--- loncom/interface/loncommon.pm	2018/01/03 04:20:54	1.1308
+++ loncom/interface/loncommon.pm	2018/01/12 13:33:38	1.1309
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # a pile of common routines
 #
-# $Id: loncommon.pm,v 1.1308 2018/01/03 04:20:54 raeburn Exp $
+# $Id: loncommon.pm,v 1.1309 2018/01/12 13:33:38 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -86,6 +86,8 @@ use MIME::Lite;
 use MIME::Types;
 use File::Copy();
 use File::Path();
+use String::CRC32();
+use Short::URL();
 
 # ---------------------------------------------- Designs
 use vars qw(%defaultdesign);
@@ -17850,6 +17852,142 @@ sub des_decrypt {
     return $plaintext;
 }
 
+sub make_short_symbs {
+    my ($cdom,$cnum,$navmap) = @_;
+    return unless (ref($navmap));
+    my ($numnew,@errors);
+    my @toshorten = &Apache::loncommon::get_env_multiple('form.addtiny');
+    if (@toshorten) {
+        my (%maps,%resources,%titles);
+        &Apache::loncourserespicker::enumerate_course_contents($navmap,\%maps,\%resources,\%titles,
+                                                               'shorturls',$cdom,$cnum);
+        my %tocreate;
+        if (keys(%resources)) {
+            foreach my $item (sort {$a <=> $b} (@toshorten)) {
+                my $symb = $resources{$item};
+                if ($symb) {
+                    $tocreate{$cnum.'&'.$symb} = 1;
+                }
+            }
+        }
+        if (keys(%tocreate)) {
+            my %coursetiny = &Apache::lonnet::dump('tiny',$cdom,$cnum);
+            my $su = Short::URL->new(no_vowels => 1);
+            my $init = '';
+            my (%newunique,%addcourse,%courseonly,%failed);
+            # get lock on tiny db
+            my $now = time;
+            my $lockhash = {
+                                "lock\0$now" => $env{'user.name'}.
+                                                ':'.$env{'user.domain'},
+                            };
+            my $tries = 0;
+            my $gotlock = &Apache::lonnet::newput_dom('tiny',$lockhash,$cdom);
+            my ($code,$error);
+            while (($gotlock ne 'ok') && ($tries<3)) {
+                $tries ++;
+                sleep 1;
+                $gotlock = &Apache::lonnet::newput_dom('uniquecodes',$lockhash,$cdom);
+            }
+            if ($gotlock eq 'ok') {
+                $init = &shorten_symbs($cdom,$init,$su,\%coursetiny,\%tocreate,\%newunique,
+                                       \%addcourse,\%courseonly,\%failed);
+                if (keys(%failed)) {
+                    my $numfailed = scalar(keys(%failed));
+                    push(@errors,&mt('error: could not obtain unique six character URL for [quant,_1,resource]',$numfailed));
+                }
+                if (keys(%newunique)) {
+                    my $putres = &Apache::lonnet::newput_dom('tiny',\%newunique,$cdom);
+                    if ($putres eq 'ok') {
+                        $numnew = scalar(keys(%newunique));
+                        my $newputres = &Apache::lonnet::newput('tiny',\%addcourse,$cdom,$cnum);
+                        unless ($newputres eq 'ok') {
+                            push(@errors,&mt('error: could not store course look-up of short URLs'));
+                        }
+                    } else {
+                        push(@errors,&mt('error: could not store unique six character URLs'));
+                    }
+                }
+                my $dellockres = &Apache::lonnet::del_dom('tiny',["lock\0$now"],$cdom);
+                unless ($dellockres eq 'ok') {
+                    push(@errors,&mt('error: could not release lockfile'));
+                }
+            } else {
+                push(@errors,&mt('error: could not obtain lockfile'));
+            }
+            if (keys(%courseonly)) {
+                my $result = &Apache::lonnet::newput('tiny',\%courseonly,$cdom,$cnum);
+                if ($result ne 'ok') {
+                    push(@errors,&mt('error: could not update course look-up of short URLs'));
+                }
+            }
+        }
+    }
+    return ($numnew,\@errors);
+}
+
+sub shorten_symbs {
+    my ($cdom,$init,$su,$coursetiny,$tocreate,$newunique,$addcourse,$courseonly,$failed) = @_;
+    return unless ((ref($su)) && (ref($coursetiny) eq 'HASH') && (ref($tocreate) eq 'HASH') &&
+                   (ref($newunique) eq 'HASH') && (ref($addcourse) eq 'HASH') &&
+                   (ref($courseonly) eq 'HASH') && (ref($failed) eq 'HASH'));
+    my (%possibles,%collisions);
+    foreach my $key (keys(%{$tocreate})) {
+        my $num = String::CRC32::crc32($key);
+        my $tiny = $su->encode($num,$init);
+        if ($tiny) {
+            $possibles{$tiny} = $key;
+        }
+    }
+    if (!$init) {
+        $init = 1;
+    } else {
+        $init ++;
+    }
+    if (keys(%possibles)) {
+        my @posstiny = keys(%possibles);
+        my $configuname = &Apache::lonnet::get_domainconfiguser($cdom);
+        my %currtiny = &Apache::lonnet::get('tiny',\@posstiny,$cdom,$configuname);
+        if (keys(%currtiny)) {
+            foreach my $key (keys(%currtiny)) {
+                next if ($currtiny{$key} eq '');
+                if ($currtiny{$key} eq $possibles{$key}) {
+                    my ($tcnum,$tsymb) = split(/\&/,$currtiny{$key});
+                    unless (($coursetiny->{$tsymb} eq $key) || ($addcourse->{$tsymb} eq $key) || ($courseonly->{$tsymb} eq $key)) {
+                        $courseonly->{$tsymb} = $key;
+                    }
+                } else {
+                    $collisions{$possibles{$key}} = 1;
+                }
+                delete($possibles{$key});
+            }
+        }
+        foreach my $key (keys(%possibles)) {
+            $newunique->{$key} = $possibles{$key};
+            my ($tcnum,$tsymb) = split(/\&/,$possibles{$key});
+            unless (($coursetiny->{$tsymb} eq $key) || ($addcourse->{$tsymb} eq $key) || ($courseonly->{$tsymb} eq $key)) {
+                $addcourse->{$tsymb} = $key;
+            }
+        }
+    }
+    if (keys(%collisions)) {
+        if ($init <5) {
+            if (!$init) {
+                $init = 1;
+            } else {
+                $init ++;
+            }
+            $init = &shorten_symbs($cdom,$init,$su,$coursetiny,\%collisions,
+                                   $newunique,$addcourse,$courseonly,$failed);
+        } else {
+            foreach my $key (keys(%collisions)) {
+                $failed->{$key} = 1;
+            }
+        }
+    }
+    return $init;
+}
+
 1;
 __END__;