Adelaide man searching for answers after random bathroom attack which left him fighting for life

A violent one-punch attack inside a South Australian hotel last month has left a 32-year-old man trying to piece together the moment which left him fighting for his life.

Soon-to-be father Adam Whetstone was assaulted in the bathroom while attending a music concert at the Bridgeway Hotel in Adelaide's north.

"As I've gone into the toilet, the door has hit into someone else," he said.

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"I've tried to laugh it off as a joke, but he said 'do you think this is funny?'

"I said something like 'you don't need to arc up' and he's just turned around and king-hit me."

Moments after the attack, while Whetstone lay face down and unconscious on the bathroom floor, the perpetrator filmed himself mocking his victim before uploading the video to social media:

"Wanna get slapped down on the floor, way to talk shit cuz, get slapped out," a voice is heard in the video.

Whetstone's injuries required treatment inside an intensive care unit, with fluid on his lungs and serious head trauma threatening his recovery.

"I had swelling on the brain, a fractured nose, and a busted-up, swollen face," he said.

The Adelaide man has been left with mounting medical bills and still no one to blame, with police yet to charge anyone over the assault.

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Police say the attack was one of several violent altercations that erupted that night.

A police helicopter was called to break up a melee as crowds left the premises.

Anyone there on the night who witnessed what happened has been urged to contact SA Police.