1: # The LearningOnline Network with CAPA
2: # Handler to resolve ambiguous file locations
3: #
4: # $Id: lonambiguous.pm,v 1.12 2004/12/20 20:13:03 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: # (TeX Content Handler
29: #
30: # 05/29/00,05/30,10/11 Gerd Kortemeyer)
31: #
32: # 10/11,10/12,10/16 Gerd Kortemeyer
33:
34: package Apache::lonambiguous;
35:
36: use strict;
37: use Apache::lonnet;
38: use Apache::Constants qw(:common REDIRECT);
39: use GDBM_File;
40: use Apache::loncommon;
41: use Apache::lonlocal;
42:
43: my %bighash;
44:
45: sub cleanup {
46: if (tied(%bighash)){
47: &Apache::lonnet::logthis('Cleanup ambiguous: bighash');
48: unless (untie(%bighash)) {
49: &Apache::lonnet::logthis('Failed cleanup ambiguous: bighash');
50: }
51: }
52: }
53:
54: # ----------------------------------------------------------- Could not resolve
55:
56: sub getlost {
57: my ($r,$errmsg)=@_;
58: $errmsg=&mt($errmsg);
59: $r->content_type('text/html');
60: $r->send_http_header;
61: $r->print(
62: '<head><title>Unknown Error</title></head>'.
63: &Apache::loncommon::bodytag('Could not handle ambiguous resource reference').
64: $errmsg.
65: '</body></html>');
66: }
67:
68: # ================================================================ Main Handler
69:
70: sub make_symb {
71: my ($id)=@_;
72: my ($mapid,$resid)=split(/\./,$id);
73: my $map=$bighash{'map_id_'.$mapid};
74: my $res=$bighash{'src_'.$id};
75: my $symb=&Apache::lonnet::encode_symb($map,$resid,$res);
76: return $symb;
77: }
78:
79: sub handler {
80: my $r=shift;
81:
82: if ($r->header_only) {
83: &Apache::loncommon::content_type($r,'text/html');
84: $r->send_http_header;
85: return OK;
86: }
87:
88: # ---------------------------------------------------------- Is this selecting?
89:
90: if ($ENV{'form.selecturl'}) {
91: my $envkey;
92: if (tie(%bighash,'GDBM_File',$ENV{'request.course.fn'}.'.db',
93: &GDBM_READER(),0640)) {
94: foreach $envkey (keys %ENV) {
95: if ($envkey=~/^form\.(\d+)\.(\d+)$/) {
96: # ---------------------------------------------------- Update symb and redirect
97: my $mapid=$1;
98: my $resid=$2;
99: my $resurl=$bighash{'src_'.$mapid.'.'.$resid};
100: &Apache::lonnet::symblist($bighash{'map_id_'.$mapid},
101: $resurl => $resid);
102: untie(%bighash);
103: $r->header_out(Location =>
104: 'http://'.$ENV{'HTTP_HOST'}.$resurl);
105: return REDIRECT;
106: }
107: }
108: untie(%bighash);
109: } else {
110: &getlost($r,'Could not access course structure.');
111: return OK;
112: }
113: }
114:
115: # ---------------------------------------------------------- Do we have a case?
116:
117: my $thisfn;
118: unless (($thisfn=$ENV{'request.ambiguous'})&&($ENV{'request.course.fn'})) {
119: &getlost($r,'Could not find information on resource.');
120: return OK;
121: }
122:
123: # ---------------------------------- Should this file have been part of a page?
124:
125: $thisfn=&Apache::lonnet::declutter($thisfn);
126: my %hash;
127: my $syval='';
128:
129: if (tie(%hash,'GDBM_File',$ENV{'request.course.fn'}.'_symb.db',
130: &GDBM_READER(),0640)) {
131: $syval=$hash{$thisfn};
132: untie(%hash);
133: }
134:
135: # ---------------------------------------------------------- There was an entry
136:
137: if ($syval) {
138:
139: if ($syval=~/\_$/) {
140: # ----------------------------------- Okay, this should have appeared on a page
141: $syval=~s/\_\_\_$//;
142: $r->content_type('text/html');
143: $r->header_out(Location =>
144: 'http://'.$ENV{'HTTP_HOST'}.'/res/'.$syval);
145: return REDIRECT;
146: } else {
147: # There is not really a problem (???), but cannot go back without endless loop
148: &getlost($r,'The nature of the problem is unclear');
149: return OK;
150: }
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: $r->content_type('text/html');
181: &Apache::lonnet::logthis('http://'.$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: $r->content_type('text/html');
189: $r->send_http_header;
190: my $bodytag=
191: &Apache::loncommon::bodytag('Pick Instance of Resource');
192: $r->print(<<ENDSTART);
193: <head><title>Choose Location</title></head>
194: $bodytag
195: The resource you had been accessing appears more than once in this course,
196: and LON-CAPA has insufficient session information to determine which instance
197: of the resource you meant.
198: <p>
199: Please click on the instance of the resource you intended to access:
200: </p>
201: <table border="2">
202: <tr><th>Title</th><th>Part of ...</th></tr>
203: ENDSTART
204: map {
205: my $resurl=$bighash{'src_'.$_};
206: my $mapurl=$bighash{'map_id_'.(split(/\./,$_))[0]};
207: my $symb=&make_symb($_);
208: $r->print('<tr><td><a href="'.$resurl.'?symb='.$symb.'">'.
209: &Apache::lonnet::gettitle($symb).
210: '</a></td><td>'.
211: &Apache::lonnet::gettitle($mapurl).' '.
212: '</td></tr>');
213: } @possibilities;
214: $r->print('</table></body></html>');
215: untie(%bighash);
216: return OK;
217: }
218: }
219: }
220: untie(%bighash);
221: }
222:
223: # ------------------------------------ This handler should not have been called
224: &getlost($r,'Invalid call of handler');
225: return OK;
226: }
227:
228: 1;
229: __END__
230:
231:
232:
233:
234:
235:
236:
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