# The LearningOnline Network with CAPA
# Utility functions for managing LON-CAPA LTI interactions 
#
# $Id: ltiutils.pm,v 1.17.2.3 2023/01/23 18:39:46 raeburn Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# LON-CAPA is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#

package LONCAPA::ltiutils;

use strict;
use Net::OAuth;
use Digest::SHA;
use Digest::MD5 qw(md5_hex);
use Encode;
use LWP::UserAgent(); 
use Apache::lonnet;
use Apache::loncommon;
use LONCAPA qw(:DEFAULT :match);

#
# LON-CAPA as LTI Consumer or LTI Provider
#
# Determine if a nonce in POSTed data has expired.
# If unexpired, confirm it has not already been used.
#
# When LON-CAPA is operating as a Consumer, nonce checking
# occurs when a Tool Provider launched from an instance of
# an external tool in a LON-CAPA course makes a request to
# (a) /adm/service/roster or (b) /adm/service/passback to, 
# respectively, retrieve a roster or store the grade for 
# the original launch by a specific user.
#
# When LON-CAPA is operating as a Provider, nonce checking 
# occurs when a user in course context in another LMS (the 
# Consumer) launches an external tool to access a LON-CAPA URL: 
# /adm/lti/ with LON-CAPA symb, map, or deep-link ID appended.
#

sub check_nonce {
    my ($nonce,$timestamp,$lifetime,$domain,$ltidir) = @_;
    if (($ltidir eq '') || ($timestamp eq '') || ($timestamp =~ /^\D/) ||
        ($lifetime eq '') || ($lifetime =~ /\D/) || ($domain eq '')) {
        return;
    }
    my $now = time;
    if (($timestamp) && ($timestamp < ($now - $lifetime))) {
        return;
    }
    if ($nonce eq '') {
        return;
    }
    if (-e "$ltidir/$domain/$nonce") {
        return;
    } else  {
        unless (-e "$ltidir/$domain") {
            unless (mkdir("$ltidir/$domain",0755)) {
                return;
            }
        }
        if (open(my $fh,'>',"$ltidir/$domain/$nonce")) {
            print $fh $now;
            close($fh);
            return 1;
        }
    }
    return;
}

#
# LON-CAPA as LTI Consumer
#
# Verify a signed request using the consumer_key and
# secret for the specific LTI Provider.
#

sub verify_request {
    my ($oauthtype,$protocol,$hostname,$requri,$reqmethod,$consumer_secret,$params,
        $authheaders,$errors) = @_;
    unless (ref($errors) eq 'HASH') {
        $errors->{15} = 1;
        return;
    }
    my $request;
    if ($oauthtype eq 'consumer') {
        my $oauthreq = Net::OAuth->request('consumer');
        $oauthreq->add_required_message_params('body_hash');
        $request = $oauthreq->from_authorization_header($authheaders,
                                  request_url => $protocol.'://'.$hostname.$requri,
                                  request_method => $reqmethod,
                                  consumer_secret => $consumer_secret,);
    } else {
        $request = Net::OAuth->request('request token')->from_hash($params,
                                  request_url => $protocol.'://'.$hostname.$requri,
                                  request_method => $reqmethod,
                                  consumer_secret => $consumer_secret,);
    }
    unless ($request->verify()) {
        $errors->{15} = 1;
        return;
    }
}

#
# LON-CAPA as LTI Consumer
#
# Sign a request used to launch an instance of an external
# tool in a LON-CAPA course, using the key and secret supplied 
# by the Tool Provider.
# 

sub sign_params {
    my ($url,$key,$secret,$paramsref,$sigmethod,$type,$callback,$post) = @_;
    return unless (ref($paramsref) eq 'HASH');
    if ($sigmethod eq '') {
        $sigmethod = 'HMAC-SHA1';
    }
    if ($type eq '') {
        $type = 'request token';
    }
    if ($callback eq '') {
        $callback = 'about:blank',
    }
    srand( time() ^ ($$ + ($$ << 15))  ); # Seed rand.
    my $nonce = Digest::SHA::sha1_hex(sprintf("%06x%06x",rand(0xfffff0),rand(0xfffff0)));
    my $request = Net::OAuth->request($type)->new(
            consumer_key => $key,
            consumer_secret => $secret,
            request_url => $url,
            request_method => 'POST',
            signature_method => $sigmethod,
            timestamp => time,
            nonce => $nonce,
            callback => $callback,
            extra_params => $paramsref,
            version      => '1.0',
            );
    $request->sign();
    if ($post) {
        return $request->to_post_body();
    } else {
        return $request->to_hash();
    }
}

#
# LON-CAPA as LTI Provider
#
# Use the part of the launch URL after /adm/lti to determine
# the scope for the current session (i.e., restricted to a
# single resource, to a single folder/map, or to an entire
# course).
#
# Returns an array containing scope: resource, map, or course
# and the LON-CAPA URL that is displayed post-launch, including
# accommodation of URL encryption, and translation of a tiny URL
# to the actual URL
#

sub lti_provider_scope {
    my ($tail,$cdom,$cnum,$getunenc) = @_;
    my ($scope,$realuri,$passkey,$unencsymb);
    if ($tail =~ m{^/?uploaded/$cdom/$cnum/(?:default|supplemental)(?:|_\d+)\.(?:sequence|page)(|___\d+___.+)$}) {
        my $rest = $1;
        if ($rest eq '') {
            $scope = 'map';
            $realuri = $tail;
        } else {
            my $symb = $tail;
            $symb =~ s{^/}{};
            my ($map,$resid,$url) = &Apache::lonnet::decode_symb($symb);
            $realuri = &Apache::lonnet::clutter($url);
            if ($url =~ /\.sequence$/) {
                $scope = 'map';
            } else {
                $scope = 'resource';
                $realuri .= '?symb='.$symb;
                $passkey = $symb;
                if ($getunenc) {
                    $unencsymb = $symb;
                }
            }
        }
    } elsif ($tail =~ m{^/?res/$match_domain/$match_username/.+\.(?:sequence|page)(|___\d+___.+)$}) {
        my $rest = $1;
        if ($rest eq '') {
            $scope = 'map';
            $realuri = $tail;
        } else {
            my $symb = $tail;
            $symb =~ s{^/?res/}{};
            my ($map,$resid,$url) = &Apache::lonnet::decode_symb($symb);
            $realuri = &Apache::lonnet::clutter($url);
            if ($url =~ /\.sequence$/) {
                $scope = 'map';
            } else {
                $scope = 'resource';
                $realuri .= '?symb='.$symb;
                $passkey = $symb;
                if ($getunenc) {
                    $unencsymb = $symb;
                }
            }
        }
    } elsif ($tail =~ m{^/tiny/$cdom/(\w+)$}) {
        my $key = $1;
        my $tinyurl;
        my ($result,$cached)=&Apache::lonnet::is_cached_new('tiny',$cdom."\0".$key);
        if (defined($cached)) {
            $tinyurl = $result;
        } else {
            my $configuname = &Apache::lonnet::get_domainconfiguser($cdom);
            my %currtiny = &Apache::lonnet::get('tiny',[$key],$cdom,$configuname);
            if ($currtiny{$key} ne '') {
                $tinyurl = $currtiny{$key};
                &Apache::lonnet::do_cache_new('tiny',$cdom."\0".$key,$currtiny{$key},600);
            }
        }
        if ($tinyurl ne '') {
            my ($cnum,$symb) = split(/\&/,$tinyurl,2);
            my ($map,$resid,$url) = &Apache::lonnet::decode_symb($symb);
            if ($url =~ /\.(page|sequence)$/) {
                $scope = 'map';
            } else {
                $scope = 'resource';
            }
            $passkey = $symb;
            if ((&Apache::lonnet::EXT('resource.0.encrypturl',$symb) =~ /^yes$/i) &&
                (!$env{'request.role.adv'})) {
                $realuri = &Apache::lonenc::encrypted(&Apache::lonnet::clutter($url));
                if ($scope eq 'resource') {
                    $realuri .= '?symb='.&Apache::lonenc::encrypted($symb);
                }
            } else {
                $realuri = &Apache::lonnet::clutter($url);
                if ($scope eq 'resource') {
                    $realuri .= '?symb='.$symb;
                }
            }
            if ($getunenc) {
                $unencsymb = $symb;
            }
        }
    } elsif (($tail =~ m{^/$cdom/$cnum$}) || ($tail eq '')) {
        $scope = 'course';
        $realuri = '/adm/navmaps';
        $passkey = '';
    }
    if ($scope eq 'map') {
        $passkey = $realuri;
    }
    if (wantarray) {
        return ($scope,$realuri,$unencsymb);
    } else {
        return $passkey;
    }
}

sub setup_logout_callback {
    my ($uname,$udom,$server,$ckey,$secret,$service_url,$idsdir,$protocol,$hostname) = @_;
    if ($service_url =~ m{^https?://[^/]+/}) {
        my $digest_user = &Encode::decode('UTF-8',$uname.':'.$udom);
        my $loginfile = &Digest::SHA::sha1_hex($digest_user).&md5_hex(&md5_hex(time.{}.rand().$$));
        if ((-d $idsdir) && (open(my $fh,'>',"$idsdir/$loginfile"))) {
            print $fh "$uname,$udom,$server\n";
            close($fh);
            my $callback = 'http://'.$hostname.'/adm/service/logout/'.$loginfile;
            my %ltiparams = (
                callback   => $callback,
            );
            my $post = &sign_params($service_url,$ckey,$secret,\%ltiparams,
                                    '','','',1);

            my $ua=new LWP::UserAgent;
            $ua->timeout(10);
            my $request=new HTTP::Request('POST',$service_url);
            $request->content($post);
            my $response=$ua->request($request); 
        }
    }
    return;
}

#
# LON-CAPA as LTI Provider
#
# Create a new user in LON-CAPA. If the domain's configuration 
# includes rules for format of "official" usernames, those rules
# will apply when determining if a user is to be created.  In
# additional if institutional user information is available that
# will be used when creating a new user account.
#

sub create_user {
    my ($ltiref,$uname,$udom,$domdesc,$data,$alerts,$rulematch,$inst_results,
        $curr_rules,$got_rules) = @_;
    return unless (ref($ltiref) eq 'HASH');
    my $checkhash = { "$uname:$udom" => { 'newuser' => 1, }, };
    my $checks = { 'username' => 1, };
    my ($lcauth,$lcauthparm);
    &Apache::loncommon::user_rule_check($checkhash,$checks,$alerts,$rulematch,
                                        $inst_results,$curr_rules,$got_rules);
    my ($userchkmsg,$lcauth,$lcauthparm);
    my $allowed = 1;
    if (ref($alerts->{'username'}) eq 'HASH') {
         if (ref($alerts->{'username'}{$udom}) eq 'HASH') {
             if ($alerts->{'username'}{$udom}{$uname}) {
                 if (ref($curr_rules->{$udom}) eq 'HASH') {
                     $userchkmsg =
                         &Apache::loncommon::instrule_disallow_msg('username',$domdesc,1).
                         &Apache::loncommon::user_rule_formats($udom,$domdesc,
                                                               $curr_rules->{$udom}{'username'},
                                                               'username');
                 }
                 $allowed = 0;
             }
         }
    }
    if ($allowed) {
        if (ref($rulematch->{$uname.':'.$udom}) eq 'HASH') {
            my $matchedrule = $rulematch->{$uname.':'.$udom}{'username'};
            my ($rules,$ruleorder) =
                &Apache::lonnet::inst_userrules($udom,'username');
            if (ref($rules) eq 'HASH') {
                if (ref($rules->{$matchedrule}) eq 'HASH') {
                    $lcauth = $rules->{$matchedrule}{'authtype'};
                    $lcauthparm = $rules->{$matchedrule}{'authparm'};
                }
            }
        }
        if ($lcauth eq '') {
            $lcauth = $ltiref->{'lcauth'};
            if ($lcauth eq 'internal') {
                $lcauthparm = &create_passwd();
            } else {
                $lcauthparm = $ltiref->{'lcauthparm'};
            }
        }
    } else {
        return 'notallowed';
    }
    my @userinfo = ('firstname','middlename','lastname','generation','permanentemail','id');
    my (%useinstdata,%info);
    if (ref($ltiref->{'instdata'}) eq 'ARRAY') {
        map { $useinstdata{$_} = 1; } @{$ltiref->{'instdata'}};
    }
    foreach my $item (@userinfo) {
        if (($useinstdata{$item}) && (ref($inst_results->{$uname.':'.$udom}) eq 'HASH') &&
            ($inst_results->{$uname.':'.$udom}{$item} ne '')) {
            $info{$item} = $inst_results->{$uname.':'.$udom}{$item};
        } else {
            if ($item eq 'permanentemail') {
                if ($data->{'permanentemail'} =~/^[^\@]+\@[^@]+$/) {
                    $info{$item} = $data->{'permanentemail'};
                }
            } elsif (($item eq 'firstname') || ($item eq 'lastname')) {
                $info{$item} = $data->{$item};
            }
        }
    }
    if (($info{'middlename'} eq '') && ($data->{'fullname'} ne '')) {
        unless ($useinstdata{'middlename'}) {
            my $fullname = $data->{'fullname'};
            if ($info{'firstname'}) {
                $fullname =~ s/^\s*\Q$info{'firstname'}\E\s*//i;
            }
            if ($info{'lastname'}) {
                $fullname =~ s/\s*\Q$info{'lastname'}\E\s*$//i;
            }
            if ($fullname ne '') {
                $fullname =~ s/^\s+|\s+$//g;
                if ($fullname ne '') {
                    $info{'middlename'} = $fullname;
                }
            }
        }
    }
    if (ref($inst_results->{$uname.':'.$udom}{'inststatus'}) eq 'ARRAY') {
        my @inststatuses = @{$inst_results->{$uname.':'.$udom}{'inststatus'}};
        $info{'inststatus'} = join(':',map { &escape($_); } @inststatuses);
    }
    my $result =
        &Apache::lonnet::modifyuser($udom,$uname,$info{'id'},
                                    $lcauth,$lcauthparm,$info{'firstname'},
                                    $info{'middlename'},$info{'lastname'},
                                    $info{'generation'},undef,undef,
                                    $info{'permanentemail'},$info{'inststatus'});
    return $result;
}

#
# LON-CAPA as LTI Provider
#
# Create a password for a new user if the authentication
# type to assign to new users created following LTI launch is
# to be LON-CAPA "internal".
#

sub create_passwd {
    my $passwd = '';
    srand( time() ^ ($$ + ($$ << 15))  ); # Seed rand.
    my @letts = ("a".."z");
    for (my $i=0; $i<8; $i++) {
        my $lettnum = int(rand(2));
        my $item = '';
        if ($lettnum) {
            $item = $letts[int(rand(26))];
            my $uppercase = int(rand(2));
            if ($uppercase) {
                $item =~ tr/a-z/A-Z/;
            }
        } else {
            $item = int(rand(10));
        }
        $passwd .= $item;
    }
    return ($passwd);
}

#
# LON-CAPA as LTI Provider
#
# Enroll a user in a LON-CAPA course, with the specified role and (optional)
# section.  If this is a self-enroll case, i.e., a user launched the LTI tool
# in the Consumer, user privs will be added to the user's environment for
# the new role.
#
# If this is a self-enroll case, a Course Coordinator role will only be assigned 
# if the current user is also the course owner.
#

sub enrolluser {
    my ($udom,$uname,$role,$cdom,$cnum,$sec,$start,$end,$selfenroll) = @_;
    my $enrollresult;
    my $area = "/$cdom/$cnum";
    if (($role ne 'cc') && ($role ne 'co') && ($sec ne '')) {
        $area .= '/'.$sec;
    }
    my $spec = $role.'.'.$area;
    my $instcid;
    if ($role eq 'st') {
        $enrollresult =
            &Apache::lonnet::modify_student_enrollment($udom,$uname,undef,undef,undef,
                                                       undef,undef,$sec,$end,$start,
                                                       'ltienroll',undef,$cdom.'_'.$cnum,
                                                       $selfenroll,'ltienroll','',$instcid);
    } elsif ($role =~ /^(cc|in|ta|ep)$/) {
        $enrollresult =
            &Apache::lonnet::assignrole($udom,$uname,$area,$role,$end,$start,
                                        undef,$selfenroll,'ltienroll');
    }
    if ($enrollresult eq 'ok') {
        if ($selfenroll) {
            my (%userroles,%newrole,%newgroups);
            &Apache::lonnet::standard_roleprivs(\%newrole,$role,$cdom,$spec,$cnum,
                                                $area);
            &Apache::lonnet::set_userprivs(\%userroles,\%newrole,\%newgroups);
            $userroles{'user.role.'.$spec} = $start.'.'.$end;
            &Apache::lonnet::appenv(\%userroles,[$role,'cm']);
        }
    }
    return $enrollresult;
}

#
# LON-CAPA as LTI Provider
#
# Gather a list of available LON-CAPA roles derived
# from a comma separated list of LTI roles.
#
# Which LON-CAPA roles are assignable by the current user
# and how LTI roles map to LON-CAPA roles (as defined in
# the domain configuration for the specific Consumer) are 
# factored in when compiling the list of available roles.
#
# Inputs: 3
#  $rolestr - comma separated list of LTI roles.
#  $allowedroles - reference to array of assignable LC roles
#  $maproles - ref to HASH of mapping of LTI roles to LC roles
#
# Outputs: 2
# (a) reference to array of available LC roles.
# (b) reference to array of LTI roles.
#

sub get_lc_roles {
    my ($rolestr,$allowedroles,$maproles) = @_;
    my (@ltiroles,@lcroles);
    my @ltiroleorder = ('Instructor','TeachingAssistant','Mentor','Learner');
    if ($rolestr =~ /,/) {
        my @possltiroles = split(/\s*,\s*/,$rolestr);
        foreach my $ltirole (@ltiroleorder) {
            if (grep(/^\Q$ltirole\E$/,@possltiroles)) {
                push(@ltiroles,$ltirole);
            }
        }
    } else {
        my $singlerole = $rolestr;
        $singlerole =~ s/^\s|\s+$//g;
        if ($singlerole ne '') {
            if (grep(/^\Q$singlerole\E$/,@ltiroleorder)) {
                @ltiroles = ($singlerole);
            }
        }
    }
    if (@ltiroles) {
        my %possroles;
        map { $possroles{$maproles->{$_}} = 1; } @ltiroles;
        if (keys(%possroles) > 0) {
            if (ref($allowedroles) eq 'ARRAY') {
                foreach my $item (@{$allowedroles}) {
                    if (($item eq 'co') || ($item eq 'cc')) {
                        if ($possroles{'cc'}) {
                            push(@lcroles,$item);
                        }
                    } elsif ($possroles{$item}) {
                        push(@lcroles,$item);
                    }
                }
            }
        }
    }
    return (\@lcroles,\@ltiroles);
}

1;