#!/bin/bash
#  rolldice -- parse requested dice to roll and simulate those rolls
#      examples: d6 = one 6-sided die
#                2d12 = two 12-sided dice
#                d4 3d8 2d20 = a 4-side die, 3 8-sided and 2 20-sided dice

rolldie()
{
   dice=$1
   dicecount=1
   sum=0

   # first step, break down arg into MdN

   if [ -z "$(echo $dice | grep 'd')" ] ; then
     quantity=1
     sides=$dice
   else
     quantity=$(echo $dice | cut -dd -f1)
     if [ -z "$quantity" ] ; then       # user specifyed dN not just N
       quantity=1
     fi
     sides=$(echo $dice | cut -dd -f2)
   fi

   echo "" ; echo "rolling $quantity $sides-sided die"

   # now roll the dice...

   while [ $dicecount -le $quantity ] ; do
     roll=$(( ( $RANDOM % $sides ) + 1 ))
     sum=$(( $sum + $roll ))
     echo "  roll #$dicecount = $roll"
     dicecount=$(( $dicecount + 1 ))
   done

   echo I rolled $dice and it added up to $sum
}

while [ $# -gt 0 ] ; do
  rolldie $1
  sumtotal=$(( $sumtotal + $sum ))
  shift
done

echo ""
echo "In total, all of those dice add up to $sumtotal"
echo ""
exit 0