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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Base class for conditional availability information (for module or section).
*
* @package core_availability
* @copyright 2014 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_availability;
defined('MOODLE_INTERNAL') || die();
/**
* Base class for conditional availability information (for module or section).
*
* @package core_availability
* @copyright 2014 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class info {
/** @var \stdClass Course */
protected $course;
/** @var \course_modinfo Modinfo (available only during some functions) */
protected $modinfo = null;
/** @var bool Visibility flag (eye icon) */
protected $visible;
/** @var string Availability data as JSON string */
protected $availability;
/** @var tree Availability configuration, decoded from JSON; null if unset */
protected $availabilitytree;
/** @var array|null Array of information about current restore if any */
protected static $restoreinfo = null;
/**
* Constructs with item details.
*
* @param \stdClass $course Course object
* @param int $visible Value of visible flag (eye icon)
* @param string $availability Availability definition (JSON format) or null
* @throws \coding_exception If data is not valid JSON format
*/
public function __construct($course, $visible, $availability) {
// Set basic values.
$this->course = $course;
$this->visible = (bool)$visible;
$this->availability = $availability;
}
/**
* Obtains the course associated with this availability information.
*
* @return \stdClass Moodle course object
*/
public function get_course() {
return $this->course;
}
/**
* Gets context used for checking capabilities for this item.
*
* @return \context Context for this item
*/
public abstract function get_context();
/**
* Obtains the modinfo associated with this availability information.
*
* Note: This field is available ONLY for use by conditions when calculating
* availability or information.
*
* @return \course_modinfo Modinfo
* @throws \coding_exception If called at incorrect times
*/
public function get_modinfo() {
if (!$this->modinfo) {
throw new \coding_exception(
'info::get_modinfo available only during condition checking');
}
return $this->modinfo;
}
/**
* Gets the availability tree, decoding it if not already done.
*
* @return tree Availability tree
*/
public function get_availability_tree() {
if (is_null($this->availabilitytree)) {
if (is_null($this->availability)) {
throw new \coding_exception(
'Cannot call get_availability_tree with null availability');
}
$this->availabilitytree = $this->decode_availability($this->availability, true);
}
return $this->availabilitytree;
}
/**
* Decodes availability data from JSON format.
*
* This function also validates the retrieved data as follows:
* 1. Data that does not meet the API-defined structure causes a
* coding_exception (this should be impossible unless there is
* a system bug or somebody manually hacks the database).
* 2. Data that meets the structure but cannot be implemented (e.g.
* reference to missing plugin or to module that doesn't exist) is
* either silently discarded (if $lax is true) or causes a
* coding_exception (if $lax is false).
*
* @param string $availability Availability string in JSON format
* @param boolean $lax If true, throw exceptions only for invalid structure
* @return tree Availability tree
* @throws \coding_exception If data is not valid JSON format
*/
protected function decode_availability($availability, $lax) {
// Decode JSON data.
$structure = json_decode($availability);
if (is_null($structure)) {
throw new \coding_exception('Invalid availability text', $availability);
}
// Recursively decode tree.
return new tree($structure, $lax);
}
/**
* Determines whether this particular item is currently available
* according to the availability criteria.
*
* - This does not include the 'visible' setting (i.e. this might return
* true even if visible is false); visible is handled independently.
* - This does not take account of the viewhiddenactivities capability.
* That should apply later.
*
* Depending on options selected, a description of the restrictions which
* mean the student can't view it (in HTML format) may be stored in
* $information. If there is nothing in $information and this function
* returns false, then the activity should not be displayed at all.
*
* This function displays debugging() messages if the availability
* information is invalid.
*
* @param string $information String describing restrictions in HTML format
* @param bool $grabthelot Performance hint: if true, caches information
* required for all course-modules, to make the front page and similar
* pages work more quickly (works only for current user)
* @param int $userid If set, specifies a different user ID to check availability for
* @param \course_modinfo $modinfo Usually leave as null for default. Specify when
* calling recursively from inside get_fast_modinfo()
* @return bool True if this item is available to the user, false otherwise
*/
public function is_available(&$information, $grabthelot = false, $userid = 0,
\course_modinfo $modinfo = null) {
global $USER;
// Default to no information.
$information = '';
// Do nothing if there are no availability restrictions.
if (is_null($this->availability)) {
return true;
}
// Resolve optional parameters.
if (!$userid) {
$userid = $USER->id;
}
if (!$modinfo) {
$modinfo = get_fast_modinfo($this->course, $userid);
}
$this->modinfo = $modinfo;
// Get availability from tree.
try {
$tree = $this->get_availability_tree();
$result = $tree->check_available(false, $this, $grabthelot, $userid);
} catch (\coding_exception $e) {
$this->warn_about_invalid_availability($e);
$this->modinfo = null;
return false;
}
// See if there are any messages.
if ($result->is_available()) {
$this->modinfo = null;
return true;
} else {
// If the item is marked as 'not visible' then we don't change the available
// flag (visible/available are treated distinctly), but we remove any
// availability info. If the item is hidden with the eye icon, it doesn't
// make sense to show 'Available from <date>' or similar, because even
// when that date arrives it will still not be available unless somebody
// toggles the eye icon.
if ($this->visible) {
$information = $tree->get_result_information($this, $result);
}
$this->modinfo = null;
return false;
}
}
/**
* Checks whether this activity is going to be available for all users.
*
* Normally, if there are any conditions, then it may be hidden depending
* on the user. However in the case of date conditions there are some
* conditions which will definitely not result in it being hidden for
* anyone.
*
* @return bool True if activity is available for all
*/
public function is_available_for_all() {
if (is_null($this->availability)) {
return true;
} else {
try {
return $this->get_availability_tree()->is_available_for_all();
} catch (\coding_exception $e) {
$this->warn_about_invalid_availability($e);
return false;
}
}
}
/**
* Obtains a string describing all availability restrictions (even if
* they do not apply any more). Used to display information for staff
* editing the website.
*
* The modinfo parameter must be specified when it is called from inside
* get_fast_modinfo, to avoid infinite recursion.
*
* This function displays debugging() messages if the availability
* information is invalid.
*
* @param \course_modinfo $modinfo Usually leave as null for default
* @return string Information string (for admin) about all restrictions on
* this item
*/
public function get_full_information(\course_modinfo $modinfo = null) {
// Do nothing if there are no availability restrictions.
if (is_null($this->availability)) {
return '';
}
// Resolve optional parameter.
if (!$modinfo) {
$modinfo = get_fast_modinfo($this->course);
}
$this->modinfo = $modinfo;
try {
$result = $this->get_availability_tree()->get_full_information($this);
$this->modinfo = null;
return $result;
} catch (\coding_exception $e) {
$this->warn_about_invalid_availability($e);
return false;
}
}
/**
* In some places we catch coding_exception because if a bug happens, it
* would be fatal for the course page GUI; instead we just show a developer
* debug message.
*
* @param \coding_exception $e Exception that occurred
*/
protected function warn_about_invalid_availability(\coding_exception $e) {
$name = $this->get_thing_name();
// If it occurs while building modinfo based on somebody calling $cm->name,
// we can't get $cm->name, and this line will cause a warning.
$htmlname = @$this->format_info($name, $this->course);
if ($htmlname === '') {
// So instead use the numbers (cmid) from the tag.
$htmlname = preg_replace('~[^0-9]~', '', $name);
}
$info = 'Error processing availability data for &lsquo;' . $htmlname
. '&rsquo;: ' . s($e->a);
debugging($info, DEBUG_DEVELOPER);
}
/**
* Called during restore (near end of restore). Updates any necessary ids
* and writes the updated tree to the database. May output warnings if
* necessary (e.g. if a course-module cannot be found after restore).
*
* @param string $restoreid Restore identifier
* @param int $courseid Target course id
* @param \base_logger $logger Logger for any warnings
* @param int $dateoffset Date offset to be added to any dates (0 = none)
* @param \base_task $task Restore task
*/
public function update_after_restore($restoreid, $courseid, \base_logger $logger,
$dateoffset, \base_task $task) {
$tree = $this->get_availability_tree();
// Set static data for use by get_restore_date_offset function.
self::$restoreinfo = array('restoreid' => $restoreid, 'dateoffset' => $dateoffset,
'task' => $task);
$changed = $tree->update_after_restore($restoreid, $courseid, $logger,
$this->get_thing_name());
if ($changed) {
// Save modified data.
if ($tree->is_empty()) {
// If the tree is empty, but the tree has changed, remove this condition.
$this->set_in_database(null);
} else {
$structure = $tree->save();
$this->set_in_database(json_encode($structure));
}
}
}
/**
* Gets the date offset (amount by which any date values should be
* adjusted) for the current restore.
*
* @param string $restoreid Restore identifier
* @return int Date offset (0 if none)
* @throws coding_exception If not in a restore (or not in that restore)
*/
public static function get_restore_date_offset($restoreid) {
if (!self::$restoreinfo) {
throw new coding_exception('Only valid during restore');
}
if (self::$restoreinfo['restoreid'] !== $restoreid) {
throw new coding_exception('Data not available for that restore id');
}
return self::$restoreinfo['dateoffset'];
}
/**
* Gets the restore task (specifically, the task that calls the
* update_after_restore method) for the current restore.
*
* @param string $restoreid Restore identifier
* @return \base_task Restore task
* @throws coding_exception If not in a restore (or not in that restore)
*/
public static function get_restore_task($restoreid) {
if (!self::$restoreinfo) {
throw new coding_exception('Only valid during restore');
}
if (self::$restoreinfo['restoreid'] !== $restoreid) {
throw new coding_exception('Data not available for that restore id');
}
return self::$restoreinfo['task'];
}
/**
* Obtains the name of the item (cm_info or section_info, at present) that
* this is controlling availability of. Name should be formatted ready
* for on-screen display.
*
* @return string Name of item
*/
protected abstract function get_thing_name();
/**
* Stores an updated availability tree JSON structure into the relevant
* database table.
*
* @param string $availabilty New JSON value
*/
protected abstract function set_in_database($availabilty);
/**
* In rare cases the system may want to change all references to one ID
* (e.g. one course-module ID) to another one, within a course. This
* function does that for the conditional availability data for all
* modules and sections on the course.
*
* @param int|\stdClass $courseorid Course id or object
* @param string $table Table name e.g. 'course_modules'
* @param int $oldid Previous ID
* @param int $newid New ID
* @return bool True if anything changed, otherwise false
*/
public static function update_dependency_id_across_course(
$courseorid, $table, $oldid, $newid) {
global $DB;
$transaction = $DB->start_delegated_transaction();
$modinfo = get_fast_modinfo($courseorid);
$anychanged = false;
foreach ($modinfo->get_cms() as $cm) {
$info = new info_module($cm);
$changed = $info->update_dependency_id($table, $oldid, $newid);
$anychanged = $anychanged || $changed;
}
foreach ($modinfo->get_section_info_all() as $section) {
$info = new info_section($section);
$changed = $info->update_dependency_id($table, $oldid, $newid);
$anychanged = $anychanged || $changed;
}
$transaction->allow_commit();
if ($anychanged) {
get_fast_modinfo($courseorid, 0, true);
}
return $anychanged;
}
/**
* Called on a single item. If necessary, updates availability data where
* it has a dependency on an item with a particular id.
*
* @param string $table Table name e.g. 'course_modules'
* @param int $oldid Previous ID
* @param int $newid New ID
* @return bool True if it changed, otherwise false
*/
protected function update_dependency_id($table, $oldid, $newid) {
// Do nothing if there are no availability restrictions.
if (is_null($this->availability)) {
return false;
}
// Pass requirement on to tree object.
$tree = $this->get_availability_tree();
$changed = $tree->update_dependency_id($table, $oldid, $newid);
if ($changed) {
// Save modified data.
$structure = $tree->save();
$this->set_in_database(json_encode($structure));
}
return $changed;
}
/**
* Converts legacy data from fields (if provided) into the new availability
* syntax.
*
* Supported fields: availablefrom, availableuntil, showavailability
* (and groupingid for sections).
*
* It also supports the groupmembersonly field for modules. This part was
* optional in 2.7 but now always runs (because groupmembersonly has been
* removed).
*
* @param \stdClass $rec Object possibly containing legacy fields
* @param bool $section True if this is a section
* @param bool $modgroupmembersonlyignored Ignored option, previously used
* @return string|null New availability value or null if none
*/
public static function convert_legacy_fields($rec, $section, $modgroupmembersonlyignored = false) {
// Do nothing if the fields are not set.
if (empty($rec->availablefrom) && empty($rec->availableuntil) &&
(empty($rec->groupmembersonly)) &&
(!$section || empty($rec->groupingid))) {
return null;
}
// Handle legacy availability data.
$conditions = array();
$shows = array();
// Groupmembersonly condition (if enabled) for modules, groupingid for
// sections.
if (!empty($rec->groupmembersonly) ||
(!empty($rec->groupingid) && $section)) {
if (!empty($rec->groupingid)) {
$conditions[] = '{"type":"grouping"' .
($rec->groupingid ? ',"id":' . $rec->groupingid : '') . '}';
} else {
// No grouping specified, so allow any group.
$conditions[] = '{"type":"group"}';
}
// Group members only condition was not displayed to students.
$shows[] = 'false';
}
// Date conditions.
if (!empty($rec->availablefrom)) {
$conditions[] = '{"type":"date","d":">=","t":' . $rec->availablefrom . '}';
$shows[] = !empty($rec->showavailability) ? 'true' : 'false';
}
if (!empty($rec->availableuntil)) {
$conditions[] = '{"type":"date","d":"<","t":' . $rec->availableuntil . '}';
// Until dates never showed to students.
$shows[] = 'false';
}
// If there are some conditions, return them.
if ($conditions) {
return '{"op":"&","showc":[' . implode(',', $shows) . '],' .
'"c":[' . implode(',', $conditions) . ']}';
} else {
return null;
}
}
/**
* Adds a condition from the legacy availability condition.
*
* (For use during restore only.)
*
* This function assumes that the activity either has no conditions, or
* that it has an AND tree with one or more conditions.
*
* @param string|null $availability Current availability conditions
* @param \stdClass $rec Object containing information from old table
* @param bool $show True if 'show' option should be enabled
* @return string New availability conditions
*/
public static function add_legacy_availability_condition($availability, $rec, $show) {
if (!empty($rec->sourcecmid)) {
// Completion condition.
$condition = '{"type":"completion","cm":' . $rec->sourcecmid .
',"e":' . $rec->requiredcompletion . '}';
} else {
// Grade condition.
$minmax = '';
if (!empty($rec->grademin)) {
$minmax .= ',"min":' . sprintf('%.5f', $rec->grademin);
}
if (!empty($rec->grademax)) {
$minmax .= ',"max":' . sprintf('%.5f', $rec->grademax);
}
$condition = '{"type":"grade","id":' . $rec->gradeitemid . $minmax . '}';
}
return self::add_legacy_condition($availability, $condition, $show);
}
/**
* Adds a condition from the legacy availability field condition.
*
* (For use during restore only.)
*
* This function assumes that the activity either has no conditions, or
* that it has an AND tree with one or more conditions.
*
* @param string|null $availability Current availability conditions
* @param \stdClass $rec Object containing information from old table
* @param bool $show True if 'show' option should be enabled
* @return string New availability conditions
*/
public static function add_legacy_availability_field_condition($availability, $rec, $show) {
if (isset($rec->userfield)) {
// Standard field.
$fieldbit = ',"sf":' . json_encode($rec->userfield);
} else {
// Custom field.
$fieldbit = ',"cf":' . json_encode($rec->shortname);
}
// Value is not included for certain operators.
switch($rec->operator) {
case 'isempty':
case 'isnotempty':
$valuebit = '';
break;
default:
$valuebit = ',"v":' . json_encode($rec->value);
break;
}
$condition = '{"type":"profile","op":"' . $rec->operator . '"' .
$fieldbit . $valuebit . '}';
return self::add_legacy_condition($availability, $condition, $show);
}
/**
* Adds a condition to an AND group.
*
* (For use during restore only.)
*
* This function assumes that the activity either has no conditions, or
* that it has only conditions added by this function.
*
* @param string|null $availability Current availability conditions
* @param string $condition Condition text '{...}'
* @param bool $show True if 'show' option should be enabled
* @return string New availability conditions
*/
protected static function add_legacy_condition($availability, $condition, $show) {
$showtext = ($show ? 'true' : 'false');
if (is_null($availability)) {
$availability = '{"op":"&","showc":[' . $showtext .
'],"c":[' . $condition . ']}';
} else {
$matches = array();
if (!preg_match('~^({"op":"&","showc":\[(?:true|false)(?:,(?:true|false))*)' .
'(\],"c":\[.*)(\]})$~', $availability, $matches)) {
throw new \coding_exception('Unexpected availability value');
}
$availability = $matches[1] . ',' . $showtext . $matches[2] .
',' . $condition . $matches[3];
}
return $availability;
}
/**
* Tests against a user list. Users who cannot access the activity due to
* availability restrictions will be removed from the list.
*
* Note this only includes availability restrictions (those handled within
* this API) and not other ways of restricting access.
*
* This test ONLY includes conditions which are marked as being applied to
* user lists. For example, group conditions are included but date
* conditions are not included.
*
* The function operates reasonably efficiently i.e. should not do per-user
* database queries. It is however likely to be fairly slow.
*
* @param array $users Array of userid => object
* @return array Filtered version of input array
*/
public function filter_user_list(array $users) {
global $CFG;
if (is_null($this->availability) || !$CFG->enableavailability) {
return $users;
}
$tree = $this->get_availability_tree();
$checker = new capability_checker($this->get_context());
// Filter using availability tree.
$this->modinfo = get_fast_modinfo($this->get_course());
$filtered = $tree->filter_user_list($users, false, $this, $checker);
$this->modinfo = null;
// Include users in the result if they're either in the filtered list,
// or they have viewhidden. This logic preserves ordering of the
// passed users array.
$result = array();
$canviewhidden = $checker->get_users_by_capability($this->get_view_hidden_capability());
foreach ($users as $userid => $data) {
if (array_key_exists($userid, $filtered) || array_key_exists($userid, $canviewhidden)) {
$result[$userid] = $users[$userid];
}
}
return $result;
}
/**
* Gets the capability used to view hidden activities/sections (as
* appropriate).
*
* @return string Name of capability used to view hidden items of this type
*/
protected abstract function get_view_hidden_capability();
/**
* Obtains SQL that returns a list of enrolled users that has been filtered
* by the conditions applied in the availability API, similar to calling
* get_enrolled_users and then filter_user_list. As for filter_user_list,
* this ONLY filters out users with conditions that are marked as applying
* to user lists. For example, group conditions are included but date
* conditions are not included.
*
* The returned SQL is a query that returns a list of user IDs. It does not
* include brackets, so you neeed to add these to make it into a subquery.
* You would normally use it in an SQL phrase like "WHERE u.id IN ($sql)".
*
* The function returns an array with '' and an empty array, if there are
* no restrictions on users from these conditions.
*
* The SQL will be complex and may be slow. It uses named parameters (sorry,
* I know they are annoying, but it was unavoidable here).
*
* @param bool $onlyactive True if including only active enrolments
* @return array Array of SQL code (may be empty) and params
*/
public function get_user_list_sql($onlyactive) {
global $CFG;
if (is_null($this->availability) || !$CFG->enableavailability) {
return array('', array());
}
// Get SQL for the availability filter.
$tree = $this->get_availability_tree();
list ($filtersql, $filterparams) = $tree->get_user_list_sql(false, $this, $onlyactive);
if ($filtersql === '') {
// No restrictions, so return empty query.
return array('', array());
}
// Get SQL for the view hidden list.
list ($viewhiddensql, $viewhiddenparams) = get_enrolled_sql(
$this->get_context(), $this->get_view_hidden_capability(), 0, $onlyactive);
// Result is a union of the two.
return array('(' . $filtersql . ') UNION (' . $viewhiddensql . ')',
array_merge($filterparams, $viewhiddenparams));
}
/**
* Formats the $cm->availableinfo string for display. This includes
* filling in the names of any course-modules that might be mentioned.
* Should be called immediately prior to display, or at least somewhere
* that we can guarantee does not happen from within building the modinfo
* object.
*
* @param \renderable|string $inforenderable Info string or renderable
* @param int|\stdClass $courseorid
* @return string Correctly formatted info string
*/
public static function format_info($inforenderable, $courseorid) {
global $PAGE;
// Use renderer if required.
if (is_string($inforenderable)) {
$info = $inforenderable;
} else {
$renderer = $PAGE->get_renderer('core', 'availability');
$info = $renderer->render($inforenderable);
}
// Don't waste time if there are no special tags.
if (strpos($info, '<AVAILABILITY_') === false) {
return $info;
}
// Handle CMNAME tags.
$modinfo = get_fast_modinfo($courseorid);
$context = \context_course::instance($modinfo->courseid);
$info = preg_replace_callback('~<AVAILABILITY_CMNAME_([0-9]+)/>~',
function($matches) use($modinfo, $context) {
$cm = $modinfo->get_cm($matches[1]);
if ($cm->has_view() and $cm->uservisible) {
// Help student by providing a link to the module which is preventing availability.
return \html_writer::link($cm->url, format_string($cm->name, true, array('context' => $context)));
} else {
return format_string($cm->name, true, array('context' => $context));
}
}, $info);
return $info;
}
/**
* Used in course/lib.php because we need to disable the completion tickbox
* JS (using the non-JS version instead, which causes a page reload) if a
* completion tickbox value may affect a conditional activity.
*
* @param \stdClass $course Moodle course object
* @param int $cmid Course-module id
* @return bool True if this is used in a condition, false otherwise
*/
public static function completion_value_used($course, $cmid) {
// Access all plugins. Normally only the completion plugin is going
// to affect this value, but it's potentially possible that some other
// plugin could also rely on the completion plugin.
$pluginmanager = \core_plugin_manager::instance();
$enabled = $pluginmanager->get_enabled_plugins('availability');
$componentparams = new \stdClass();
foreach ($enabled as $plugin => $info) {
// Use the static method.
$class = '\availability_' . $plugin . '\condition';
if ($class::completion_value_used($course, $cmid)) {
return true;
}
}
return false;
}
}