#!/usr/local/bin/perl
############################################################################
# Generic 1-x-2 question engine                                            #
# by Anders Hultman, July 1996                                             #
# Distributed under GNU General Public License                             #
#                                                                          #
# The referring form should have the following hidden name-value pairs:    #
# name="answerfile"                                                        #
# value="{full system path to a file with the correct answers}"            #
# name="scorefile"                                                         #
# value="{full system path to a file where the score is written}"          #
#                                                                          #
# The referring form should have the following visible name-value pairs:   #
# name="contestant" value="{the contestant fills in his/hers name here}"   #
# name="address" value="{the contestant fills in his/hers email/physical   #
#       address here}"                                                     #
# Hint for advanced users: The input to "address" is typically done with   #
# a plain text submission field but can also be done in some other way,    #
# e.g. a popup menu where the contestant chooses from a list of locations, #
# countries, offices etc.                                                  #
#                                                                          #
# The referring form should have a number of questions with selectable     #
# answers. None of these should be marked as default. The layout could be  #
# radio buttons or popup menus. Each question should give a name/value-    #
# pair like this: name="qn" value="a" where n is the number of the         #
# question and a is the answer. The answer should be one character long    #
# and be exact the same as the answer in the answerfile (see below).       #
# Any characters (except for the period character) are allowed as          #
# answers, but the most common would be 1x2, 1234, abcde or something      #
# like that. Note that any number of alternative answers is allowed.       #
#                                                                          #
# The answerfile should be formatted like 1xx212xx. followed by a newline  #
# character. Each character is the answer to a question (in that specified #
# order) and the last character on the line should be a period             #
# (the "." character).                                                     #
#                                                                          #
# The scorefile could, but doesn't have to be, in a directory accessible   #
# from the web.                                                            #
#                                                                          #
############################################################################
# Configure the script by defining these variables:

# Fill in the full URL to this script
$scripturl = "http://www.server.se/cgi-bin/contest.cgi";

# No more configuring below this line.
############################################################################

# Get the input
read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});

# Split the name-value pairs
@pairs = split(/&/, $buffer);
$i = 0;
foreach $pair (@pairs) {
   ($name, $value) = split(/=/, $pair);

   $value =~ tr/+/ /;
   $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
   $value =~ s/<([^>]|\n)*>//g;
   $value =~ s/<//g;
   $value =~ s/>//g;
   if (substr($name, 0, 1) eq "q") { @given[substr($name, 1, 5)-1] =
$value; $i++; }
   else { $FORM{$name} = $value; }
}

# Read the correct answers
open (AFIL,  "$FORM{'answerfile'}");
$answers = <AFIL>;
close (AFIL);

# How many questions are there?
# The number of questions is considered to be equal to the number of
# answers the answerfile, not the number of questions answered by the 
# contestant, since the contestant could choose not to answer all 
# of the questions.
$questno = index ($answers, ".");

# Compare correct and given answers
$correct = 0;
for ($i = 0; $i  <= ($questno-1); $i++) {
  if (substr ($answers, $i, 1) eq (@given[$i])) {$correct++ }
}

# Write the score
open (SFIL, ">>$FORM{'scorefile'}");
$tid = time;
print SFIL "$FORM{'contestant'}\t$correct correct answers of $questno\t";
print SFIL "$FORM{'address'}\t$ENV{'REMOTE_ADDR'}\t$tid\n";
close (SFIL);

# Write a web page
print "Content-type: text/html\n\n";
print "<html>\n<head>\n<title>Results</title>\n</head>\n<body>\n";
print "<h1>Results</h1>\n";
print "Congratulations $FORM{'contestant'}! You had $correct correct ",
      "answers out of $questno.<p>\n";
print "<a href=\"$ENV{'HTTP_REFERER'}\">Back to where I came from</a>\n";
print "</body>\n</html>\n";