#!/bin/bash
#########################################################################
#                                                                       #
#     msedge-updater - Automatically update Microsoft Edge on Solus     #
#                                                                       #
#                             Dependencies:                             #
#                                 bash                                  #
#                                 wget                                  #
#                                  git                                  #
#                                gunzip                                 #
#                                  tar                                  #
#                          coreutils (>= 8.32)                          #
#                          binutils (>=2.35.1)                          #
#                  procps (only BusyBox-based systems)                  #
#                              notify-send                              #
#                                                                       #
#                                                                       #
#     Disclaimer: This version only works for amd64 architectures.      #
#          A later release may allow for update of Dev builds           #
#                         and potentially both.                         #
#                                                                       #
#                       Author: Ethan Smith-Coss                        #
#                            Version: 0.2.1                             #
#                    Created: 2021-12-09T16:51+0000                     #
#                  Last Modified: 2021-09-9T15:43+0100                  #
#                                                                       #
#                 ####################################                  #
#                                                                       #
#     msedge-updater - Automatically update Microsoft Edge on Solus     #
#                   Copyright ©️ 2021 Ethan Smith-Coss                   #
#                                                                       #
# This program is free software: you can redistribute it and/or modify  #
# it under the terms of the GNU General Public License as published by  #
#   the Free Software Foundation, either version 3 of the License, or   #
#                  (at your option) any later version.                  #
#                                                                       #
#    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.              #
#                                                                       #
#   You should have received a copy of the GNU General Public License   #
# along with this program.  If not, see <http://www.gnu.org/licenses/>. #
#                                                                       #
#########################################################################
## program name
prog_name="Microsoft Edge Updater"
## version
version="0.2.1"
## usage statement
usage="Usage: $(basename $0) [OPTION]
$prog_name ($version) - An updater program which can install the latest available version of Microsoft Edge to non-Debian-based Linux distros.

DISCLAIMER: Currently this program has only updated Microsoft Edge for amd64 architectures, other architectures might be possible but not tested.

Options:
  -nn, --no-notify     Prevent notifications from being set after a session.
   -c, --set-channel=  Change the channel to be updated for Microsoft Edge. Will default to the value defined in source.list if flag is not present.
                         * beta - update Beta channel release.
                         * dev  - update Dev channel release.
   -q, --quiet         Operate strictly with no output on STDOUT or STDERR, prompts will NOT assume yes however. Logging still occurs in background.
       --mode=         Set the mode of the program to be ran in. Default mode occurs without this flag.
                         * debug - run program in debug mode. (WIP)
       --full-clean    Remove all content generated by the updater after a session, this includes all logs.
   -y, --yes-all       Assume yes to all yes/no decisions.
   -v, --version       Print out the version of the script and exit.
   -h, --help          Print this help message and exit.
"

runtime_dir=$(realpath "${BASH_SOURCE[0]}" | xargs -r dirname)
## runtime locations
log_file="$runtime_dir/.log.1"
logs_dir="$runtime_dir/logs"
tmp_path="/tmp/microsoft-edge-autoupdater"
garbage="$tmp_path/garbage.tmp"
## program timer
SECONDS=0

## create the logs directory and tmp location if they don't already exist
[[ ! -d "$logs_dir" ]] && mkdir "$logs_dir"
[[ ! -d "$tmp_path" ]] && mkdir "$tmp_path"

# function responsible for cleaning up after a session execution
function clean_up {
	log "DEBUG" "EXIT signal was raised, cleaning up system after session before exiting..." "$log_file"
	[[ ! $quiet -eq 0 ]] && echo -n "Cleaning up system after session..."
	cp "$log_file" "$logs_dir/updater.log"

	while read -r garbage_collection ; do
		[[ -f "$garbage_collection" || -d "$garbage_collection" ]] && rm -r "$garbage_collection"
	done < <(cat "$garbage")
	[[ -f "$garbage" ]] && rm "$garbage"


	log "CLEANER" "Finished cleaning up system after session. Nice and clean :D Goodbye." "$runtime_dir/logs/updater.log"
	[[ ! $quiet -eq 0 ]] && echo "done. Goodbye."

	elapsed_time=$SECONDS
	script_time="$(($elapsed_time / 60))m $(($elapsed_time % 60))s"
	log "END" "Total time for script execution was: $script_time" "$runtime_dir/logs/updater.log"

	echo >> "$runtime_dir/logs/updater.log"
	cat "$logs_dir/updater.log" >> "$logs_dir/updater.history"

	[[ $debug_run -eq 0 ]] && cat "$logs_dir/updater.log"
}

# ensure that the restoration was sucessful in reverting the system back
function check_restoration {
	[[ ! $1 -eq 0 ]] && { [[ ! $quiet -eq 0 ]] && echo "failed." && >&2 echo "There was an error trying to restore system files." \
		"Either there no back was made or another issue occurred. Consult $log_file for more information." ; exit $1 ; }
	log "DEBUG" "System restoration was successful, safe to use; however, the update was still failed. Exiting...($2+$1)" \
		"$log_file"
	[[ ! $quiet -eq 0 ]] && echo "completed." && >&2 echo "However, there was still an issue trying to update Microsoft Edge" \
		"($edge_channel) to the latest version. Consult $log_file for more information. Exiting..."
	[[ ! $nn_flag -eq 0 ]] && notify "Microsoft Edge ($edge_channel) Update" "There was an issue installing the update to your system." \
		"The previous version, v$current_version, has been restored."
	echo "$backup_file" >>"$garbage"
}

## iterate over all user inputs
while test $# -gt 0 ; do
	case $1 in
		-nn | --no-notify)
			nn_flag=0 ; shift
			;;
		-c | --set-channel=*)
			## if long flag, check if value is equal to beta or dev, set flag respectfully if so
			[[ "$1" =~ "beta" || "$1" =~ "dev" ]] && edge_channel=$(echo "$1" | cut -d= -f2)
			## if short flag, check if the next value is beta or dev, set flag respectfully if so
			[[ "$1" == "-c" && "$2" == "beta" || "$2" == "dev" ]] && edge_channel="$2"
			shift
			;;
		-q | --quiet)
			quiet=0 ; shift
			;;
		--full-clean)
			echo -n "Fully cleaning system of generated content..."
			[[ -d "$tmp_path" ]] && rm -rf "$tmp_path"
			[[ -d "$runtime_dir/logs" ]] && rm -rf "$runtime_dir/logs"
			echo "done."
			exit 0
			;;
		--mode=*)
			[[ "$1" == "--mode=debug" ]] && debug_run=0
			shift
			;;
		-y | --yes-all)
			yes_flag=0 ; shift
			;;
		-h | --help)
			echo "$usage"
			exit 0
			;;
		-v | --version)
			echo "$prog_name ($version)"
			exit 0
			;;
		*)
			shift
			;;
	esac
done

## check if the script is being ran as root - exit otherwise
[[ $(id -u) -ne 0 ]] && { >&2 echo "Please run script with root privilages." ; exit 1 ; }

# set trap to trigger clean up function on any exit
trap clean_up EXIT

source "$runtime_dir/utils/common"
log "PREINIT" "----[New instance of script has been started: $(date -Iseconds)]----" "$log_file"
echo "$log_file" >> "$garbage"

# initialise all flags which require a value
## setup the yes flag to automatically accept all yes/no inputs
yes_flag=${yes_flag:-1}
log "DEBUG" "The yes flag has been set to: $yes_flag." "$log_file"
## setup the no-notify (nn) flag if notify-send isn't installed
command -v notify-send >/dev/null 2>&1 || nn_flag=0
nn_flag=${nn_flag:-1}
## set the debugging flag if not already
debug_run=${debug_run:-1}
[[ $debug_run -eq 0 ]] && log "DEBUG" "The mode flag has been set so script will operate in debug mode." "$log_file"
## setup the quiet flag to determine if program should be slient
quiet=${quiet:-1}
log "DEBUG" "The quiet flag has been set to: $quiet." "$log_file"

## ensure source.list exists
source_list="$runtime_dir/source.list"
log "DEBUG" "Checking for a source.list in current runtime directory..." "$log_file"
[[ ! $quiet -eq 0 ]] && echo -n "Checking for source.list..."
[[ ! -f "$source_list" ]] && { [[ ! $quiet -eq 0 ]] && >&2 echo -e "\nUpdater encountered an issue: source.list not found. Exiting..." ;
log "ERROR" "Cannot find source.list in runtime directory ($source_list). Exiting...(2)" "$log_file" ; exit 2 ; }

log "DEBUG" "Found a souce.list in $runtime_dir." "$log_file"
[[ ! $quiet -eq 0 ]] && echo "found."

## set the channel flag
log "DEBUG" "Determining the channel of Edge and checking if it is installed to the system..."
edge_channel="${edge_channel:-$(grep -o "\[dists.*\]" "$source_list" | sed -E 's/\[dists=(.*)\]/\1/' | cut -d, -f2)}"
## if for some reason there is no value, exit 254
[[ "$edge_channel" == "" ]] && { [[ ! $quiet -eq 0 ]] && >&2 echo "There is no channel specified for Microsoft Edge. Please check the source.list file has a correct value, or use  --set-channel  to set the channel for that session." ;
log "ERROR" "Encountered an issue trying to determine the channel of Microsoft Edge to update on the system. source.list is potentially corrupt since no default value was found. Exiting...(254)" ; exit 254 ; }
## check if Microsoft Edge is already installed - :@Ethan: this is some Tom Foolery, Bashism Fuckery
command -v microsoft-edge-$edge_channel &>/dev/null
exit_code=$?
[[ ! $exit_code -eq 0 ]] && { [[ ! $quiet -eq 0 ]] && >&2 echo "Microsoft Edge ($edge_channel) is not installed. Exiting updater..." ;
	log "DEBUG" "Microsoft Edge ($edge_channel) not recognised as an installed program. Exiting...(1)" ; exit 1 ; }
log "DEBUG" "Microsoft Edge ($edge_channel) is installed to system. Proceeding with update..." "$log_file"

## ensure host is reachable
host=$(grep "\[host\]" "$source_list" | cut -d' ' -f 2)
log "DEBUG" "Checking if host is available according to defined value of [host]: $host..." "$log_file"
[[ ! $quiet -eq 0 ]] && echo -n "Checking to see if the host is known and reachable..."
if ! wget --spider "$host" >/dev/null 2>&1 ; then
	>&2 echo "Cannot reach end-point for distribution information. Check your Internet connection and try again. Exiting..."
	log "DEBUG" "Upstream end-point is cannot be contacted. Potential Internet connection issue or end-point address ($dist_upstream). Exiting...(3)" "$log_file"
	[[ ! $nn_flag -eq 0 ]] && notify "Microsoft Edge ($edge_channel) Update" "There seems to be an issue connecting to the end-point of Microsoft. Check your Internet connection and try again."

	exit 3
fi
log "DEBUG" "Host is known and reachable. Continuing update to fetch data..." "$log_file"
[[ ! $quiet -eq 0 ]] && echo "host known and reachable: (host) $host"

## identify the end-point URL for distribution information
dist_upstream=$(grep "\[dists.*\]" "$source_list" | cut -d' ' -f 2-4 --output-delimiter '/')
archi=$(grep -o "\[dists.*\]" "$source_list" | sed -E 's/\[dists=(.*)\]/\1/' | cut -d, -f1)
log "DEBUG" "Fetching Packages file from $dist_upstream for $archi architectures..." "$log_file"
## fetch the file - :@Ethan: there's no reason to inform the user of this operation unless it fails
wget -a "$log_file" -O "$tmp_path/Packages.gz" "$dist_upstream/binary-$archi/Packages.gz"
exit_code=$?
[[ ! $exit_code -eq 0 ]] && { [[ ! $quiet -eq 0 ]] && >&2 echo "There was an issue retrieving the package information for the update. Please check $logs_dir/updater.log, for more information. Exiting..." ;
	log "DEBUG" "Encountered an issue with wget. Exiting...(4)" "$log_file" ; exit 4 ; }
log "DEBUG" "Successfully downloaded release package information." "$log_file"

log "DEBUG" "Fetching Contents-$archi.gz from ${dist_upstream::-4}" "$log_file"
wget -a "$log_file" -O "$tmp_path/Contents-$archi.gz" "${dist_upstream::-4}/Contents-$archi.gz"
exit_code=$?
[[ ! $exit_code -eq 0 ]] && { [[ ! $quiet -eq 0 ]] && >&2 echo "There was an issue retrieving the package contents for the update. Please check $log_file/updater.log, so more information. Exiting..." ;
	log "ERROR" "Encountered an issue with wget. Exiting...(4)" "$log_file" ; exit 4 ; }
log "DEBUG" "Successfully downloaded release contents information." "$log_file"
## decompress the packages file
log "DEBUG" "Uncompressing downloaded gz file using gunzip, $tmp_path/Packages.gz..." "$log_file"
## force gunzip to overwrite decompressed file if it already exists
gunzip -f "$tmp_path/Packages.gz" "$tmp_path/Contents-$archi.gz" >/dev/null 2>&1
log "DEBUG" "Successfully uncompressed content." "$log_file"

## get the most recent package entry from Packages list for Beta version of browser
log "DEBUG" "Identifying the most recent package information from Packages catelogue..." "$log_file"
## find the earliest entry for Edge Beta release
start_point=$(grep -n "Package:.*-$edge_channel" "$tmp_path/Packages" | tr '\n' ' ' | cut -d: -f1)
## make a list of all lines which are blank - used to identify end of package information entry
end_points=( $(grep -n '^\s*$' "$tmp_path/Packages" | sed 's/://g') )
## loop over all potential end points
for (( i=0 ; i<"${#end_points[@]}"; i++)) ; do
	## if the end point is greater than start point, set $end_point to the index of i
	### :@NOTE: this will more often then not be the first value in the array. However,
	### if a dev release comes out before the next beta version, the package entry may be
	### much later in the file. We break once the correct end point is found.
	[[ "${end_points[$i]}" -gt $start_point ]] && end_point="${end_points[$i]}" && break
done
## adjust the start and end point values
((start_point--)) ; ((end_point++))
## this ensures end_point is set. :@Ethan: I could just test if the variable exists but I like the clarity of this for now
end_point="${end_point:--1}"
## if for some reason $end_point is set to -1, we have an issue with the Packages file and should exit
[[ $end_point -eq -1 ]] && { log "ERROR" "EOF reached and indexing out of bounds value has been set. Exiting...(5)" "$log_file" ; exit 255 ; }
## extrapolate the package information and save to Release
package_entry=$(awk -v start=$start_point -v end=$end_point 'NR>1*start&&NR<1*end' "$tmp_path/Packages" > "$tmp_path/Release")
log "DEBUG" "Extrapolated most recent package information entry from $tmp_path/Release. Package information selected is as below:" "$log_file"
## pretty print each line when appending to make it easier to read in log file
sed 's/^/  (Release Info)   /' "$tmp_path/Release" | sed -E 's/(^\s*\(Release Info\)\s*$)/\1(END)/' >> "$log_file"

### :@Ethan: at this point we can start ensuring that a newer release is available, inform the user of the new size,
### check dependences, and just ensure the user wants to go ahead with the update.

## get the current version number and the version in Release
current_version=$(microsoft-edge-$edge_channel --version | cut -d' ' -f3)
release_version=$(grep 'Version' "$tmp_path/Release" | sed -E 's/Version:\s*(.*)-.*/\1/')
log "DEBUG" "Checking if there is an update available (release: $release_version) or if most recent version is already installed to the system..." "$log_file"
## compare the versions - using sort -V.
if [[ "$release_version" == "$current_version" ]]; then
	upgradeable=1
else
	[[ "$current_version" != "$(echo -e "$current_version\n$release_version" | sort -V | head -n2)" ]] && upgradeable=0
fi
## this should never be substituted to 1 - but it's a cover if the release version happens to be behind the current version
##"${upgradeable:=1}"
upgradeable=${upgradeable:-1}
## check if we can upgrade, can exit 1 for passive exit - exit not notifying a failure for another reason
if [[ $upgradeable -eq 1 ]] ; then
	elapsed_time=$SECONDS
	script_time="$(($elapsed_time / 60))m $(($elapsed_time % 60))s"
	[[ ! $quiet -eq 0 ]] && >&2 echo "Most recent version of Microsoft Edge ($edge_channel) [v$current_version] is already installed on this system, no need to update. Finished in $script_time"
	log "DEBUG" "Most recent version of Microsoft Edge ($edge_channel) is already installed to the system (v$current_version). Completed in $script_time. Exiting...(1)" "$log_file"
	[[ ! $nn_flag -eq 0 ]] && notify "Microsoft Edge ($edge_channel) Update" "There is no newer version of Microsoft Edge ($edge_channel) to install. Newest version is already installed: v$current_version"

	exit 0
fi
log "DEBUG" "There is a more recent release of Microsoft Edge ($edge_channel) available for download (v$release_version). Continuing with update." "$log_file"
[[ ! $quiet -eq 0 ]] && >&2 echo "Identified a new release of Microsoft Edge ($edge_channel) [Current: v$current_version. New: v$release_version]. Starting the download and installation process..."

## check if msedge process is already running
is_running="$(pidof msedge | xargs ps -ocmd -p | grep -m1 "msedge-$edge_channel")"
if [[ ! -z "$is_running" ]] ; then
	log "DEBUG" "Identified running processes for msedge. Determining how script should handle process..." "$log_file"
	if [[ ! $yes_flag -eq 0 ]] ; then
		echo -n "Microsoft Edge ($edge_channel) is already open. To continue update, the browser must be closed. Are you sure you wish to proceed? [(Y)es/No]: " && read -n 1 choice ; echo
		[[ $(echo $choice | awk '{print tolower($0)}') == "n" ]] && { log "DEBUG" "User opted against allowing the script to close Microsoft Edge ($edge_channel) by default. Exiting...(1)" "$log_file" ; exit 1 ; }
	fi
	log "DEBUG" "Confirmation has been given to proceed with killing Microsoft Edge ($edge_channel) processes. Killing msedge..." "$log_file"

	kill_attempts=0
	while [[ -n $(pidof msedge) ]] ; do
		[[ $? -eq 0 && $kill_attempts -ge 1 ]] && {
			log "WARNING" "Process is refusing to exit. Attempting to kill process again after 2 seconds..." "$log_file" ;
			sleep 2 ; }
		[[ $kill_attempts -eq 3 ]] && {
			echo "There was an issue trying to close Microsoft Edge ($edge_channel). Please close the browser and restart the updater." ;
			log "ERROR" "Process has refused to close $kill_attempts time(s). Update cannot continue in current state, exiting...(253)" "$log_file" ;
			exit 253 ; }
		pkill msedge
	done
#	killall_stdout="$(killall msedge 2>&1)"
#	exit_code=$?
#	[[ ! $exit_code -eq 0 ]] && {
		## :@TODO: employ a similar mechanism to that created by Rob in autostart script (https://robmc.duckdns.org/git/robert/dotfiles/src/branch/master/.local/share/dwm/autostart.sh) to keep attempting to end msedge process if it refuses.
#		if [[ "$killall_stdout" == "msedge: no process found" ]] ; then
#			log "DEBUG" "Process has already been closed by another means, either by an external process or user."
#		else
#			pkill -9 msedge
#		fi ; }
fi
log "DEBUG" "Microsoft Edge ($edge_channel) has been closed, either by yes flag enabled or by user decision. Process may not have been running thus never killed." "$log_file"


# Download the newest version of Microsoft Edge ($edge_channel)
## get the end-point for .deb file location and filename
pool=$(grep '\[pool\]' "$source_list" | cut -d' ' -f2)
filename=$(grep 'Filename:.*' "$tmp_path/Release" | cut -d' ' -f2)
url="$pool$filename" ## set URL to be concatenation of pool + filename
## check if the file end-point is actually reachable before trying to download
log "DEBUG" "Checking the following release version file end-point is accessible ($url)..." "$log_file"

### :@Ethan: This is trying to download the file for a response so effectively we will be doing the same work twice
### so is inefficient for testing if the end-point is reachable. ping and telnet are not suitable for this operation.
### An assumption will have to be made for now.

### :@Ethan: The above message has been addressed and wget commands for checking end-points has been changed from
### `wget -qO- [URL] >/dev/null 2>&1` to: `wget --spider [URL] >/dev/null 2>&1`. Check manpage for more about the
### spider argument.

if ! wget --spider "$url" >/dev/null 2>&1 ; then
	[[ ! $quiet -eq 0 ]] && >&2 echo "Cannot reach end-point for latest release. Check your Internet connection and try again."
	log "DEBUG" "Pool end-point is cannot be contacted. Potential Internet connection issue or end-point address ($url). Exiting...(5)" "$log_file"
	[[ ! $nn_flag -eq 0 ]] && notify "Microsoft Edge ($edge_channel) Update" "There seems to be an issue connecting to the end-point of Microsoft. Check your Internet connection and try again."
	exit 5
fi
log "DEBUG" "Pool is known and reachable. Beginning download..." "$log_file"
[[ ! $quiet -eq 0 ]] && echo "Host known and reachable: (download) $url"

## set filename to not be pool address but the name of file
filename=$(echo "$url" | rev | cut -d'/' -f1 | rev)
filesize=$(grep '^Size:.*' "$tmp_path/Release" | cut -d' ' -f2)
log "DEBUG" "Checking if user wishes to proceed with the update installation..." "$log_file"
## inform the user of the new download size before downloading
if [[ $yes_flag -eq 1 ]] ; then
	echo -n "The following package will be installed, $filename [$filesize]. Are you sure you wish to continue? [(Y)es/No]: " && read -n 1 choice && echo
	[[ "$(echo $choice | awk '{print tolower($0)}')" == "n" ]] && { [[ ! $quiet -eq 0 ]] && >&2 echo "The following update to Microsoft Edge ($edge_channel) v$release_version will not be installed. Exiting updater..." ;
	log "DEBUG" "User opted out for updating from $current_version to $release_version. Exiting...(1)" "$log_file" ; exit 1 ; }
fi
log "DEBUG" "Confirmation has been given to proceed with the following update of Microsoft Edge ($edge_channel) [v$release_version]." "$log_file"

# download the debian file
log "DEBUG" "Checking if the file is already downloaded to the system..." "$log_file"
if [[ ! -f "$tmp_path/$filename" ]] ; then
	log "DEBUG" "Downloading the latest release version [v$release_version], file: $filename (URL: $url)" "$log_file"
	[[ ! $quiet -eq 0 ]] && echo "Downloading the following release file: $filename. This may take a moment..."
	# wget_timed=$(\time --format "%x:%e" wget -a "$tmp_path/wget_dump.log" -O "$tmp_path/$filename" "$url" 2>&1)
	wget -a "$tmp_path/wget_dump.log" --progress=bar --show-progress -O "$tmp_path/$filename" "$url"
	exit_code=$? # $(echo $wget_timed | cut -d: -f1)
	[[ ! $exit_code -eq 0 ]] && { [[ ! $quiet -eq 0 ]] && >&2 echo "There was an issue downloading the Debian version of Microsoft Edge ($edge_channel)." \
		"Please check $logs_dir/updater.log, for more information. Exiting update..." ;
		log "DEBUG" "Encountered an issue with wget. Exiting...(6)" "$log_file" ; exit 6 ; }
	awk -v end=$(grep -n '^\s*$' "$tmp_path/wget_dump.log" | tr '\n' ' ' | cut -d: -f1) 'NR>1*0&&NR<1*end+1' "$tmp_path/wget_dump.log" >> "$log_file"
	log "DEBUG" "Download completed successfully, wget log shown above." "$log_file"
	[[ ! $quiet -eq 0 ]] && echo -n "Download complete. Validating checksums..."
else
	log "DEBUG" "File already downloaded to system. Skipped download and verifying checksum..." "$log_file"
	[[ ! $quiet -eq 0 ]] && echo -n "Latest Debian release file is downloaded to the system, skipping download. Validating checksums..."
fi
## add the .deb file to garbage list
echo "$tmp_path/$filename" >> "$garbage"

## verify the downloaded file
if [[ "$(sha256sum "$tmp_path/$filename" | cut -d' ' -f1)" != "$(grep 'SHA256:.*' "$tmp_path/Release" | cut -d' ' -f2)" ]] ; then
	## automatically remove the file - :@Ethan: it's either corrupt or hazardous to the health of the system
	rm "$tmp_path/$filename"
	log "DEBUG" "Checksum (SHA256) failed and integrity of file lost. File has been removed as either corrupt or hazardous/dangerous. Exiting...(7)" "$log_file"
	[[ ! $quiet -eq 0 ]] && echo "failed." && \
		>&2 echo "The checksum (SHA256) failed for some reason and removed either because it was corrupt or dangerous. Exiting updater..."
	[[ ! $nn_flag -eq 0 ]] && notify "Microsoft Edge ($edge_channel) Update" "There was an issue with the checksum to verify the latest release. The Debian file has been automatically removed to prevent potential danger to the system."
	exit 7
fi
[[ ! $quiet -eq 0 ]] && echo "complete."


# unarchive the .deb file and extract data.tar.gz
log "DEBUG" "Unarchiving the downloaded DEB file ($tmp_path/$filename)..." "$log_file"
[[ ! $quiet -eq 0 ]] && echo -n "Unzipping download..."
## use ar to unarchive .deb file
ar vx "$tmp_path/$filename" --output "$tmp_path" >/dev/null 2>&1
exit_code=$?
[[ ! $exit_code -eq 0 ]] && { [[ ! $quiet -eq 0 ]] && echo "incomplete." && \
	>&2 echo "There was an issue unarchiving $filename. Exiting updater...\n" ;
	log "ERROR" "There was an issue when unarchiving $filename. Exiting...(8)" "$log_file" ; exit 8 ; }
log "DEBUG" "Successfully unarchived $filename, decompressing the data.tar.gz file..." "$log_file"
## extract data from data.tar.gz
tar --overwrite -xf "$tmp_path/data.tar.xz" --directory "$tmp_path" 1>"$tmp_path/tar_dump.log" 2>>"$log_file"
exit_code=$?
[[ ! $exit_code -eq 0 ]] && { [[ ! $quiet -eq 0 ]] && echo "incomplete." && \
	>&2 echo "There was an extracting data.tar.gz. Exiting updater..." ;
	log "ERROR" "There was an issue when decompressing data.tar.gz using tar -xvf. Exiting...(8)" "$tmp_path" ; exit 8 ; }
log "DEBUG" "Successfully extracted files from data.tar.gz." "$log_file"
[[ ! $quiet -eq 0 ]] && echo "completed."
## etc/ directory only contains a cron daily directory, remove it
[[ ! $quiet -eq 0 ]] && rm -r "$tmp_path/etc/"
## add data.tar.xz to the garbage list
echo "$tmp_path/data.tar.xz" >> "$garbage"

# compress archive the currently installed version of Edge ($edge_channel) for restoration on failure
log "DEBUG" "Creating an archive gzip tarball of system /opt/ and /usr/ directories..." "$log_file"
[[ ! $quiet -eq 0 ]] && echo -n "Installing new version to system. This may take a few minutes..."
archive_system "microsoft/msedge-$edge_channel"
exit_code=$?
if [[ ! $exit_code -eq 0 ]] ; then
	### :@Ethan: there was an issue with creating an archive, should probably inform the user to make a decision (unless -y is set)
	[[ ! $quiet -eq 0 ]] && echo "failed." && >&2 echo "There was an issue creating a backup of the system. Exiting..."
	log "ERROR" "There was an issue creating a gzip tarball of the system. Exiting...($exit_code)" "$log_file"
	exit $exit_code
fi
log "DEBUG" "Successfully created an archive gzip tarball of the system. Safe to continue with installation." "$log_file"

### :@NOTE: used to terminate the program at a certain point for incremental testing of functionality recently added up to the point of this exit.
### exit 0

# install the new version to system
log "DEBUG" "Copying files to there appropriate location..." "$log_file"
cp -ar "$tmp_path/opt" "/" >>"$log_file" 2>&1
exit_code=$?
if [[ ! $exit_code -eq 0 ]] ; then
	[[ ! $quiet -eq 0 ]] && echo "failed." && \
	>&2 echo -n "There was an issue installing files to the system. Reverting to previous version..."
	log "DEBUG" "There was an issue copying $tmp_path/opt/ file to system /opt/. Reverting system files and exiting...(9)" \
		"$log_file"

	## attempt restoration of system
	restore_files "microsoft_msedge-$edge_channel"
	return_code=$?
	## check the restoration was successful
	check_restoration $return_code 9

	exit 9
fi

cp -ar "$tmp_path/usr" "/" >>"$log_file" 2>&1
exit_code=$?
if [[ ! $exit_code -eq 0 ]] ; then
	[[ ! $quiet -eq 0 ]] && echo "failed." && \
	>&2 echo -n "There was an issue installing files to the system. Reverting to previous version..."
	log "DEBUG" "There was an issue copying $tmp_path/usr/ file to system /usr/. Reverting system files and exiting...(9)" \
		"$log_file"

	## attempt restoration of system
	restore_files "microsoft_msedge-$edge_channel"
	return_code=$?
	## check the restoration was successful
	check_restoration $return_code 9

	exit 9
fi
log "DEBUG" "Successfully installed files to their appropriate location." "$log_file"
[[ ! $quiet -eq 0 ]] && echo "installation complete."
## add directories usr/ and opt/ to garbage
echo "$tmp_path/usr" >> "$garbage"
echo "$tmp_path/opt" >> "$garbage"

## confirm the update was successful - try to restore system otherwise
if [[ "$(microsoft-edge-$edge_channel --version | cut -d' ' -f3)" != "$release_version" ]] ; then
	log "ERROR" "There was an issue with the update and installation. Restoring to previous version..." "$log_file"
	printf "Update was unsuccessful. Restoring to previous version..."

	## attempt restoration of system
	restore_files "microsoft_msedge-$edge_channel"
	return_code=$?
	## check the restoration was successful
	check_restoration $return_code 11

	exit 11
fi

## end of update. Inform user of time taken to complete, notify and log.
elapsed_time=$SECONDS
script_time="$(($elapsed_time / 60))m $(($elapsed_time % 60))s"
log "DEBUG" "Installation and update was successful (completed in: $script_time) and system can be cleaned up to remove any waste." "$log_file"
[[ ! $quiet -eq 0 ]] && echo "Microsoft Edge ($edge_channel) has been successfully updated to the latest version: v$current_version -> v$release_version, in $script_time."
[[ ! $nn_flag -eq 0 ]] && notify "Microsoft Edge ($edge_channel) Update" "Successfully updated Microsoft Edge ($edge_channel) to the latest version: v$release_version"

# exit from script, clean up function is called by default exit of script (EOF)