<?php
// This file is part of Moodle - https://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 <https://www.gnu.org/licenses/>.
namespace core\context;
use core\context;
use stdClass;
use coding_exception, moodle_url;
/**
* Block context class
*
* @package core_access
* @category access
* @copyright Petr Skoda
* @license https://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
* @since Moodle 4.2
*/
class block extends context {
/** @var int numeric context level value matching legacy CONTEXT_BLOCK */
public const LEVEL = 80;
/**
* Please use \core\context\block::instance($blockinstanceid) if you need the instance of context.
* Alternatively if you know only the context id use \core\context::instance_by_id($contextid)
*
* @param stdClass $record
*/
protected function __construct(stdClass $record) {
parent::__construct($record);
if ($record->contextlevel != self::LEVEL) {
throw new coding_exception('Invalid $record->contextlevel in core\context\block constructor');
}
}
/**
* Returns short context name.
*
* @since Moodle 4.2
*
* @return string
*/
public static function get_short_name(): string {
return 'block';
}
/**
* Returns human readable context level name.
*
* @return string the human readable context level name.
*/
public static function get_level_name() {
return get_string('block');
}
/**
* Returns human readable context identifier.
*
* @param boolean $withprefix whether to prefix the name of the context with Block
* @param boolean $short does not apply to block context
* @param boolean $escape does not apply to block context
* @return string the human readable context name.
*/
public function get_context_name($withprefix = true, $short = false, $escape = true) {
global $DB;
$name = '';
if ($blockinstance = $DB->get_record('block_instances', array('id' => $this->_instanceid))) {
$blockobject = block_instance($blockinstance->blockname);
if ($blockobject) {
if ($withprefix) {
$name = get_string('block').': ';
}
$name .= $blockobject->title;
}
}
return $name;
}
/**
* Returns the most relevant URL for this context.
*
* @return moodle_url
*/
public function get_url() {
$parentcontexts = $this->get_parent_context();
return $parentcontexts->get_url();
}
/**
* Returns list of all possible parent context levels.
* @since Moodle 4.2
*
* @return int[]
*/
public static function get_possible_parent_levels(): array {
// Blocks may be added to any other context instance.
$alllevels = \core\context_helper::get_all_levels();
unset($alllevels[self::LEVEL]);
return array_keys($alllevels);
}
/**
* Returns array of relevant context capability records.
*
* @param string $sort
* @return array
*/
public function get_capabilities(string $sort = self::DEFAULT_CAPABILITY_SORT) {
global $DB;
$bi = $DB->get_record('block_instances', array('id' => $this->_instanceid));
$select = '(contextlevel = :level AND component = :component)';
$params = [
'level' => self::LEVEL,
'component' => 'block_' . $bi->blockname,
];
$extracaps = block_method_result($bi->blockname, 'get_extra_capabilities');
if ($extracaps) {
list($extra, $extraparams) = $DB->get_in_or_equal($extracaps, SQL_PARAMS_NAMED, 'cap');
$select .= " OR name $extra";
$params = array_merge($params, $extraparams);
}
return $DB->get_records_select('capabilities', $select, $params, $sort);
}
/**
* Is this context part of any course? If yes return course context.
*
* @param bool $strict true means throw exception if not found, false means return false if not found
* @return course context of the enclosing course, null if not found or exception
*/
public function get_course_context($strict = true) {
$parentcontext = $this->get_parent_context();
return $parentcontext->get_course_context($strict);
}
/**
* Returns block context instance.
*
* @param int $blockinstanceid id from {block_instances} table.
* @param int $strictness
* @return block|false context instance
*/
public static function instance($blockinstanceid, $strictness = MUST_EXIST) {
global $DB;
if ($context = context::cache_get(self::LEVEL, $blockinstanceid)) {
return $context;
}
if (!$record = $DB->get_record('context', array('contextlevel' => self::LEVEL, 'instanceid' => $blockinstanceid))) {
if ($bi = $DB->get_record('block_instances', array('id' => $blockinstanceid), 'id,parentcontextid', $strictness)) {
$parentcontext = context::instance_by_id($bi->parentcontextid);
$record = context::insert_context_record(self::LEVEL, $bi->id, $parentcontext->path);
}
}
if ($record) {
$context = new block($record);
context::cache_add($context);
return $context;
}
return false;
}
/**
* Block do not have child contexts...
* @return array
*/
public function get_child_contexts() {
return array();
}
/**
* Create missing context instances at block context level
*/
protected static function create_level_instances() {
global $DB;
$sql = <<<EOF
INSERT INTO {context} (
contextlevel,
instanceid
) SELECT
:contextlevel,
bi.id as instanceid
FROM {block_instances} bi
WHERE NOT EXISTS (
SELECT 'x' FROM {context} cx WHERE bi.id = cx.instanceid AND cx.contextlevel = :existingcontextlevel
)
EOF;
$DB->execute($sql, [
'contextlevel' => self::LEVEL,
'existingcontextlevel' => self::LEVEL,
]);
}
/**
* Returns sql necessary for purging of stale context instances.
*
* @return string cleanup SQL
*/
protected static function get_cleanup_sql() {
$sql = "
SELECT c.*
FROM {context} c
LEFT OUTER JOIN {block_instances} bi ON c.instanceid = bi.id
WHERE bi.id IS NULL AND c.contextlevel = ".self::LEVEL."
";
return $sql;
}
/**
* Rebuild context paths and depths at block context level.
*
* @param bool $force
*/
protected static function build_paths($force) {
global $DB;
if ($force || $DB->record_exists_select('context', "contextlevel = ".self::LEVEL." AND (depth = 0 OR path IS NULL)")) {
if ($force) {
$ctxemptyclause = '';
} else {
$ctxemptyclause = "AND (ctx.path IS NULL OR ctx.depth = 0)";
}
// The pctx.path IS NOT NULL prevents fatal problems with broken block instances that point to invalid context parent.
$sql = "INSERT INTO {context_temp} (id, path, depth, locked)
SELECT ctx.id, ".$DB->sql_concat('pctx.path', "'/'", 'ctx.id').", pctx.depth+1, ctx.locked
FROM {context} ctx
JOIN {block_instances} bi ON (bi.id = ctx.instanceid AND ctx.contextlevel = " . self::LEVEL . ")
JOIN {context} pctx ON (pctx.id = bi.parentcontextid)
WHERE (pctx.path IS NOT NULL AND pctx.depth > 0)
$ctxemptyclause";
$trans = $DB->start_delegated_transaction();
$DB->delete_records('context_temp');
$DB->execute($sql);
context::merge_context_temp_table();
$DB->delete_records('context_temp');
$trans->allow_commit();
}
}
}