#!/bin/bash
# validint--Validates integer input, allowing negative ints too.

proc validint
{
  # Validate first field and test that value against min value $2 and/or 
  # max value $3 if they are supplied: If the value isn't within range or
  # it's not composed of just digits, fail.

  setglobal number = $1;      setglobal min = $2;      setglobal max = $3

  if test -z $number  {
    echo "You didn't enter anything. Please enter a number." > !2 ; return 1
  }

  # Is the first character a '-' sign?
  if test $(number%${number#?}) = "-"  {
    setglobal testvalue = $(number#?) # Grab all but the first character to test.
  } else {
    setglobal testvalue = $number
  }
  
  # Create a version of the number that has no digits, for testing.
  setglobal nodigits = $[echo $testvalue | sed 's/[[:digit:]]//g]
  
  # Check for non-digit characters.
  if test ! -z $nodigits  {
    echo "Invalid number format! Only digits, no commas, spaces, etc" > !2
    return 1
  }
  
  if test ! -z $min  {
    # Is the input less than the minimum value?
    if test $number -lt $min  {
      echo "$number is too small: smallest acceptable value is $min" > !2
      return 1
    }
  }
  if test ! -z $max  {
    # Is the input greater than the maximum value?
    if test $number -gt $max  {
      echo "Your value is too big: largest acceptable value is $max" > !2
      return 1
    }
  }
  return 0
}

# Input validation
#if validint "$1" "$2" "$3" ; then
#  echo "That input is a valid integer value within your constraints"
#fi