# 开启BBR加速
enable_kernel_bbr(){
    if [ "$(id -u)" -ne 0 ]; then
        echo "请使用 root 权限运行该操作"
        return 1
    fi

    # 检测容器环境
    local virt_type=""
    if command -v systemd-detect-virt >/dev/null 2>&1; then
        virt_type=$(systemd-detect-virt 2>/dev/null)
    fi

    case "$virt_type" in
        lxc|openvz|docker|podman|container-other)
            echo "检测到当前运行于容器环境: $virt_type"
            echo "请在宿主机开启 BBR"
            return 1
            ;;
    esac

    if [ "$(sysctl -n net.ipv4.tcp_congestion_control 2>/dev/null)" = "bbr" ]; then
        echo "BBR加速 已经开启，无需重复操作"
        return 0
    fi

    # 尝试加载 bbr 模块（新内核可能已内建）
    if command -v modprobe >/dev/null 2>&1; then
        modprobe tcp_bbr 2>/dev/null || true
    fi

    # 检查内核是否支持 BBR
    if ! sysctl net.ipv4.tcp_available_congestion_control 2>/dev/null | grep -qw bbr; then
        echo "当前系统内核不支持 BBR"
        return 1
    fi

    set_sysctl_conf(){
        local key="$1"
        local value="$2"
        local file="/etc/sysctl.conf"

        touch "$file"

        # 转义 key，避免 . 被 grep/sed 当作正则
        local escaped_key
        escaped_key=$(printf '%s\n' "$key" | sed 's/[.[\*^$()+?{|]/\\&/g')

        if grep -qE "^[[:space:]]*#?[[:space:]]*$escaped_key[[:space:]]*=" "$file"; then
            sed -i "s|^[[:space:]]*#\?[[:space:]]*$escaped_key[[:space:]]*=.*|$key = $value|" "$file"
        else
            echo "$key = $value" >> "$file"
        fi
    }

    # 写入配置
    set_sysctl_conf "net.core.default_qdisc" "fq"
    set_sysctl_conf "net.ipv4.tcp_congestion_control" "bbr"

    # 立即生效
    sysctl -w net.core.default_qdisc=fq >/dev/null 2>&1
    sysctl -w net.ipv4.tcp_congestion_control=bbr >/dev/null 2>&1

    # 验证是否成功
    if [ "$(sysctl -n net.ipv4.tcp_congestion_control 2>/dev/null)" = "bbr" ]; then
        echo "BBR加速 已开启"
    else
        echo "BBR开启失败"
        return 1
    fi
}