#!/bin/sh
unset QUIET MILLIWATTS TOTAL
BATTERY="ALL"

while getopts "b:mqt" o; do case "${o}" in
  q) QUIET="y" ;;
  m) MILLIWATTS="y" ;;
  t)
    TOTAL="y"
    BATTERY="ALL"
    ;;
  b) BATTERY="$OPTARG" ;;
esac done

#TOTALPOWER='0'

case "$BATTERY" in
  "ALL")
    for battery in $(ls -1 /sys/class/power_supply | grep 'BAT'); do
      DIRNAME="/sys/class/power_supply/${battery}"
      if [ -f "${DIRNAME}/power_now" ]; then
        if [ -n "${MILLIWATTS}" ]; then
          POWER="$(cat "${DIRNAME}/power_now" | awk '{print $1/1e3}' | head -1)"
        else
          POWER="$(cat "${DIRNAME}/power_now" | awk '{print $1/1e6}' | head -1)"
        fi
      elif [ -f "${DIRNAME}/current_now" ]; then
        if [ -n "${MILLIWATTS}" ]; then
          POWER="$(cat "${DIRNAME}/current_now" "${DIRNAME}/voltage_now" | paste -d' ' -s | awk '{print $1*$2/1e9}' | head -1)"
        else
          POWER="$(cat "${DIRNAME}/current_now" "${DIRNAME}/voltage_now" | paste -d' ' -s | awk '{print $1*$2/1e12}' | head -1)"
        fi
      fi
      if [ -n "${TOTAL}" ]; then
        TOTALPOWER="$(echo "${TOTALPOWER}" "${POWER}" | awk '{print $1+$2}'| head -1)"
      else
        if [ -z "${QUIET}" ]; then
          printf "Power in ${battery} is "
        fi
        printf "${POWER}"
        if [ -n "${MILLIWATTS}" ]; then
          echo " mW"
        else
          echo " W"
        fi
      fi
    done
    if [ -n "${TOTAL}" ]; then
      if [ -z "${QUIET}" ]; then
        printf "Total power is "
      fi
      printf "${TOTALPOWER}"
      if [ -n "${MILLIWATTS}" ]; then
        echo " mW"
      else
        echo " W"
      fi
    fi
    ;;
  *)
    DIRNAME="/sys/class/power_supply/${BATTERY}"
    [ -d "${DIRNAME}" ] || echo "No such battery!"
    if [ -f "${DIRNAME}/power_now" ]; then
      if [ -n "${MILLIWATTS}" ]; then
        POWER="$(cat "${DIRNAME}/power_now" | awk '{print $1/1e3}' | head -1)"
      else
        POWER="$(cat "${DIRNAME}/power_now" | awk '{print $1/1e6}' | head -1)"
      fi
    elif [ -f "${DIRNAME}/current_now" ]; then
      if [ -n "${MILLIWATTS}" ]; then
        POWER="$(cat "${DIRNAME}/current_now" "${DIRNAME}/voltage_now" | paste -d' ' -s | awk '{print $1*$2/1e9}' | head -1)"
      else
        POWER="$(cat "${DIRNAME}/current_now" "${DIRNAME}/voltage_now" | paste -d' ' -s | awk '{print $1*$2/1e12}' | head -1)"
      fi
    fi
    if [ -z "${QUIET}" ]; then
      printf "Power in ${BATTERY} is "
    fi
    printf "${POWER}"
    if [ -n "${MILLIWATTS}" ]; then
      echo " mW"
    else
      echo " W"
    fi
    ;;
esac