added import and export recurring bills

app/Exports/Purchases/Bills/Sheets/BillItemTaxes.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace App\Exports\Purchases\Bills\Sheets;
+
+use App\Abstracts\Export;
+use App\Models\Document\DocumentItemTax as Model;
+
+class BillItemTaxes extends Export
+{
+    public function collection()
+    {
+        return Model::with('document', 'item', 'tax')->bill()->collectForExport($this->ids, null, 'document_id');
+    }
+
+    public function map($model): array
+    {
+        $document = $model->document;
+
+        if (empty($document)) {
+            return [];
+        }
+
+        $model->bill_number = $document->document_number;
+        $model->item_name = $model->item->name;
+        $model->tax_rate = $model->tax->rate;
+
+        return parent::map($model);
+    }
+
+    public function fields(): array
+    {
+        return [
+            'bill_number',
+            'item_name',
+            'tax_rate',
+            'amount',
+        ];
+    }
+}