auth-middleware.js

export default async ({ store, redirect, req }) => {
    /**
     * Unautheticated client handler.
     */
    const unauthenticated = () => redirect('/login')

    /**
     * Fetch the user from an API.
     */
    const fetch = async () => {
        return await store.dispatch('auth/fetchUser').catch(() => unauthenticated)
    }

    /**
     * Perform authentication on the server.
     */
    const serverAuthentication = async () => {
        if (store.state.auth.user) {
            return
        }

        if (req.signedCookies.access_token) {
            return await fetch()
        }

        return unauthenticated()
    }

    /**
     * Perfom authentication on the client.
     */
    const clientAuthentication = async () => {
        if (!store.state.auth.user) {
            return await fetch()
        }
    }

    return process.server
        ? serverAuthentication()
        : clientAuthentication()
}