fix amount

app/Http/Controllers/Single/SingleOrderController.php

@@ -239,6 +239,19 @@ class SingleOrderController extends Controller
         $feeFromGold = $config->feeDeductFromGold();
         $targetCash = $this->resolveTargetCash($data);
         $data['price'] += $data['difference'];
+
+        if ($targetCash !== null) {
+            $data['amount'] = $this->resolveBuyAmountFromTargetCash(
+                $targetCash,
+                (float) $data['price'],
+                (float) ($data['service_charge_percentage'] ?? 0),
+                $feeFromGold,
+                isset($data['fee_free']) && $data['fee_free'] === true
+            );
+        } else {
+            $data['amount'] = $this->normalizeGoldAmount((float) ($data['amount'] ?? 0));
+        }
+
         $data['total_price'] = $data['amount'] * $data['price'];
 
         $this->enforceProductOrderLimits($data, (float) $data['total_price']);
@@ -256,6 +269,7 @@ class SingleOrderController extends Controller
         } else {
             $data['payment_amount'] = $data['total_price'];
             $data['amount'] -= $data['service_charge'];
+            $data['amount'] = $this->normalizeGoldAmount((float) $data['amount']);
         }
 
         if ($targetCash !== null) {
@@ -441,7 +455,18 @@ class SingleOrderController extends Controller
         $response = [];
         $config = app(ConfigService::class);
         $feeFromGold = $config->feeDeductFromGold();
+        $targetCash = $this->resolveTargetCash($data);
         $data['price'] -= $data['difference'];
+
+        if ($targetCash !== null && $feeFromGold) {
+            $price = (float) $data['price'];
+            $data['amount'] = $price > 0
+                ? $this->normalizeGoldAmount($targetCash / $price)
+                : 0.0;
+        } else {
+            $data['amount'] = $this->normalizeGoldAmount((float) ($data['amount'] ?? 0));
+        }
+
         $grossTotal = $data['amount'] * $data['price'];
         $this->enforceProductOrderLimits($data, (float) $grossTotal);
         $data['service_charge'] = isset($data['fee_free']) && $data['fee_free'] === true ? 0 : $data['service_charge_percentage'] * $data['amount'];
@@ -456,7 +481,6 @@ class SingleOrderController extends Controller
             $goldDebit = $data['amount'];
         }
 
-        $targetCash = $this->resolveTargetCash($data);
         if ($targetCash !== null) {
             $data['payment_amount'] = $targetCash;
             $data['total_price'] = $targetCash;
@@ -893,6 +917,31 @@ class SingleOrderController extends Controller
         return $target > 0 ? $target : null;
     }
 
+    private function normalizeGoldAmount(float $amount): float
+    {
+        return round($amount, 10);
+    }
+
+    private function resolveBuyAmountFromTargetCash(
+        int $targetCash,
+        float $unitPrice,
+        float $serviceChargePercentage,
+        bool $feeFromGold,
+        bool $feeFree
+    ): float {
+        if ($unitPrice <= 0 || $targetCash <= 0) {
+            return 0.0;
+        }
+
+        $feeRate = $feeFree ? 0.0 : $serviceChargePercentage;
+
+        if ($feeFromGold) {
+            return $this->normalizeGoldAmount($targetCash / ($unitPrice * (1 + $feeRate)));
+        }
+
+        return $this->normalizeGoldAmount($targetCash / $unitPrice);
+    }
+
     private function resolveGoldPaymentProductId(array $data): ?int
     {
         if (!empty($data['payment_product_id'])) {

database/migrations/2026_07_04_000001_increase_orders_amount_decimal_precision.php

@@ -0,0 +1,17 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Support\Facades\DB;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        DB::statement('ALTER TABLE `orders` MODIFY `amount` DECIMAL(20,10) UNSIGNED NULL');
+    }
+
+    public function down(): void
+    {
+        DB::statement('ALTER TABLE `orders` MODIFY `amount` DOUBLE(15,6) UNSIGNED NULL');
+    }
+};