import type { mastodon } from 'masto' import type { Ref } from 'vue' import type { PaginatorState } from '~/types' export function usePaginator( _paginator: mastodon.Paginator, stream: Ref, preprocess: (items: (T | U)[]) => U[] = items => items as unknown as U[], buffer = 10, ) { // called `next` method will mutate the internal state of the variable, // and we need its initial state after HMR // so clone it const paginator = _paginator.clone() const state = ref(isHydrated.value ? 'idle' : 'loading') const items = ref([]) const nextItems = ref([]) const prevItems = ref([]) const endAnchor = ref() const bound = useElementBounding(endAnchor) const isInScreen = computed(() => bound.top.value < window.innerHeight * 2) const error = ref() const deactivated = useDeactivated() async function update() { (items.value as U[]).unshift(...preprocess(prevItems.value as T[])) prevItems.value = [] } watch(stream, async (stream) => { if (!stream) return for await (const entry of stream) { if (entry.event === 'update') { const status = entry.payload if ('uri' in entry) 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) } else if (entry.event === 'status.update') { const status = entry.payload 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 } else if (entry.event === 'delete') { const id = entry.payload 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) } } }, { immediate: true }) 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) { console.error(e) error.value = e state.value = 'error' } await nextTick() bound.update() } if (process.client) { useIntervalFn(() => { bound.update() }, 1000) if (!isHydrated.value) { onHydrated(() => { state.value = 'idle' loadNext() }) } watchEffect( () => { if ( isInScreen.value && 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, } }