well it all started when i was passing a power wire for my amp through a grommet in the firewall. my friend lifted up the carpet on the drivers side and discovered oil leaking behind the clutch pedal. he said my master cylinder has a leak. last night i drove it around 1am and it was feeling fine. today, i drove my car and noticed the clutch pedal is super soft and has a lot of slack. the sweet spot is a lot lower than regular too. whats happening?

and how much do you think repairs would cost?