#!/usr/bin/env bash
set -euo pipefail

echo "[pre-commit] Running cargo fmt --all" >&2

if ! command -v cargo >/dev/null 2>&1; then
  echo "[pre-commit] cargo not found in PATH" >&2
  exit 1
fi

cargo fmt --all

# Stage any Rust files that were reformatted
changed=$(git diff --name-only --diff-filter=M | grep -E '\\.rs$' || true)
if [ -n "$changed" ]; then
  echo "$changed" | xargs git add
  echo "[pre-commit] Added formatted files" >&2
fi

# Fail if further diffs remain (shouldn't happen normally)
unfmt=$(git diff --name-only --diff-filter=M | grep -E '\\.rs$' || true)
if [ -n "$unfmt" ]; then
  echo "[pre-commit] Some Rust files still differ after formatting:" >&2
  echo "$unfmt" >&2
  exit 1
fi

exit 0