const JWTAuthMiddleware = async function (request, reply) {
    const startedAt = Date.now();

    const authHeader = request.headers['authorization'];

    // HEADER NOT PROVIDED
    if (!authHeader)
        return notAuthorized(reply);

    // let's assume it is always `Bearer token`
    const [ protocol, token ] = authHeader.split(' ');

    // TOKEN NOT PROVIDED
    if (!token)
        return notAuthorized(reply);

    try {
        // VERIFY TOKEN
        const decoded = this.jwt.verify(token);

        const Users = this.mongo.db.collection('users');
        const { email, iat } = decoded;

        try {
            const user = await Users.findOne({ email }, profileProjection);

            // CHECK FOR USER EXISTENCE
            if (!user)
                return notAuthorized(reply);

            // CHECK FOR BLACKLISTED TOKEN
            if (!!user.tokenMinValidity && (iat * 1000) < user.tokenMinValidity)
                return notAuthorized(reply);

            // ALL FINE, FORWARD USER PROFILE
            request.user = user;

            request.authTime = Date.now() - startedAt;

            return;
        } catch (error) {
            console.error(error);
            reply.code(500);
            reply.send({ code: errorTypes.INTERNAL_SERVER_ERROR });
            return;
        }

    } catch (error) {
        // TOKEN MALFORMED OR EXPIRED
        console.error(error);
        return notAuthorized(reply);
    }
}