#!/bin/bash
# 2015.06.04

# Usage:
# markscaler "f_1 f_2 ... f_k" "t_1 t_2 .. t_k" [file]
# where k is any integer at least 2, f_1 is the smallest possible raw mark, f_1...f_k is a strictly increasing sequence, f_k is the highest possible raw mark,
# t_1...t_k is a non-decreasing sequence of scaled marks that correspond in order to the raw marks f_1...f_k.
# Only integers are allowed in scaling scheme.
#
# input file: a csv file with a single column of raw mark numbers.
# output is the scaled marks, plus a log with the scale parameters.

raw=($1)
scaled=($2)
real='^[0-9]+([.][0-9]+)?$'

# Let's do some tests.

if [ "${#raw[@]}" -ne "${#scaled[@]}" ] ; then
 echo "The numbers of arguments don't match!"
 exit
fi

for (( i=1; i<${#raw[@]}; i++ ))
do
 if [[ ${raw[i-1]} -ge ${raw[i]} ]] || [[ ${scaled[i-1]} -gt ${scaled[i]} ]] ; then
  echo "I have problems with the order of the arguments."
  exit
 fi
done

if [[ ! -f "$3" ]] ; then
 echo "Can't find the file $3. Usage: markscaler [raw] [scaled] [file]."
 exit
fi

ffront=${3%.*}
fsc="$ffront"_scaled.csv

if [[ -f "$fsc" ]] ; then
 read -p "File $fsc exists, overwrite? [y]" nos
 if [ "$nos" != "y" ] ; then
  echo "Haven't done anything, bye."
  exit
 else
  rm $fsc
 fi
fi


# And now the real thing.

while read line
do
 crm=$line
 csm="oops"
 if [[ ! $crm =~ $real ]] ; then
  echo "$crm in the file $3 is not a number."
  >&2 echo "$crm in the file $3 is not a number."
  exit
 fi

 for (( i=1; i<${#raw[@]}; i++ ))
 do
  comp=`echo "${raw[i]} >= $crm" | bc`
  if [ $comp -eq 1 ] ; then
   csm=`echo "scale=6;(${scaled[i]}-${scaled[i-1]})/(${raw[i]}-${raw[i-1]})*($crm-${raw[i-1]})+${scaled[i-1]}" | bc`
   #echo "${raw[i-1]}; $crm; ${raw[i]}"
   break
  fi
 done
# If out of range to above:
 if [ "$csm" == "oops" ] ; then
  i=$((${#raw[@]}-1))
  csm=`echo "scale=6;(${scaled[i]}-${scaled[i-1]})/(${raw[i]}-${raw[i-1]})*($crm-${raw[i-1]})+${scaled[i-1]}" | bc`
  #echo "${raw[i-1]}; $crm; ${raw[i]}"
 fi
 echo "$csm"
done < $3 >> "$fsc"