#!/bin/sh -u
#  $0 [pathname]
# Word count non-comment lines, only in files that appear to be C++ programs.
# Prompt for and read a pathname if not supplied on the command line.
# -IAN!  idallen@ncf.ca

export PATH=/bin:/usr/bin
umask 022

# Get the pathname from the command line or stdin.
#
case "$#" in
0)	echo 1>&2 "Enter a file name:"
	read filename
	;;
1)	filename="$1"
	;;
*)	echo 1>&2 "$0: Expecting one argument, found $# ($*)"
	exit 1
	;;
esac

# Check pathname for blanks or a non-C++ name.
#
case "$filename" in
*" "*)	echo 1>&2 "$0: '$filename' contains blanks"
	exit 1
	;;
[a-z]*.cpp)
	# This case is a valid C++ pathname - do nothing.
	;;
*)	echo 1>&2 "$0: '$filename' must start with a letter and end in .cpp"
	exit 1
	;;
esac

# Validate that the pathname is an existing file and is readable.
#
if [ ! -f "$filename" ]; then
	echo 1>&2 "$0: '$filename' is not an existing file"
	exit 1
fi

if [ ! -r "$filename" ]; then
	echo 1>&2 "$0: '$filename' is not a readable file"
	exit 1
fi

# Make sure the file starts with a correct #include line.
# Bonus: Don't display any superfluous output on the screen.
#
line=$(head -1 "$filename")
case "$line" in
'#include <iostream.h>')
	# This case is a valid C++ #include line - do nothing.
	;;
*)	echo 1>&2 "$0: '$filename' does not start with iostream.h"
	echo 1>&2 "   Found: $line"
	exit 1
	;;
esac

# Make sure the file contains the string "main" somewhere.
# Bonus: Don't display the superfluous grep output on the screen.
#
if ! grep main "$filename" >/dev/null ; then
	echo 1>&2 "$0: '$filename': Cannot find 'main'"
	exit 1
fi

# Count the words in lines that do not contain comments.
# Exit the script (bad status) if the counting fails.
#
count=$(grep -v // "$filename" | wc -w) || exit $?

echo "File '$filename' contains $count non-comment words."

# script exits with status of last command