vue'
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import type { PaginatorState } from '~/types'
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export function usePaginator<T, P, U = T>(
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_paginator: mastodon.Paginator<T[], P>,
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stream: Ref<mastodon.streaming.Subscription | undefined>,
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preprocess: (items: (T | U)[]) => U[] = items => items as unknown as U[],
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buffer = 10,
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) {
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// called `next` method will mutate the internal state of the variable,
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// and we need its initial state after HMR
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// so clone it
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const paginator = _paginator.clone()
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const state = ref<PaginatorState>(isHydrated.value ? 'idle' : 'loading')
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const items = ref<U[]>([])
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const nextItems = ref<U[]>([])
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const prevItems = ref<T[]>([])
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const endAnchor = ref<HTMLDivElement>()
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const bound = useElementBounding(endAnchor)
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const isInScreen = computed(() => bound.top.value < window.innerHeight * 2)
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const error = ref<unknown | undefined>()
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const deactivated = useDeactivated()
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async function update() {
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(items.value as U[]).unshift(...preprocess(prevItems.value as T[]))
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prevItems.value = []
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}
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watch(stream, async (stream) => {
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if (!stream)
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return
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for await (const entry of stream) {
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if (entry.event === 'update' || entry.event === 'notification') {
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const status = entry.payload
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if ('uri' in status)
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cacheStatus(status, undefined, true)
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const index = prevItems.value.findIndex((i: any) => i.id === status.id)
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if (index >= 0)
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prevItems.value.splice(index, 1)
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prevItems.value.unshift(status as any)
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}
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else if (entry.event === 'status.update') {
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const status = entry.payload
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cacheStatus(status, undefined, true)
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const data = items.value as mastodon.v1.Status[]
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const index = data.findIndex(s => s.id === status.id)
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if (index >= 0)
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data[index] = status
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}
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else if (entry.event === 'delete') {
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const id = entry.payload
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removeCachedStatus(id)
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const data = items.value as mastodon.v1.Status[]
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const index = data.findIndex(s => s.id === id)
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if (index >= 0)
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data.splice(index, 1)
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}
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}
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}, { immediate: true })
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async function loadNext() {
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if (state.value !== 'idle')
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return
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state.value = 'loading'
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try {
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const result = await paginator.next()
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if (!result.done && result.value.length) {
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const preprocessedItems = preprocess([...nextItems.value, ...result.value] as (U | T)[])
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const itemsToShowCount
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= preprocessedItems.length <= buffer
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? preprocessedItems.length
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: preprocessedItems.length - buffer
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;(nextItems.value as U[]) = preprocessedItems.slice(itemsToShowCount)
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;(items.value as U[]).push(...preprocessedItems.slice(0, itemsToShowCount))
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state.value = 'idle'
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}
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else {
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items.value.push(...nextItems.value)
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nextItems.value = []
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state.value = 'done'
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}
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}
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catch (e) {
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console.error(e)
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error.value = e
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state.value = 'error'
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}
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await nextTick()
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bound.update()
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}
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if (import.meta.client) {
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useIntervalFn(() => {
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bound.update()
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}, 1000)
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if (!isHydrated.value) {
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onHydrated(() => {
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state.value = 'idle'
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loadNext()
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})
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}
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watchEffect(
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() => {
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if (
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isInScreen.value
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&& state.value === 'idle'
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// No new content is loaded when the keepAlive page enters the background
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&& deactivated.value === false
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)
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loadNext()
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},
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)
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}
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return {
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items,
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prevItems,
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update,
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state,
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error,
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endAnchor,
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}
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}
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