Angel Di Maria has arrived in Doha to undergo his medical ahead of a proposed £44m move from Manchester United to PSG.
Luton have signed former Peterborough and Brighton striker Craig Mackail-Smith on a two-year deal.
The 21-year-old had over a year left to run on his existing deal but the club were keen to tie him to a longer-term agreement.
Alfei, who has spent most of the season on loan at Wrexham, said: "I'm absolutely delighted. It's good to know the club has faith in me and there is nowhere I would rather be than Swansea."