#!/usr/bin/env bash
#
# breeze/githooks/pre-commit
#
# Runs clang-format and clang-tidy against staged C/C++ files before each
# commit — no Python, no pre-commit framework, just bash and (optionally)
# the clang tools themselves.
#
# Neither tool is required to have this hook installed: if a binary isn't
# on PATH, this prints a warning and skips that check instead of blocking
# the commit. Only *actual formatting/lint issues* from a tool that IS
# installed will block a commit.
#
# Platforms:
#   - Linux / macOS: runs under the system bash (or Homebrew bash on macOS)
#     with no extra setup.
#   - Windows: runs automatically through Git for Windows' bundled Git Bash —
#     git.exe recognizes the "#!/usr/bin/env bash" line above and executes
#     hooks through it directly, so no WSL, Cygwin, or separate bash install
#     is needed. Everything this script uses (mktemp, diff, grep, printf,
#     command -v) ships with Git for Windows out of the box.
#
# One-time setup per clone (same command on every OS):
#   chmod +x breeze/githooks/pre-commit   (no-op on Windows, harmless either way)
#   git config core.hooksPath breeze/githooks

set -uo pipefail

# Colors only when writing to an interactive terminal — avoids raw escape
# codes in CI logs, redirected output, or terminals that don't support ANSI.
if [ -t 1 ]; then
    RED=$'\033[0;31m'
    YELLOW=$'\033[0;33m'
    GREEN=$'\033[0;32m'
    RESET=$'\033[0m'
else
    RED=''
    YELLOW=''
    GREEN=''
    RESET=''
fi

exit_code=0

# --- Collect staged C/C++ files (added/copied/modified) ---
# ':!vendor/*' excludes third-party code vendored under vendor/ (see
# breeze/cmake/Dependencies.cmake in the parent project) -- it isn't this
# project's code, so it isn't held to this style guide. Not part of the
# toolkit as shipped; added for this project's vendor/ convention.
files=()
while IFS= read -r line; do
    [ -n "$line" ] && files+=("$line")
done < <(git diff --cached --name-only --diff-filter=ACM -- \
    '*.c' '*.h' '*.cpp' '*.hpp' '*.cc' '*.cxx' '*.tpp' ':!vendor/*')

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

# On macOS, Homebrew's llvm (the formula that ships clang-tidy) is keg-only:
# installed but not on PATH. Look there too, AFTER the normal PATH so Apple's
# tools stay first. (breeze/scripts/_common.sh's _pmn_extend_tool_path does the same
# for the scripts; a git hook is kept standalone, so it's repeated here.)
if [ "$(uname -s)" = Darwin ]; then
    for _llvm_bin in /opt/homebrew/opt/llvm/bin /usr/local/opt/llvm/bin; do
        if [ -d "$_llvm_bin" ]; then PATH="$PATH:$_llvm_bin"; break; fi
    done
fi

# --- clang-format: check staged files are already formatted ---
if command -v clang-format >/dev/null 2>&1; then
    unformatted=()
    for f in "${files[@]}"; do
        [ -f "$f" ] || continue
        if ! diff -q <(clang-format "$f") "$f" >/dev/null 2>&1; then
            unformatted+=("$f")
        fi
    done

    if [ ${#unformatted[@]} -gt 0 ]; then
        echo "${RED}clang-format: these files aren't formatted:${RESET}"
        printf '  %s\n' "${unformatted[@]}"
        echo "Fix with: clang-format -i ${unformatted[*]}"
        exit_code=1
    fi
else
    echo "${YELLOW}warning: clang-format not found on PATH — skipping format check.${RESET}"
fi

# --- clang-tidy: static analysis, needs a compile database ---
if command -v clang-tidy >/dev/null 2>&1; then
    if [ ! -f compile_commands.json ]; then
        echo "${YELLOW}warning: compile_commands.json not found — skipping clang-tidy.${RESET}"
        echo "${YELLOW}Generate one with: cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ...${RESET}"
    else
        # A template, because BSD mktemp (macOS) wants one where GNU's doesn't.
        tidy_output=$(mktemp "${TMPDIR:-/tmp}/pmn-clang-tidy.XXXXXX")
        tidy_had_issues=0

        for f in "${files[@]}"; do
            [ -f "$f" ] || continue
            if ! clang-tidy --quiet "$f" >>"$tidy_output" 2>&1; then
                tidy_had_issues=1
            fi
        done

        if grep -q "warning:\|error:" "$tidy_output" 2>/dev/null; then
            echo "${RED}clang-tidy found issues:${RESET}"
            cat "$tidy_output"
            exit_code=1
        elif [ "$tidy_had_issues" -eq 1 ]; then
            # Non-zero exit with no warning/error text usually means clang-tidy
            # itself couldn't run (e.g. missing headers) — surface it, but
            # don't block the commit on a tooling problem rather than a style one.
            echo "${YELLOW}warning: clang-tidy exited with an error unrelated to style:${RESET}"
            cat "$tidy_output"
        fi

        rm -f "$tidy_output"
    fi
else
    echo "${YELLOW}warning: clang-tidy not found on PATH — skipping static analysis.${RESET}"
fi

if [ $exit_code -eq 0 ]; then
    echo "${GREEN}pre-commit checks passed.${RESET}"
fi

exit $exit_code