#!/bin/bash
set -euo pipefail

# exit on existing commit message
[[ -z "$2" ]] || exit 0

diff=$(git diff --staged --stat | head -n -1)
[[ $(echo "$diff" | wc -l) == 1 ]] || exit 0

file=$(echo "$diff" | cut -f 2 -d' ')
orig=$(cat "$1")
echo "feat($file):" > $1
echo "$orig" >> $1