#!/bin/bash

_IFS="$IFS" # save IFS
IFS="$_IFS:" # append colon to IFS

syntax () {
	echo "Syntax: ${0##*/} [-es] file..."
	exit 1
}

#
# set output option: 0=standard 1=extended
#
output=0 # default when option is not specified
OPTERR=1 # verbose getopts errors
while getopts 'es' opt
do
	case $opt in
	(s) output=0; shift;;
	(e) output=1; shift;;
	(*) syntax;; # illegal option
	esac
done

# globals
declare -i files i j s exam ghd gd gc gp gpc gf average total

#
# test files
#
files=0
if [ $# -gt 0 ]
then
	for f in $@
	do
		if [ -f $f ]
		then
			if [ -r $f ]
			then
				if [ -s $f ]
				then
					let files+=1
				else
					echo file $f is empty
				fi
			else
				echo file $f is not readable
			fi
		else
			echo file $f does not exist
		fi
	done
	if [ $# -ne $files ]
	then
		echo File errors. Abort.
		exit 1
	fi
else
	echo No data files specified.
	syntax
fi

#
# functions
#

rname () {
	echo '?'
}

exe_marks () {
	i=0 j=0
	for i in ${exe[@]}
	do
		let j+=i
	done
	if [ $j -gt 10 ]
	then
		j=10
	fi
	echo $j
}

total_marks () {
	i=0 j=0
	for i in ${as[@]} ${exe[@]} $exam
	do
		let j+=i
	done
	if [ $j -gt 100 ]
	then
		j=100
	fi
	echo $j
}

grade () {
	if [ $total -ge 85 ]
	then
		let ghd+=1
		echo HD $ghd
	elif [ $total -ge 75 ]
	then
		let gd+=1
		echo D $gd
	elif [ $total -ge 65 ]
	then
		let gc+=1
		echo C $gc
	elif [ $total -ge 50 ]
	then
		let gp+=1
		echo P $gp
	elif [ $total -ge 45 ]
	then
		let gpc+=1
		echo PC $gpc
	else
		let gf+=1
		echo F $gf
	fi
}


#
# main loop
#
for f in $@
do
	ghd=0 gd=0 gc=0 gp=0 gpc=0 gf=0 average=0
	while read snum uname scores
	do
		i=0 s=0 exam=0 total=0
		declare -a as exe
		for s in $scores
		do
			if [ $i -le 4 ]
			then
				as[${#as[@]}]=$s
			elif [ $i -le 15 ]
			then
				exe[${#exe[@]}]=$s
			elif [ $i -eq 16 ]
			then
				exam=$s
			fi
			let i+=1
		done

		exemarks=$(exe_marks)
		total=$(total_marks)
		grade=$(grade)

		echo -e "$snum\t$(rname)\t${as[@]}\t$exemarks\t$exam\t$total\t$grade"

		unset as exe
	done < $f

	if [ $output -eq 1 ]
	then
		echo Grades: HD $ghd  D $gd  C $gc  P $gp  PC $gpc  F $gf
		echo Average: $average
	fi
done