fix payment issues

app/Controllers/View/PaymentController.php

@@ -995,15 +995,11 @@ class PaymentController extends ResourceController
                 );
             }
 
-            // Installment sequence
-            $paidCount      = $this->getSuccessfulPaymentCount($invoiceId);
-            $installmentSeq = $paidCount + 1;
-
             // Generate a stable transaction id
             $transactionId = 'INV-' . $invoiceId . '-' . str_replace('.', '', (string)microtime(true));
 
             // Record payment
-            $ok = $this->processPayment(
+            $paymentResult = $this->processPayment(
                 $invoiceId,
                 $amount,
                 $paymentMethod,
@@ -1012,15 +1008,16 @@ class PaymentController extends ResourceController
                 $paymentDate,
                 $invYear,
                 $checkNumber,
-                $installmentSeq,
-                (array) $this->invoiceModel->find($invoiceId),
+                null,
+                (array) $row,
                 $currentBalance
             );
 
-            if (!$ok) {
+            if ($paymentResult === false) {
                 $this->db->transRollback();
                 return redirect()->back()->with('error', 'Failed to record payment.');
             }
+            $installmentSeq = (int) ($paymentResult['installment_seq'] ?? 1);
 
             if (!$this->recordManualPayment(
                 (string)($row['invoice_number'] ?? $invoiceId),
@@ -1383,34 +1380,57 @@ class PaymentController extends ResourceController
         $checkNumber = null,
         ?int $installmentSeq = null,
         ?array $invoice = null,
-        ?float $currentBalance = null
+        ?float $currentBalance = null,
+        ?string $idempotencyKey = null
     ) {
         $invoice = $invoice ?? $this->invoiceModel->find($invoiceId);
         if (!$invoice) {
             return false;
         }
 
+        $invoiceId = (int) ($invoice['id'] ?? $invoiceId);
+        $amount = round((float) $amount, 2);
+        if ($amount <= 0) {
+            return false;
+        }
+
         $transactionId = $transactionId ?? 'INV-' . $invoiceId . '-' . time();
         $paymentDate   = $paymentDate   ?? utc_now();
 
-        // If sequence wasn't provided (legacy callers), compute it here.
-        // NOTE: If you call this from inside a transaction (recommended), this will be consistent.
+        if ($this->paymentModel->where('transaction_id', $transactionId)->first()) {
+            return false;
+        }
+
+        if ($idempotencyKey !== null && $idempotencyKey !== '') {
+            $existing = $this->paymentModel->where('idempotency_key', $idempotencyKey)->first();
+            if ($existing) {
+                return [
+                    'payment_id' => (int) ($existing['id'] ?? 0),
+                    'installment_seq' => (int) ($existing['installment_seq'] ?? $existing['number_of_installments'] ?? 1),
+                    'duplicate' => true,
+                ];
+            }
+        }
+
+        // If sequence wasn't provided, compute it inside the caller's invoice lock.
         if ($installmentSeq === null || $installmentSeq < 1) {
-            $exclude = ['void', 'voided', 'refunded', 'failed', 'chargeback', 'declined', 'reversed', 'canceled', 'cancelled'];
-            $priorCount = $this->paymentModel
+            $row = $this->db->table('payments')
+                ->select('COALESCE(MAX(installment_seq), 0) + 1 AS next_seq', false)
                 ->where('invoice_id', $invoiceId)
-                ->where('paid_amount >', 0)
-                ->whereNotIn('status', $exclude)
-                ->countAllResults();
-            $installmentSeq = $priorCount + 1;
+                ->get()
+                ->getRowArray();
+            $installmentSeq = (int) ($row['next_seq'] ?? 1);
         }
 
 
         $preBalance = $currentBalance ?? $this->getCurrentInvoiceBalance((int) $invoiceId);
-        $newBalance = max(0.0, round($preBalance - (float) $amount, 2));
+        if ($amount > $preBalance + 0.00001) {
+            return false;
+        }
+        $newBalance = max(0.0, round($preBalance - $amount, 2));
 
         $paymentData = [
-            'parent_id' => $invoice['parent_id'],
+            'parent_id' => (int) $invoice['parent_id'],
             'invoice_id' => $invoiceId,
             'total_amount' => $invoice['total_amount'],
             'paid_amount' => $amount,
@@ -1418,6 +1438,7 @@ class PaymentController extends ResourceController
             'number_of_installments' => $installmentSeq, // <-- installment sequence (1,2,3,...)
             'installment_seq' => $installmentSeq,
             'transaction_id' => $transactionId,
+            'idempotency_key' => $idempotencyKey,
             'payment_method' => strtolower($paymentMethod),
             'payment_date' => $paymentDate,
             'status' => FinancialStatus::PAYMENT_RECORDED,
@@ -1427,11 +1448,16 @@ class PaymentController extends ResourceController
             'school_year' => $schoolYear ?? ($invoice['school_year'] ?? $this->schoolYear),
         ];
 
-        if (!$this->paymentModel->insert($paymentData)) {
+        $paymentId = $this->paymentModel->insert($paymentData);
+        if (!$paymentId) {
             return false;
         }
 
-        return true;
+        return [
+            'payment_id' => (int) $paymentId,
+            'installment_seq' => $installmentSeq,
+            'duplicate' => false,
+        ];
     }
 
     private function getSuccessfulPaymentCount(int $invoiceId): int