web/apps/scandic-web/app/[lang]/(live)/(protected)/logout/route.ts

import { type NextRequest, NextResponse } from "next/server"
import { AuthError } from "next-auth"

import { Lang } from "@/constants/languages"
import { env } from "@/env/server"
import { internalServerError } from "@/server/errors/next"
import { getPublicURL } from "@/server/utils"

import { signOut } from "@/auth"

export async function GET(
  request: NextRequest,
  context: { params: Promise<{ lang: Lang }> }
) {
  const publicURL = getPublicURL(request)

  let redirectTo: string = ""

  const returnUrl = request.headers.get("x-returnurl")
  const isSeamless = request.headers.get("x-logout-source") === "seamless"

  console.log(
    `[logout] source: ${request.headers.get("x-logout-source") || "normal"}`
  )

  const redirectToSearchParamValue =
    request.nextUrl.searchParams.get("redirectTo")
  const redirectToFallback = "/"

  if (isSeamless) {
    if (returnUrl) {
      redirectTo = returnUrl
    } else {
      console.log(
        `[login] missing returnUrl, using fallback: ${redirectToFallback}`
      )
      redirectTo = redirectToFallback
    }
  } else {
    redirectTo = redirectToSearchParamValue || redirectToFallback

    // Make relative URL to absolute URL
    if (redirectTo.startsWith("/")) {
      console.log(`[logout] make redirectTo absolute, from ${redirectTo}`)
      redirectTo = new URL(redirectTo, publicURL).href
      console.log(`[logout] make redirectTo absolute, to ${redirectTo}`)
    }

    try {
      // Initiate the seamless logout flow
      let redirectUrlValue
      const params = await context.params
      switch (params.lang) {
        case Lang.da:
          redirectUrlValue = env.SEAMLESS_LOGOUT_DA
          break
        case Lang.de:
          redirectUrlValue = env.SEAMLESS_LOGOUT_DE
          break
        case Lang.en:
          redirectUrlValue = env.SEAMLESS_LOGOUT_EN
          break
        case Lang.fi:
          redirectUrlValue = env.SEAMLESS_LOGOUT_FI
          break
        case Lang.no:
          redirectUrlValue = env.SEAMLESS_LOGOUT_NO
          break
        case Lang.sv:
          redirectUrlValue = env.SEAMLESS_LOGOUT_SV
          break
      }
      const redirectUrl = new URL(redirectUrlValue)
      console.log(
        `[logout] creating redirect to seamless logout: ${redirectUrl}`
      )
      redirectTo = redirectUrl.toString()
    } catch (e) {
      console.error(
        "Unable to create URL for seamless logout, proceeding without it."
      )
      console.error(e)
    }
  }

  try {
    redirectTo = `${env.CURITY_ISSUER_USER}/authn/authenticate/logout?redirect_uri=${encodeURIComponent(redirectTo)}`
    console.log(`[logout] final redirectUrl: ${redirectTo}`)

    /**
     * Passing `redirect: false` to `signOut` will return a result object
     * instead of automatically redirecting inside of `signOut`.
     * https://github.com/nextauthjs/next-auth/blob/3c035ec/packages/next-auth/src/lib/actions.ts#L104
     */
    const redirectUrlObj = await signOut({
      redirectTo,
      redirect: false,
    })

    if (redirectUrlObj) {
      console.log(`[logout] redirecting to: ${redirectUrlObj.redirect}`)
      return NextResponse.redirect(redirectUrlObj.redirect)
    } else {
      console.error(`[logout] missing redirectUrlObj reponse from signOut()`)
    }
  } catch (error) {
    if (error instanceof AuthError) {
      console.log({ signOutAuthError: error })
    } else {
      console.log({ signOutError: error })
    }
  }

  return internalServerError()
}