EntityNavigation.php

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<?php

namespace Elgg\Menus;

use Elgg\Menu\MenuItems;

class EntityNavigation {

    public static function registerPreviousNext(\Elgg\Event $event) {
        $entity = $event->getEntityParam();
        if (!$entity instanceof \ElggEntity) {
            return;
        }
        
        /* @var $return MenuItems */
        $return = $event->getValue();
        
        $options = [
            'type' => $entity->getType(),
            'subtype' => $entity->getSubtype(),
            'container_guid' => $entity->container_guid,
            'limit' => 1,
        ];
        
        $previous = self::getPreviousMenuItem($entity, $options);
        if ($previous instanceof \ElggMenuItem) {
            $return[] = $previous;
        }
        
        $next = self::getNextMenuItem($entity, $options);
        if ($next instanceof \ElggMenuItem) {
            $return[] = $next;
        }
        
        return $return;
    }
    
    protected static function getPreviousMenuItem(\ElggEntity $entity, array $base_options) {
        $base_options['wheres'] = [
            function (\Elgg\Database\QueryBuilder $qb, $main_alias) use ($entity) {
                return $qb->merge([
                    $qb->compare("{$main_alias}.time_created", '<', $entity->time_created, ELGG_VALUE_INTEGER),
                    $qb->merge([
                        $qb->compare("{$main_alias}.time_created", '=', $entity->time_created, ELGG_VALUE_INTEGER),
                        $qb->compare("{$main_alias}.guid", '<', $entity->guid, ELGG_VALUE_GUID),
                    ], 'AND'),
                ], 'OR');
            },
        ];
        $base_options['order_by'] = [
            new \Elgg\Database\Clauses\OrderByClause('time_created', 'DESC'),
            new \Elgg\Database\Clauses\OrderByClause('guid', 'DESC'),
        ];
        
        $previous = elgg_get_entities($base_options);
        if (empty($previous)) {
            return;
        }
        
        $previous = $previous[0];
        return \ElggMenuItem::factory([
            'name' => 'previous',
            'text' => elgg_echo('previous'),
            'title' => $previous->getDisplayName(),
            'href' => $previous->getUrl(),
            'entity' => $previous,
            'icon' => 'angle-double-left',
            'link_class' => 'elgg-button elgg-button-outline',
            'priority' => 100,
        ]);
    }
    
    protected static function getNextMenuItem(\ElggEntity $entity, array $base_options) {
        $base_options['wheres'] = [
            function (\Elgg\Database\QueryBuilder $qb, $main_alias) use ($entity) {
                return $qb->merge([
                    $qb->compare("{$main_alias}.time_created", '>', $entity->time_created, ELGG_VALUE_INTEGER),
                    $qb->merge([
                        $qb->compare("{$main_alias}.time_created", '=', $entity->time_created, ELGG_VALUE_INTEGER),
                        $qb->compare("{$main_alias}.guid", '>', $entity->guid, ELGG_VALUE_GUID),
                    ], 'AND'),
                ], 'OR');
            },
        ];
        $base_options['order_by'] = [
            new \Elgg\Database\Clauses\OrderByClause('time_created', 'ASC'),
            new \Elgg\Database\Clauses\OrderByClause('guid', 'ASC'),
        ];
        
        $next = elgg_get_entities($base_options);
        if (empty($next)) {
            return;
        }
        
        $next = $next[0];
        return \ElggMenuItem::factory([
            'name' => 'next',
            'text' => elgg_echo('next'),
            'title' => $next->getDisplayName(),
            'href' => $next->getUrl(),
            'entity' => $next,
            'icon_alt' => 'angle-double-right',
            'link_class' => 'elgg-button elgg-button-outline',
            'priority' => 800,
        ]);
    }
}