#!/bin/sh -u
# Script Practice #4 answer - 69 marks
#------------------------------------------------------------
# One line summary: Compile a program as C or C++ based on its contents
#------------------------------------------------------------
# Syntax:  $0 [ source_file ]
#------------------------------------------------------------
# Purpose: not required
#------------------------------------------------------------
# Assignment Label: not required
#------------------------------------------------------------
# -IAN!  idallen@idallen.ca

# Step 1 - 6 marks - script header
#          (interpreter, one-line summary, syntax, PATH, umask, collate)
# Use a standard shell search path and friendly umask.
# Use standard ASCII sort ordering.
#
PATH=/bin:/usr/bin ; export PATH
umask 022
LC_COLLATE=C ; export LC_COLLATE

# Step 2 - 7 marks
# Validate the number of arguments; issue a good error message.
#
if [ $# -gt 1 ]; then
        echo 1>&2 "$0: Expecting one optional source file; found $# ($*)"
        exit 1
fi

# Step 3 - 7 marks
# Prompt (always on stderr) for a missing program source file.
# Put the file name into a named variable.
#
if [ $# -eq 0 ]; then
        echo 1>&2 "Enter the program source file name:"
        read myprog || exit 1
else
        myprog="$1"
fi

# Step 4 - 2 marks
echo "Processing file '$myprog'."

# Step 5 - 14 marks
# Verify that the input is a file and is readable.
#
if [ ! -f "$myprog" ]; then
        echo 1>&2 "$0: '$myprog' is not a file"
        exit 1
fi
if [ ! -r "$myprog" ]; then
        echo 1>&2 "$0: '$myprog' is not readable"
        exit 1
fi

# Step 6 - 10 marks
# Select the C++ compiler if a string is found indicating a C++ program.
# if grep '<iostream' "$myprog" >/dev/null ; then
#   g++ -Wall -o newcpp "$myprog" 2>warnings.out
#   cstatus=$?
# fi
# Step 7 - 2 marks
# Select the C compiler if a string is found indicating a C program.
# if grep '<stdio' "$myprog" >/dev/null ; then
#   gcc -Wall -o newccc "$myprog" 2>warnings.out
#   cstatus=$?
# fi
# Step 8 - 7 marks
# combine the above into one step:
#
if grep '<iostream' "$myprog" >/dev/null ; then
        compiler=g++
        outfile=newcpp
elif grep '<stdio' "$myprog" >/dev/null ; then
        compiler=gcc
        outfile=newccc
else
        echo 1>&2 "$0: your source file '$myprog' cannot be compiled"
        exit 1
fi
"$compiler" -Wall -o "$outfile" "$myprog" 2>warnings.out
cstatus=$?

# Step 9 - 3 marks
if [ $cstatus -ne 0 ]; then
    echo "Compiler $compiler exit status was $cstatus."
fi

# Step 10 - 4 marks
# Remove an empty error file and exit zero.
#
if [ ! -s warnings.out ]; then
        rm warnings.out
        echo "Output is in $outfile"
        exit 0
fi

# Step 11 - 7 marks
# Rename file and display count of errors on stdout.
#
mv warnings.out warnings.txt
chmod 400 warnings.txt
lines=$( wc -l <warnings.txt )
echo "Number of warning lines for '$myprog' is $lines."