#!/bin/sh

set -e

error () {
    echo "$0": "$@" >&2
    exit 1
}

usage () {
    echo 'usage: kvmstats [-a] [-u k|m|g]' >&2
    exit 1
}

for DEP in bc virsh
do
    command -v $DEP > /dev/null || error $DEP command not found
done

POW=$(echo 1024 ^ 3 | bc)
while [ $# -ne 0 ] && echo "$1" | grep -q '^-[[:alnum:]]'
do
    case $1 in
    '-u')
        case $2 in
        'k')
            POW=$(echo 1024 ^ 1 | bc)
            ;;
        'm')
            POW=$(echo 1024 ^ 2 | bc)
            ;;
        'g')
            POW=$(echo 1024 ^ 3 | bc)
            ;;
        *)
            usage
        esac
        ;;
    '-a')
        SHOW_AVAIL=y
        ;;
    *)
        usage
    esac
    shift
done

for VM in $(virsh list --name --all)
do
    echo "$VM"
    virsh vcpucount --maximum --current "$VM"
    # libvirt store memory in KiB, POW must be lowered by 1
    virsh domstats --balloon "$VM" | awk 'BEGIN { FS="=" } /balloon.maximum/ { print $2 / '$((POW / 1024))'}'
    for BLK in $(virsh domblklist "$VM" | sed '1,2d;/-$/d;/^$/d' | cut -d\  -f1)
    do
        virsh domblkinfo "$VM" "$BLK"
    done | awk '/Physical:/ { size += $2 } END { print int(size / '${POW}') }'
    virsh domstate "$VM" | grep -q '^running$' && echo yes || echo no
done | xargs -n5 | (
    echo vm vcpu ram disk running
    awk '{ print } /yes$/ { vcpu += $2; ram += $3; disk += $4; running++ } END { print "TOTAL(running)", vcpu, ram, disk, running }'
    if [ "$SHOW_AVAIL" ]
    then
        AV_CPU=$(nproc)
        AV_MEM=$(awk '/^MemTotal:/ { print int($2 / '$((POW / 1024))' ) }' /proc/meminfo)
        echo AVAILABLE "$AV_CPU" "$AV_MEM"
    fi
) | column -t