#!/bin/bash
set -e

[[ -z $1 ]] && echo timezone? && exit 1
timezone=$1

[[ ! -x `which timedatectl` ]] && echo error: timedatectl executable not found && exit 1

export DEBIAN_FRONTEND=noninteractive
export SYSTEMD_COLORS=0
export SYSTEMD_URLIFY=0
export LANG=en_US.UTF-8
export LANGUAGE=en_US:en
export LC_ALL=en_US.UTF-8

echo -n setting up time-zone $timezone ...
timedatectl set-timezone $timezone && echo done

available_clocks=`cat /sys/devices/system/clocksource/clocksource0/available_clocksource`
echo available clocks are $available_clocks

current_clock=`cat /sys/devices/system/clocksource/clocksource0/current_clocksource`
echo current clock is $current_clock

# select the right clock in order of preference
if [[ -n `echo $available_clocks | grep kvm-clock` ]]; then
       if [[ $current_clock != kvm-clock ]]; then
        echo -n enable kvm-clock ...
        echo kvm-clock > /sys/devices/system/clocksource/clocksource0/current_clocksource && echo done
       fi
elif [[ -n `echo $available_clocks | grep hpet` ]]; then
       if [[ $current_clock != hpet ]]; then
        echo -n enable hpet ...
        echo hpet > /sys/devices/system/clocksource/clocksource0/current_clocksource && echo done
       fi
fi

echo -n current boot args are\ 
cat /proc/cmdline | sed -r '
	s/BOOT_IMAGE=[^ ]* //;
	s/root=[^ ]* //;
	s/ro //;
	'

echo -n tuning grub2 ...
if [[ ! -f /etc/default/grub.dist ]]; then
        if [[ $ansible_group != stations ]]; then
                cmdline_def="net.ifnames=0 biosdevname=0 console=ttyS0"
        else
                cmdline_def="net.ifnames=0 biosdevname=0"
        fi
        echo -n " $cmdline_def "

        if [[ -n `echo $available_clocks | grep kvm-clock` ]]; then
                cmdline="notsc clocksource=kvm-clock"
                echo -n " $cmdline "
        elif [[ -n `echo $available_clocks | grep hpet` ]]; then
                cmdline="notsc clocksource=hpet"
                echo -n " $cmdline "
        fi

        [[ -f /etc/grub.d/30_os-prober ]] && rm -f /etc/grub.d/30_os-prober

        [[ -d /etc/default/grub.d/ && ! -d /etc/default/grub.d.disabled/ ]] && mv -i /etc/default/grub.d/ /etc/default/grub.d.disabled/
        mv -i /etc/default/grub /etc/default/grub.dist
        grep -vE '^$|^#' /etc/default/grub.dist > /etc/default/grub.clean

	# warning escapes are in there
        cat > /etc/default/grub <<EOF
GRUB_DEFAULT=0
GRUB_TIMEOUT=3
GRUB_DISTRIBUTOR=\`lsb_release -i -s 2> /dev/null || echo Debian\`
GRUB_CMDLINE_LINUX_DEFAULT="$cmdline_def"
GRUB_CMDLINE_LINUX="$cmdline"
GRUB_DISABLE_OS_PROBER=true
EOF

        # mitigations=0
        # note linux mint has GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
        # note yandex cloud images have GRUB_CMDLINE_LINUX_DEFAULT="net.ifnames=0 biosdevname=0 console=ttyS0"

        update-grub2 >/dev/null 2>&1 && echo done || echo FAIL

        changed=1

        unset cmdline_def cmdline
else
        echo already
fi

(( changed == 1 )) && echo changed - all done && exit 0

echo all done - nothing changed