--- trunk/webwork2/lib/WeBWorK/ContentGenerator/Problem.pm	2003/06/06 02:24:42	1038
+++ trunk/webwork2/lib/WeBWorK/ContentGenerator/Problem.pm	2003/08/14 20:10:01	1459
@@ -7,21 +7,22 @@
 use base qw(WeBWorK::ContentGenerator);
 
 =head1 NAME
-
+ 
 WeBWorK::ContentGenerator::Problem - Allow a student to interact with a problem.
 
 =cut
-
+my $timer0_ON=1;  # times pg translation phase
 use strict;
 use warnings;
 use CGI qw();
 use File::Path qw(rmtree);
-use File::Temp qw(tempdir);
 use WeBWorK::Form;
 use WeBWorK::PG;
+use WeBWorK::PG::ImageGenerator;
 use WeBWorK::PG::IO;
-use WeBWorK::Utils qw(writeLog encodeAnswers decodeAnswers ref2string);
+use WeBWorK::Utils qw(writeLog writeCourseLog encodeAnswers decodeAnswers ref2string makeTempDirectory);
 use WeBWorK::DB::Utils qw(global2user user2global findDefaults);
+use WeBWorK::Timing;
 
 ############################################################
 # 
@@ -44,6 +45,10 @@
 #
 ############################################################
 
+sub templateName {
+	"problem";
+}
+
 sub pre_header_initialize {
 	my ($self, $setName, $problemNumber) = @_;
 	my $r                    = $self->{r};
@@ -51,64 +56,85 @@
 	my $db                   = $self->{db};
 	my $userName             = $r->param('user');
 	my $effectiveUserName    = $r->param('effectiveUser');
-	my $key					 = $r->param('key');
+	my $key                  = $r->param('key');
 	my $user                 = $db->getUser($userName);
 	my $effectiveUser        = $db->getUser($effectiveUserName);
-
-	# obtain the effective user set, or if that is not yet defined obtain global set
-	my $set                  = $db->getGlobalUserSet($effectiveUserName, $setName);
-	unless (defined $set) {
-		my $userSetClass     = $courseEnv->{dbLayout}->{set_user}->{record};
-		$set                 = global2user($userSetClass, $db->getGlobalSet($setName));
-		$set->psvn('000');
-	}
-	my	$psvn                = $set->psvn();
-	
-	# obtain the effective user problem, or if that is not yet defined obtain global problem
-	my $problem              = $db->getGlobalUserProblem($effectiveUserName, $setName, $problemNumber);
-	unless (defined $problem) {
-		my $userProblemClass = $courseEnv->{dbLayout}->{problem_user}->{record};
-		$problem             = global2user($userProblemClass, $db->getGlobalProblem($setName,$problemNumber));
-
-#		$problem->max_attempts(-1);   # default is infinite number of attempts
-#		$problem->value;
-#		$problem->problem_seed;
-#		$problem->source_file;
-		$problem->user_id($userName);    # is this the right value for this unassigned problem? FIXME
-		$problem->status(0);
-		$problem->attempted(0);
-		$problem->num_correct(0);
-		$problem->num_incorrect(0);
-		$problem->last_answer(' ');		
-	}
-	#$problem            = $db->getGlobalProblem($setName, $problemNumber) unless defined($problem);
-	# FIXME  
-	# a better solution at this point would be to take set and problem, convert them to global_user type
-	# so that they have the right methods.
-	# Stuff the local copy of $set and $problem with default data where it won't have been defined 
-	# Make sure that nothing bad is stored back in the database. 
-	# It would be nice to store lastAnswer somewhere -- perhaps that could be done as a special case.
-	
-	
-	# This supplies a psvn if $set doesn't have it.  Unfortunately the problem is called on to provide
-	# data in many places and it might not even have methods defined.
-	
-	# global sets will not have a defined psvn
-# 	my $psvn;
-# 	if ($set->can('psvn') ) {
-# 		$psvn           = $set->psvn();
-# 	} else {            # we are viewing an unassigned problem set, psvn's are irrelevant
-# 		$psvn           = '0000';
-# 	}
-	
-	my $permissionLevel = $db->getPermissionLevel($userName)->permission();
-	
-	$self->{userName}        = $userName;
-	$self->{user}            = $user;
-	$self->{effectiveUser}   = $effectiveUser;
-	$self->{set}             = $set;
-	$self->{problem}         = $problem;
-	$self->{permissionLevel} = $permissionLevel;
+	my $permissionLevel      = $db->getPermissionLevel($userName)->permission();
+	
+	# obtain the merged set for $effectiveUser
+	my $set = $db->getMergedSet($effectiveUserName, $setName);
+	
+	# obtain the merged problem for $effectiveUser
+	my $problem = $db->getMergedProblem($effectiveUserName, $setName, $problemNumber);
+	
+	my $editMode = $r->param("editMode");
+	
+	if ($permissionLevel > 0 and defined $editMode) {
+		# professors are allowed to fabricate sets and problems not
+		# assigned to them (or anyone). this allows them to use the
+		# editor to 
+		
+		# if that is not yet defined obtain the global set, convert
+		# it to a user set, and add fake user data
+		unless (defined $set) {
+			my $userSetClass = $db->{set_user}->{record};
+			$set = global2user($userSetClass,
+				$db->getGlobalSet($setName));
+			die "Set $setName does not exist"
+				unless defined $set;
+			$set->psvn(0);
+		}
+		
+		# if that is not yet defined obtain the global problem,
+		# convert it to a user problem, and add fake user data
+		unless (defined $problem) {
+			my $userProblemClass = $db->{problem_user}->{record};
+			$problem = global2user($userProblemClass,
+				$db->getGlobalProblem($setName,$problemNumber));
+			die "Problem $problemNumber in set $setName does not exist"
+				unless defined $problem;
+			$problem->user_id($effectiveUserName);
+			$problem->problem_seed(0);
+			$problem->status(0);
+			$problem->attempted(0);
+			$problem->last_answer("");
+			$problem->num_correct(0);
+			$problem->num_incorrect(0);
+		}
+		
+		# now we're sure we have valid UserSet and UserProblem objects
+		# yay!
+		
+		# now deal with possible editor overrides:
+		
+		# if the caller is asking to override the source file, and
+		# editMode calls for a temporary file, do so
+		my $sourceFilePath = $r->param("sourceFilePath");
+		if (defined $sourceFilePath and $editMode eq "temporaryFile") {
+			$problem->source_file($sourceFilePath);
+		}
+		
+		# if the caller is asking to override the problem seed, do so
+		my $problemSeed = $r->param("problemSeed");
+		if (defined $problemSeed) {
+			$problem->problem_seed($problemSeed);
+		}
+	} else {
+		# students can't view problems not assigned to them
+		die "Set $setName is not assigned to $effectiveUserName"
+			unless defined $set;
+		die "Problem $problemNumber in set $setName is not assigned to $effectiveUserName"
+			unless defined $problem;
+	}
+	
+	$self->{userName}          = $userName;
+	$self->{effectiveUserName} = $effectiveUserName;
+	$self->{user}              = $user;
+	$self->{effectiveUser}     = $effectiveUser;
+	$self->{permissionLevel}   = $permissionLevel;
+	$self->{set}               = $set;
+	$self->{problem}           = $problem;
+	$self->{editMode}          = $editMode;
 	
 	##### form processing #####
 	
@@ -120,25 +146,24 @@
 	my $previewAnswers     = $r->param("previewAnswers");
 	
 	# fields which may be defined when using Problem Editor
-	my $override_seed		   = ($permissionLevel>=10) ? $r->param('problemSeed') : undef;
-	my $override_problem_source = ($permissionLevel>=10) ? $r->param('sourceFilePath') : undef;
-	my $editMode = undef;
-	my $submit_button = $r->param('submit_button');
-	if ( defined($submit_button ) ) {
-		$editMode = "temporaryFile" if $submit_button eq 'Refresh';
-		$editMode = 'savedFile'     if $submit_button eq 'Save';
-	}	
-	
-	#override using the source file data from the form field
-	$problem->source_file($override_problem_source) if defined($override_problem_source);
-	$problem->problem_seed($override_seed)          if defined($override_seed);
-	
-	# store path to source file for title.
-	$self->{problem_source_name}    =  $problem->source_file;
-	$self->{edit_mode}		=	$editMode;
-# 	$self->{current_problem_source} 	=	(defined($override_problem_source) ) ?
-# 									 		$override_problem_source :
-# 											$problem->source_file;
+	#my $override_seed = ($permissionLevel>=10) ? $r->param('problemSeed') : undef;
+	#my $override_problem_source = ($permissionLevel>=10) ? $r->param('sourceFilePath') : undef;
+	#my $editMode = undef;
+	#my $submit_button = $r->param('submit_button');
+	#if ( defined($submit_button ) ) {
+	#	$editMode = "temporaryFile" if $submit_button eq 'Refresh';
+	#	$editMode = 'savedFile'     if $submit_button eq 'Save';
+	#}
+	#
+	##override using the source file data from the form field
+	#$problem->source_file($override_problem_source) if defined($override_problem_source);
+	#$problem->problem_seed($override_seed)          if defined($override_seed);
+	#
+	## store path to source file for title.
+	#$self->{problem_source_name}    =  $problem->source_file;
+	#$self->{edit_mode}		=	$editMode;
+	#$self->{current_problem_source} 	=	(defined($override_problem_source) ) ?
+	
 	# coerce form fields into CGI::Vars format
 	my $formFields = { WeBWorK::Form->new_from_paramable($r)->Vars };
 	
@@ -149,7 +174,6 @@
 	$self->{previewAnswers} = $previewAnswers;
 	$self->{formFields}     = $formFields;
 	
-
 	##### permissions #####
 	
 	# are we allowed to view this problem?
@@ -196,26 +220,25 @@
 	
 	##### sticky answers #####
 	
-	if (not $submitAnswers and $will{showOldAnswers}) {
+	if (not ($submitAnswers or $previewAnswers or $checkAnswers) and $will{showOldAnswers}) {
 		# do this only if new answers are NOT being submitted
 		my %oldAnswers = decodeAnswers($problem->last_answer);
 		$formFields->{$_} = $oldAnswers{$_} foreach keys %oldAnswers;
 	}
 	
 	##### translation #####
-	
+
+	$WeBWorK::timer0->continue("begin pg processing") if $timer0_ON;
 	my $pg = WeBWorK::PG->new(
 		$courseEnv,
 		$effectiveUser,
 		$key,
 		$set,
 		$problem,
-		$psvn,
+		$set->psvn, # FIXME: this field should be removed
 		$formFields,
 		{ # translation options
 			displayMode     => $displayMode,
-			override_seed	=> $override_seed, 
-			override_problem_source	=>$override_problem_source,
 			showHints       => $will{showHints},
 			showSolutions   => $will{showSolutions},
 			refreshMath2img => $will{showHints} || $will{showSolutions},
@@ -223,6 +246,7 @@
 		},
 	);
 	
+	$WeBWorK::timer0->continue("end pg processing") if $timer0_ON;
 	##### fix hint/solution options #####
 	
 	$can{showHints}     &&= $pg->{flags}->{hintExists};
@@ -238,11 +262,11 @@
 	$self->{pg} = $pg;
 }
 
-sub if_warnings($$) {
-	my ($self, $arg) = @_;
-	return 0 unless $self->{isOpen};
-	return $self->{pg}->{warnings} ne "";
-}
+#sub if_warnings($$) {
+#	my ($self, $arg) = @_;
+#	return 0 unless $self->{isOpen};
+#	return $self->{pg}->{warnings} ne "";
+#}
 
 sub if_errors($$) {
 	my ($self, $arg) = @_;
@@ -256,6 +280,19 @@
 	return $self->{pg}->{head_text} if $self->{pg}->{head_text};
 }
 
+sub options {
+	my $self = shift;
+	return join("",
+		CGI::start_form("POST", $self->{r}->uri),
+		$self->hidden_authen_fields,
+		CGI::hr(), 
+		CGI::start_div({class=>"viewOptions"}),
+		$self->viewOptions(),
+		CGI::end_div(),
+		CGI::end_form()
+	);
+}
+
 sub path {
 	my $self = shift;
 	my $args = $_[-1];
@@ -282,21 +319,21 @@
 	my $db = $self->{db};
 	my $root = $ce->{webworkURLs}->{root};
 	my $courseName = $ce->{courseName};
-	
 	print CGI::strong("Problems"), CGI::br();
 	
 	my $effectiveUser = $self->{r}->param("effectiveUser");
-	my @problems;
-	push @problems, $db->getGlobalUserProblem($effectiveUser, $setName, $_)
-		foreach ($db->listUserProblems($effectiveUser, $setName));
-	foreach my $problem (sort { $a->problem_id <=> $b->problem_id } @problems) {
-		print CGI::a({-href=>"$root/$courseName/$setName/".$problem->problem_id."/?"
+	my @problemIDs = $db->listUserProblems($effectiveUser, $setName);
+	foreach my $problem (sort { $a <=> $b } @problemIDs) {
+		print '&nbsp;&nbsp;'.CGI::a({-href=>"$root/$courseName/$setName/".$problem."/?"
 			. $self->url_authen_args . "&displayMode=" . $self->{displayMode}},
-				"Problem ".$problem->problem_id), CGI::br();
+			"Problem ".$problem), CGI::br();
 	}
+
+	return "";
 }
 
 sub nav {
+	$WeBWorK::timer0->continue("begin nav subroutine") if $timer0_ON;
 	my $self = shift;
 	my $args = $_[-1];
 	my $setName = $self->{set}->set_id;
@@ -313,32 +350,30 @@
 	
 	my @links = ("Problem List" , "$root/$courseName/$setName", "navProbList");
 	
-	my $prevProblem = $db->getGlobalUserProblem($effectiveUser, $setName, $problemNumber-1);
-	my $nextProblem = $db->getGlobalUserProblem($effectiveUser, $setName, $problemNumber+1);
-	unshift @links, "Previous Problem" , ($prevProblem
-		? "$root/$courseName/$setName/".$prevProblem->problem_id
+	my @problemIDs = $db->listUserProblems($effectiveUser, $setName);
+	my ($prevID, $nextID);
+	foreach my $id (@problemIDs) {
+		$prevID = $id if $id < $problemNumber
+			and (not defined $prevID or $id > $prevID);
+		$nextID = $id if $id > $problemNumber
+			and (not defined $nextID or $id < $nextID);
+	}
+	unshift @links, "Previous Problem" , ($prevID
+		? "$root/$courseName/$setName/".$prevID
 		: "") , "navPrev";
-	push @links, "Next Problem" , ($nextProblem
-		? "$root/$courseName/$setName/".$nextProblem->problem_id
+	push @links, "Next Problem" , ($nextID
+		? "$root/$courseName/$setName/".$nextID
 		: "") , "navNext";
 	
-	return $self->navMacro($args, $tail, @links);
+	my $result = $self->navMacro($args, $tail, @links);
+	$WeBWorK::timer0->continue("end nav subroutine") if $timer0_ON;
+	return $result;
 }
 
 sub title {
 	my $self = shift;
 	my $setName = $self->{set}->set_id;
-	
-	my $file_action;
-	my $edit_mode = $self->{edit_mode};
-	if ( not defined($edit_mode) ) {
-		$file_action = '';
-	} elsif (  $edit_mode eq 'temporaryFile') {
-		$file_action 	.=	 'Editing temporary file : '. CGI::br() . $self->{problem_source_name};
-	} elsif ( $edit_mode eq 'savedFile' ){
-		$file_action 	.=	 'Problem saved to : '. CGI::br()  . $self->{problem_source_name};
-	}
-	my $problemNumber = $self->{problem}->problem_id . " : " . $file_action;
+	my $problemNumber = $self->{problem}->problem_id;
 	
 	return "$setName : Problem $problemNumber";
 }
@@ -354,12 +389,13 @@
 	my $db              = $self->{db};
 	my $set             = $self->{set};
 	my $problem         = $self->{problem};
+	my $editMode        = $self->{editMode};
 	my $permissionLevel = $self->{permissionLevel};
 	my $submitAnswers   = $self->{submitAnswers};
 	my $checkAnswers    = $self->{checkAnswers};
 	my $previewAnswers  = $self->{previewAnswers};
 	my %want            = %{ $self->{want} };
-	my %can             = %{ $self->{can} };
+	my %can             = %{ $self->{can}  };
 	my %must            = %{ $self->{must} };
 	my %will            = %{ $self->{will} };
 	my $pg              = $self->{pg};
@@ -371,31 +407,27 @@
 	}
 	
 	##### answer processing #####
-	
+	$WeBWorK::timer0->continue("begin answer processing") if $timer0_ON;
 	# if answers were submitted:
+	my $scoreRecordedMessage;
 	if ($submitAnswers) {
 		# get a "pure" (unmerged) UserProblem to modify
 		# this will be undefined if the problem has not been assigned to this user
 		my $pureProblem = $db->getUserProblem($problem->user_id, $problem->set_id, $problem->problem_id);
-		# store answers in DB for sticky answers
-		my %answersToStore;
-		my %answerHash = %{ $pg->{answers} };
-		$answersToStore{$_} = $answerHash{$_}->{original_student_ans}
-			foreach (keys %answerHash);
-		my $answerString = encodeAnswers(%answersToStore,
-			@{ $pg->{flags}->{ANSWER_ENTRY_ORDER} });
-		
-		$problem->last_answer($answerString);
-		# if $pureProblem is defined ( there is a user ) then record the last answer.
-		# FIXME  (we're assuming that not being able to get a pure problem is enough to determine
-		# whether or not the problem database needs to be updated.  This should be thought through
-		# more carefully to be sure.
-		if ( defined($pureProblem) )  {
+		if (defined $pureProblem) {
+			# store answers in DB for sticky answers
+			my %answersToStore;
+			my %answerHash = %{ $pg->{answers} };
+			$answersToStore{$_} = $answerHash{$_}->{original_student_ans}
+				foreach (keys %answerHash);
+			my $answerString = encodeAnswers(%answersToStore,
+				@{ $pg->{flags}->{ANSWER_ENTRY_ORDER} });
+			
+			# store last answer to database
+			$problem->last_answer($answerString);
 			$pureProblem->last_answer($answerString);
 			$db->putUserProblem($pureProblem);
-			#die "pureProblem = ", defined($pureProblem);
-		
-		
+			
 			# store state in DB if it makes sense
 			if ($will{recordAnswers}) {
 				$problem->status($pg->{state}->{recorded_score});
@@ -406,7 +438,11 @@
 				$pureProblem->attempted(1);
 				$pureProblem->num_correct($pg->{state}->{num_of_correct_ans});
 				$pureProblem->num_incorrect($pg->{state}->{num_of_incorrect_ans});
-				$db->putUserProblem($pureProblem);
+				if ($db->putUserProblem($pureProblem)) {
+					$scoreRecordedMessage = "Your score was recorded.";
+				} else {
+					$scoreRecordedMessage = "Your score was not recorded because there was a failure in storing the problem record to the database.";
+				}
 				# write to the transaction log, just to make sure
 				writeLog($self->{ce}, "transaction",
 					$problem->problem_id."\t".
@@ -422,37 +458,57 @@
 					$pureProblem->num_correct."\t".
 					$pureProblem->num_incorrect
 				);
+			} else {
+				if (time < $set->open_date or time > $set->due_date) {
+					$scoreRecordedMessage = "Your score was not recorded because this problem set is closed.";
+				} else {
+					$scoreRecordedMessage = "Your score was not recorded.";
+				}
 			}
+		} else {
+			$scoreRecordedMessage = "Your score was not recorded because this problem has not been built for you.";
 		}
 	}
-	# logging student answers
-	my $pastAnswerLog = undef;
-	if (defined( $self->{ce}->{webworkFiles}->{logs}->{'pastAnswerList'} )) {
 	
-		$pastAnswerLog 	= 	$self->{ce}->{webworkFiles}->{logs}->{'pastAnswerList'};
-	
-		if ($submitAnswers and defined($pastAnswerLog) ) {
+	# logging student answers
+
+	my $answer_log    = $self->{ce}->{courseFiles}->{logs}->{'answer_log'};
+	if ( defined($answer_log )) {
+		if ($submitAnswers ) {
 			my $answerString = "";
 			my %answerHash = %{ $pg->{answers} };
 			$answerString = $answerString . $answerHash{$_}->{original_student_ans}."\t"
 				foreach (sort keys  %answerHash);
 			$answerString = '' unless defined($answerString); # insure string is defined. 
-			writeLog($self->{ce}, "pastAnswerList",
-					'|'.$problem->user_id.
-					'|'.$problem->set_id.
-					'|'.$problem->problem_id.'|'."\t".
-					time()."\t".
-					$answerString,
-					
-				);
-		
+			writeCourseLog($self->{ce}, "answer_log",
+			        join("",
+						'|', $problem->user_id,
+						'|', $problem->set_id,
+						'|', $problem->problem_id,
+						'|',"\t",
+						time(),"\t",
+						$answerString,
+					),
+			);
+			
 		}
+	}
 	
-	 }
-	# end logging student answers
+	$WeBWorK::timer0->continue("end answer processing") if $timer0_ON;
 	
 	##### output #####
+	
 	print CGI::start_div({class=>"problemHeader"});
+	
+	# custom message for editor
+	if ($permissionLevel >= 10 and defined $editMode) {
+		if ($editMode eq "temporaryFile") {
+			print CGI::p(CGI::i("Editing temporary file: ", $problem->source_file));
+		} elsif ($editMode eq "savedFile") {
+			print CGI::p(CGI::i("Problem saved to: ", $problem->source_file));
+		}
+	}
+	
 	# attempt summary
 	if ($submitAnswers or $will{showCorrectAnswers}) {
 		# print this if user submitted answers OR requested correct answers
@@ -478,7 +534,7 @@
 	print CGI::end_div();
 	
 	print CGI::start_div({class=>"problem"});
-	#print CGI::hr();
+	
 	# main form
 	print
 		CGI::startform("POST", $r->uri),
@@ -486,11 +542,18 @@
 		CGI::p($pg->{body_text}),
 		CGI::p($pg->{result}->{msg} ? CGI::b("Note: ") : "", CGI::i($pg->{result}->{msg})),
 		CGI::p(
+			($can{showCorrectAnswers} 
+				? CGI::checkbox(
+						-name    => "showCorrectAnswers",
+						-checked => $will{showCorrectAnswers},
+						-label   => "Show correct answers",
+					) . CGI::br()
+				: "" ),
 			($can{recordAnswers}
 				? CGI::submit(-name=>"submitAnswers",
 					-label=>"Submit Answers")
 				: ""),
-			($can{checkAnswers}
+			( ($can{checkAnswers} and not $can{recordAnswers})
 				? CGI::submit(-name=>"checkAnswers",
 					-label=>"Check Answers")
 				: ""),
@@ -500,6 +563,7 @@
 	print CGI::end_div();
 	
 	print CGI::start_div({class=>"scoreSummary"});
+	
 	# score summary
 	my $attempts = $problem->num_correct + $problem->num_incorrect;
 	my $attemptsNoun = $attempts != 1 ? "times" : "time";
@@ -520,12 +584,13 @@
 		$setClosed = 1;
 		$setClosedMessage = "This problem set is closed.";
 		if ($permissionLevel > 0) {
-			$setClosedMessage .= " Since you are a privileged user, additional attempts will be recorded.";
+			$setClosedMessage .= " However, since you are a privileged user, additional attempts will be recorded.";
 		} else {
 			$setClosedMessage .= " Additional attempts will not be recorded.";
 		}
 	}
 	print CGI::p(
+		$submitAnswers ? $scoreRecordedMessage . CGI::br() : "",
 		"You have attempted this problem $attempts $attemptsNoun.", CGI::br(),
 		$problem->attempted
 			? "Your recorded score is $lastScore." . CGI::br()
@@ -533,64 +598,69 @@
 		$setClosed ? $setClosedMessage : "You have $attemptsLeft $attemptsLeftNoun remaining."
 	);
 	print CGI::end_div();
-#	print CGI::hr(), CGI::start_div({class=>"viewOptions"});
-#	print		$self->viewOptions(),CGI::end_div(),
-#   save state for viewOptions
-	print  CGI::hidden(-name    => "showOldAnswers",
-			            -value   => $will{showOldAnswers},
-		  ),
-		  CGI::hidden(-name    => "showCorrectAnswers",
-			           -value   => $will{showCorrectAnswers},
-		  ),
-		  CGI::hidden(-name    => "showHints",
-			           -value   => $will{showHints},
-		  ),
-		  CGI::hidden(-name    => "showSolutions",
-			          -value   => $will{showSolutions},
-	      ),
-		  CGI::hidden(-name    => "displayMode",
-			          -value => $self->{displayMode}
-		  );
-    print		CGI::endform();
 		
-	print  CGI::start_div({class=>"problemFooter"});
-	# feedback form
+	# save state for viewOptions
+	print CGI::hidden(
+			-name  => "showOldAnswers",
+			-value => $will{showOldAnswers}
+		),
+		CGI::hidden(
+			-name  => "showCorrectAnswers",
+			-value => $will{showCorrectAnswers}
+		),
+		CGI::hidden(
+			-name  => "showHints",
+			-value => $will{showHints}),
+		CGI::hidden(
+			-name  => "showSolutions",
+			-value => $will{showSolutions},
+		),
+		CGI::hidden(
+			-name  => "displayMode",
+			-value => $self->{displayMode}
+		);
+	
+	# end of main form
+	print CGI::endform();
+	
+	# stuff we need below (pull these out at the beginning?)
 	my $ce = $self->{ce};
 	my $root = $ce->{webworkURLs}->{root};
 	my $courseName = $ce->{courseName};
-	my $feedbackURL = "$root/$courseName/feedback/";
+	
+	print  CGI::start_div({class=>"problemFooter"});
 	
 	# arguments for answer inspection button
 	my $prof_url = $ce->{webworkURLs}->{oldProf};
+	my $webworkURL = $ce->{webworkURLs}->{root};
 	my $cgi_url = $prof_url;
 	$cgi_url=~ s|/[^/]*$||;  # clip profLogin.pl
 	my $authen_args = $self->url_authen_args();
-	my $showPastAnswersURL = "$cgi_url/showPastAnswers.pl";
+	my $showPastAnswersURL = "$webworkURL/$courseName/instructor/show_answers/";
 	
-
-	print CGI::end_div();
-	print CGI::start_div();
 	# print answer inspection button
-	if ($self->{permissionLevel} >0)      {
-    	
-
+	if ($self->{permissionLevel} > 0) {
 		print "\n",
 			CGI::start_form(-method=>"POST",-action=>$showPastAnswersURL,-target=>"information"),"\n",
-				$self->hidden_authen_fields,"\n",
-				CGI::hidden(-name => 'course',  -value=>$courseName), "\n",
-				CGI::hidden(-name => 'probNum', -value=>$problem->problem_id), "\n",
-				CGI::hidden(-name => 'setNum',  -value=>$problem->set_id), "\n",
-				CGI::hidden(-name => 'User',    -value=>$problem->user_id), "\n",
-				CGI::p( {-align=>"left"},
-					CGI::submit(-name => 'action',  -value=>'Show Past Answers')
-				), "\n",
-				CGI::endform();
-	
+			$self->hidden_authen_fields,"\n",
+			CGI::hidden(-name => 'course',  -value=>$courseName), "\n",
+			CGI::hidden(-name => 'problemNumber', -value=>$problem->problem_id), "\n",
+			CGI::hidden(-name => 'setName',  -value=>$problem->set_id), "\n",
+			CGI::hidden(-name => 'studentUser',    -value=>$problem->user_id), "\n",
+			CGI::p( {-align=>"left"},
+				CGI::submit(-name => 'action',  -value=>'Show Past Answers')
+			), "\n",
+			CGI::endform();
+	}
+	
+	#print CGI::end_div();
+	#
+	#print CGI::start_div();
 	
+	# arguments for feedback form
+	my $feedbackURL = "$root/$courseName/feedback/";
 	
-	}	#print feedback form
-
-	
+	#print feedback form
 	print
 		CGI::start_form(-method=>"POST", -action=>$feedbackURL),"\n",
 		$self->hidden_authen_fields,"\n",
@@ -610,17 +680,16 @@
 	# FIXME print editor link
 	# print editor link if the user is an instructor AND the file is not in temporary editing mode
 	if ($self->{permissionLevel}>=10 and ( (not defined($self->{edit_mode}))  or $self->{edit_mode} eq 'savedFile') ) {
-		print CGI::a({-href=>"/webwork/$courseName/instructor/pgProblemEditor/".$set->set_id.
+		print CGI::a({-href=>$ce->{webworkURLs}->{root}."/$courseName/instructor/pgProblemEditor/".$set->set_id.
 		'/'.$problem->problem_id.'?'.$self->url_authen_args},'Edit this problem');
 	}
 	
-    print CGI::end_div();
+	print CGI::end_div();
 	
-	# end answer inspection button
 	# warning output
-	if ($pg->{warnings} ne "") {
-		print CGI::hr(), $self->warningOutput($pg->{warnings});
-	}
+	#if ($pg->{warnings} ne "") {
+	#	print CGI::hr(), $self->warningOutput($pg->{warnings});
+	#}
 	
 	# debugging stuff
 	if (0) {
@@ -652,12 +721,24 @@
 	my $showAttemptResults = $showAttemptAnswers && shift;
 	my $showSummary = shift;
 	my $showAttemptPreview = shift || 0;
+	my $ce = $self->{ce};
 	my $problemResult = $pg->{result}; # the overall result of the problem
 	my @answerNames = @{ $pg->{flags}->{ANSWER_ENTRY_ORDER} };
 	
 	my $showMessages = $showAttemptAnswers && grep { $pg->{answers}->{$_}->{ans_message} } @answerNames;
 	
-	my $header = CGI::th("Part");
+	my $basename = "equation-" . $self->{set}->psvn. "." . $self->{problem}->problem_id . "-preview";
+	my $imgGen = WeBWorK::PG::ImageGenerator->new(
+		tempDir  => $ce->{webworkDirs}->{tmp},
+		dir	 => $ce->{courseDirs}->{html_temp},
+		url	 => $ce->{courseURLs}->{html_temp},
+		basename => $basename,
+		latex	 => $ce->{externalPrograms}->{latex},
+		dvipng   => $ce->{externalPrograms}->{dvipng},
+	);
+	
+	my $header;
+	#$header .= CGI::th("Part");
 	$header .= $showAttemptAnswers ? CGI::th("Entered")  : "";
 	$header .= $showAttemptPreview ? CGI::th("Answer Preview")  : "";
 	$header .= $showCorrectAnswers ? CGI::th("Correct")  : "";
@@ -669,8 +750,8 @@
 		my $answerResult  = $pg->{answers}->{$name};
 		my $studentAnswer = $answerResult->{student_ans}; # original_student_ans
 		my $preview       = ($showAttemptPreview
-		                    	? $self->previewAnswer($answerResult)
-					: "");
+		                    	? $self->previewAnswer($answerResult, $imgGen)
+		                    	: "");
 		my $correctAnswer = $answerResult->{correct_ans};
 		my $answerScore   = $answerResult->{score};
 		my $answerMessage = $showMessages ? $answerResult->{ans_message} : "";
@@ -682,22 +763,31 @@
 		# of the answer names is changeable. this only fixes it for "AnSwEr"
 		$name =~ s/^AnSwEr//;
 		
-		my $row = CGI::td($name);
-		$row .= $showAttemptAnswers ? CGI::td($studentAnswer) : "";
-		$row .= $showAttemptPreview ? CGI::td($preview)       : "";
-		$row .= $showCorrectAnswers ? CGI::td($correctAnswer) : "";
-		$row .= $showAttemptResults ? CGI::td($resultString)  : "";
-		$row .= $answerMessage      ? CGI::td($answerMessage) : "";
+		my $row;
+		#$row .= CGI::td($name);
+		$row .= $showAttemptAnswers ? CGI::td(nbsp($studentAnswer)) : "";
+		$row .= $showAttemptPreview ? CGI::td(nbsp($preview))       : "";
+		$row .= $showCorrectAnswers ? CGI::td(nbsp($correctAnswer)) : "";
+		$row .= $showAttemptResults ? CGI::td(nbsp($resultString))  : "";
+		$row .= $answerMessage      ? CGI::td(nbsp($answerMessage)) : "";
 		push @tableRows, $row;
 	}
 	
+	# render equation images
+	$imgGen->render(refresh => 1);
+	
 	my $numIncorrectNoun = scalar @answerNames == 1 ? "question" : "questions";
-	my $scorePercent = int ($problemResult->{score} * 100) . "\%";
+	my $scorePercent = sprintf("%.0f%%", $problemResult->{score} * 100);
 	my $summary = "On this attempt, you answered $numCorrect out of "
 		. scalar @answerNames . " $numIncorrectNoun correct, for a score of $scorePercent.";
-	return CGI::table({-class=>"attemptResults"}, CGI::Tr(\@tableRows)) . ($showSummary ? CGI::p($summary) : "");
+	return CGI::table({-class=>"attemptResults"}, CGI::Tr(\@tableRows)) . ($showSummary ? CGI::p({class=>'emphasis'},$summary) : "");
+}
+sub nbsp {
+	my $str = shift;
+	($str =~/\S/) ? $str : '&nbsp;'  ;  # returns non-breaking space for empty strings
+	                                    # tricky cases:   $str =0;
+	                                    #  $str is a complex number
 }
-
 sub viewOptions($) {
 	my $self = shift;
 	my $displayMode = $self->{displayMode};
@@ -713,12 +803,6 @@
 			-checked => $will{showOldAnswers},
 			-label   => "Saved answers",
 		), "&nbsp;&nbsp;".CGI::br();
-	$can{showCorrectAnswers} and $optionLine .= join "",
-		CGI::checkbox(
-			-name    => "showCorrectAnswers",
-			-checked => $will{showCorrectAnswers},
-			-label   => "Correct answers",
-		), "&nbsp;&nbsp;".CGI::br();
 	$can{showHints} and $optionLine .= join "",
 		CGI::checkbox(
 			-name    => "showHints",
@@ -752,7 +836,7 @@
 }
 
 sub previewAnswer($$) {
-	my ($self, $answerResult) = @_;
+	my ($self, $answerResult, $imgGen) = @_;
 	my $ce            = $self->{ce};
 	my $effectiveUser = $self->{effectiveUser};
 	my $set           = $self->{set};
@@ -766,7 +850,7 @@
 	
 	my $tex = $answerResult->{preview_latex_string};
 	
-	return "" if $tex eq "";
+	return "" unless defined $tex and $tex ne "";
 	
 	if ($displayMode eq "plainText") {
 		return $tex;
@@ -783,46 +867,35 @@
 		}
 		return $result;
 	} elsif ($displayMode eq "images") {
-		# how are we going to name this?
-		my $targetPathCommon = "/m2i/"
-			. $effectiveUser->user_id . "."
-			. $set->set_id . "."
-			. $problem->problem_id . "."
-			. $answerResult->{ans_name} . ".png";
-
-		# figure out where to put things
-		my $wd = tempdir("webwork-dvipng-XXXXXXXX", DIR => $ce->{courseDirs}->{html_temp});
-		my $latex = $ce->{externalPrograms}->{latex};
-		my $dvipng = $ce->{externalPrograms}->{dvipng};
-		my $targetPath = $ce->{courseDirs}->{html_temp} . $targetPathCommon;
-				# should use surePathToTmpFile, but we have to
-				# isolate it from the problem enivronment first
-		my $targetURL = $ce->{courseURLs}->{html_temp} . $targetPathCommon;
-
-		# call dvipng to generate a preview
-		dvipng($wd, $latex, $dvipng, $tex, $targetPath);
-		rmtree($wd, 0, 0);
-		if (-e $targetPath) {
-			return "<img src=\"$targetURL\" alt=\"$tex\" />";
-		} else {
-			return "<b>[math2img failed]</b>";
-		}
+		## how are we going to name this?
+		#my $targetPathCommon = "/m2i/"
+		#	. $effectiveUser->user_id . "."
+		#	. $set->set_id . "."
+		#	. $problem->problem_id . "."
+		#	. $answerResult->{ans_name} . ".png";
+		#
+		## figure out where to put things
+		#my $wd = makeTempDirectory($ce->{courseDirs}->{html_temp}, "webwork-dvipng");
+		#my $latex = $ce->{externalPrograms}->{latex};
+		#my $dvipng = $ce->{externalPrograms}->{dvipng};
+		#my $targetPath = $ce->{courseDirs}->{html_temp} . $targetPathCommon;
+		#		# should use surePathToTmpFile, but we have to
+		#		# isolate it from the problem enivronment first
+		#my $targetURL = $ce->{courseURLs}->{html_temp} . $targetPathCommon;
+		#
+		## call dvipng to generate a preview
+		#dvipng($wd, $latex, $dvipng, $tex, $targetPath);
+		#rmtree($wd, 0, 0);
+		#if (-e $targetPath) {
+		#	return "<img src=\"$targetURL\" alt=\"$tex\" />";
+		#} else {
+		#	return "<b>[math2img failed]</b>";
+		#}
+		$imgGen->add($answerResult->{preview_latex_string});
+		
 	}
 }
 
-sub options {
-	my $self=shift;
-	my $out;
-	$out     .=join("", 
-                    CGI::startform("POST", $self->{r}->uri),
-                    $self->hidden_authen_fields,
-                    CGI::hr(), 
-                    CGI::start_div({class=>"viewOptions"}),
-                    $self->viewOptions(),CGI::end_div(),
-	);
-return $out;
-
-}
 ##### logging subroutine ####