Celtic announced on Friday that midfielder Stuart Armstrong had signed a two-year deal at the club, keeping him in Glasgow until 2019, a year beyond his current contract which was due to expire next summer.

His situation was one that worried Celtic fans all summer, with the prospect of a move away from the club before the end of August growing more likely as the saga rolled on.

His exceptional form last season made him a real favourite in the Hoops as he emerged as one of the key performers in Brendan Rodgers' treble winning side.

One of the key aims of the club this summer has been retaining the big stars in Rodgers' squad and you'd certainly count Armstrong as one of those.

However, it's unusual for the club to sign short-term contracts with players and the one-year extension raises a few questions and perhaps a few doubts about where his future lies.

Here are TWO positives and TWO negatives of the new contract for the Scottish international...

Positive: Another 12 months of goalscoring

The fact that Stuart Armstrong will be at the club for another season at least is undoubtedly a massive positive for Celtic in the short-term. They don't have another central midfielder who can play the all-round game he has in Brendan Rodgers' time at the club, possessing the energy and ability to defend out of possession but also the desire to get himself forward and score goals.

It's his goalscoring that won so many plaudits last season, he netted a massive 17 from midfield, a huge amount for a midfielder who wasn't even deployed in attacking positions in all of his matches.

If there is one major positive of him signing a new deal, it's that this will likely continue all season again. He's already scored two this summer and the season has barely started.

Now he is happy with his new deal he can come back into Rodgers' plans once again and become the driving force in the Hoops midfield.

Negative: He likely isn't the man to build a team around

When he was on top form last season, scoring goals and even taking the captain's armband when Scott Brown missed games, many Celtic fans he might be the man to take over from Brown long-term, a man to build the team around and maybe even become the future club captain.

It seems unlikely, based on just a single year extension to his current contract, that this will be the case though. If he had that potential or want to stay at the club for the rest of his career you'd imagine he'd be happy to commit more years to his playing days in Glasgow.

Does he have ambitions to play in the Premier League, or even move abroad? His intentions aren't clear nor certain but you'd expect him to be leaving Celtic in a year's time, when the situation will be exactly the same as this summer.

This contract allows him to develop further and experience more UEFA Champions League football, but his long-term future is far from certain.

Positive: The club have protected his value

Aside from his ability, this new contract is a perfect business situation for Celtic. They've now protected the value of one of their key assets in the squad from clubs looking to capitalise on his situation in Glasgow. Whether they sell him in January, next summer or even before the end of August, they should now receive a healthy fee for the player.

Players like Victor Wanyama, Virgil van Dijk, Fraser Forster and Aiden McGeady have all left for monster fees by Scottish standards in years gone past and if Stuart Armstrong has another good few months or full season at Celtic then he could reach a similar figure and provide an excellent return on the investment that brought him to the Hoops from Dundee United in 2014.

Negative: Speculation about his future will rumble on

What this contract signing is unlikely to have achieved is closure on reports linking the midfielder with a move away from the club. For supporters of a certain vintage it will be reminiscent of when Stiliyan Petrov signed a new deal with the club before moving down to the English Premier League shortly after, an agreement that suited both the player and Celtic after many years of service.

Stuart Armstrong hasn't quite reached that status at Celtic Park but given the short-term nature of the deal you can already picture speculative headlines and question marks about his future well into the Autumn and Winter ahead of the January transfer window.

That'll be especially true if he's one of the players that can impress in the group stages of the UEFA Champions League.