Issue #3448162: Add relationships to report

Closes #3448162

modules/schemadotorg_export/src/Controller/SchemaDotOrgExportReportRelationshipsController.php

+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\schemadotorg_export\Controller;
+
+use Drupal\Component\Utility\NestedArray;
+use Drupal\schemadotorg_report\Controller\SchemaDotOrgReportRelationshipsController;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpFoundation\StreamedResponse;
+
+/**
+ * Returns responses for Schema.org relationships export.
+ */
+class SchemaDotOrgExportReportRelationshipsController extends SchemaDotOrgExportMappingDefaultBaseController {
+
+  /**
+   * The Schema.org report relationships controller.
+   */
+  protected SchemaDotOrgReportRelationshipsController $controller;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container): static {
+    $instance = parent::create($container);
+    $instance->controller = SchemaDotOrgReportRelationshipsController::create($container);
+    return $instance;
+  }
+
+  /**
+   * Returns response for Schema.org mapping set CSV export request.
+   *
+   * @return \Symfony\Component\HttpFoundation\StreamedResponse
+   *   A streamed HTTP response containing a Schema.org mapping set CSV export.
+   */
+  public function index(): StreamedResponse {
+    $response = new StreamedResponse(function (): void {
+      $build = $this->controller->index();
+      $table = $build['table'];
+
+      $handle = fopen('php://output', 'r+');
+
+      // Header.
+      $header = [];
+      foreach ($table['#header'] as $table_header) {
+        // Get the header value.
+        $value = NestedArray::getValue($table_header, ['data', '#markup'])
+          ?? NestedArray::getValue($table_header, ['data'])
+          ?? $table_header;
+
+        $header[] = $value;
+      }
+      fputcsv($handle, $header);
+
+      // Rows.
+      foreach ($table['#rows'] as $table_row) {
+        $row = [];
+        foreach ($table_row as $row_id => $item) {
+          // Get the row value.
+          $value = NestedArray::getValue($item, ['data', '#markup'])
+            ?? NestedArray::getValue($item, ['data', '#title'])
+            ?? NestedArray::getValue($item, ['data', '#items'])
+            ?? $item;
+
+          // Prefix all Schema.org type and properties with https://schema.org/.
+          if (is_array($value) && $row_id !== 'starterkit') {
+            $value = array_map(
+              fn ($item) => 'https://schema.org/' . ($item['#title'] ?? $item),
+              $value
+            );
+          }
+
+          $row[] = implode(PHP_EOL, (array) $value);
+        }
+        fputcsv($handle, $row);
+      }
+      fclose($handle);
+    });
+
+    $response->headers->set('Content-Type', 'application/force-download');
+    $response->headers->set('Content-Disposition', 'attachment; filename="schemadotorg_relationships.csv"');
+    return $response;
+  }
+
+}