pre-commit

#!/bin/bash

set -o errexit
set -o pipefail
set -o nounset
IFS=$'\n\t'

# functions
function elementIn () {
  local elem="$1"  # Save first argument in a variable
  shift            # Shift all arguments to the left (original $1 gets lost)
  local arr=("$@") # Rebuild the array with rest of arguments
  if printf '%s\n' "${arr[@]}" | grep -q --line-regexp "${elem}"; then
    return 0
  fi
  return 1
}

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

# If there are whitespace errors, print the offending file names and fail.
(
exec git diff-index --check --cached $against --
) 1>&2

IPYNB_FILES=()
while IFS='' read -r line; do
	IPYNB_FILES+=( "$line" );
# finding all staged *.ipynb files added, copied, modified or renamed since last commit
done < <(git diff-index --name-only --cached --diff-filter=ACMR "${against}" -- | grep -i \.ipynb$ )

for FILE in "${IPYNB_FILES[@]}"; do
	echo "Processing file: '$FILE'"
	# you may need to provide the full path to 'jupyter' executable
	# if it is not in the path
	jupyter nbconvert --ClearOutputPreprocessor.enabled=True --ClearMetadataPreprocessor.enabled=True --inplace "$FILE"
	# echo "Current EXIT_CODE value: $?"
done

MODIFIED_FILES=()
while IFS='' read -r line; do
	MODIFIED_FILES+=( "$line" );
# list all modified files
done < <(git ls-files --modified --exclude-standard)
AMOUNT=0
for mfile in "${MODIFIED_FILES[@]}"; do
	if elementIn "$mfile" "${IPYNB_FILES[@]}"; then
		echo "'$mfile' has been modified by pre-commit hook!"
		AMOUNT=$((AMOUNT+1))
	fi
done
if [[ $AMOUNT -eq 0 ]]; then
	echo "No ipynb files were modified!"
	exit 0
else
	echo "Pre-commit hook modified $AMOUNT ipynb files! You must be recommit \`git commit --amend\` maybe?"
	exit 1
fi