#!/bin/bash

# globals-------------------------------------------------------------------
script_name="${0##*/}"
script_dir=$(readlink -f "${0%/*}")
script_version=1

# this can be modded to be supplied from command line
named_dir='/var/named'
serialfile="ufis-common.txt"

# main----------------------------------------------------------------------
[[ "$1" ]] && {
    (( ${#1} == 10 )) && newserial=$1
    (( ${#1} == 8 )) && date=$1
    (( ${#1} == 2 )) && revision=$1
    ! [[ "$1" =~ ^[0-9]+$ ]] || [[ -z "$newserial$date$revision" ]] && echo "$script_name: ERROR: can't do anything with $1" && exit 1
}   

curserial="$( sed -ne 's/^.*\([0-9]\{10\}\).*/\1/g; /^[0-9]*$/p' "$named_dir/$serialfile" )"

# if we haven't been passed a serial lets build one
[[ -z "$newserial" ]] && {
# if we don't have a date get current
    [[ -z "$date" ]] && date="$(date +%Y%m%d)"
# if we don't have revision number get next from the current, if current=99 or date<>today it'll be "01"
    [[ -z "$contador" ]] && {
        revision="01"
        (( ${curserial:0:8} == $date )) && {
            revision=$( printf "%02d" $(( 10#${curserial:8:2}+1 )) )
            (( 10#$revision == 100 )) && echo "$script_name: warning: revision counter looped to 01" && revision="01"
        }
    }
    newserial=$date$revision
}

# replace the serial
# some sanity checks here won't hurt
# this is a minimal one
(( ${#newserial} == 10 )) && {
    echo "$script_name: new serial number $newserial"
    sed -i "s/\(^.*\)$curserial\(.*$\)/\1$newserial\2/" "$named_dir/$serialfile"
}