moodle_local_treestudyplan/classes/local/helpers/webservicehelper.php

<?php

namespace local_treestudyplan\local\helpers;
require_once($CFG->dirroot.'/webservice/lib.php');


class webservicehelper {
    /** @var \context_system */
    private static $systemcontext = null;
    private static $validated_contexts = [];

    /**
     * Test for capability in the given context for the current user and throw a \webservice_access_exception if not 
     * Note: The context is not validate
     * @param array|string $capability One or more capabilities to be tested OR wise (if one capability is given, the function passes)
     * @param \context $context The context in which to check for the capability.
     * @throws \webservice_access_exception If none of the capabilities provided are given to the current user
     * @return boolean 
     */
    public static function has_capabilities($capability,$context){

        if($context == null){
            $context = \context_system::instance();
        }
       
        if(is_array($capability)){
            //TODO: replace this by accesslib function \has_any_capability()
            foreach($capability as $cap){
                if(has_capability($cap,$context)){
                    return true;
                }
            }
        }
        elseif(has_capability($capability,$context)){
            return true;
        }
    }

    /**
     * Test if the current user has a certain capability in any of the categories they have access to
     * @param string $capability The capability to scan for in the categories
     * @param \core_course_category  $parent The parent category to use as a scanning base. Used in recursing Leave empty if calling this function
     * @return boolean 
     */
    public static function has_capability_in_any_category($capability,\core_course_category $parent=null){

        // List the categories in which the user has a specific capability
        $list = [];
        // initialize parent if needed
        if($parent == null){
            $parent = \core_course_category::user_top();
            if(has_capability($capability,$parent->get_context())){
                $list[] = $parent;
            }
        }
        
        $children = $parent->get_children();
        // Since the change for a category permission is greatest at the lower levels,
        // we scan in two stages, to focus the search more on the lower levels instead of diving deep into the first category
        // Stage one (surface check): check all children for the capability
        foreach($children as $child){
            // Check if we should add this category
            if(has_capability($capability,$child->get_context())){
                return true;
            } 
        }
        // Stage two (deep dive): recurse into the child categories
        foreach($children as $child){
            if($child->get_children_count() > 0){
                if(self::has_capability_in_any_category($capability,$child)){
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Test for capability in the given context for the current user and throw a \webservice_access_exception if not 
     * @param array|string $capability One or more capabilities to be tested OR wise (if one capability is given, the function passes)
     * @param \context $context The context in which to check for the capability. Leave empty to use the system context.
     * @param bool $validate Validate the context before checking capabilities
     * @throws \webservice_access_exception If none of the capabilities provided are given to the current user
     */
    public static function require_capabilities($capability,$context=null,$validate=true){
        if($validate) { 
            \external_api::validate_context($context); 
        }
        if(! static::has_capabilities($capability,$context)){
            throw new \webservice_access_exception("The capability {$capability} is required on this context ({$context->get_context_name()})");
        }
    }

    /**
     * Find and validate a given context by id
     * @param int $contextid The id of the context
     * @return \context The found context by id
     * @throws \InvalidArgumentException When the context is not found
     */
    public static function find_context($contextid): \context{
        if(isset($contextid) && is_int($contextid) && $contextid > 0){
            
            if(!in_array($contextid,self::$validated_contexts)){ // Cache the context and make sure it is only validated once...
                try{
                    $context = \context::instance_by_id($contextid);
                }
                catch(\dml_missing_record_exception $x){
                    throw new \InvalidArgumentException("Context {$contextid} not available"); // Just throw it up again. catch is included here to make sure we know it throws this exception
                }
                // Validate the found context
                \external_api::validate_context($context);
                self::$validated_contexts[$contextid] = $context;
            }
            return self::$validated_contexts[$contextid];
        }
        else{
            return static::system_context(); // This function ensures the system context is validated just once this call
        }
    }

    /** 
     * Return the validated system context (validation happens only once for this call)
     * @return \context_system The system context, validated to use as this context
     */
    public static function system_context(): \context_system {
        if(!isset(static::$systemcontext)){
            static::$systemcontext = \context_system::instance();
            \external_api::validate_context(static::$systemcontext);
        }
        return static::$systemcontext;
    }

}