#!/bin/bash
#wait time to discover new devices in seconds
SCAN_PERIOD=5
#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="turn off
turn on
pair
unpair"

#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

#start scanning as early as possible to speed up pairing process:
bluetoothctl power on & bluetoothctl scan on &>/dev/null &
start_scan="$( date +'%s' )"

#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"  )"

#Don't print empty device list, removes unnecessary empty choice in dmenu
[ "$disp_devices" = "" ] && choice=$( echo "$actions" | dmenu -i -p 'What BT action would you like to perform:' )
[ "$disp_devices" != "" ] && choice=$( echo "$disp_devices" "$actions" | dmenu -i -p 'What BT action would you like to perform:' )

cleanup(){
	bluetoothctl 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.
	bluetoothctl power on &>/dev/null &
	bluetoothctl scan on &>/dev/null &
#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 "$sleep_period"
	fi
	echo "$paired_devices" > /tmp/paired_devices
	new_devices="$( bluetoothctl devices | awk '{for (i=3; i<NF; i++) printf $i " "; print $NF}' | grep -vf /tmp/paired_devices )"
	rm -f /tmp/paired_devices
	choice=$( (echo "$new_devices" && echo 'rescan' ) | dmenu -l 10 -i -p 'pair with which device?' )
	if [ -n "$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 device is not already hard coded as paired, add to paired devices list
		if grep -q "$dev_id" "$PAIRLIST"
		then
			echo Device "$dev_id" "$choice" >> "$PAIRLIST"
		fi
	fi
	cleanup
}

case $choice in
	"turn on") bluetoothctl power on
		cleanup;;
	"turn off") bluetoothctl power off
		cleanup;;
	"scan on") bluetoothctl power on && echo power on && sleep 2
		([ -n "$TERMINAL" ] && $TERMINAL -e bluetoothctl scan on ) || st bluetoothctl scan on
		cleanup;;
	"pair") pair;;
	"unpair") choice=$( 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
		cleanup;;
esac

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 $2}')
	bluetoothctl power on
	bluetoothctl pair "$dev_id"
	bluetoothctl connect "$dev_id"
fi

cleanup