zeichen-legacy/src/services/Storage.ts

import { addTime, TimeDivision } from '../utilities/Date'
import * as Serialization from '../utilities/Serialization'
import LocalStorage from './LocalStorage'

type StorageParams = {
  id: string,
  url: string,
}

type LoadItems = <T extends Record<string, unknown>>(params: StorageParams) => () => Promise<T[]>

const loadItems: LoadItems = <T extends Record<string, unknown>>(params) => async (): Promise<T[]> => {
  const { id, url, } = params
  const storage = new LocalStorage(
    window.localStorage,
    Serialization.serialize,
    Serialization.deserialize
  )
  const localData = storage.getItem(id)
  if (localData === null) {
    const remoteItems = await window.fetch(url)
    // TODO add custom serialization method
    const theItems: T[] = await remoteItems.json()
    storage.setItem(id, {
      // TODO backend should set expiry
      expiry: addTime(new Date(), 30)(TimeDivision.DAYS).getTime(),
      items: theItems,
    })
    return theItems
  }

  const dataExpiry = new Date(Number(localData.expiry))
  const now = new Date()
  if (now.getTime() > dataExpiry.getTime()) {
    storage.removeItem(id)
    const loader: () => Promise<T[]> = loadItems(params)
    return loader()
  }
  return localData.items
}

type SaveItem = <T extends Record<string, unknown>>(p: StorageParams) => (item: T) => Promise<T>

const saveItem: SaveItem = <T extends Record<string, unknown>>(params) => async (item) => {
  const { id: storageId, url } = params
  const storage = new LocalStorage(
    window.localStorage,
    Serialization.serialize,
    Serialization.deserialize
  )
  const localData = storage.getItem(storageId, {
    expiry: addTime(new Date(), 30)(TimeDivision.DAYS).getTime(),
    items: [],
  })
  const { items: localItems } = localData
  const { id: itemId, ...theBody } = item
  const theItems: T[] = (
    localItems.some(i => i.id === itemId)
      ? localItems.map(i => i.id === itemId ? item : i)
      : [...localItems, item]
  )
  storage.setItem(storageId, { ...localData, items: theItems })
  const response = await window.fetch(`${url}/${itemId}`, {
    method: 'put',
    body: JSON.stringify(theBody),
    headers: {
      'Content-Type': 'application/json',
    },
  })

  const responseBody = await response.json()
  if (response.status !== 201 && response.status !== 200) {
    throw responseBody
  }
  return responseBody as T
}

type DeleteItem = <T extends Record<string, unknown>>(p: StorageParams) => (item: T) => Promise<boolean>

const deleteItem: DeleteItem = <T extends Record<string, unknown>>(params) => async (item) => {
  const { id: storageId, url } = params
  const storage = new LocalStorage(
    window.localStorage,
    Serialization.serialize,
    Serialization.deserialize
  )

  const localData = storage.getItem(storageId, {
    expiry: addTime(new Date(), 30)(TimeDivision.DAYS).getTime(),
    items: [],
  })
  const { items: localItems } = localData
  const { id: itemId } = item
  const theItems: T[] = localItems.filter(i => i.id !== itemId)
  storage.setItem(storageId, { ...localData, items: theItems })
  const response = await window.fetch(`${url}/${itemId}`, {
    method: 'delete',
  })
  return response.status === 204
}

export const loadNotes = loadItems({ id: 'notes', url: '/api/notes' })
export const loadFolders = loadItems({ id: 'folders', url: '/api/folders' })
export const saveNote = saveItem({ id: 'notes', url: '/api/notes' })
export const saveFolder = saveItem({ id: 'folders', url: '/api/folders' })
export const deleteNote = deleteItem({ id: 'notes', url: '/api/notes' })