pre-commit hook for elm packages with a package.json

pre-commit

#!/bin/sh

ELM_JSON_VERSION="$(jq -r .version elm.json)"
PACKAGE_JSON_VERSION="$(jq -r .version package.json)"

if [ $ELM_JSON_VERSION != $PACKAGE_JSON_VERSION ]; then
  echo "Version in elm.json ($ELM_JSON_VERSION) does not match version in package.json ($PACKAGE_JSON_VERSION)"
  if [ -n "$(git status --porcelain package.json)" ]; then
    echo "Cannot fix package.json as it contains unstaged changes" >&2
    exit 1
  fi
  echo "Assuming elm.json is correct, fixing package.json"
  mv package.json package.json.tmp
  jq ".version |= \"$ELM_JSON_VERSION\"" package.json.tmp > package.json
  rm package.json.tmp
  git add package.json
fi