#!/usr/bin/bash
# Pre-commit hook: run clang-format via kt-kernel's CMake 'format' target and Black for Python
# before allowing commit. If formatting makes changes, stage them and abort so user can review.
set -euo pipefail

REPO_ROOT="$(git rev-parse --show-toplevel)"
# kt-kernel project directory within the monorepo
KERNEL_DIR="$REPO_ROOT/kt-kernel"
# Relative path for matching staged files under repo root
REL_KERNEL_DIR="kt-kernel"
BUILD_DIR="$KERNEL_DIR/build"
FORMAT_TARGET="format"
CLANG_FORMAT_BIN="${CLANG_FORMAT_BIN:-clang-format}"
BLACK_BIN="${BLACK_BIN:-black}"

# Simple check clang-format present (optional)
# clang-format optional: if missing, skip C/C++ formatting
if ! command -v "$CLANG_FORMAT_BIN" >/dev/null 2>&1; then
  echo "[pre-commit] clang-format not found (looked for $CLANG_FORMAT_BIN). Skipping C/C++ format." >&2
fi

# black optional: if missing, skip Python formatting
if ! command -v "$BLACK_BIN" >/dev/null 2>&1; then
  echo "[pre-commit] black not found (looked for $BLACK_BIN). Skipping Python format." >&2
fi

## Format only staged changes within kt-kernel
# Collect staged files (Added/Modified/Copied/Renamed)
mapfile -d '' STAGED < <(git diff --cached --name-only -z --diff-filter=AMCR)

PY_CHANGED=()
CPP_CHANGED=()

for f in "${STAGED[@]}"; do
  case "$f" in
    "$REL_KERNEL_DIR"/*)
      ext="${f##*.}"
      case "$ext" in
        py)
          PY_CHANGED+=("$f")
          ;;
        c|cc|cpp|cxx|h|hh|hpp|hxx|cu|cuh)
          CPP_CHANGED+=("$f")
          ;;
      esac
      ;;
  esac
done

# Run clang-format only on staged C/C++ files
if command -v "$CLANG_FORMAT_BIN" >/dev/null 2>&1 && [ ${#CPP_CHANGED[@]} -gt 0 ]; then
  echo "[pre-commit] clang-format on ${#CPP_CHANGED[@]} files" >&2
  for f in "${CPP_CHANGED[@]}"; do
    "$CLANG_FORMAT_BIN" -i "$f"
  done
fi

## Run black only on staged Python files
if command -v "$BLACK_BIN" >/dev/null 2>&1 && [ ${#PY_CHANGED[@]} -gt 0 ]; then
  echo "[pre-commit] black on ${#PY_CHANGED[@]} files" >&2
  "$BLACK_BIN" "${PY_CHANGED[@]}"
fi

# Stage any formatting changes for tracked, formatted files only
FMT_FILES=("${PY_CHANGED[@]}" "${CPP_CHANGED[@]}")
if [ ${#FMT_FILES[@]} -gt 0 ] && ! git diff --quiet --exit-code -- "${FMT_FILES[@]}"; then
  echo "[pre-commit] Formatting applied; updating index." >&2
  git add "${FMT_FILES[@]}"
  echo "[pre-commit] Re-run git commit to proceed after reviewing changes." >&2
  exit 1
fi

echo "[pre-commit] format OK." >&2
exit 0