index.ts

import type { EventHookOn, Fn, MaybeComputedRef, Stoppable } from '@vueuse/shared'
import { containsProp, createEventHook, resolveRef, resolveUnref, until, useTimeoutFn } from '@vueuse/shared'
import type { ComputedRef, Ref } from 'vue-demi'
import { computed, isRef, ref, shallowRef, watch } from 'vue-demi'
import { defaultWindow } from '../_configurable'

export interface UseFetchReturn<T> {
  /**
   * Indicates if the fetch request has finished
   */
  isFinished: Ref<boolean>

  /**
   * The statusCode of the HTTP fetch response
   */
  statusCode: Ref<number | null>

  /**
   * The raw response of the fetch response
   */
  response: Ref<Response | null>

  /**
   * Any fetch errors that may have occurred
   */
  error: Ref<any>

  /**
   * The fetch response body, may either be JSON or text
   */
  data: Ref<T | null>

  /**
   * Indicates if the request is currently being fetched.
   */
  isFetching: Ref<boolean>

  /**
   * Indicates if the fetch request is able to be aborted
   */
  canAbort: ComputedRef<boolean>

  /**
   * Indicates if the fetch request was aborted
   */
  aborted: Ref<boolean>

  /**
   * Abort the fetch request
   */
  abort: Fn

  /**
   * Manually call the fetch
   * (default not throwing error)
   */
  execute: (throwOnFailed?: boolean) => Promise<any>

  /**
   * Fires after the fetch request has finished
   */
  onFetchResponse: EventHookOn<Response>

  /**
   * Fires after a fetch request error
   */
  onFetchError: EventHookOn

  /**
   * Fires after a fetch has completed
   */
  onFetchFinally: EventHookOn

  // methods
  get(): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
  post(payload?: MaybeComputedRef<unknown>, type?: string): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
  put(payload?: MaybeComputedRef<unknown>, type?: string): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
  delete(payload?: MaybeComputedRef<unknown>, type?: string): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
  patch(payload?: MaybeComputedRef<unknown>, type?: string): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
  head(payload?: MaybeComputedRef<unknown>, type?: string): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
  options(payload?: MaybeComputedRef<unknown>, type?: string): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>

  // type
  json<JSON = any>(): UseFetchReturn<JSON> & PromiseLike<UseFetchReturn<JSON>>
  text(): UseFetchReturn<string> & PromiseLike<UseFetchReturn<string>>
  blob(): UseFetchReturn<Blob> & PromiseLike<UseFetchReturn<Blob>>
  arrayBuffer(): UseFetchReturn<ArrayBuffer> & PromiseLike<UseFetchReturn<ArrayBuffer>>
  formData(): UseFetchReturn<FormData> & PromiseLike<UseFetchReturn<FormData>>
}

type DataType = 'text' | 'json' | 'blob' | 'arrayBuffer' | 'formData'
type HttpMethod = 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH' | 'HEAD' | 'OPTIONS'
type Combination = 'overwrite' | 'chain'

const payloadMapping: Record<string, string> = {
  json: 'application/json',
  text: 'text/plain',
}

export interface BeforeFetchContext {
  /**
   * The computed url of the current request
   */
  url: string

  /**
   * The request options of the current request
   */
  options: RequestInit

  /**
   * Cancels the current request
   */
  cancel: Fn
}

export interface AfterFetchContext<T = any> {
  response: Response

  data: T | null
}

export interface OnFetchErrorContext<T = any, E = any> {
  error: E

  data: T | null
}

export interface UseFetchOptions {
  /**
   * Fetch function
   */
  fetch?: typeof window.fetch

  /**
   * Will automatically run fetch when `useFetch` is used
   *
   * @default true
   */
  immediate?: boolean

  /**
   * Will automatically refetch when:
   * - the URL is changed if the URL is a ref
   * - the payload is changed if the payload is a ref
   *
   * @default false
   */
  refetch?: MaybeComputedRef<boolean>

  /**
   * Initial data before the request finished
   *
   * @default null
   */
  initialData?: any

  /**
   * Timeout for abort request after number of millisecond
   * `0` means use browser default
   *
   * @default 0
   */
  timeout?: number

  /**
   * Will run immediately before the fetch request is dispatched
   */
  beforeFetch?: (ctx: BeforeFetchContext) => Promise<Partial<BeforeFetchContext> | void> | Partial<BeforeFetchContext> | void

  /**
   * Will run immediately after the fetch request is returned.
   * Runs after any 2xx response
   */
  afterFetch?: (ctx: AfterFetchContext) => Promise<Partial<AfterFetchContext>> | Partial<AfterFetchContext>

  /**
   * Will run immediately after the fetch request is returned.
   * Runs after any 4xx and 5xx response
   */
  onFetchError?: (ctx: { data: any; response: Response | null; error: any }) => Promise<Partial<OnFetchErrorContext>> | Partial<OnFetchErrorContext>
}

export interface CreateFetchOptions {
  /**
   * The base URL that will be prefixed to all urls unless urls are absolute
   */
  baseUrl?: MaybeComputedRef<string>

  /**
   * Determine the inherit behavior for beforeFetch, afterFetch, onFetchError
   * @default 'chain'
   */
  combination?: Combination

  /**
   * Default Options for the useFetch function
   */
  options?: UseFetchOptions

  /**
   * Options for the fetch request
   */
  fetchOptions?: RequestInit
}

/**
 * !!!IMPORTANT!!!
 *
 * If you update the UseFetchOptions interface, be sure to update this object
 * to include the new options
 */
function isFetchOptions(obj: object): obj is UseFetchOptions {
  return obj && containsProp(obj, 'immediate', 'refetch', 'initialData', 'timeout', 'beforeFetch', 'afterFetch', 'onFetchError', 'fetch')
}

// A URL is considered absolute if it begins with "<scheme>://" or "//" (protocol-relative URL).
function isAbsoluteURL(url: string) {
  return /^([a-z][a-z\d+\-.]*:)?\/\//i.test(url)
}

function headersToObject(headers: HeadersInit | undefined) {
  if (typeof Headers !== 'undefined' && headers instanceof Headers)
    return Object.fromEntries([...headers.entries()])
  return headers
}

function combineCallbacks<T = any>(combination: Combination, ...callbacks: (((ctx: T) => void | Partial<T> | Promise<void | Partial<T>>) | undefined)[]) {
  if (combination === 'overwrite') {
    // use last callback
    return async (ctx: T) => {
      const callback = callbacks[callbacks.length - 1]
      if (callback !== undefined)
        await callback(ctx)
      return ctx
    }
  }
  else {
    // chaining and combine result
    return async (ctx: T) => {
      await callbacks.reduce((prevCallback, callback) => prevCallback.then(async () => {
        if (callback)
          ctx = { ...ctx, ...(await callback(ctx)) }
      }), Promise.resolve())
      return ctx
    }
  }
}

export function createFetch(config: CreateFetchOptions = {}) {
  const _combination = config.combination || 'chain' as Combination
  const _options = config.options || {}
  const _fetchOptions = config.fetchOptions || {}

  function useFactoryFetch(url: MaybeComputedRef<string>, ...args: any[]) {
    const computedUrl = computed(() => {
      const baseUrl = resolveUnref(config.baseUrl)
      const targetUrl = resolveUnref(url)

      return (baseUrl && !isAbsoluteURL(targetUrl))
        ? joinPaths(baseUrl, targetUrl)
        : targetUrl
    })

    let options = _options
    let fetchOptions = _fetchOptions

    // Merge properties into a single object
    if (args.length > 0) {
      if (isFetchOptions(args[0])) {
        options = {
          ...options,
          ...args[0],
          beforeFetch: combineCallbacks(_combination, _options.beforeFetch, args[0].beforeFetch),
          afterFetch: combineCallbacks(_combination, _options.afterFetch, args[0].afterFetch),
          onFetchError: combineCallbacks(_combination, _options.onFetchError, args[0].onFetchError),
        }
      }
      else {
        fetchOptions = {
          ...fetchOptions,
          ...args[0],
          headers: {
            ...(headersToObject(fetchOptions.headers) || {}),
            ...(headersToObject(args[0].headers) || {}),
          },
        }
      }
    }

    if (args.length > 1 && isFetchOptions(args[1])) {
      options = {
        ...options,
        ...args[1],
        beforeFetch: combineCallbacks(_combination, _options.beforeFetch, args[1].beforeFetch),
        afterFetch: combineCallbacks(_combination, _options.afterFetch, args[1].afterFetch),
        onFetchError: combineCallbacks(_combination, _options.onFetchError, args[1].onFetchError),
      }
    }

    return useFetch(computedUrl, fetchOptions, options)
  }

  return useFactoryFetch as typeof useFetch
}

export function useFetch<T>(url: MaybeComputedRef<string>): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
export function useFetch<T>(url: MaybeComputedRef<string>, useFetchOptions: UseFetchOptions): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>
export function useFetch<T>(url: MaybeComputedRef<string>, options: RequestInit, useFetchOptions?: UseFetchOptions): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>>

export function useFetch<T>(url: MaybeComputedRef<string>, ...args: any[]): UseFetchReturn<T> & PromiseLike<UseFetchReturn<T>> {
  const supportsAbort = typeof AbortController === 'function'

  let fetchOptions: RequestInit = {}
  let options: UseFetchOptions = { immediate: true, refetch: false, timeout: 0 }
  interface InternalConfig { method: HttpMethod; type: DataType; payload: unknown; payloadType?: string }
  const config: InternalConfig = {
    method: 'GET',
    type: 'text' as DataType,
    payload: undefined as unknown,
  }

  if (args.length > 0) {
    if (isFetchOptions(args[0]))
      options = { ...options, ...args[0] }
    else
      fetchOptions = args[0]
  }

  if (args.length > 1) {
    if (isFetchOptions(args[1]))
      options = { ...options, ...args[1] }
  }

  const {
    fetch = defaultWindow?.fetch,
    initialData,
    timeout,
  } = options

  // Event Hooks
  const responseEvent = createEventHook<Response>()
  const errorEvent = createEventHook<any>()
  const finallyEvent = createEventHook<any>()

  const isFinished = ref(false)
  const isFetching = ref(false)
  const aborted = ref(false)
  const statusCode = ref<number | null>(null)
  const response = shallowRef<Response | null>(null)
  const error = shallowRef<any>(null)
  const data = shallowRef<T | null>(initialData)

  const canAbort = computed(() => supportsAbort && isFetching.value)

  let controller: AbortController | undefined
  let timer: Stoppable | undefined

  const abort = () => {
    if (supportsAbort && controller) {
      controller.abort()
      controller = undefined
    }
  }

  const loading = (isLoading: boolean) => {
    isFetching.value = isLoading
    isFinished.value = !isLoading
  }

  if (timeout)
    timer = useTimeoutFn(abort, timeout, { immediate: false })

  const execute = async (throwOnFailed = false) => {
    loading(true)
    error.value = null
    statusCode.value = null
    aborted.value = false

    if (supportsAbort) {
      abort()
      controller = new AbortController()
      controller.signal.onabort = () => aborted.value = true
      fetchOptions = {
        ...fetchOptions,
        signal: controller.signal,
      }
    }

    const defaultFetchOptions: RequestInit = {
      method: config.method,
      headers: {},
    }

    if (config.payload) {
      const headers = headersToObject(defaultFetchOptions.headers) as Record<string, string>
      if (config.payloadType)
        headers['Content-Type'] = payloadMapping[config.payloadType] ?? config.payloadType

      const payload = resolveUnref(config.payload)
      defaultFetchOptions.body = config.payloadType === 'json'
        ? JSON.stringify(payload)
        : payload as BodyInit
    }

    let isCanceled = false
    const context: BeforeFetchContext = {
      url: resolveUnref(url),
      options: {
        ...defaultFetchOptions,
        ...fetchOptions,
      },
      cancel: () => { isCanceled = true },
    }

    if (options.beforeFetch)
      Object.assign(context, await options.beforeFetch(context))

    if (isCanceled || !fetch) {
      loading(false)
      return Promise.resolve(null)
    }

    let responseData: any = null

    if (timer)
      timer.start()

    return new Promise<Response | null>((resolve, reject) => {
      fetch(
        context.url,
        {
          ...defaultFetchOptions,
          ...context.options,
          headers: {
            ...headersToObject(defaultFetchOptions.headers),
            ...headersToObject(context.options?.headers),
          },
        },
      )
        .then(async (fetchResponse) => {
          response.value = fetchResponse
          statusCode.value = fetchResponse.status

          responseData = await fetchResponse[config.type]()

          if (options.afterFetch && statusCode.value >= 200 && statusCode.value < 300)
            ({ data: responseData } = await options.afterFetch({ data: responseData, response: fetchResponse }))

          data.value = responseData

          // see: https://www.tjvantoll.com/2015/09/13/fetch-and-errors/
          if (!fetchResponse.ok)
            throw new Error(fetchResponse.statusText)

          responseEvent.trigger(fetchResponse)
          return resolve(fetchResponse)
        })
        .catch(async (fetchError) => {
          let errorData = fetchError.message || fetchError.name

          if (options.onFetchError)
            ({ data: responseData, error: errorData } = await options.onFetchError({ data: responseData, error: fetchError, response: response.value }))
          data.value = responseData
          error.value = errorData

          errorEvent.trigger(fetchError)
          if (throwOnFailed)
            return reject(fetchError)

          return resolve(null)
        })
        .finally(() => {
          loading(false)
          if (timer)
            timer.stop()
          finallyEvent.trigger(null)
        })
    })
  }

  const refetch = resolveRef(options.refetch)
  watch(
    [
      refetch,
      resolveRef(url),
    ],
    ([refetch]) => refetch && execute(),
    { deep: true },
  )

  const shell: UseFetchReturn<T> = {
    isFinished,
    statusCode,
    response,
    error,
    data,
    isFetching,
    canAbort,
    aborted,
    abort,
    execute,

    onFetchResponse: responseEvent.on,
    onFetchError: errorEvent.on,
    onFetchFinally: finallyEvent.on,
    // method
    get: setMethod('GET'),
    put: setMethod('PUT'),
    post: setMethod('POST'),
    delete: setMethod('DELETE'),
    patch: setMethod('PATCH'),
    head: setMethod('HEAD'),
    options: setMethod('OPTIONS'),
    // type
    json: setType('json'),
    text: setType('text'),
    blob: setType('blob'),
    arrayBuffer: setType('arrayBuffer'),
    formData: setType('formData'),
  }

  function setMethod(method: HttpMethod) {
    return (payload?: unknown, payloadType?: string) => {
      if (!isFetching.value) {
        config.method = method
        config.payload = payload
        config.payloadType = payloadType

        // watch for payload changes
        if (isRef(config.payload)) {
          watch(
            [
              refetch,
              resolveRef(config.payload),
            ],
            ([refetch]) => refetch && execute(),
            { deep: true },
          )
        }

        const rawPayload = resolveUnref(config.payload)
        // Set the payload to json type only if it's not provided and a literal object is provided and the object is not `formData`
        // The only case we can deduce the content type and `fetch` can't
        if (!payloadType && rawPayload && Object.getPrototypeOf(rawPayload) === Object.prototype && !(rawPayload instanceof FormData))
          config.payloadType = 'json'

        return {
          ...shell,
          then(onFulfilled: any, onRejected: any) {
            return waitUntilFinished()
              .then(onFulfilled, onRejected)
          },
        } as any
      }
      return undefined
    }
  }

  function waitUntilFinished() {
    return new Promise<UseFetchReturn<T>>((resolve, reject) => {
      until(isFinished).toBe(true)
        .then(() => resolve(shell))
        .catch(error => reject(error))
    })
  }

  function setType(type: DataType) {
    return () => {
      if (!isFetching.value) {
        config.type = type
        return {
          ...shell,
          then(onFulfilled: any, onRejected: any) {
            return waitUntilFinished()
              .then(onFulfilled, onRejected)
          },
        } as any
      }
      return undefined
    }
  }

  if (options.immediate)
    setTimeout(execute, 0)

  return {
    ...shell,
    then(onFulfilled, onRejected) {
      return waitUntilFinished()
        .then(onFulfilled, onRejected)
    },
  }
}

function joinPaths(start: string, end: string): string {
  if (!start.endsWith('/') && !end.startsWith('/'))
    return `${start}/${end}`

  return `${start}${end}`
}