Add new config registry flat.

The flat config registry is there to map a data definition that has a parent definition as a flat.
In this registry, no filtering or similar is applied by the parent.

src/Config/FlatConfigRegistry.php

@@ -0,0 +1,105 @@
+<?php
+
+/**
+ * This file is part of contao-community-alliance/dc-general.
+ *
+ * (c) 2013-2021 Contao Community Alliance.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ *
+ * This project is provided in good faith and hope to be usable by anyone.
+ *
+ * @package    contao-community-alliance/dc-general
+ * @author     Sven Baumann <[email protected]>
+ * @copyright  2013-2021 Contao Community Alliance.
+ * @license    https://github.com/contao-community-alliance/dc-general/blob/master/LICENSE LGPL-3.0-or-later
+ * @filesource
+ */
+
+declare(strict_types=1);
+
+namespace ContaoCommunityAlliance\DcGeneral\Config;
+
+use ContaoCommunityAlliance\DcGeneral\Contao\DataDefinition\Definition\Contao2BackendViewDefinitionInterface;
+use ContaoCommunityAlliance\DcGeneral\Data\ConfigInterface;
+use ContaoCommunityAlliance\DcGeneral\Data\ModelIdInterface;
+use ContaoCommunityAlliance\DcGeneral\EnvironmentFlatConfigRegistryInterface;
+use ContaoCommunityAlliance\DcGeneral\EnvironmentInterface;
+
+/**
+ * Registry for default data provider configurations to only resolve them once.
+ * The flat config registry is there to map a data definition that has a parent definition as a flat.
+ * In this registry, no filtering or similar is applied by the parent.
+ */
+final class FlatConfigRegistry implements BaseConfigRegistryInterface
+{
+    /**
+     * The attached environment.
+     *
+     * @var EnvironmentFlatConfigRegistryInterface|null
+     */
+    private $environment;
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getBaseConfig(ModelIdInterface $parentId = null): ConfigInterface
+    {
+        $environment = $this->getEnvironment();
+        $config      = $environment->getDataProvider()->getEmptyConfig();
+        $definition  = $environment->getDataDefinition();
+        $additional  = $definition->getBasicDefinition()->getAdditionalFilter();
+
+        // Custom filter common for all modes.
+        if ($additional) {
+            $config->setFilter($additional);
+        }
+
+        $this->addDefaultSorting($config);
+
+        return $config;
+    }
+
+    /**
+     * Add the default sorting fields.
+     *
+     * @param ConfigInterface $config The data provider config.
+     *
+     * @return void
+     */
+    private function addDefaultSorting(ConfigInterface $config): void
+    {
+        if (!empty($config->getSorting())) {
+            return;
+        }
+
+        $environment = $this->getEnvironment();
+        $definition  = $environment->getDataDefinition();
+        /** @var Contao2BackendViewDefinitionInterface $viewDefinition */
+        $viewDefinition = $definition->getDefinition(Contao2BackendViewDefinitionInterface::NAME);
+        $config->setSorting($viewDefinition->getListingConfig()->getDefaultSortingFields());
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getEnvironment(): ?EnvironmentFlatConfigRegistryInterface
+    {
+        return $this->environment;
+    }
+
+    /**
+     * Set the environment.
+     *
+     * @param EnvironmentInterface $environment The environment.
+     *
+     * @return FlatConfigRegistry
+     */
+    public function setEnvironment(EnvironmentInterface $environment): FlatConfigRegistry
+    {
+        $this->environment = $environment;
+
+        return $this;
+    }
+}