Show PyCharm's diff tool with what's black is about to change

charm-black-show-diff.sh

#!/bin/bash

# Check if black and charm is available
if ! which black > /dev/null; then
	echo "black is not installed"
	exit 1
elif ! which charm > /dev/null; then
	echo "charm command is not available"
	exit 1
fi

arg=$1

# Exit if no argument given
if [ -z "$arg" ]; then
	exit 1
fi

# Get arg file extension
extension="${arg##*.}"

# Prepare tmp files
filetmp="$(mktemp -u).$extension"
difftmp=$(mktemp -u)

# copy contents of given file to tmp
cat "$arg" > $filetmp

# generate diff and save to tmp
black -l 120 --fast --diff "$arg" > $difftmp

# patch copied file with diff from black
patch $filetmp < $difftmp

# start py-charm diff
charm diff "$arg" $filetmp
exit 0