#!/bin/bash
# calculate boa constrictor ideal weight per given length.
# 
# Feel free to leave suggestions for improvement.
#
# Inspired by: http://home.att.net/~crinaustin/BoaHerpetoculture.htm
# Script by GrapefruiTgirl (LQ) -- presently at crawlingwithsnakes at hush dot com
# November 2009 - GPL licensed.
# Thanks to fellow LQ members for their interest & input.

error () {
cat << EOF

Something wrong with your input.
Supply a numeric or floating-point value, suffixed with i,f,m, or c
to indicate inches, feet, meters, centimeters.
Examples: 48i, 7f, 2.2m, 186c

EOF
exit 1
}

echo -en "\nEnter length of snake (examples: 48i, 7f, 2.2m, 186c) > "
read length

[ ! "$(echo "$length" | gawk '/[0-9.][fmic]$/{print}')" ] && error

units=$(echo "$length" | grep -o [[:alpha:]])
length=$(echo "$length" | sed 's/[[:alpha:]]$//')

case $units in
 m) length=$(echo "scale = 3; $length*3.2808399" | bc -l) ;;
 i) length=$(echo "scale = 3; $length*0.0833333333" | bc -l) ;;
 c) length=$(echo "scale = 3; $length*0.032808399" | bc -l) ;;
esac

weight_kgs=$(echo "scale = 3; e(3.216*l($length)-3.537)" | bc -l)

upper_weight_kgs=$(echo "scale = 3; $weight_kgs*1.15" | bc -l)
lower_weight_kgs=$(echo "scale = 3; $weight_kgs*0.85" | bc -l)

weight_lbs=$(echo "scale = 3; $weight_kgs*2.2046" | bc -l)

upper_weight_lbs=$(echo "scale = 3; $weight_lbs*1.15" | bc -l)
lower_weight_lbs=$(echo "scale = 3; $weight_lbs*0.85" | bc -l)

echo -e "\nUpper limit weight: \t$upper_weight_lbs lbs. \t($upper_weight_kgs kg.)"
echo -e "Ideal weight: \t\t$weight_lbs lbs. \t($weight_kgs kg.)"
echo -e "Lower limit weight: \t$lower_weight_lbs lbs. \t($lower_weight_kgs kg.)"

exit 0

shopt -s extglob
case "$inches" in
    +([0-9])*(.)*([0-9]) )
        echo 'DEBUG: cool'
        ;;
    * )
        echo "What are you thinking of, length '$inches' inches!" >&2
        \exit 1
esac