#!/bin/bash

if git rev-parse --verify HEAD >/dev/null 2>&1
then
	against=HEAD
else
	# Initial commit: diff against an empty tree object
	against=$(git hash-object -t tree /dev/null)
fi

FILES=$(git diff-index --name-only $against | grep ".*.py" | xargs)

if [ -z "$FILES" ]; then
    # No python files, skip
    exit 0
fi

if black --line-length=100 --target-version=py38  $FILES; then
    git add  $FILES
    exit 0
fi

exit 1