index.tsx

// Note about signIn() and signOut() methods:
//
// On signIn() and signOut() we pass 'json: true' to request a response in JSON
// instead of HTTP as redirect URLs on other domains are not returned to
// requests made using the fetch API in the browser, and we need to ask the API
// to return the response as a JSON object (the end point still defaults to
// returning an HTTP response with a redirect for non-JavaScript clients).
//
// We use HTTP POST requests with CSRF Tokens to protect against CSRF attacks.

import * as React from "react"
import _logger, { proxyLogger } from "../lib/logger"
import parseUrl from "../lib/parse-url"
import { Session } from ".."
import {
  BroadcastChannel,
  CtxOrReq,
  apiBaseUrl,
  fetchData,
  now,
  NextAuthClientConfig,
} from "../client/_utils"

import type {
  ClientSafeProvider,
  LiteralUnion,
  SessionProviderProps,
  SignInAuthorizationParams,
  SignInOptions,
  SignInResponse,
  SignOutParams,
  SignOutResponse,
  UseSessionOptions,
} from "./types"

import type {
  BuiltInProviderType,
  RedirectableProviderType,
} from "../providers"

export * from "./types"

// This behaviour mirrors the default behaviour for getting the site name that
// happens server side in server/index.js
// 1. An empty value is legitimate when the code is being invoked client side as
//    relative URLs are valid in that context and so defaults to empty.
// 2. When invoked server side the value is picked up from an environment
//    variable and defaults to 'http://localhost:3000'.
const __NEXTAUTH: NextAuthClientConfig = {
  baseUrl: parseUrl(process.env.NEXTAUTH_URL ?? process.env.VERCEL_URL).origin,
  basePath: parseUrl(process.env.NEXTAUTH_URL).path,
  baseUrlServer: parseUrl(
    process.env.NEXTAUTH_URL_INTERNAL ??
      process.env.NEXTAUTH_URL ??
      process.env.VERCEL_URL
  ).origin,
  basePathServer: parseUrl(
    process.env.NEXTAUTH_URL_INTERNAL ?? process.env.NEXTAUTH_URL
  ).path,
  _lastSync: 0,
  _session: undefined,
  _getSession: () => {},
}

const broadcast = BroadcastChannel()

const logger = proxyLogger(_logger, __NEXTAUTH.basePath)

export type SessionContextValue<R extends boolean = false> = R extends true
  ?
      | { data: Session; status: "authenticated" }
      | { data: null; status: "loading" }
  :
      | { data: Session; status: "authenticated" }
      | { data: null; status: "unauthenticated" | "loading" }

const SessionContext = React.createContext<SessionContextValue | undefined>(
  undefined
)

/**
 * React Hook that gives you access
 * to the logged in user's session data.
 *
 * [Documentation](https://next-auth.js.org/getting-started/client#usesession)
 */
export function useSession<R extends boolean>(options?: UseSessionOptions<R>) {
  // @ts-expect-error Satisfy TS if branch on line below
  const value: SessionContextValue<R> = React.useContext(SessionContext)
  if (!value && process.env.NODE_ENV !== "production") {
    throw new Error(
      "[next-auth]: `useSession` must be wrapped in a <SessionProvider />"
    )
  }

  const { required, onUnauthenticated } = options ?? {}

  const requiredAndNotLoading = required && value.status === "unauthenticated"

  React.useEffect(() => {
    if (requiredAndNotLoading) {
      const url = `/api/auth/signin?${new URLSearchParams({
        error: "SessionRequired",
        callbackUrl: window.location.href,
      })}`
      if (onUnauthenticated) onUnauthenticated()
      else window.location.href = url
    }
  }, [requiredAndNotLoading, onUnauthenticated])

  if (requiredAndNotLoading) {
    return { data: value.data, status: "loading" } as const
  }

  return value
}

export type GetSessionParams = CtxOrReq & {
  event?: "storage" | "timer" | "hidden" | string
  triggerEvent?: boolean
  broadcast?: boolean
}

export async function getSession(params?: GetSessionParams) {
  const session = await fetchData<Session>(
    "session",
    __NEXTAUTH,
    logger,
    params
  )
  if (params?.broadcast ?? true) {
    broadcast.post({ event: "session", data: { trigger: "getSession" } })
  }
  return session
}

/**
 * Returns the current Cross Site Request Forgery Token (CSRF Token)
 * required to make POST requests (e.g. for signing in and signing out).
 * You likely only need to use this if you are not using the built-in
 * `signIn()` and `signOut()` methods.
 *
 * [Documentation](https://next-auth.js.org/getting-started/client#getcsrftoken)
 */
export async function getCsrfToken(params?: CtxOrReq) {
  const response = await fetchData<{ csrfToken: string }>(
    "csrf",
    __NEXTAUTH,
    logger,
    params
  )
  return response?.csrfToken
}

/**
 * It calls `/api/auth/providers` and returns
 * a list of the currently configured authentication providers.
 * It can be useful if you are creating a dynamic custom sign in page.
 *
 * [Documentation](https://next-auth.js.org/getting-started/client#getproviders)
 */
export async function getProviders() {
  return await fetchData<
    Record<LiteralUnion<BuiltInProviderType>, ClientSafeProvider>
  >("providers", __NEXTAUTH, logger)
}

/**
 * Client-side method to initiate a signin flow
 * or send the user to the signin page listing all possible providers.
 * Automatically adds the CSRF token to the request.
 *
 * [Documentation](https://next-auth.js.org/getting-started/client#signin)
 */
export async function signIn<
  P extends RedirectableProviderType | undefined = undefined
>(
  provider?: LiteralUnion<BuiltInProviderType>,
  options?: SignInOptions,
  authorizationParams?: SignInAuthorizationParams
): Promise<
  P extends RedirectableProviderType ? SignInResponse | undefined : undefined
> {
  const { callbackUrl = window.location.href, redirect = true } = options ?? {}

  const baseUrl = apiBaseUrl(__NEXTAUTH)
  const providers = await getProviders()

  if (!providers) {
    window.location.href = `${baseUrl}/error`
    return
  }

  if (!provider || !(provider in providers)) {
    window.location.href = `${baseUrl}/signin?${new URLSearchParams({
      callbackUrl,
    })}`
    return
  }

  const isCredentials = providers[provider].type === "credentials"
  const isEmail = providers[provider].type === "email"
  const isSupportingReturn = isCredentials || isEmail

  const signInUrl = `${baseUrl}/${
    isCredentials ? "callback" : "signin"
  }/${provider}`

  const _signInUrl = `${signInUrl}?${new URLSearchParams(authorizationParams)}`

  const res = await fetch(_signInUrl, {
    method: "post",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
    },
    // @ts-expect-error
    body: new URLSearchParams({
      ...options,
      csrfToken: await getCsrfToken(),
      callbackUrl,
      json: true,
    }),
  })

  const data = await res.json()

  if (redirect || !isSupportingReturn) {
    const url = data.url ?? callbackUrl
    window.location.href = url
    // If url contains a hash, the browser does not reload the page. We reload manually
    if (url.includes("#")) window.location.reload()
    return
  }

  const error = new URL(data.url).searchParams.get("error")

  if (res.ok) {
    await __NEXTAUTH._getSession({ event: "storage" })
  }

  return {
    error,
    status: res.status,
    ok: res.ok,
    url: error ? null : data.url,
  } as any
}

/**
 * Signs the user out, by removing the session cookie.
 * Automatically adds the CSRF token to the request.
 *
 * [Documentation](https://next-auth.js.org/getting-started/client#signout)
 */
export async function signOut<R extends boolean = true>(
  options?: SignOutParams<R>
): Promise<R extends true ? undefined : SignOutResponse> {
  const { callbackUrl = window.location.href } = options ?? {}
  const baseUrl = apiBaseUrl(__NEXTAUTH)
  const fetchOptions = {
    method: "post",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
    },
    // @ts-expect-error
    body: new URLSearchParams({
      csrfToken: await getCsrfToken(),
      callbackUrl,
      json: true,
    }),
  }
  const res = await fetch(`${baseUrl}/signout`, fetchOptions)
  const data = await res.json()

  broadcast.post({ event: "session", data: { trigger: "signout" } })

  if (options?.redirect ?? true) {
    const url = data.url ?? callbackUrl
    window.location.href = url
    // If url contains a hash, the browser does not reload the page. We reload manually
    if (url.includes("#")) window.location.reload()
    // @ts-expect-error
    return
  }

  await __NEXTAUTH._getSession({ event: "storage" })

  return data
}

/**
 * Provider to wrap the app in to make session data available globally.
 * Can also be used to throttle the number of requests to the endpoint
 * `/api/auth/session`.
 *
 * [Documentation](https://next-auth.js.org/getting-started/client#sessionprovider)
 */
export function SessionProvider(props: SessionProviderProps) {
  const { children, basePath } = props

  if (basePath) __NEXTAUTH.basePath = basePath

  /**
   * If session was `null`, there was an attempt to fetch it,
   * but it failed, but we still treat it as a valid initial value.
   */
  const hasInitialSession = props.session !== undefined

  /** If session was passed, initialize as already synced */
  __NEXTAUTH._lastSync = hasInitialSession ? now() : 0

  const [session, setSession] = React.useState(() => {
    if (hasInitialSession) __NEXTAUTH._session = props.session
    return props.session
  })

  /** If session was passed, initialize as not loading */
  const [loading, setLoading] = React.useState(!hasInitialSession)

  React.useEffect(() => {
    __NEXTAUTH._getSession = async ({ event } = {}) => {
      try {
        const storageEvent = event === "storage"
        // We should always update if we don't have a client session yet
        // or if there are events from other tabs/windows
        if (storageEvent || __NEXTAUTH._session === undefined) {
          __NEXTAUTH._lastSync = now()
          __NEXTAUTH._session = await getSession({
            broadcast: !storageEvent,
          })
          setSession(__NEXTAUTH._session)
          return
        }

        if (
          // If there is no time defined for when a session should be considered
          // stale, then it's okay to use the value we have until an event is
          // triggered which updates it
          !event ||
          // If the client doesn't have a session then we don't need to call
          // the server to check if it does (if they have signed in via another
          // tab or window that will come through as a "stroage" event
          // event anyway)
          __NEXTAUTH._session === null ||
          // Bail out early if the client session is not stale yet
          now() < __NEXTAUTH._lastSync
        ) {
          return
        }

        // An event or session staleness occurred, update the client session.
        __NEXTAUTH._lastSync = now()
        __NEXTAUTH._session = await getSession()
        setSession(__NEXTAUTH._session)
      } catch (error) {
        logger.error("CLIENT_SESSION_ERROR", error as Error)
      } finally {
        setLoading(false)
      }
    }

    __NEXTAUTH._getSession()

    return () => {
      __NEXTAUTH._lastSync = 0
      __NEXTAUTH._session = undefined
      __NEXTAUTH._getSession = () => {}
    }
  }, [])

  React.useEffect(() => {
    // Listen for storage events and update session if event fired from
    // another window (but suppress firing another event to avoid a loop)
    // Fetch new session data but tell it to not to fire another event to
    // avoid an infinite loop.
    // Note: We could pass session data through and do something like
    // `setData(message.data)` but that can cause problems depending
    // on how the session object is being used in the client; it is
    // more robust to have each window/tab fetch it's own copy of the
    // session object rather than share it across instances.
    const unsubscribe = broadcast.receive(() =>
      __NEXTAUTH._getSession({ event: "storage" })
    )

    return () => unsubscribe()
  }, [])

  React.useEffect(() => {
    const { refetchOnWindowFocus = true } = props
    // Listen for when the page is visible, if the user switches tabs
    // and makes our tab visible again, re-fetch the session, but only if
    // this feature is not disabled.
    const visibilityHandler = () => {
      if (refetchOnWindowFocus && document.visibilityState === "visible")
        __NEXTAUTH._getSession({ event: "visibilitychange" })
    }
    document.addEventListener("visibilitychange", visibilityHandler, false)
    return () =>
      document.removeEventListener("visibilitychange", visibilityHandler, false)
  }, [props.refetchOnWindowFocus])

  React.useEffect(() => {
    const { refetchInterval } = props
    // Set up polling
    if (refetchInterval) {
      const refetchIntervalTimer = setInterval(() => {
        if (__NEXTAUTH._session) {
          __NEXTAUTH._getSession({ event: "poll" })
        }
      }, refetchInterval * 1000)
      return () => clearInterval(refetchIntervalTimer)
    }
  }, [props.refetchInterval])

  const value: any = React.useMemo(
    () => ({
      data: session,
      status: loading
        ? "loading"
        : session
        ? "authenticated"
        : "unauthenticated",
    }),
    [session, loading]
  )

  return (
    <SessionContext.Provider value={value}>{children}</SessionContext.Provider>
  )
}