Mature grape black rot

Hi I recently bought a house that has a very mature grape vine. We were hoping to get a healthy harvest of grapes this year but have seen that all of them turned black before reaching maturity. From google I believe this is black rot. The vine do not seem to be well cared for as there are a lot of dead branches woven in around the living.

I know we will not be able to save anything this year but want to make sure we do the proper pruning and take the proper preparations to get a good harvests in future years. Looking for advice on where to start and how much to prune.