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<?php
class Courseware_LtiController extends AuthenticatedController
{
/**
* Display the launch form for a tool as an iframe in a courseware LTI block.
*
* @param int $block_id courseware block id
*/
public function iframe_action($block_id)
{
$cw_block = \Courseware\Block::find($block_id);
if (!$cw_block->container->structural_element->canRead($GLOBALS['user']->id)) {
throw new AccessDeniedException();
}
$cw_block = \Courseware\Block::find($block_id);
$lti_link = $this->getLtiLink($cw_block);
$this->launch_url = $lti_link->getLaunchURL();
$this->launch_data = $lti_link->getBasicLaunchData();
$this->signature = $lti_link->getLaunchSignature($this->launch_data);
$this->set_layout(null);
$this->render_template('course/lti/iframe');
}
/**
* Return an LtiLink object for the passed courseware LTI block.
*
* @param \Courseware\Block $cw_block courseware LTI block
*
* @return LtiLink LTI link representation
*/
public function getLtiLink($cw_block)
{
$block_payload = json_decode($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) {
$tool = LtiTool::find($tool_id);
// Prefer custom url
if (!$tool->allow_custom_url && !$tool->deep_linking || !$launch_url) {
$launch_url = $tool->launch_url;
}
$consumer_key = $tool->consumer_key;
$consumer_secret = $tool->consumer_secret;
$send_lis_person = $tool->send_lis_person;
$oauth_signature_method = $tool->oauth_signature_method;
$custom_parameters = $tool->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';
}
// 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);
$lti_link->setUser($GLOBALS['user']->id, $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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