#!/bin/bash

# default values
PROGNAME=$(basename $0)
FULLPROG=$0

# usage
function usage () {
    echo "usage: $PROGNAME [-h] [-r] file"
    echo " -h: help message"
    echo " -s: set stats"
    echo " -r: reset stats"
    echo " file: data to monitor"
}

# reset
function reset () {
    echo "reseting stats"
    [ -f $resource ] && rm $resource
}

# variables
set=
files=
resource=$HOME/.$PROGNAME

# parameter processing
while [ $# -gt 0 ]; do
    case "$1" in
    -h) usage; exit 0;;
    -s) set="yes";;
    -r) reset; exit 0;;
    *) files="$files $1";;
    esac
    shift
done

# check arguments
[ "$files" ] || { echo "no file specified"; exit 1; }

# read old values
[ -f $resource ] && source $resource

for f in $files; do

    # check file
    f=$(echo $f | sed 's,//*,/,g')
    [ -f $f ] || { echo "can't find file '$f'"; exit 1; }

    # main
    var=${f//\//_}
    newvar=($(awk '{ for (i = 1; i <= NF; i++) if ($(i) ~ /^[-+0-9][0-9]*$/) printf " %s", $(i) }' $f))
    eval oldvar=(\${$var[@]})

    # compute diff
    for ((i=0; i<${#newvar[@]}; i++)); do
        [ "${oldvar[$i]}" ] && v[$i]=$((newvar[i] - oldvar[i])) || v[$i]=${newvar[$i]}
    done

    # ouput
    if [ "$set" = "yes" ]; then
        echo "$var=(${newvar[@]})" >>$resource
    else
        str=""
        for ((i=0; i<${#v[@]}; i++)); do
            str="$str; v[$i]=${v[$i]}"
        done
        awk 'BEGIN { k=0 '"$str"' } { for (i=1; i<=NF; i++) if ($(i) ~ /^[-+0-9][0-9]*$/) $(i)=v[k++]; print }' $f
    fi

done

# clean resource file
if [ "$set" = "yes" ]; then
    awk -F= '{ a[$1]=$2 } END { for (i in a) print i "=" a[i] }' $resource > $resource.n
    mv -f $resource.n $resource
fi