import { Paginator } from 'masto' import type { WsEvents, mastodon } from 'masto' import type { PaginatorState } from '~/types' export function usePaginator( _paginator: Paginator, stream?: Promise, eventType: 'notification' | 'update' = 'update', preprocess: (items: (T | U)[]) => U[] = items => items as unknown as U[], buffer = 10, ) { // TODO: wait PR https://github.com/neet/masto.js/pull/801 // called `next` method will mutate the internal state of the variable, and we need its initial state after HMR // so clone it // @ts-expect-error clone it const paginator: Paginator = new Paginator(_paginator.http, _paginator.nextPath, _paginator.nextParams) const state = ref(isMastoInitialised.value ? 'idle' : 'loading') const items = ref([]) const nextItems = ref([]) const prevItems = ref([]) const endAnchor = ref() const bound = reactive(useElementBounding(endAnchor)) const isInScreen = $computed(() => bound.top < window.innerHeight * 2) const error = ref() const deactivated = useDeactivated() async function update() { (items.value as U[]).unshift(...preprocess(prevItems.value as T[])) prevItems.value = [] } stream?.then((s) => { s.on(eventType, (status) => { if ('uri' in status) cacheStatus(status, undefined, true) const index = prevItems.value.findIndex((i: any) => i.id === status.id) if (index >= 0) prevItems.value.splice(index, 1) prevItems.value.unshift(status as any) }) // TODO: update statuses s.on('status.update', (status) => { cacheStatus(status, undefined, true) const data = items.value as mastodon.v1.Status[] const index = data.findIndex(s => s.id === status.id) if (index >= 0) data[index] = status }) s.on('delete', (id) => { removeCachedStatus(id) const data = items.value as mastodon.v1.Status[] const index = data.findIndex(s => s.id === id) if (index >= 0) data.splice(index, 1) }) }) async function loadNext() { if (state.value !== 'idle') return state.value = 'loading' try { const result = await paginator.next() if (!result.done && result.value.length) { const preprocessedItems = preprocess([...nextItems.value, ...result.value] as (U | T)[]) const itemsToShowCount = preprocessedItems.length <= buffer ? preprocessedItems.length : preprocessedItems.length - buffer ;(nextItems.value as U[]) = preprocessedItems.slice(itemsToShowCount) ;(items.value as U[]).push(...preprocessedItems.slice(0, itemsToShowCount)) state.value = 'idle' } else { items.value.push(...nextItems.value) nextItems.value = [] state.value = 'done' } } catch (e) { error.value = e state.value = 'error' } await nextTick() bound.update() } if (process.client) { useIntervalFn(() => { bound.update() }, 1000) if (!isMastoInitialised.value) { onMastoInit(() => { state.value = 'idle' loadNext() }) } watch( () => [isInScreen, state], () => { if ( isInScreen && state.value === 'idle' // No new content is loaded when the keepAlive page enters the background && deactivated.value === false ) loadNext() }, ) } return { items, prevItems, update, state, error, endAnchor, } }