--- loncom/interface/lonnavmaps.pm	2003/04/24 18:18:38	1.181
+++ loncom/interface/lonnavmaps.pm	2003/05/16 17:54:21	1.192
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Navigate Maps Handler
 #
-# $Id: lonnavmaps.pm,v 1.181 2003/04/24 18:18:38 bowersj2 Exp $
+# $Id: lonnavmaps.pm,v 1.192 2003/05/16 17:54:21 bowersj2 Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -47,6 +47,7 @@ use Apache::Constants qw(:common :http);
 use Apache::loncommon();
 use Apache::lonmenu();
 use POSIX qw (floor strftime);
+use Data::Dumper; # for debugging, not always used
 
 # symbolic constants
 sub SYMB { return 1; }
@@ -71,7 +72,8 @@ my %statusIconMap =
       $resObj->TRIES_LEFT         => 'navmap.open.gif',
       $resObj->INCORRECT          => 'navmap.wrong.gif',
       $resObj->OPEN               => 'navmap.open.gif',
-      $resObj->ATTEMPTED          => 'navmap.open.gif' );
+      $resObj->ATTEMPTED          => 'navmap.open.gif',
+      $resObj->ANSWER_SUBMITTED   => '' );
 
 my %iconAltTags = 
     ( 'navmap.correct.gif' => 'Correct',
@@ -199,15 +201,91 @@ sub real_handler {
         }
     }
 
-    # renderer call
-    my $render = render({ 'cols' => [0,1,2,3],
-                          'url' => '/adm/navmaps',
-                          'navmap' => $navmap,
-                          'suppressNavmap' => 1,
-                          'r' => $r});
+    my $jumpToFirstHomework = 0;
+    # Check to see if the student is jumping to next open, do-able problem
+    if ($ENV{QUERY_STRING} eq 'jumpToFirstHomework') {
+        $jumpToFirstHomework = 1;
+        # Find the next homework problem that they can do.
+        my $iterator = $navmap->getIterator(undef, undef, undef, 1);
+        my $depth = 1;
+        $iterator->next();
+        my $curRes = $iterator->next();
+        my $foundDoableProblem = 0;
+        my $problemRes;
+        
+        while ($depth > 0 && !$foundDoableProblem) {
+            if ($curRes == $iterator->BEGIN_MAP()) { $depth++; }
+            if ($curRes == $iterator->END_MAP()) { $depth--; }
+
+            if (ref($curRes) && $curRes->is_problem()) {
+                my $status = $curRes->status();
+                if ($curRes->completable()) {
+                    $problemRes = $curRes;
+                    $foundDoableProblem = 1;
+
+                    # Pop open all previous maps
+                    my $stack = $iterator->getStack();
+                    pop @$stack; # last resource in the stack is the problem
+                                 # itself, which we don't need in the map stack
+                    my @mapPcs = map {$_->map_pc()} @$stack;
+                    $ENV{'form.filter'} = join(',', @mapPcs);
+
+                    # Mark as both "here" and "jump"
+                    $ENV{'form.postsymb'} = $curRes->symb();
+                }
+            }
+        } continue {
+            $curRes = $iterator->next();
+        }
 
+        # If we found no problems, print a note to that effect.
+        if (!$foundDoableProblem) {
+            $r->print("<font size='+2'>All homework assignments have been completed.</font><br /><br />");
+        }
+    } else {
+        $r->print("<a href='navmaps?jumpToFirstHomework'>" .
+                  "Go To My First Homework Problem</a><br />");
+    }
+
+    my $suppressEmptySequences = 0;
+    my $filterFunc = undef;
+    # Display only due homework.
+    my $showOnlyHomework = 0;
+    if ($ENV{QUERY_STRING} eq 'showOnlyHomework') {
+        $showOnlyHomework = 1;
+        $suppressEmptySequences = 1;
+        $filterFunc = sub { my $res = shift; 
+                            return $res->completable() || $res->is_sequence();
+                        };
+        $r->print("<p><font size='+2'>Uncompleted Homework</font></p>");
+        $ENV{'form.filter'} = '';
+        $ENV{'form.condition'} = 1;
+    } else {
+        $r->print("<a href='navmaps?showOnlyHomework'>" .
+                  "Show Only Uncompleted Homework</a><br />");
+    }
+
+    # renderer call
+    my $renderArgs = { 'cols' => [0,1,2,3],
+                       'url' => '/adm/navmaps',
+                       'navmap' => $navmap,
+                       'suppressNavmap' => 1,
+                       'suppressEmptySequences' => $suppressEmptySequences,
+                       'filterFunc' => $filterFunc,
+                       'r' => $r};
+    my $render = render($renderArgs);
     $navmap->untieHashes();
 
+    # If no resources were printed, print a reassuring message so the
+    # user knows there was no error.
+    if ($renderArgs->{'counter'} == 0) {
+        if ($showOnlyHomework) {
+            $r->print("<p><font size='+1'>All homework is currently completed.</font></p>");
+        } else { # both jumpToFirstHomework and normal use the same: course must be empty
+            $r->print("<p><font size='+1'>This course is empty.</font></p>");
+        }
+    }
+
     $r->print("</body></html>");
     $r->rflush();
 
@@ -271,7 +349,9 @@ sub getDescription {
     my $part = shift;
     my $status = $res->status($part);
 
-    if ($status == $res->NETWORK_FAILURE) { return ""; }
+    if ($status == $res->NETWORK_FAILURE) { 
+        return "Having technical difficulties; please check status later"; 
+    }
     if ($status == $res->NOTHING_SET) {
         return "Not currently assigned.";
     }
@@ -317,6 +397,9 @@ sub getDescription {
             return "No due date $triesString";
         }
     }
+    if ($status == $res->ANSWER_SUBMITTED) {
+        return 'Answer submitted';
+    }
 }
 
 # Convenience function, so others can use it: Is the problem due in less then
@@ -685,6 +768,14 @@ returns a true or false value. If true,
 false, it is simply skipped in the display. By default, all resources
 are shown.
 
+=item * B<suppressEmptySequences>:
+
+If you're using a filter function, and displaying sequences to orient
+the user, then frequently some sequences will be empty. Setting this to
+true will cause those sequences not to display, so as not to confuse the
+user into thinking that if the sequence is there there should be things
+under it.
+
 =item * B<suppressNavmaps>:
 
 If true, will not display Navigate Content resources. Default to
@@ -748,7 +839,7 @@ sub render_resource {
     my $icon = "<img src='/adm/lonIcons/html.gif' alt='' border='0' />";
     
     if ($resource->is_problem()) {
-        if ($part eq "" || $params->{'condensed'}) {
+        if ($part eq '0' || $params->{'condensed'}) {
             $icon = '<img src="/adm/lonIcons/problem.gif" alt="" border="0" />';
         } else {
             $icon = $params->{'indentString'};
@@ -818,7 +909,7 @@ sub render_resource {
         $params->{'displayedHereMarker'} = 1;
     }
 
-    if ($resource->is_problem() && $part ne "" && 
+    if ($resource->is_problem() && $part ne '0' && 
         !$params->{'condensed'}) {
         $partLabel = " (Part $part)";
         $title = "";
@@ -910,7 +1001,7 @@ sub render_long_status {
         $params->{'multipart'} && $part eq "0";
                 
     my $color;
-    if ($resource->is_problem()) {
+    if ($resource->is_problem() && ($resource->countParts() <= 1 || $part ne '') ) {
         $color = $colormap{$resource->status};
         
         if (dueInLessThen24Hours($resource, $part) ||
@@ -981,6 +1072,19 @@ sub render {
         }
     }
 
+    # Filter: Remember filter function and add our own filter: Refuse
+    # to show hidden resources unless the user can see them.
+    my $userCanSeeHidden = advancedUser();
+    my $filterFunc = setDefault($args->{'filterFunc'},
+                                sub {return 1;});
+    if (!$userCanSeeHidden) {
+        # Without renaming the filterfunc, the server seems to go into
+        # an infinite loop
+        my $oldFilterFunc = $filterFunc;
+        $filterFunc = sub { my $res = shift; return !$res->randomout() && 
+                                &$oldFilterFunc($res);};
+    }
+
     my $condition = 0;
     if ($ENV{'form.condition'}) {
         $condition = 1;
@@ -1077,6 +1181,8 @@ sub render {
     }
     
     # (re-)Locate the jump point, if any
+    # Note this does not take filtering or hidden into account... need
+    # to be fixed?
     my $mapIterator = $navmap->getIterator(undef, undef, $filterHash, 0);
     my $depth = 1;
     $mapIterator->next();
@@ -1109,8 +1215,6 @@ sub render {
     my $printKey = $args->{'printKey'};
     my $printCloseAll = $args->{'printCloseAll'};
     if (!defined($printCloseAll)) { $printCloseAll = 1; }
-    my $filterFunc = setDefault($args->{'filterFunc'},
-                                sub {return 1;});
     
     # Print key?
     if ($printKey) {
@@ -1171,6 +1275,43 @@ sub render {
     $args->{'indentString'} = setDefault($args->{'indentString'}, "<img src='/adm/lonIcons/whitespace1.gif' width='25' height='1' alt='' border='0' />");
     $args->{'displayedHereMarker'} = 0;
 
+    # If we're suppressing empty sequences, look for them here. Use DFS for speed,
+    # since structure actually doesn't matter, except what map has what resources.
+    if ($args->{'suppressEmptySequences'}) {
+        my $dfsit = Apache::lonnavmaps::DFSiterator->new($navmap,
+                                                         $it->{FIRST_RESOURCE},
+                                                         $it->{FINISH_RESOURCE},
+                                                         {}, undef, 1);
+        $depth = 0;
+        $dfsit->next();
+        my $curRes = $dfsit->next();
+        while ($depth > -1) {
+            if ($curRes == $dfsit->BEGIN_MAP()) { $depth++; }
+            if ($curRes == $dfsit->END_MAP()) { $depth--; }
+
+            if (ref($curRes)) { 
+                # Parallel pre-processing: Do sequences have non-filtered-out children?
+                if ($curRes->is_sequence()) {
+                    $curRes->{DATA}->{HAS_VISIBLE_CHILDREN} = 0;
+                    # Sequences themselves do not count as visible children,
+                    # unless those sequences also have visible children.
+                    # This means if a sequence appears, there's a "promise"
+                    # that there's something under it if you open it, somewhere.
+                } else {
+                    # Not a sequence: if it's filtered, ignore it, otherwise
+                    # rise up the stack and mark the sequences as having children
+                    if (&$filterFunc($curRes)) {
+                        for my $sequence (@{$dfsit->getStack()}) {
+                            $sequence->{DATA}->{HAS_VISIBLE_CHILDREN} = 1;
+                        }
+                    }
+                }
+            }
+        } continue {
+            $curRes = $dfsit->next();
+        }
+    }
+
     my $displayedJumpMarker = 0;
     # Set up iteration.
     $depth = 1;
@@ -1206,19 +1347,25 @@ sub render {
             next;
         }
 
-        $args->{'counter'}++;
-
         # If this has been filtered out, continue on
         if (!(&$filterFunc($curRes))) {
             $args->{'isNewBranch'} = 0; # Don't falsely remember this
             next;
         } 
 
+        # If this is an empty sequence and we're filtering them, continue on
+        if ($curRes->is_sequence() && $args->{'suppressEmptySequences'} &&
+            !$curRes->{DATA}->{HAS_VISIBLE_CHILDREN}) {
+            next;
+        }
+
         # If we're suppressing navmaps and this is a navmap, continue on
         if ($suppressNavmap && $curRes->src() =~ /^\/adm\/navmaps/) {
             next;
         }
 
+        $args->{'counter'}++;
+
         # Does it have multiple parts?
         $args->{'multipart'} = 0;
         $args->{'condensed'} = 0;
@@ -1227,7 +1374,7 @@ sub render {
         # Decide what parts to show.
         if ($curRes->is_problem() && $showParts) {
             @parts = @{$curRes->parts()};
-            $args->{'multipart'} = scalar(@parts) > 1;
+            $args->{'multipart'} = $curRes->multipart();
             
             if ($condenseParts) { # do the condensation
                 if (!$curRes->opendate("0")) {
@@ -1236,13 +1383,13 @@ sub render {
                 }
                 if (!$args->{'condensed'}) {
                     # Decide whether to condense based on similarity
-                    my $status = $curRes->status($parts[1]);
-                    my $due = $curRes->duedate($parts[1]);
-                    my $open = $curRes->opendate($parts[1]);
+                    my $status = $curRes->status($parts[0]);
+                    my $due = $curRes->duedate($parts[0]);
+                    my $open = $curRes->opendate($parts[0]);
                     my $statusAllSame = 1;
                     my $dueAllSame = 1;
                     my $openAllSame = 1;
-                    for (my $i = 2; $i < scalar(@parts); $i++) {
+                    for (my $i = 1; $i < scalar(@parts); $i++) {
                         if ($curRes->status($parts[$i]) != $status){
                             $statusAllSame = 0;
                         }
@@ -1263,7 +1410,7 @@ sub render {
                     if (($statusAllSame && defined($condenseStatuses{$status})) ||
                         ($dueAllSame && $status == $curRes->OPEN && $statusAllSame)||
                         ($openAllSame && $status == $curRes->OPEN_LATER && $statusAllSame) ){
-                        @parts = ();
+                        @parts = ($parts[0]);
                         $args->{'condensed'} = 1;
                     }
                     
@@ -1274,14 +1421,14 @@ sub render {
         # If the multipart problem was condensed, "forget" it was multipart
         if (scalar(@parts) == 1) {
             $args->{'multipart'} = 0;
+        } else {
+            # Add part 0 so we display it correctly.
+            unshift @parts, '0';
         }
 
         # Now, we've decided what parts to show. Loop through them and
         # show them.
-        foreach my $part ('', @parts) {
-            if ($part eq '0') {
-                next;
-            }
+        foreach my $part (@parts) {
             $rownum ++;
             my $backgroundColor = $backgroundColors[$rownum % scalar(@backgroundColors)];
             
@@ -1472,15 +1619,13 @@ sub init {
             unless ((time-$courserdatas{$cid.'.last_cache'})<240) {
                 my $reply=&Apache::lonnet::reply('dump:'.$cdom.':'.$cnum.
                                                  ':resourcedata',$chome);
-                if ($reply!~/^error\:/) {
+                # Check for network failure
+                if ( $reply =~ /no.such.host/i || $reply =~ /con_lost/i) {
+                    $self->{NETWORK_FAILURE} = 1;
+                } elsif ($reply!~/^error\:/) {
                     $courserdatas{$cid}=$reply;
                     $courserdatas{$cid.'.last_cache'}=time;
                 }
-                # check to see if network failed
-                elsif ( $reply=~/no.such.host/i || $reply=~/con.*lost/i )
-                {
-                    $self->{NETWORK_FAILURE} = 1;
-                }
             }
             foreach (split(/\&/,$courserdatas{$cid})) {
                 my ($name,$value)=split(/\=/,$_);
@@ -2144,7 +2289,8 @@ sub new {
                 
                 $curRes->{DATA}->{DISPLAY_DEPTH} = $finalDepth;
                 if ($finalDepth > $maxDepth) {$maxDepth = $finalDepth;}
-                }
+            }
+        } continue {
             $curRes = $iterator->next();
         }
     }
@@ -2521,6 +2667,31 @@ sub next {
     return $self->{HERE};
 }
 
+# Identical to the full iterator methods of the same name. Hate to copy/paste
+# but I also hate to "inherit" either iterator from the other.
+
+sub getStack {
+    my $self=shift;
+
+    my @stack;
+
+    $self->populateStack(\@stack);
+
+    return \@stack;
+}
+
+# Private method: Calls the iterators recursively to populate the stack.
+sub populateStack {
+    my $self=shift;
+    my $stack = shift;
+
+    push @$stack, $self->{HERE} if ($self->{HERE});
+
+    if ($self->{RECURSIVE_ITERATOR_FLAG}) {
+        $self->{RECURSIVE_ITERATOR}->populateStack($stack);
+    }
+}
+
 1;
 
 package Apache::lonnavmaps::resource;
@@ -2544,6 +2715,12 @@ You will probably never need to instanti
 Apache::lonnavmaps::navmap, and use the "start" method to obtain the
 starting resource.
 
+Resource objects respect the parameter_hiddenparts, which suppresses 
+various parts according to the wishes of the map author. As of this
+writing, there is no way to override this parameter, and suppressed
+parts will never be returned, nor will their response types or ids be
+stored.
+
 =head2 Public Members
 
 resource objects have a hash called DATA ($resourceRef->{DATA}) that
@@ -2753,7 +2930,10 @@ sub is_sequence {
 sub parmval {
     my $self = shift;
     my $what = shift;
-    my $part = shift || "0";
+    my $part = shift;
+    if (!defined($part)) { 
+        $part = '0'; 
+    }
     return $self->{NAV_MAP}->parmval($part.'.'.$what, $self->symb());
 }
 
@@ -2927,6 +3107,10 @@ sub opendate {
     }
     return $self->parmval("opendate");
 }
+sub problemstatus {
+    (my $self, my $part) = @_;
+    return $self->parmval("problemstatus", $part);
+}
 sub sig {
     (my $self, my $part) = @_;
     return $self->parmval("sig", $part);
@@ -3037,9 +3221,22 @@ each part. Filtering part 0 if you want
 Returns the number of parts of the problem a student can answer. Thus,
 for single part problems, returns 1. For multipart, it returns the
 number of parts in the problem, not including psuedo-part 0. Thus,
-B<parts> may return an array with fewer parts in it then countParts
+B<parts> may return an array with more parts in it then countParts
 might lead you to believe.
 
+=item * B<multipart>():
+
+Returns true if the problem is multipart, false otherwise.
+
+=item * B<responseType>($part):
+
+Returns the response type of the part, without the word "response" on the
+end. Example return values: 'string', 'essay', 'numeric', etc.
+
+=item * B<responseId>($part):
+
+Retreives the response ID for the given part, which may be an empty string.
+
 =back
 
 =cut
@@ -3047,7 +3244,7 @@ might lead you to believe.
 sub parts {
     my $self = shift;
 
-    if ($self->ext) { return ['0']; }
+    if ($self->ext) { return []; }
 
     $self->extractParts();
     return $self->{PARTS};
@@ -3057,19 +3254,43 @@ sub countParts {
     my $self = shift;
     
     my $parts = $self->parts();
-    my $delta = 0;
-    for my $part (@$parts) {
-        if ($part eq '0') { $delta--; }
-    }
+
+    # If I left this here, then it's not necessary.
+    #my $delta = 0;
+    #for my $part (@$parts) {
+    #    if ($part eq '0') { $delta--; }
+    #}
 
     if ($self->{RESOURCE_ERROR}) {
         return 0;
     }
 
-    return scalar(@{$parts}) + $delta;
+    return scalar(@{$parts}); # + $delta;
+}
+
+sub multipart {
+    my $self = shift;
+    return $self->countParts() > 1;
+}
+
+sub responseType {
+    my $self = shift;
+    my $part = shift;
+
+    $self->extractParts();
+    return $self->{RESPONSE_TYPE}->{$part};
+}
+
+sub responseId {
+    my $self = shift;
+    my $part = shift;
+
+    $self->extractParts();
+    return $self->{RESPONSE_IDS}->{$part};
 }
 
-# Private function: Extracts the parts information and saves it
+# Private function: Extracts the parts information, both part names and
+# part types, and saves it. 
 sub extractParts { 
     my $self = shift;
     
@@ -3086,15 +3307,16 @@ sub extractParts {
         if (!$metadata) {
             $self->{RESOURCE_ERROR} = 1;
             $self->{PARTS} = [];
+            $self->{PART_TYPE} = {};
             return;
         }
         foreach (split(/\,/,$metadata)) {
             if ($_ =~ /^part_(.*)$/) {
                 my $part = $1;
-                # This floods the logs
-                #if (defined($parts{$part})) {
-                #    Apache::lonnet::logthis("$part multiply defined in metadata for " . $self->symb());
-                #  }
+                # This floods the logs if it blows up
+                if (defined($parts{$part})) {
+                    Apache::lonnet::logthis("$part multiply defined in metadata for " . $self->symb());
+                  }
 
                 # check to see if part is turned off.
 
@@ -3107,6 +3329,46 @@ sub extractParts {
         
         my @sortedParts = sort keys %parts;
         $self->{PARTS} = \@sortedParts;
+
+        my %responseIdHash;
+        my %responseTypeHash;
+
+
+        # Init the responseIdHash
+        foreach (@{$self->{PARTS}}) {
+            $responseIdHash{$_} = [];
+        }
+
+        # Now, the unfortunate thing about this is that parts, part name, and
+        # response if are delimited by underscores, but both the part
+        # name and response id can themselves have underscores in them.
+        # So we have to use our knowlege of part names to figure out 
+        # where the part names begin and end, and even then, it is possible
+        # to construct ambiguous situations.
+        foreach (split /,/, $metadata) {
+            if ($_ =~ /^([a-zA-Z]+)response_(.*)/) {
+                my $responseType = $1;
+                my $partStuff = $2;
+                my $partIdSoFar = '';
+                my @partChunks = split /_/, $partStuff;
+                my $i = 0;
+
+                for ($i = 0; $i < scalar(@partChunks); $i++) {
+                    if ($partIdSoFar) { $partIdSoFar .= '_'; }
+                    $partIdSoFar .= $partChunks[$i];
+                    if ($parts{$partIdSoFar}) {
+                        my @otherChunks = @partChunks[$i+1..$#partChunks];
+                        my $responseId = join('_', @otherChunks);
+                        push @{$responseIdHash{$partIdSoFar}}, $responseId;
+                        $responseTypeHash{$partIdSoFar} = $responseType;
+                        last;
+                    }
+                }
+            }
+        }
+
+        $self->{RESPONSE_IDS} = \%responseIdHash;
+        $self->{RESPONSE_TYPES} = \%responseTypeHash;
     }
 
     return;
@@ -3310,7 +3572,7 @@ sub queryRestoreHash {
     my $self = shift;
     my $hashentry = shift;
     my $part = shift;
-    $part = "0" if (!defined($part));
+    $part = "0" if (!defined($part) || $part eq '');
     return $self->NETWORK_FAILURE if ($self->{NAV_MAP}->{NETWORK_FAILURE});
 
     $self->getReturnHash();
@@ -3325,10 +3587,15 @@ B<Composite Status>
 Along with directly returning the date or completion status, the
 resource object includes a convenience function B<status>() that will
 combine the two status tidbits into one composite status that can
-represent the status of the resource as a whole. The precise logic is
+represent the status of the resource as a whole. This method represents
+the concept of the thing we want to display to the user on the nav maps
+screen, which is a combination of completion and open status. The precise logic is
 documented in the comments of the status method. The following results
 may be returned, all available as methods on the resource object
-($res->NETWORK_FAILURE):
+($res->NETWORK_FAILURE): In addition to the return values that match
+the date or completion status, this function can return "ANSWER_SUBMITTED"
+if that problemstatus parameter value is set to No, suppressing the
+incorrect/correct feedback.
 
 =over 4
 
@@ -3387,11 +3654,16 @@ The item is open and not yet tried.
 
 The problem has been attempted.
 
+=item * B<ANSWER_SUBMITTED>:
+
+An answer has been submitted, but the student should not see it.
+
 =back
 
 =cut
 
-sub TRIES_LEFT { return 10; }
+sub TRIES_LEFT       { return 20; }
+sub ANSWER_SUBMITTED { return 21; }
 
 sub status {
     my $self = shift;
@@ -3406,10 +3678,12 @@ sub status {
 
     if ($completionStatus == NETWORK_FAILURE) { return NETWORK_FAILURE; }
 
+    my $suppressFeedback = lc($self->parmval("problemstatus", $part)) eq 'no';
+
     # There are a few whole rows we can dispose of:
     if ($completionStatus == CORRECT ||
         $completionStatus == CORRECT_BY_OVERRIDE ) {
-        return CORRECT; 
+        return $suppressFeedback? ANSWER_SUBMITTED : CORRECT; 
     }
 
     if ($completionStatus == ATTEMPTED) {
@@ -3450,7 +3724,7 @@ sub status {
         if ($self->tries($part) < $self->maxtries($part) || !$self->maxtries($part)) {
             return TRIES_LEFT;
         }
-        return INCORRECT; # otherwise, return orange; student can't fix this
+        return $suppressFeedback ? ANSWER_SUBMITTED : INCORRECT; # otherwise, return orange; student can't fix this
     }
 
     # Otherwise, it's untried and open
@@ -3458,6 +3732,48 @@ sub status {
 }
 
 =pod
+
+B<Completable>
+
+The completable method represents the concept of I<whether the student can
+currently do the problem>. If the student can do the problem, which means
+that it is open, there are tries left, and if the problem is manually graded
+or the grade is suppressed via problemstatus, the student has not tried it
+yet, then the method returns 1. Otherwise, it returns 0, to indicate that 
+either the student has tried it and there is no feedback, or that for
+some reason it is no longer completable (not open yet, successfully completed,
+out of tries, etc.). As an example, this is used as the filter for the
+"Uncompleted Homework" option for the nav maps.
+
+If this does not quite meet your needs, do not fiddle with it (unless you are
+fixing it to better match the student's conception of "completable" because
+it's broken somehow)... make a new method.
+
+=cut
+
+sub completable {
+    my $self = shift;
+    if (!$self->is_problem()) { return 0; }
+    my $partCount = $self->countParts();
+
+    foreach my $part (@{$self->parts()}) {
+        if ($part eq '0' && $partCount != 1) { next; }
+        my $status = $self->status($part);
+        # "If any of the parts are open, or have tries left (implies open),
+        # and it is not "attempted" (manually graded problem), it is
+        # not "complete"
+        if (!(($status == OPEN() || $status == TRIES_LEFT()) 
+              && $self->getCompletionStatus($part) != ATTEMPTED()
+              && $status != ANSWER_SUBMITTED())) {
+            return 0;
+        }
+    }
+        
+    # If all the parts were complete, so was this problem.
+    return 1;
+}
+
+=pod
 
 =head2 Resource/Nav Map Navigation