1: # The LearningOnline Network with CAPA
2: # Handler to resolve ambiguous file locations
3: #
4: # $Id: lonambiguous.pm,v 1.19 2006/03/19 23:09:07 albertel Exp $
5: #
6: # Copyright Michigan State University Board of Trustees
7: #
8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
9: #
10: # LON-CAPA is free software; you can redistribute it and/or modify
11: # it under the terms of the GNU General Public License as published by
12: # the Free Software Foundation; either version 2 of the License, or
13: # (at your option) any later version.
14: #
15: # LON-CAPA is distributed in the hope that it will be useful,
16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18: # GNU General Public License for more details.
19: #
20: # You should have received a copy of the GNU General Public License
21: # along with LON-CAPA; if not, write to the Free Software
22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23: #
24: # /home/httpd/html/adm/gpl.txt
25: #
26: # http://www.lon-capa.org/
27: #
28:
29: package Apache::lonambiguous;
30:
31: use strict;
32: use Apache::lonnet;
33: use Apache::Constants qw(:common REDIRECT);
34: use GDBM_File;
35: use Apache::loncommon;
36: use Apache::lonlocal;
37:
38: my %bighash;
39:
40: sub cleanup {
41: if (tied(%bighash)){
42: &Apache::lonnet::logthis('Cleanup ambiguous: bighash');
43: unless (untie(%bighash)) {
44: &Apache::lonnet::logthis('Failed cleanup ambiguous: bighash');
45: }
46: }
47: return OK;
48: }
49:
50: # ----------------------------------------------------------- Could not resolve
51:
52: sub getlost {
53: my ($r,$errmsg)=@_;
54: $errmsg=&mt($errmsg);
55: &Apache::loncommon::content_type($r,'text/html');
56: $r->send_http_header;
57: $r->print(&Apache::loncommon::start_page('Could not handle ambiguous resource reference').
58: $errmsg.
59: &Apache::loncommon::end_page());
60: }
61:
62: # ================================================================ Main Handler
63:
64: sub make_symb {
65: my ($id)=@_;
66: my ($mapid,$resid)=split(/\./,$id);
67: my $map=$bighash{'map_id_'.$mapid};
68: my $res=$bighash{'src_'.$id};
69: my $symb=&Apache::lonnet::encode_symb($map,$resid,$res);
70: return $symb;
71: }
72:
73: sub handler {
74: my $r=shift;
75:
76: if ($r->header_only) {
77: &Apache::loncommon::content_type($r,'text/html');
78: $r->send_http_header;
79: return OK;
80: }
81:
82: # ---------------------------------------------------------- Is this selecting?
83:
84: if ($env{'form.selecturl'}) {
85: my $envkey;
86: if (tie(%bighash,'GDBM_File',$env{'request.course.fn'}.'.db',
87: &GDBM_READER(),0640)) {
88: foreach $envkey (keys %env) {
89: if ($envkey=~/^form\.(\d+)\.(\d+)$/) {
90: # ---------------------------------------------------- Update symb and redirect
91: my $mapid=$1;
92: my $resid=$2;
93: my $resurl=$bighash{'src_'.$mapid.'.'.$resid};
94: &Apache::lonnet::symblist($bighash{'map_id_'.$mapid},
95: $resurl => [$resurl,$resid]);
96: untie(%bighash);
97: $r->header_out(Location =>
98: 'http://'.$ENV{'HTTP_HOST'}.$resurl);
99: return REDIRECT;
100: }
101: }
102: untie(%bighash);
103: } else {
104: &getlost($r,'Could not access course structure.');
105: return OK;
106: }
107: }
108:
109: # ---------------------------------------------------------- Do we have a case?
110:
111: my $thisfn;
112: unless (($thisfn=$env{'request.ambiguous'})&&($env{'request.course.fn'})) {
113: &getlost($r,'Could not find information on resource.');
114: return OK;
115: }
116:
117: # ---------------------------------- Should this file have been part of a page?
118:
119: $thisfn=&Apache::lonnet::declutter($thisfn);
120: my %hash;
121: my $syval='';
122:
123: if (tie(%hash,'GDBM_File',$env{'request.course.fn'}.'_symb.db',
124: &GDBM_READER(),0640)) {
125: $syval=$hash{$thisfn};
126: untie(%hash);
127: }
128:
129: # ---------------------------------------------------------- There was an entry
130:
131: if ($syval) {
132: my ($page,undef,$res)=&Apache::lonnet::decode_symb($syval);
133: if ($res eq 'page') {
134: # ----------------------------------- Okay, this should have appeared on a page
135: &Apache::loncommon::content_type($r,'text/html');
136: $r->header_out(Location =>
137: 'http://'.$ENV{'HTTP_HOST'}.
138: &Apache::lonnet::clutter($page));
139: return REDIRECT;
140: } else {
141: # There is not really a problem (???), but cannot go back without endless loop
142: &getlost($r,'The nature of the problem is unclear');
143: return OK;
144: }
145: }
146: # ------------------------------------Encrypted requests go straight to navmaps
147: if ($env{'request.enc'}) {
148: &Apache::loncommon::content_type($r,'text/html');
149: $r->header_out(Location => 'http://'.$ENV{'HTTP_HOST'}.'/adm/navmaps');
150: return REDIRECT;
151: }
152: # ------------------------------------------------ Would be standalone resource
153:
154: if (tie(%bighash,'GDBM_File',$env{'request.course.fn'}.'.db',
155: &GDBM_READER(),0640)) {
156: # ---------------------------------------------- Get ID(s) for current resource
157: my $ids=$bighash{'ids_'.&Apache::lonnet::clutter($thisfn)};
158: if ($ids) {
159: # ------------------------------------------------------------------- Has ID(s)
160: my @possibilities=split(/\,/,$ids);
161: my $couldbe='';
162: foreach (@possibilities) {
163: if ($bighash{'encrypted_'.$_}) { next; }
164: my $symb=&make_symb($_);
165: if (&Apache::lonnet::allowed('bre',$bighash{'src_'.$_},$symb)) {
166: if ($couldbe) {
167: $couldbe.=','.$_;
168: } else {
169: $couldbe=$_;
170: }
171: }
172: }
173: if ($couldbe) {
174: @possibilities=split(/\,/,$couldbe);
175: if ($#possibilities==0) {
176: my $id=$possibilities[0];
177: my $resurl=$bighash{'src_'.$id};
178: my $mapurl=$bighash{'map_id_'.(split(/\./,$id))[0]};
179: my $symb=&make_symb($id);
180: &Apache::loncommon::content_type($r,'text/html');
181: &Apache::lonnet::logthis('http://'.$ENV{'HTTP_HOST'}.$resurl.'?symb='.$symb);
182: $r->header_out(Location =>
183: 'http://'.$ENV{'HTTP_HOST'}.$resurl.'?symb='.$symb);
184: return REDIRECT;
185: }
186: if ($#possibilities>0) {
187: # ----------------------------------------------- Okay, really multiple choices
188: &Apache::loncommon::content_type($r,'text/html');
189: $r->send_http_header;
190: my $start_page=
191: &Apache::loncommon::start_page('Pick Instance of Resource');
192: $r->print(<<ENDSTART);
193: $start_page
194: The resource you had been accessing appears more than once in this course,
195: and LON-CAPA has insufficient session information to determine which instance
196: of the resource you meant.
197: <p>
198: Please click on the instance of the resource you intended to access:
199: </p>
200: <table border="2">
201: <tr><th>Title</th><th>Part of ...</th></tr>
202: ENDSTART
203: map {
204: my $resurl=$bighash{'src_'.$_};
205: my $mapurl=$bighash{'map_id_'.(split(/\./,$_))[0]};
206: my $symb=&make_symb($_);
207: $r->print('<tr><td><a href="'.$resurl.'?symb='.$symb.'">'.
208: &Apache::lonnet::gettitle($symb).
209: '</a></td><td>'.
210: &Apache::lonnet::gettitle($mapurl).' '.
211: '</td></tr>');
212: } @possibilities;
213: $r->print('</table>'.&Apache::loncommon::end_page());
214: untie(%bighash);
215: return OK;
216: }
217: }
218: }
219: untie(%bighash);
220: }
221:
222: # ------------------------------------ This handler should not have been called
223: &getlost($r,'Invalid call of handler');
224: return OK;
225: }
226:
227: 1;
228: __END__
229:
230:
231:
232:
233:
234:
235:
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