public static function get_context_instance_customdata(\context $context) {

        $persistent = \tool_dataprivacy\context_instance::get_record_by_contextid($context->id, false);
        if (!$persistent) {
            $persistent = new \tool_dataprivacy\context_instance();
            $persistent->set('contextid', $context->id);
        }

        $purposes = [];
        foreach (api::get_purposes() as $purpose) {
            $purposes[$purpose->get('id')] = $purpose;
        }
        $purposeoptions = \tool_dataprivacy\output\data_registry_page::purpose_options($purposes);
        $categoryoptions = \tool_dataprivacy\output\data_registry_page::category_options(api::get_categories());

        $customdata = [
            'context' => $context,
            'subjectscope' => data_registry::get_subject_scope($context),
            'contextname' => $context->get_context_name(),
            'persistent' => $persistent,
            'purposes' => $purposeoptions,
            'categories' => $categoryoptions,
        ];

        $effectivepurpose = api::get_effective_context_purpose($context);
        if ($effectivepurpose) {

            $customdata['currentretentionperiod'] = self::get_retention_display_text($effectivepurpose, $context->contextlevel,
                $context);

            $customdata['purposeretentionperiods'] = [];
            foreach (array_keys($purposeoptions) as $optionvalue) {

                if (isset($purposes[$optionvalue])) {
                    $purpose = $purposes[$optionvalue];
                } else {
                    // Get the effective purpose if $optionvalue would be the selected value.
                    $purpose = api::get_effective_context_purpose($context, $optionvalue);
                }

                $retentionperiod = self::get_retention_display_text(
                    $purpose,
                    $context->contextlevel,
                    $context
                );
                $customdata['purposeretentionperiods'][$optionvalue] = $retentionperiod;
            }
        }

        return $customdata;
    }