bthandler/bt

#!/bin/bash
#wait time to discover new devices in seconds
SCAN_PERIOD=5
AUTOTRUST=false
#locations of blacklist and hard coded list of paired devices (watch out, need to modify Makefile as well if you want to change these values and still use make install)
BLACKLIST=${XDG_DATA_HOME:-$HOME/.local/share}/bt/blacklist
PAIRLIST=${XDG_DATA_HOME:-$HOME/.local/share}/bt/paired

actions="pair
disconnect
unpair"

[ "$AUTOTRUST" = false ] && actions+="
trust"

#Checks for necessary programs to be present. Very unlikely not to be present but let's just err on the safer side.
for prog in dmenu bluetoothctl awk cat date nl; do
   if ! hash "$prog" 2>/dev/null; then
      printf 'bthandler: %s: command not found\n' "$prog" >&2
      exit 127
   fi
done

power(){
	powerstatus="$( bluetoothctl show | grep Powered | awk '{print $2}' )"
	[ "$powerstatus" = "no" ] && [ "$1" = on ] && bluetoothctl power on
	[ "$powerstatus" = "yes" ] && [ "$1" = off ] && bluetoothctl power off
}
scan(){
	scanstatus="$( bluetoothctl show | grep Discovering | awk '{print $2}' )"
	if [ "$1" = "on" ]; then
		#sets variable in case scanning was already on before the start of bt
		[ "$start_scan" = "" ] && start_scan="$( date +'%s' )"
		if [ "$scanstatus" = "no" ]; then
			bluetoothctl scan on &
			start_scan="$( date +'%s' )"
		fi
	elif [ "$1" = off ]; then
		if [ "$scanstatus" = "yes" ]; then
			bluetoothctl scan off
		fi
	fi
}

#start scanning as early as possible to speed up pairing process
#=> maybe use an option to do this? Otherwise ever invocation of bt powers on the controller.
power on
scan on

#Compile list of all Bluetooth IDS of paired devices (from bluetoothctl and from hardcoded list)
bt_IDS="$( ( bluetoothctl paired-devices && cat "$PAIRLIST" ) | sort -u | awk '{print $2}' )"

#Compile list of all device Names of paired devices (from bluetoothctl and from hardcoded list)
paired_devices="$( ( bluetoothctl paired-devices && cat "$PAIRLIST" ) | sort -u | awk '{for (i=3; i<NF; i++) printf $i " "; print $NF}' )"

disp_devices="$( echo "$paired_devices" | grep -vf "$BLACKLIST"  )"

#detects current power mode of controller and adjusts options accordingly
poweroption="$( echo "$powerstatus" | sed 's/yes/power off/; s/no/power on/' )"
#Don't print empty device list, removes unnecessary empty choice in dmenu
[ "$disp_devices" = "" ] && choice=$( printf "%s\n%s" "$poweroption" "$actions" | dmenu -i -p 'What BT action would you like to perform:' )
[ "$disp_devices" != "" ] && choice=$( ( echo "$disp_devices" && printf "%s\n%s" "$poweroption" "$actions"  ) | dmenu -i -p 'What BT action would you like to perform:' )

cleanup(){
	scan off
	exit 0
}

pair(){
	#since this function can get called indefinitely, make sure to always be scanning and controller has power in the case that it got deactived by some other process.
	power on
	scan on
	#check whether $SCAN_PERIOD seconds has already passed since starting scanning, if not, wait for the rest of that time.
	if [ $((( "$(date +'%s')" - "$start_scan" ))) -lt $SCAN_PERIOD ]; then
		sleep_period="$((( "$SCAN_PERIOD" - "$( date +'%s')" + "$start_scan" )))"
		if [ "$sleep_period" -eq 1 ]; then
			notify-send "Bluetooth" "Searching for devices, please wait 1 second"
		else
			notify-send "Bluetooth" "Searching for devices, please wait $sleep_period seconds"
		fi

		sleep "$sleep_period"
	fi
	if [ $paired_devices = "" ]; then
		echo "$paired_devices" > /tmp/paired_devices
		new_devices="$( bluetoothctl devices | awk '{for (i=3; i<NF; i++) printf $i " "; print $NF}' | grep -vf /tmp/paired_devices )"
		rm -f /tmp/paired_devices
	else
		new_devices="$( bluetoothctl devices | awk '{for (i=3; i<NF; i++) printf $i " "; print $NF}' )"
	fi
	[ $new_devices = "" ] && options="rescan" || options=$(echo "$new_devices" && echo 'rescan')
	choice=$( echo "$options" | dmenu -l 10 -i -p 'pair with which device?' )
	if [ -n "$choice" ]; then
		if [ "$choice" = "rescan" ]; then
			start_scan="$( date +'%s')"
			pair
		fi
		bt_IDS="$( bluetoothctl devices | awk '{print $2}' )"
		dev_no=$( echo "$new_devices" | nl | grep "$choice" | awk '{print $1}')
		dev_id=$( echo "$bt_IDS" | nl | grep -P "^.*$dev_no\t" | awk '{print $2}' )

		bluetoothctl pair "$dev_id" && sleep 2
		bluetoothctl connect "$dev_id"
		if $AUTOTRUST; then
			bluetoothctl trust "$dev_id"
		fi
		#if device is not already hard coded as paired, add to paired devices list
		if [ "$( grep "$dev_id" "$PAIRLIST")" != "" ]
		then
			echo to be added to $PAIRLIST
			echo Device "$dev_id" "$choice"
			echo Device "$dev_id" "$choice" >> "$PAIRLIST"
		fi
	fi
}

case $choice in
	"turn on") bluetoothctl power on;;
	"turn off") bluetoothctl power off;;
	"scan on") bluetoothctl power on && echo power on && sleep 2
		([ -n "$TERMINAL" ] && $TERMINAL -e bluetoothctl scan on ) || st bluetoothctl scan on;;
	"pair") pair;;
	"unpair") choice=$( echo "$paired_devices" | dmenu -l 10 -i -p 'remove which paired device?')
		if [ -n "$choice" ]; then
			dev_no=$( echo "$paired_devices" | nl | grep -P "[0-9]+\t$choice$" | awk '{print $1}')
			dev_id=$( echo "$bt_IDS" | nl | grep -P "^.*$dev_no\t" | awk '{print $2}' )
			bluetoothctl remove "$dev_id"
			#remove device to unpair from hard coded paired devices list
			new_paired_list="$( grep -v "$dev_id" "$PAIRLIST" )"
			echo "$new_paired_list" > "$PAIRLIST"
		fi;;
	"trust") choice=$( echo "$paired_devices" | dmenu -l 10 -i -p 'remove which paired device?')
		if [ -n "$choice" ]; then
			dev_no=$( echo "$paired_devices" | nl | grep -P "[0-9]+\t$choice$" | awk '{print $1}')
			dev_id=$( echo "$bt_IDS" | nl | grep -P "^.*$dev_no\t" | awk '{print $2}' )
			bluetoothctl trust "$dev_id"
		fi;;
	"disconnect") choice=$( echo "$paired_devices" | dmenu -l 10 -i -p 'remove which paired device?')
			if [ -n "$choice" ]; then
				dev_no=$( echo "$paired_devices" | nl | grep -P "[0-9]+\t$choice$" | awk '{print $1}')
				dev_id=$( echo "$bt_IDS" | nl | grep -P "^.*$dev_no\t" | awk '{print $2}' )
				bluetoothctl disconnect "$dev_id"
			fi;;
	*)
		echo "$choice"
		dev_no=$( echo "$paired_devices" | nl | grep -P "[0-9]+\t$choice$" | awk '{print $1}')
		dev_id=$( echo "$bt_IDS" | nl | grep -P "^.*$dev_no\t" | awk '{print $2}')
		bluetoothctl power on
		bluetoothctl pair "$dev_id"
		bluetoothctl connect "$dev_id";;
esac
cleanup