Invoice PAIN & CSV can be uploaded

app/Providers/PdfMergeProvider.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace App\Providers;
+
+use InvalidArgumentException;
+use RuntimeException;
+use setasign\Fpdi\Fpdi;
+
+class PdfMergeProvider {
+    protected array $files = [];
+
+    /**
+     * Fügt eine PDF-Datei zur Merge-Liste hinzu.
+     */
+    public function add(string $filePath): self
+    {
+        $this->files[] = $filePath;
+        return $this;
+    }
+
+    /**
+     * Führt alle hinzugefügten PDFs zusammen und speichert sie.
+     */
+    public function merge(string $outputPath): void
+    {
+        if (empty($this->files)) {
+            throw new RuntimeException("No PDF files added for merging.");
+        }
+
+        $pdf = new FPDI();
+
+        foreach ($this->files as $file) {
+            $pageCount = $pdf->setSourceFile($file);
+
+            for ($page = 1; $page <= $pageCount; $page++) {
+                $tpl = $pdf->importPage($page);
+                $size = $pdf->getTemplateSize($tpl);
+
+                $pdf->AddPage($size['orientation'], [$size['width'], $size['height']]);
+                $pdf->useTemplate($tpl);
+            }
+        }
+
+        $pdf->Output('F', $outputPath);
+    }
+}