Joomla Namespaces, Autoloading and Dependency Injection

<?xml version="1.0" encoding="utf-8"?>
<extension type="component" method="upgrade">
    <name>com_tallpine</name>
    <author>Tallpine Hiking Club</author>
    <version>1.0.0</version>
    <description>COM_TALLPINE_XML_DESCRIPTION</description>
    <namespace path="src">Tallpine\Component\Tallpine</namespace>

    <administration>
        <files folder="administrator">
            <folder>forms</folder>
            <folder>services</folder>
            <folder>src</folder>
            <folder>tmpl</folder>
            <file>access.xml</file>
            <file>config.xml</file>
        </files>
    </administration>

    <files folder="site">
        <folder>src</folder>
        <folder>tmpl</folder>
    </files>
</extension>

<?php
defined('_JEXEC') or die;
return [
	'Tallpine\\Component\\Tallpine\\Administrator\\' => [JPATH_ADMINISTRATOR . '/components/com_tallpine/src'],
	'Tallpine\\Component\\Tallpine\\Api\\' => [JPATH_API . '/components/com_tallpine/src'],
	'Tallpine\\Component\\Tallpine\\Site\\' => [JPATH_SITE . '/components/com_tallpine/src'],
	'Tallpine\\Module\\NextHikes\\Site\\' => [JPATH_SITE . '/modules/mod_tallpine_nexthikes/src'],
	'Tallpine\\Plugin\\Content\\TallpineConditions\\' => [JPATH_PLUGINS . '/content/tallpine_conditions/src'],
];

<?php

/**
 * @package     Tallpine.Administrator
 * @subpackage  com_tallpine
 *
 * @copyright   (C) 2026 Tallpine Hiking Club
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

\defined('_JEXEC') or die;

use Joomla\CMS\Categories\CategoryFactoryInterface;
use Joomla\CMS\Component\Router\RouterFactoryInterface;
use Joomla\CMS\Dispatcher\ComponentDispatcherFactoryInterface;
use Joomla\CMS\Extension\ComponentInterface;
use Joomla\CMS\Extension\Service\Provider\CategoryFactory;
use Joomla\CMS\Extension\Service\Provider\ComponentDispatcherFactory;
use Joomla\CMS\Extension\Service\Provider\MVCFactory;
use Joomla\CMS\Extension\Service\Provider\RouterFactory;
use Joomla\CMS\HTML\Registry;
use Joomla\CMS\MVC\Factory\MVCFactoryInterface;
use Joomla\DI\Container;
use Joomla\DI\ServiceProviderInterface;
use Tallpine\Component\Tallpine\Administrator\Extension\TallpineComponent;

return new class () implements ServiceProviderInterface {
    /**
     * Registers the service provider with a DI container.
     *
     * @param   Container  $container  The DI container (a child container for this component).
     *
     * @return  void
     */
    public function register(Container $container): void
    {
        $namespace = '\\Tallpine\\Component\\Tallpine';

        // Step 1: the factories this component needs.
        $container->registerServiceProvider(new CategoryFactory($namespace));
        $container->registerServiceProvider(new MVCFactory($namespace));
        $container->registerServiceProvider(new ComponentDispatcherFactory($namespace));
        $container->registerServiceProvider(new RouterFactory($namespace));

        // Step 2: the extension class, with its sub-dependencies injected.
        $container->set(
            ComponentInterface::class,
            function (Container $container) {
                $component = new TallpineComponent($container->get(ComponentDispatcherFactoryInterface::class));

                $component->setRegistry($container->get(Registry::class));
                $component->setMVCFactory($container->get(MVCFactoryInterface::class));
                $component->setCategoryFactory($container->get(CategoryFactoryInterface::class));
                $component->setRouterFactory($container->get(RouterFactoryInterface::class));

                return $component;
            }
        );
    }
};

<?php

namespace Tallpine\Component\Tallpine\Administrator\Extension;

use Joomla\CMS\Categories\CategoryServiceInterface;
use Joomla\CMS\Categories\CategoryServiceTrait;
use Joomla\CMS\Component\Router\RouterServiceInterface;
use Joomla\CMS\Component\Router\RouterServiceTrait;
use Joomla\CMS\Extension\BootableExtensionInterface;
use Joomla\CMS\Extension\MVCComponent;
use Joomla\CMS\HTML\HTMLRegistryAwareTrait;
use Psr\Container\ContainerInterface;
use Tallpine\Component\Tallpine\Administrator\Service\HTML\TrailIcon;

\defined('_JEXEC') or die;

/**
 * Component class for com_tallpine.
 */
class TallpineComponent extends MVCComponent implements
    BootableExtensionInterface,
    CategoryServiceInterface,
    RouterServiceInterface
{
    use CategoryServiceTrait;
    use RouterServiceTrait;
    use HTMLRegistryAwareTrait;

    /**
     * Called by Joomla right after the component was fetched from its child container.
     */
    public function boot(ContainerInterface $container): void
    {
        $icon = new TrailIcon();
        $icon->setUserFactory($container->get(\Joomla\CMS\User\UserFactoryInterface::class));

        $this->getRegistry()->register('trailicon', $icon);
    }
}

<?php

/**
 * @package     Tallpine.Site
 * @subpackage  mod_tallpine_nexthikes
 *
 * @copyright   (C) 2026 Tallpine Hiking Club
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

\defined('_JEXEC') or die;

use Joomla\CMS\Extension\Service\Provider\HelperFactory;
use Joomla\CMS\Extension\Service\Provider\Module;
use Joomla\CMS\Extension\Service\Provider\ModuleDispatcherFactory;
use Joomla\DI\Container;
use Joomla\DI\ServiceProviderInterface;

return new class () implements ServiceProviderInterface {
    public function register(Container $container): void
    {
        $container->registerServiceProvider(new ModuleDispatcherFactory('\\Tallpine\\Module\\NextHikes'));
        $container->registerServiceProvider(new HelperFactory('\\Tallpine\\Module\\NextHikes\\Site\\Helper'));

        $container->registerServiceProvider(new Module());
    }
};

<?php

namespace Tallpine\Module\NextHikes\Site\Dispatcher;

use Joomla\CMS\Dispatcher\AbstractModuleDispatcher;
use Joomla\CMS\Helper\HelperFactoryAwareInterface;
use Joomla\CMS\Helper\HelperFactoryAwareTrait;

\defined('_JEXEC') or die;

/**
 * Dispatcher class for mod_tallpine_nexthikes.
 */
class Dispatcher extends AbstractModuleDispatcher implements HelperFactoryAwareInterface
{
    use HelperFactoryAwareTrait;

    protected function getLayoutData(): array
    {
        $data = parent::getLayoutData();

        // The factory builds Tallpine\Module\NextHikes\Site\Helper\NextHikesHelper and injects the database.
        $helper = $this->getHelperFactory()->getHelper('NextHikesHelper');

        $data['hikes'] = $helper->getNextHikes($data['params'], $data['app']);

        return $data;
    }
}

<?php

namespace Tallpine\Module\NextHikes\Site\Helper;

use Joomla\CMS\Application\CMSApplicationInterface;
use Joomla\Database\DatabaseAwareInterface;
use Joomla\Database\DatabaseAwareTrait;
use Joomla\Database\ParameterType;
use Joomla\Registry\Registry;

\defined('_JEXEC') or die;

class NextHikesHelper implements DatabaseAwareInterface
{
    use DatabaseAwareTrait;

    /**
     * @return  array<int, object>
     */
    public function getNextHikes(Registry $params, CMSApplicationInterface $app): array
    {
        $db    = $this->getDatabase();
        $limit = (int) $params->get('count', 5);
        $today = (new \DateTimeImmutable('today'))->format('Y-m-d');

        $query = $db->createQuery()
            ->select($db->quoteName(['id', 'title', 'hike_date']))
            ->from($db->quoteName('#__tallpine_hikes'))
            ->where($db->quoteName('hike_date') . ' >= :today')
            ->where($db->quoteName('published') . ' = 1')
            ->bind(':today', $today, ParameterType::STRING)
            ->order($db->quoteName('hike_date') . ' ASC')
            ->setLimit($limit);

        return $db->setQuery($query)->loadObjectList();
    }
}

<?php

/**
 * @package     Tallpine.Plugin
 * @subpackage  Content.tallpine_conditions
 *
 * @copyright   (C) 2026 Tallpine Hiking Club
 * @license     GNU General Public License version 2 or later; see LICENSE.txt
 */

\defined('_JEXEC') or die;

use Joomla\CMS\Extension\PluginInterface;
use Joomla\CMS\Factory;
use Joomla\CMS\Plugin\PluginHelper;
use Joomla\Database\DatabaseInterface;
use Joomla\DI\Container;
use Joomla\DI\ServiceProviderInterface;
use Tallpine\Plugin\Content\TallpineConditions\Extension\TallpineConditions;

return new class () implements ServiceProviderInterface {
    public function register(Container $container): void
    {
        $container->set(
            PluginInterface::class,
            $container->lazy(TallpineConditions::class, function (Container $container) {
                $plugin = new TallpineConditions(
                    (array) PluginHelper::getPlugin('content', 'tallpine_conditions')
                );
                $plugin->setApplication(Factory::getApplication());
                $plugin->setDatabase($container->get(DatabaseInterface::class));

                return $plugin;
            })
        );
    }
};

<?php

namespace Tallpine\Plugin\Content\TallpineConditions\Extension;

use Joomla\CMS\Event\Content\ContentPrepareEvent;
use Joomla\CMS\Plugin\CMSPlugin;
use Joomla\CMS\User\UserFactoryAwareTrait;
use Joomla\Database\DatabaseAwareTrait;
use Joomla\Event\SubscriberInterface;

\defined('_JEXEC') or die;

/**
 * Appends the current trail conditions to Tallpine trail articles.
 */
final class TallpineConditions extends CMSPlugin implements SubscriberInterface
{
    use DatabaseAwareTrait;
    use UserFactoryAwareTrait;

    public static function getSubscribedEvents(): array
    {
        return [
            'onContentPrepare' => 'onContentPrepare',
        ];
    }

    public function onContentPrepare(ContentPrepareEvent $event): void
    {
        // The application, injected by the provider, replaces the old $app property.
        if (!$this->getApplication()->isClient('site')) {
            return;
        }

        $item = $event->getItem();

        if ($event->getContext() !== 'com_content.article' || !isset($item->id)) {
            return;
        }

        $db    = $this->getDatabase();
        $query = $db->createQuery()
            ->select($db->quoteName('status'))
            ->from($db->quoteName('#__tallpine_conditions'))
            ->where($db->quoteName('article_id') . ' = :id')
            ->bind(':id', $item->id, \Joomla\Database\ParameterType::INTEGER);

        $status = $db->setQuery($query)->loadResult();

        if ($status !== null) {
            $item->text .= '<p class="trail-conditions">' . htmlspecialchars((string) $status, ENT_QUOTES, 'UTF-8') . '</p>';
        }
    }
}