batterycheck

#!/bin/bash
# Monitor the battery level and send a notification if it falls below 20%.
# Also notify if the battery is fully charged.

# Path to sysfs power_supply
POW_PATH="/sys/class/power_supply"

# Get adapter status. '0' if offline/discharging, '1' if online/charging.
STATUS=$(cat $POW_PATH/ADP0/online)

# Get battery capacity.
BAT_LVL=$(cat $POW_PATH/BAT0/capacity)

# Hard limits for cautions
LOW_CAP=20 # how low is too low?
FULL_CAP=100 # full capacity

# Eye Candy

ICON_DIR="/usr/share/icons/gnome/32x32/status"
LOW="$ICON_DIR/battery-caution.png"
FULL="$ICON_DIR/battery-full-charged.png"
CHARGING="$ICON_DIR/battery-low-charging.png"
DISCHARGING="$ICON_DIR/battery-good.png"

# Persistence for one-time notifications

CHARGE_FILE="/home/bharath/scripts/charge"
DISCHARGE_FILE="/home/bharath/scripts/discharge"

# TODO: How much time is left for the battery to discharge?


# Case 1, caution that battery is low.

[ "$STATUS" -eq 0 -a $BAT_LVL -le $LOW_CAP ] && $(which notify-send) -i $LOW \
	-t 5000 -u critical \
	"Battery Low!" "Battery level is ${BAT_LVL}%.\n Plug in your charger."

# Case 2, caution that battery is full.

[ "$STATUS" -eq 1 -a $BAT_LVL -eq $FULL_CAP ] && $(which notify-send) -i $FULL \
	-t 5000 -u normal \
	"Battery Full." "Battery at ${BAT_LVL}%.\n Unplug your charger."

# Case 3, notify that battery is charging, once, when plugging into the wall.

[ "$STATUS" -eq 1 -a  ! -f $CHARGE_FILE ] && $(which notify-send) -i $CHARGING \
	-t 3000 -u low \
	"Battery Charging." "Current battery level is ${BAT_LVL}%." &&
	touch $CHARGE_FILE &&
	[ -f $DISCHARGE_FILE ] && rm $DISCHARGE_FILE

# Case 4, notify that battery is discharging, once, when plugging out of the wall.
# TODO: Fix this! Notifies about discharging every minute!
[ "$STATUS" -eq 0 -a ! -f $DISCHARGE_FILE ] && 
	T=$(echo "( $(cat $POW_PATH/BAT0/energy_now) / $(cat $POW_PATH/BAT0/power_now) )" | bc -l ) \
	H=$(echo "scale=0; $T / 1" | bc ) \
	M=$(echo "scale=0; (($T - $H) * 60) / 1" | bc ) \
	S=$(echo "scale=0; ((($T - $H) * 60 - $M) * 60) / 1" | bc ) \
	REM="${H}h ${M}m ${S}s Remaining" &&
	$(which notify-send) -i $DISCHARGING \
	-t 3000 -u low \
	"Battery Discharging." "Current battery level is ${BAT_LVL}%.\n$REM." &&
	touch $DISCHARGE_FILE &&
	[ -f $CHARGE_FILE ] && rm $CHARGE_FILE

exit 0