uninstall.sh

#!/usr/bin/env bash

# Variables
db_gravity='/etc/pihole/gravity.db'
installer_comment='github.com/mmotti/pihole-regex'

# Set regex outputs
file_pihole_regex="/etc/pihole/regex.list"
file_mmotti_regex="/etc/pihole/mmotti-regex.list"

# Determine whether we are using Pi-hole DB
if [[ -s "${db_gravity}" ]]; then
	usingDB=true
fi

# Functions
function fetchResults {

	local selection="${1}" action="${2}" queryStr

	# Select * if not set
	[[ -z "${selection}" ]] && selection='*'

	# Determine course of action
	case "${action}" in
		migrated_regexps ) queryStr="Select ${selection} FROM regex WHERE comment='${installer_comment}'";;
		current_id       ) queryStr="Select ${selection} FROM regex ORDER BY id DESC LIMIT 1";;
		*                ) queryStr="Select ${selection} FROM regex";;
	esac

	# Execute SQL query
	sqlite3 ${db_gravity} "${queryStr}" 2>&1

	# Check exit status
	status="$?"
	[[ "${status}" -ne 0 ]]  && { (>&2 echo '[i] An error occured whilst fetching results'); return 1; }

	return 0
}

function updateDB() {

	local inputData="${1}" action="${2}" queryStr

	# Determine course of action
	case "${action}" in
		remove_pre_migrated ) queryStr="DELETE FROM regex WHERE domain in (${inputData})";;
		remove_migrated     ) queryStr="DELETE FROM regex WHERE comment = '${installer_comment}'";;
		*                   ) return ;;
	esac

	# Execute SQL query
	sudo sqlite3 ${db_gravity} "${queryStr}"

	# Check exit status
	status="$?"
	[[ "${status}" -ne 0 ]]  && { (>&2 echo '[i] An error occured whilst updating database'); return 1; }

	return 0
}

echo "[i] Fetching mmotti's regexps"
mmotti_remote_regex=$(wget -qO - https://raw.githubusercontent.com/mmotti/pihole-regex/master/regex.list | grep '^[^#]')
[[ -z "${mmotti_remote_regex}" ]] && { echo '[i] Failed to download mmotti regex list'; exit 1; }

echo '[i] Fetching existing regexps'

# Conditional (db / old) variables
if [[ "${usingDB}" == true ]]; then
	str_regex=$(fetchResults "domain")
else
	str_regex=$(grep '^[^#]' < "${file_pihole_regex}")
fi

# If we are uninstalling from the Pi-hole DB, we need to accommodate for
# pi-hole migrated and installer migrated

# Start the uninstall process
# If we're using the Pi-hole DB
if [[ "${usingDB}" == true ]]; then
	# If we found regexps in the database
	if [[ -n "${str_regex}" ]] ; then
		echo '[i] Checking for previous migration'
		# Check whether this script has previously migrated our regexps
		db_migrated_regexps=$(fetchResults "domain" "migrated_regexps")
		# If migration is detected
		if [[ -n "${db_migrated_regexps}" ]]; then
			echo '[i] Previous migration detected'
			# As we have already migrated the user, we can easily
			# remove by the comment filed
			echo '[i] Running removal query'
			# Clear our previously migrated domains from the regex table
			updateDB "" "remove_migrated"
		else
			echo '[i] No previous migration detected'
			# As we haven't yet migrated, we need to manually remove matches
			# If we have a local mmotti-regex.list, read from that as it was used on the last install (pre-db)
			# Otherwise, default to the latest remote copy
			if [[ -s "${file_mmotti_regex}" ]]; then
				# Only return regexps in both the regex table and regex file
				mapfile -t result <<< "$(comm -12 <(sort <<< "${str_regex}") <(sort < "${file_mmotti_regex}"))"

			else
				# Only return regexps in both the regex table and regex file
				mapfile -t result <<< "$(comm -12 <(sort <<< "${str_regex}") <(sort <<< "${mmotti_remote_regex}"))"
			fi
			# If we have matches in both the regex table and regex file
			if [[ -n "${result[*]}" ]]; then
				echo '[i] Forming removal string'
				# regexstring --> 'regexstring1','regexstring2',
				# Then remove the trailing comma
				removalStr=$(printf "'%s'," "${result[@]}" | sed 's/,$//')
				# If our removal string is not empty (sanity check)
				if [[ -n "${removalStr}" ]]; then
					echo '[i] Running removal query'
					# Remove regexps from the regex table if there are in the
					# removal string
					updateDB "${removalStr}" "remove_pre_migrated"
				fi
			fi
		fi
	else
		echo '[i] No regexps currently exist in the database'
		exit 0
	fi

	# Refresh Pi-hole
	echo '[i] Refreshing Pi-hole'
	pihole restartdns reload > /dev/null

	# Remove the old mmotti-regex file
	[[ -e "${file_mmotti_regex}" ]] && sudo rm -f "${file_mmotti_regex}"

else
	# Removal for standard regex.list (non-db)
	# If the pihole regex.list is not empty
	if [[ -n "${str_regex}" ]]; then
		# Restore config prior to previous install
		# Keep entries only unique to pihole regex
		if [[ -s "${file_mmotti_regex}" ]]; then
			echo "[i] Removing mmotti's regex.list from a previous install"
			comm -23 <(sort <<< "${str_regex}") <(sort "${file_mmotti_regex}") | sudo tee $file_pihole_regex > /dev/null
		else
			# In the event that file_mmotti_regex is not available
			# Match against the latest remote list instead
			echo "[i] Removing mmotti's regex.list from a previous install"
			comm -23 <(sort <<< "${str_regex}") <(sort <<< "${mmotti_remote_regex}") | sudo tee $file_pihole_regex > /dev/null
		fi
	else
		echo '[i] Regex.list is empty. No need to process.'
		exit 0
	fi

	# Refresh Pi-hole
	echo "[i] Refreshing Pi-hole"
	pihole restartdns reload > /dev/null

	# Remove the old mmotti-regex file
	[[ -e "${file_mmotti_regex}" ]] && sudo rm -f "${file_mmotti_regex}"

	echo "[i] Done"
fi