#!/bin/bash

# Purpose: Remove Realtek out-of-kernel USB WiFi adapter drivers.
#
# Supports dkms and non-dkms removals.

# Copyright(c) 2022 Nick Morrow
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of version 2 of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.

SCRIPT_NAME="remove-driver.sh"
SCRIPT_VERSION="20221218"
MODULE_NAME="8821cu"
DRV_VERSION="5.12.0.4"

KVER="$(uname -r)"
KARCH="$(uname -m)"
KSRC="/lib/modules/${KVER}/build"
MODDESTDIR="/lib/modules/${KVER}/kernel/drivers/net/wireless/"

DRV_NAME="rtl${MODULE_NAME}"
DRV_DIR="$(pwd)"
OPTIONS_FILE="${MODULE_NAME}.conf"

# check to ensure sudo was used
if [[ $EUID -ne 0 ]]
then
	echo "You must run this script with superuser (root) privileges."
	echo "Try: \"sudo ./${SCRIPT_NAME}\""
	exit 1
fi

# support for the NoPrompt option allows non-interactive use of this script
NO_PROMPT=0

# get the script options
while [ $# -gt 0 ]
do
	case $1 in
		NoPrompt)
			NO_PROMPT=1 ;;
		*h|*help|*)
			echo "Syntax $0 <NoPrompt>"
			echo "       NoPrompt - noninteractive mode"
			echo "       -h|--help - Show help"
			exit 1
			;;
	esac
	shift
done

# displays script name and version
echo "Running ${SCRIPT_NAME} version ${SCRIPT_VERSION}"

# check for and remove non-dkms installation
if [[ -f "${MODDESTDIR}${MODULE_NAME}.ko" ]]
then
	echo "Removing a non-dkms installation."
	rm -f ${MODDESTDIR}${MODULE_NAME}.ko
	/sbin/depmod -a ${KVER}
fi

# information that helps with bug reports

# display kernel version
echo "Linux Kernel=${KVER}"

# display architecture
echo "CPU Architecture=${KARCH}"

# determine if dkms is installed and run the appropriate routines
if command -v dkms >/dev/null 2>&1
then
	echo "Removing a dkms installation."
	#  2>/dev/null suppresses the output of dkms
	dkms remove -m ${DRV_NAME} -v ${DRV_VERSION} --all 2>/dev/null
	RESULT=$?
	#echo "Result=${RESULT}"

	# RESULT will be 3 if there are no instances of module to remove
	# however we still need to remove various files or the install script
	# may complain.
	if [[ ("$RESULT" = "0")||("$RESULT" = "3") ]]
	then
		if [[ ("$RESULT" = "0") ]]
		then
			echo "${DRV_NAME}/${DRV_VERSION} has been removed"
		fi
	else
		echo "An error occurred. dkms remove error = ${RESULT}"
		echo "Please report this error."
		exit $RESULT
	fi
fi

echo "Removing ${OPTIONS_FILE} from /etc/modprobe.d"
rm -f /etc/modprobe.d/${OPTIONS_FILE}
echo "Removing source files from /usr/src/${DRV_NAME}-${DRV_VERSION}"
rm -rf /usr/src/${DRV_NAME}-${DRV_VERSION}
make clean >/dev/null 2>&1
echo "The driver was removed successfully."
echo "You may now delete the driver directory if desired."

# if NoPrompt is not used, ask user some questions to complete removal
if [ $NO_PROMPT -ne 1 ]
then
	read -p "Do you want to reboot now? (recommended) [y/N] " -n 1 -r
	echo
	if [[ $REPLY =~ ^[Yy]$ ]]
	then
		reboot
	fi
fi

exit 0