# Setup PKG_CONFIG_PATH for Apple Silicon Homebrew on macOS and LSB/standard paths on Linux
_setup_pkgconfig() {
    [ -n "$ZSH_VERSION" ] && setopt localoptions nonomatch nullglob

    _add_pkg_config_path() {
        [ -d "$1" ] || return 0
        case ":${PKG_CONFIG_PATH}:" in
            *":$1:"*) ;;
            *)
                if [ -n "$PKG_CONFIG_PATH" ]; then
                    PKG_CONFIG_PATH="${PKG_CONFIG_PATH}:$1"
                else
                    PKG_CONFIG_PATH="$1"
                fi
                ;;
        esac
    }

    # macOS: Apple Silicon Homebrew
    if [ -d "/opt/homebrew" ]; then
        _add_pkg_config_path "/opt/homebrew/lib/pkgconfig"
        _add_pkg_config_path "/opt/homebrew/share/pkgconfig"
        for _dir in /opt/homebrew/opt/*/lib/pkgconfig \
                    /opt/homebrew/opt/*/share/pkgconfig; do
            _add_pkg_config_path "$_dir"
        done
    fi

    # Linux (apt / rpm / LSB / manual build & install paths) and user paths
    for _dir in \
        "$HOME/.local/lib/pkgconfig" \
        "$HOME/.local/share/pkgconfig" \
        /usr/local/lib/pkgconfig \
        /usr/local/lib64/pkgconfig \
        /usr/local/share/pkgconfig \
        /usr/lib/pkgconfig \
        /usr/lib64/pkgconfig \
        /usr/share/pkgconfig \
        /usr/lib/*-linux-gnu*/pkgconfig \
        /usr/local/lib/*-linux-gnu*/pkgconfig
    do
        _add_pkg_config_path "$_dir"
    done

    export PKG_CONFIG_PATH
}
_setup_pkgconfig
unset -f _setup_pkgconfig _add_pkg_config_path