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<?php
use Courseware\Block;
use Lti\Registration;
use Studip\LTIException;
class Courseware_LtiController extends AuthenticatedController
{
/**
* Display the launch form for a tool as an iframe in a courseware LTI block.
*
* @param Block $cwBlock courseware block
*/
public function launch_action(Block $cwBlock): void
{
if (!$cwBlock->container->structural_element->canRead(User::findCurrent())) {
throw new AccessDeniedException();
}
$ltiLink = $this->getLtiLink($cwBlock);
$this->launchUrl = $ltiLink->getLaunchURL();
$this->launchData = $ltiLink->getBasicLaunchData();
$this->signature = $ltiLink->getLaunchSignature($this->launchData);
$this->set_layout(null);
$this->render_template('lti/1p1/index/launch');
}
/**
* Return an LtiLink object for the passed courseware LTI block.
*
* @param Block $cw_block courseware LTI block
*
* @return LtiLink LTI link representation
*/
public function getLtiLink(Block $cw_block): LtiLink
{
$block_payload = json_decode($cw_block->payload, true);
// Collect LTI Data from courseware block payload
$id = $cw_block->id;
$context_id = Context::getId();
$range_id = $cw_block->getStructuralElement()->range_id;
$title = trim($block_payload['title']);
$tool_id = $block_payload['tool_id'];
$launch_url = trim($block_payload['launch_url']);
$custom_parameters = trim($block_payload['custom_parameters']);
$document_target = 'iframe';
if ($tool_id) {
$tool = Registration::findTool($tool_id);
if ($tool->version !== '1.1') {
throw new LTIException('Only LTI 1.1 tools are currently supported.');
}
$toolConfigs = $tool->getConfigValues();
// Prefer custom url
if (empty($toolConfigs['allow_custom_url'])) {
$launch_url = $toolConfigs['launch_url'];
}
$consumer_key = $toolConfigs['consumer_key'];
$consumer_secret = $toolConfigs['consumer_secret'];
$send_lis_person = $toolConfigs['send_lis_person'];
$oauth_signature_method = $toolConfigs['oauth_signature_method'];
$custom_parameters = $toolConfigs['custom_parameters'] ?? '' . "\n" . $custom_parameters;
} else {
$consumer_key = trim($block_payload['consumer_key']);
$consumer_secret = trim($block_payload['consumer_secret']);
$send_lis_person = $block_payload['send_lis_person'];
$oauth_signature_method = $block_payload['oauth_signature_method'] ?? 'sha1';
}
if ($context_id) {
// Role in course
$roles = $GLOBALS['perm']->have_studip_perm('tutor', $context_id) ? 'Instructor' : 'Learner';
} else {
// Role in workspace
$roles = $range_id === $GLOBALS['user']->id ? 'Instructor' : 'Learner';
}
$resourceDescription = $tool ? kill_format($tool->description) : '';
// Create LTI Link for setting up launch request
$lti_link = new LtiLink($launch_url, $consumer_key, $consumer_secret, $oauth_signature_method);
$lti_link->setResource($id, $title, $resourceDescription);
$lti_link->setUser(User::findCurrent(), $roles, $send_lis_person);
$lti_link->setCourse($range_id);
$lti_link->addLaunchParameters([
'launch_presentation_locale' => str_replace('_', '-', $_SESSION['_language']),
'launch_presentation_document_target' => $document_target,
]);
$custom_parameters = explode("\n", $custom_parameters);
foreach ($custom_parameters as $param) {
if (strpos($param, '=') !== false) {
list($key, $value) = explode('=', $param, 2);
$lti_link->addCustomParameter(trim($key), trim($value));
}
}
return $lti_link;
}
}
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