#!/usr/bin/env bash

# Copy me to .git/hooks/pre-commit

set -euo pipefail

tmpdir=
cleanup_tmpdir() {
  if [[ "$tmpdir" && -e "$tmpdir" ]];then
    rm -rf "$tmpdir"
  fi
}
trap cleanup_tmpdir EXIT

# Check out the git index (what's about to be committed) in a temporary
# directory & run the supplied command there.
in_git_index_in_tmpdir() {
  tmpdir=$(mktemp -d)
  [[ "$tmpdir" && -d "$tmpdir" ]]
  start_index=$(sha256sum "${GIT_INDEX_FILE:-.git/index}")
  git checkout-index --prefix="$tmpdir/" -a
  pushd "$tmpdir"
  "$@"
  popd
  end_index=$(sha256sum "${GIT_INDEX_FILE:-.git/index}")
  if [[ "$start_index" != "$end_index" ]];then
    echo "Index changed while pre-commit tests were running.  Aborting!"
    exit 1
  fi
}

verify() {
  cargo test --offline
  cargo clippy -- -D warnings -W clippy::pedantic
  rustfmt --check src/*.rs
}

in_git_index_in_tmpdir verify