#!/bin/sh
# /etc/sensorsd/lowbattery.sh
# sensorsd script for querying Xorg user on remaining battery capacity.

### Provided by sensorsd(8)
xuser="$1"
sd_status="$2"
sd_current="$3"
sd_low="$4"

### Use sysctl(8) values instead of apm(8).
use_sysctl="YES" # "NO"

## Required sysctls
# AC power indicator
sc_ac="hw.sensors.acpiac0.indicator0"
# CRITICAL battery capacity
sc_bat_crit="hw.sensors.acpibat0.watthour2"
# Override CRITICAL battery capacity returned value
sc_bat_crit_override="2.00 Wh"

## Optional sysctls, for percentage/minute calculation.
sc_bat_rate="hw.sensors.power0"
sc_bat_capacity="hw.sensors.watthour0"

action() {
    local msg_type=$1
    local msg_text=$2
    local log_msg="lowbattery: ${msg_type}: ${msg_text}"

    echo "${log_msg}" | /usr/bin/logger

    case "${msg_type}" in
        WARNING|ERROR)
            echo "${log_msg}" | /usr/bin/wall
            ;;
        CRITICAL)
            echo "${log_msg}" | /sbin/shutdown -p +60
            ;;
        IGNORE)
            ;;
        SLEEP)
            /usr/sbin/apm -z
            ;;
        HIBERNATE)
            /usr/sbin/apm -Z
            ;;
        HALT)
            /sbin/shutdown -p now
            ;;
    esac
}

query_sc() {
    # Trim sysctls to device level.
    sc_ac_device="${sc_ac%.*}"
    sc_bat_device="${sc_bat_crit%.*}"

    # Populate sysctl array
    set -A sc_array $(/usr/sbin/sysctl "${sc_ac_device}" "${sc_bat_device}")

    # Extract available sysctl values.
    if [ "${#sc_array[@]}" -le 1 ]; then
        action "ERROR" "Failed to retrieve sensor values from /usr/sbin/sysctl."
        exit 1
    else
        for sc_elem in "${sc_array[@]}"; do
            case "${sc_elem%=*}" in
                "${sc_ac}")
                    sc_ac_val="${sc_elem#*=}"
                    ;;
                "${sc_bat_crit}")
                    sc_bat_crit_val="${sc_elem#*=}"
                    ;;
                "${sc_bat_rate}")
                    sc_bat_rate_val="${sc_elem#*=}"
                    ;;
                "${sc_bat_capacity}")
                    sc_bat_capacity_val="${sc_elem#*=}"
                    ;;
            esac
        done
    fi

    # Check AC power status
    [[ ${sc_ac_val} == On* ]] && ac_online="YES" || ac_online="NO"

    # Check battery critical status (use override value if set).
    [ "${sc_bat_crit_override}" ] && sc_bat_crit_val="${sc_bat_crit_override}"
    bat_crit_check=$(echo "${sd_current}-${sc_bat_crit_val%% *}" | /usr/bin/bc)
    [[ ${bat_crit_check} == -* ]] && bat_crit="YES" || bat_crit="NO"

    # Check battery remaining percentage/minutes if required sysctls set.
    if [ "${sc_bat_rate_val}" -a "${sc_bat_capacity_val}" ]; then
        bat_mins=$(echo "scale=2;(${sd_current}/${sc_bat_rate_val})*60"\
            | /usr/bin/bc)
        bat_mins="${bat_mins%.*}"
        bat_percent=$(echo "scale=2;(${sd_current}/${sc_bat_capacity_val})*100"\
            | /usr/bin/bc)
        bat_percent="${bat_percent%.*}"
    else
        bat_mins="unknown"
        bat_percent="unknown"
    fi
    bat_text="Battery ${bat_percent}% (${bat_mins} mins)"
}

query_apm() {
    # Populate apm array.
    set -A apm_array $(/usr/sbin/apm -ablm)
    if [ $? -ne 0 ]; then
        action "ERROR" "/usr/bin/apm returned non-zero exit status."
        exit 1
    else
        # 0=disconnected, 1=connected, 2=backup power, 255=unknown.
        apm_ac_status="${apm_array[3]}"
        # 0=high, 1=low, 2=critical, 3=charging, 4=absent, 255=unknown.
        apm_bat_status="${apm_array[2]}"
        apm_bat_percent="${apm_array[1]}"
        apm_bat_minutes="${apm_array[0]}"
    fi

    # Set ac/bat vars, battery status
    [ "${apm_ac_status}" = @(1|2) ] && ac_online="YES" || ac_online="NO"
    [ "${apm_bat_status}" = 2 ] && bat_crit="YES" || bat_crit="NO"
    bat_mins="${apm_bat_minutes}"
    bat_percent="${apm_bat_percent}"
    bat_text="Battery ${bat_percent}% (${bat_mins} mins)"
}

verify_xuser() {
    local msg_type=$1

    if xuser_entry=$(/usr/bin/getent passwd "${xuser}"); then
        xuser_home=$(echo "${xuser_entry}" | /usr/bin/cut -d : -f 6)
        if [ ! -s "${xuser_home}/.Xauthority" ]; then
            action "${msg_type}" "${bat_text}, no current Xorg user ${xuser}."
            return 1
        else
            return 0
        fi
    else
        action "${msg_type}" "${bat_text}, unknown user ${xuser}."
        return 1
    fi
}

xmsg() {
    local msg_type=$1

    if ! verify_xuser "${msg_type}" && exit 1

    xmsg_env="/usr/bin/env DISPLAY=:0 XAUTHORITY=${xuser_home}/.Xauthority"
    xmsg_cmd="/usr/X11R6/bin/xmessage -center -default Ignore \
        -buttons Ignore:2,Sleep:3,Hibernate:4,Halt:5 -timeout 20"
    xmsg_text="'${msg_type}: ${bat_text}'"

    /usr/bin/su "${xuser}" -c "${xmsg_env} ${xmsg_cmd} ${xmsg_text}"

    case "$?" in
        0)
            # $xuser failed to respond to dialog
            action "${msg_type}" "${bat_text}, Xorg user ${xuser} failed to \
                respond to warning dialog."
            ;;
        1)
            # xmessage reported an error status
            action "${msg_type}" "${bat_text}, /usr/X11R6/bin/xmessage \
                returned an error status."
            ;;
        2)
            # $xuser selected 'ignore'
            action "IGNORE" "${bat_text}, Xorg user ${xuser} opted to \
                ignore warning dialog."
            ;;
        3)
            # $xuser selected 'sleep'
            action "SLEEP" "${bat_text}, Xorg user ${xuser} opted to enter \
                suspend."
            ;;
        4)
            # $xuser selected 'hibernate'
            action "HIBERNATE" "${bat_text}, Xorg user ${xuser} opted to enter \
                hibernate."
            ;;
        5)
            # $xuser selected 'halt'
            action "HALT" "${bat_text}, Xorg user ${xuser} opted to halt the \
                system."
            ;;
    esac
}

check_sensorsd_text() {
    case "${sd_status}" in
        above|within)
            # No action required
            ;;
        below)
            # Battery below warning threshold, check AC and critical status
            [ "${use_sysctl}" = "NO" ] && query_apm || query_sc
            if [ "${ac_online}" = "NO" ]; then
                [ "${bat_crit}" = "NO" ] && xmsg "WARNING" || xmsg "CRITICAL"
            fi
            ;;
        invalid|uninitialised)
            # Recieved an invalid status from sensorsd, report if no AC
            [ "${use_sysctl}" = "NO" ] && query_apm || query_sc
            if [ "${ac_online}" = "NO" ]; then
                action "ERROR" "sensord reported invalid/uninitialised status."
            fi
            ;;
        *)
            # Recieved null/unexpected status from sensorsd, report if no AC
            [ "${use_sysctl}" = "NO" ] && query_apm || query_sc
            if [ "${ac_online}" = "NO" ]; then
                action "ERROR" "sensord reported unexpected status."
            fi
            ;;
    esac
}


lockfile="/var/tmp/lowbattery.pid"
if ( set -C; echo "$$" > "$lockfile" 2> /dev/null; then
    trap 'rm -f "$lockfile"; exit $?' INT TERM EXIT
    check_sensorsd_text
    rm -f "$lockfile"
    trap - INT TERM EXIT
else
    echo "LOCKED: $lockfile, $(cat $lockfile)"
fi