index.ts

/* eslint-env node */
// ^^^^ This comment is need to prevent browser bundles of this file

/**
 * [[include:src/server/README.md]]
 *
 * @packageDocumentation
 * @module twind/server
 */

import { executionAsyncId, createHook } from 'async_hooks'

import type { Sheet, SheetInit } from 'twind'
import { virtualSheet } from 'twind/sheets'

export * from 'twind'
export * from 'twind/sheets'

export interface AsyncVirtualSheet extends Sheet {
  readonly target: readonly string[]
  init: SheetInit
  reset: () => void
  enable: () => void
  disable: () => void
}

interface Snapshot {
  state: unknown[] | undefined
}

export const asyncVirtualSheet = (): AsyncVirtualSheet => {
  const sheet = virtualSheet()
  const initial = sheet.reset()

  const store = new Map<number, Snapshot>()

  const asyncHook = createHook({
    init(asyncId, type, triggerAsyncId) {
      const snapshot = store.get(triggerAsyncId)

      if (snapshot) {
        store.set(asyncId, snapshot)
      }
    },

    before(asyncId) {
      const snapshot = store.get(asyncId)

      if (snapshot) {
        sheet.reset(snapshot.state)
      }
    },

    after(asyncId) {
      const snapshot = store.get(asyncId)

      if (snapshot) {
        snapshot.state = sheet.reset(initial)
      }
    },

    destroy(asyncId) {
      store.delete(asyncId)
    },
  }).enable()

  return {
    get target() {
      return sheet.target
    },
    insert: sheet.insert,
    init: sheet.init,
    reset: () => {
      const asyncId = executionAsyncId()

      const snapshot = store.get(asyncId)

      if (snapshot) {
        snapshot.state = undefined
      } else {
        store.set(asyncId, { state: undefined })
      }

      sheet.reset()
    },
    enable: () => asyncHook.enable(),
    disable: () => asyncHook.disable(),
  }
}