pre-commit

#!/usr/bin/env bash

# Pre-commit hook: clang-format check on staged C/C++ files.
#
# Enable once per clone:
#   git config core.hooksPath scripts/git-hooks
#
# Bypass for a single commit: git commit --no-verify
# Bypass for the session:     SKIP_FORMAT=1 git commit ...

set -euo pipefail

if [ "${SKIP_FORMAT:-0}" = "1" ]; then
    exit 0
fi

repo_root=$(git rev-parse --show-toplevel)
cd "$repo_root"

# shellcheck source=scripts/ci/clang-format-select.sh
. scripts/ci/clang-format-select.sh
if [ -z "$clang_format" ]; then
    echo "pre-commit: clang-format ${CLANG_FORMAT_MAJOR} not found; skipping format check." >&2
    echo "            install clang-format-${CLANG_FORMAT_MAJOR}, or set SKIP_FORMAT=1 to silence." >&2
    exit 0
fi

# Staged, added/copied/modified/renamed files only (skip deletes).
mapfile -d '' -t staged < <(
    git diff --cached --name-only --diff-filter=ACMR -z -- \
        '*.c' '*.C' '*.cpp' '*.CPP' '*.h' '*.H' '*.hpp' '*.HPP'
)

if [ "${#staged[@]}" -eq 0 ]; then
    exit 0
fi

# Reuse the CI exclusion filter so local and CI evaluate the same set.
mapfile -d '' -t files < <(
    printf '%s\0' "${staged[@]}" | python3 scripts/ci/filter-format-files.py
)

if [ "${#files[@]}" -eq 0 ]; then
    exit 0
fi

status=0
bad=()
for file in "${files[@]}"; do
    # Check the staged blob, not the working tree, so unrelated unstaged
    # edits don't get blamed and partial-stage workflows still work.
    if ! git show ":$file" | "$clang_format" --dry-run --Werror \
            -style=file --assume-filename="$file" >/dev/null 2>&1; then
        bad+=("$file")
        status=1
    fi
done

if [ "$status" -ne 0 ]; then
    echo "pre-commit: clang-format issues in staged content:" >&2
    for f in "${bad[@]}"; do
        echo "  $f" >&2
    done
    echo >&2
    echo "Fix with: bash ./scripts/ci/apply-format.sh && git add -u" >&2
    echo "Bypass:   git commit --no-verify   (or SKIP_FORMAT=1)" >&2
fi

exit "$status"