#!/bin/sh

set -eu

format_files () {
  eslint --fix "$@"
}
test_files () {
  jest --findRelatedTests --passWithNoTests "$@"
}

# compute the list of staged files we are interested in
set --
buf=$(mktemp -u)
git diff-index --cached --diff-filter=AM --name-only HEAD > "$buf"
while IFS= read -r file
do
  case "$file" in
    *.js)
      set -- "$@" "$file";;
  esac
done < "$buf"
rm -f "$buf"

if [ $# -eq 0 ]
then
  exit
fi

format_files "$@"

# stash unstaged changes
if stash=$(git stash create --keep-index --quiet)
then
  # remove those changes from the worktree
  git checkout .

  format_files "$@"

  # unstash on exit
  on_exit () {
    git read-tree HEAD
    git checkout $stash "$@"
  }
  trap 'GIT_INDEX_FILE=$buf on_exit "$@"; rm -f "$buf"' EXIT
fi

test_files "$@"

# add any changes made by the commands
git add "$@"