#!/bin/bash -x

# kernel-cleanup.sh - Remove obsolete packages and config files
# {{ ansible_managed }}

# Determine the active running kernel
RUNNING_KERNEL="$( uname -v | awk '{ print $4 }' )"

# Determine the list of installed kernels (latest is always last)
INSTALLED_KERNELS=( $( dpkg -l | grep 'linux-image-[0-9]' | awk '{ print $3 }' | sort -n ) )
echo ${INSTALLED_KERNELS}
NUM_INSTALLED=${{ '{#' }}INSTALLED_KERNELS[@]}

if [[ ${NUM_INSTALLED} -le 1 ]]; then
    echo "A single kernel is installed, aborting cleanly."
    exit 0
fi

LATEST_KERNEL="${INSTALLED_KERNELS[-1]}"
if [[ ${LATEST_KERNEL} == ${RUNNING_KERNEL} ]]; then
    force=""
else
    force="--allow-remove-essential"
fi

# Remove the latest kernel from the array
NUM_REMOVABLE=$(( ${NUM_INSTALLED} - 1 ))
REMOVABLE_KERNELS=( ${INSTALLED_KERNELS[@]:0:${NUM_REMOVABLE}} )

PURGE_PACKAGES=()
for KERNEL in ${REMOVABLE_KERNELS[@]}; do
    PURGE_PACKAGES+=( $( dpkg -l | grep ${KERNEL} | grep -v 'linux-image-amd64\|linux-headers-amd64' | awk '{ print $2 }' ) )
done

# Override the "linux-check-removal" script
mv /usr/bin/linux-check-removal /usr/bin/linux-check-removal.orig
echo -e '#!/bin/sh\necho "Overriding default linux-check-removal script!"\nexit 0' > /usr/bin/linux-check-removal
chmod +x /usr/bin/linux-check-removal

# Remove the packages
echo "Removing: ${PURGE_PACKAGES[@]}"
apt-get purge --yes ${force} ${PURGE_PACKAGES[@]}

# Restore the "linux-check-removal" script
mv /usr/bin/linux-check-removal.orig /usr/bin/linux-check-removal

# Make sure there is still a valid kernel installed (just in case something broke)
if [[ $( dpkg -l | grep 'linux-image-[0-9]' | wc -l ) -lt 1 ]]; then
    echo "WARNING: NO KERNEL IS INSTALLED. THROWING ERROR AND ABORTING."
    exit 1
fi

update-grub

exit 0