#! /bin/bash

# small script to log battery usage in txt file for conky to parse
# lovingly stolen from battery-stats by petter reinholdtsen

DST_FILE="$XDG_CACHE_HOME/batmon.log"
SYS_BAT_PATH="/sys/class/power_supply/BAT0"
BAT_CAP_PATH="$SYS_BAT_PATH/charge_now"
BAT_CAP_FULL_PATH="$SYS_BAT_PATH/charge_full"
MAX_ENTRIES=1440 # number of minutes in day

read_bat_percent() {
	timestamp=$(date +%s)
	charge_now=$(cat "$BAT_CAP_PATH")
	charge_full=$(cat "$BAT_CAP_FULL_PATH")
	percent=$(echo "100 * $charge_now / $charge_full" | bc)
	echo $timestamp $percent >> "$DST_FILE"
}

read_bat_percent
# truncate to most recent entries by max_entries
tail -n $MAX_ENTRIES "$DST_FILE" > /tmp/batmon.tmp.log && mv /tmp/batmon.tmp.log "$DST_FILE"