#!/usr/bin/env bash
set -e

ref_name=$1
new_rev=$3

# only check branches, not tags or bare commits
if [ -z $(echo $ref_name | grep "refs/heads/") ]; then
	exit 0
fi

# don't check empty branches
if [ "$(expr "${new_rev}" : '0*$')" -ne 0 ]; then
	exit 0
fi

# Checkout a copy of the branch (but also changes HEAD)
my_work_tree=$(mktemp -d -t git-work-tree.XXXXXXXX) 2>/dev/null
git --work-tree="${my_work_tree}" --git-dir="." checkout $new_rev -f >/dev/null

# Do the formatter check
echo "Checking code formatting..."
pushd ${my_work_tree} >/dev/null
prettier './**/*.{js,css,html,json,md}' --list-different
my_status=$?
popd >/dev/null

# reset HEAD to master, and cleanup
git --work-tree="${my_work_tree}" --git-dir="." checkout master -f >/dev/null
rm -rf "${my_work_tree}"

# handle error, if any
if [ "0" != "$my_status" ]; then
	echo "Please format the files listed above and re-commit."
	echo "(and don't forget your .prettierrc, if you have one)"
	exit 1
fi