Automatically detect the delimiter of generic BOM imports

The detectFields does this anyway, so use that guessed value further on

src/Controller/ProjectController.php

@@ -240,7 +240,8 @@ class ProjectController extends AbstractController
         }
 
         // Detect fields and get suggestions
-        $detected_fields = $BOMImporter->detectFields($file_content);
+        $detected_delimiter = $BOMImporter->detectDelimiter($file_content);
+        $detected_fields = $BOMImporter->detectFields($file_content, $detected_delimiter);
         $suggested_mapping = $BOMImporter->getSuggestedFieldMapping($detected_fields);
 
         // Create mapping of original field names to sanitized field names for template
@@ -257,7 +258,7 @@ class ProjectController extends AbstractController
         $builder->add('delimiter', ChoiceType::class, [
             'label' => 'project.bom_import.delimiter',
             'required' => true,
-            'data' => ',',
+            'data' => $detected_delimiter,
             'choices' => [
                 'project.bom_import.delimiter.comma' => ',',
                 'project.bom_import.delimiter.semicolon' => ';',

src/Services/ImportExportSystem/BOMImporter.php

@@ -722,12 +722,12 @@ class BOMImporter
     }
 
     /**
-     * Detect available fields in CSV data for field mapping UI
+     * Try to detect the separator used in the CSV data by analyzing the first line and counting occurrences of common delimiters.
+     * @param  string  $data
+     * @return string
      */
-    public function detectFields(string $data, ?string $delimiter = null): array
+    public function detectDelimiter(string $data): string
     {
-        if ($delimiter === null) {
-            // Detect delimiter by counting occurrences in the first row (header)
         $delimiters = [',', ';', "\t"];
         $lines = explode("\n", $data, 2);
         $header_line = $lines[0] ?? '';
@@ -741,6 +741,16 @@ class BOMImporter
         if ($max_count === 0 || $delimiter === false) {
             $delimiter = ',';
         }
+        return $delimiter;
+    }
+
+    /**
+     * Detect available fields in CSV data for field mapping UI
+     */
+    public function detectFields(string $data, ?string $delimiter = null): array
+    {
+        if ($delimiter === null) {
+            $delimiter = $this->detectDelimiter($data);
         }
         // Handle potential BOM (Byte Order Mark) at the beginning
         $data = preg_replace('/^\xEF\xBB\xBF/', '', $data);