#!/bin/bash
# Backend script for Lubuntu Update (does text processing and update installation, can be run as root and must be in order to install updates)

set -e
export LC_ALL='C'

# Returns 0 if the release is supported, 1 if unsupported, 2 if if didn't exist at all, and 3 if something went wrong.
isReleaseSupported () {
	releaseYear="${1:-}";
	releaseMonth="${2:-}";
	metaReleaseStr="${3:-}";

	if [ -z "$releaseYear" ]; then
		echo '! ! ! releaseYear is blank';
		return 3;
	elif [ -z "$releaseMonth" ]; then
		echo '! ! ! releaseMonth is blank';
		return 3;
	elif [ -z "$metaReleaseStr" ]; then
		echo '! ! ! metaReleaseStr is blank';
		return 3;
	fi

	releaseCode="$releaseYear.$releaseMonth";
	scanForSupported='n';

	while IFS= read -r line || [[ -n $line ]]; do
		if [[ "$line" =~ $releaseCode ]]; then
			scanForSupported='y';
		fi
		if [ "$scanForSupported" = 'y' ]; then
			if [[ "$line" =~ Supported ]]; then
				if [ "$(echo "$line" | cut -d':' -f2 | tail -c+2)" = '0' ]; then
					return 1;
				else
					return 0;
				fi
			fi
		fi
	done < <(printf '%s' "$metaReleaseStr")
	return 2;
}

if [ "$1" = 'pkgver' ]; then
	shift
	while [ "$1" != '' ]; do
		source="$(apt-cache show "$1" | grep 'Source:' | cut -d' ' -f2)"
		version="$(apt-cache show "$1" | grep Version: | head -n1 | cut -d' ' -f2)"
		if [ "$source" = '' ]; then
			echo "$1"
		else
			echo "$source"
		fi
		echo "$version"
		shift
	done
elif [ "$1" = 'checkupdate' ]; then
	apt-get -o Apt::Color='0' -o Dpkg::Use-Pty='0' update
elif [ "$1" = 'doupdate' ]; then
	# Prepare to be able to grep through the logs
	rm /run/lubuntu-update-apt-log || true
	touch /run/lubuntu-update-apt-log
	chmod 0600 /run/lubuntu-update-apt-log # prevent non-root from being able to trick the script into deleting arbitrary files later on

	# Repair an interrupted upgrade if necessary
	dpkg --configure -a

	# Run the real update
	DEBIAN_FRONTEND='kde' apt-get -o Dpkg::Options::='--force-confdef' -o Dpkg::Options::='--force-confold' -o Apt::Color='0' -o Dpkg::Use-Pty='0' -y dist-upgrade |& tee /run/lubuntu-update-apt-log

	# Find all the conffiles
	mapfile conffileRawList <<< "$(grep -P "^Configuration file \'.*\'$" '/run/lubuntu-update-apt-log')"
	if [ "$(echo "${conffileRawList[0]}" | head -c1)" != 'C' ]; then # Empty or invalid list, we're done
		exit 0
	fi

	conffileList=()
	counter=0
	while [ "$counter" -lt "${#conffileRawList[@]}" ]; do
		# Cut off "Configuration file '" from the start and "'" plus a couple trailing characters from the end
		conffileList[counter]="$(echo "${conffileRawList[$counter]}" | tail -c+21 | head -c-3)"
		counter=$((counter+1))
	done

	echo "Lubuntu Update !!! CONFIGURATION FILE LIST START";
	counter=0
	while [ "$counter" -lt "${#conffileList[@]}" ]; do
		echo "${conffileList[$counter]}"
		counter=$((counter+1))
	done
	echo "Lubuntu Update !!! CONFIGURATION FILE LIST END";

	# If we make it this far, there were conffiles to deal with
	breakLoop='no'
	gotCommand='no'
	commandName=''
	while [ "$breakLoop" = 'no' ]; do
		read -r inputVal
		if [ "$gotCommand" = 'no' ]; then
			if [ "$inputVal" = 'done' ]; then
				breakLoop='yes'
			else
				commandName="$inputVal"
				gotCommand='yes'
			fi
		else
			if [ "$commandName" = 'replace' ]; then # Replace an existing file
				counter=0
				while [ "$counter" -lt "${#conffileList[@]}" ]; do
					if [ "$inputVal" = "${conffileList[$counter]}" ]; then
						mv "$inputVal.dpkg-dist" "$inputVal"
						break
					fi
					counter=$((counter+1))
				done
			elif [ "$commandName" = 'keep' ]; then # Keep an existing file
				counter=0
				while [ "$counter" -lt "${#conffileList[@]}" ]; do
					if [ "$inputVal" = "${conffileList[$counter]}" ]; then
						rm "$inputVal.dpkg-dist"
						break
					fi
					counter=$((counter+1))
				done
			fi
			gotCommand='no'
		fi
	done

	echo 'Checking release status...'

	releaseCode="$(cat /etc/lsb-release | grep "DISTRIB_RELEASE" | cut -d'=' -f2)";
	releaseYear="$(cut -d'.' -f1 <<< "$releaseCode")";
	releaseMonth="$(cut -d'.' -f2 <<< "$releaseCode")";
	metaReleaseData="$(curl https://changelogs.ubuntu.com/meta-release)";
	nextReleaseMonth='';
	nextReleaseYear='';
	nextLTSReleaseMonth='';
	nextLTSReleaseYear='';

	if ((releaseMonth == 4)); then
		nextReleaseMonth=((releaseMonth + 6));
		nextReleaseYear="$releaseYear";
		if (((releaseYear % 2) == 0)); then
			nextLTSReleaseMonth='04';
			nextLTSReleaseYear=((releaseYear + 2));
		fi
	else
		nextReleaseMonth="$releaseMonth";
		nextReleaseYear=((releaseYear + 1));
	fi

	if [ -n "$nextLTSReleaseYear" ]; then
		if isReleaseSupported "$nextLTSReleaseYear" "$nextLTSReleaseMonth" "$metaReleaseData"; then
			echo 'Lubuntu Update !!! NEW LTS RELEASE';
			echo "$nextLTSReleaseYear.$nextLTSReleaseMonth";
		fi
	fi

	if ! (((nextReleaseYear == nextLTSReleaseYear) && (nextReleaseMonth == nextLTSReleaseMonth))); then
		if isReleaseSupported "$nextReleaseYear" "$nextReleaseMonth" "$metaReleaseData"; then
			echo 'Lubuntu Update !!! NEW STABLE RELEASE';
			echo "$nextReleaseYear.$nextReleaseMonth";
		fi
	fi

	echo 'Update installation complete.'
fi