update api and add more features

app/Services/Billing/BillingTotalsService.php

@@ -10,41 +10,109 @@ class BillingTotalsService
 {
     public function eventSubtotal(int $parentId, string $schoolYear): float
     {
-        $eventSubtotal = 0.0;
+        return round(array_sum($this->eventSubtotalsByStudent($parentId, $schoolYear)), 2);
+    }
+
+    /**
+     * @return array<int, float> student_id => amount
+     */
+    public function eventSubtotalsByStudent(int $parentId, string $schoolYear): array
+    {
+        $byStudent = [];
+
         try {
             $events = EventCharges::getChargesWithEventInfo($parentId, $schoolYear) ?? [];
             foreach ($events as $event) {
-                $eventSubtotal += (float) ($event['charged'] ?? 0.0);
+                $amount = (float) ($event['charged'] ?? 0);
+                if ($amount <= 0) {
+                    continue;
+                }
+
+                $studentId = (int) ($event['student_id'] ?? 0);
+                if ($studentId > 0) {
+                    $byStudent[$studentId] = ($byStudent[$studentId] ?? 0.0) + $amount;
+                } else {
+                    $byStudent[0] = ($byStudent[0] ?? 0.0) + $amount;
+                }
             }
         } catch (\Throwable $e) {
             Log::warning('Failed to sum event charges.', ['error' => $e->getMessage()]);
         }
 
-        return round($eventSubtotal, 2);
+        foreach ($byStudent as $studentId => $amount) {
+            $byStudent[$studentId] = round($amount, 2);
+        }
+
+        return $byStudent;
     }
 
     public function additionalSubtotal(int $invoiceId, ?string $schoolYear = null): float
     {
-        $additionalSubtotal = 0.0;
+        return $this->sumAdditionalChargeRows(
+            $this->fetchAdditionalChargeRows(invoiceId: $invoiceId, schoolYear: $schoolYear)
+        );
+    }
+
+    public function additionalSubtotalByParent(int $parentId, string $schoolYear): float
+    {
+        return $this->sumAdditionalChargeRows(
+            $this->fetchAdditionalChargeRows(parentId: $parentId, schoolYear: $schoolYear)
+        );
+    }
+
+    /**
+     * @return array<int, array{charge_type: string, amount: float}>
+     */
+    private function fetchAdditionalChargeRows(
+        ?int $parentId = null,
+        ?int $invoiceId = null,
+        ?string $schoolYear = null
+    ): array {
+        $rows = [];
+
         try {
             $builder = AdditionalCharge::query()
                 ->select('charge_type', 'amount')
-                ->where('invoice_id', $invoiceId)
                 ->where('status', 'applied');
 
+            if ($parentId !== null) {
+                $builder->where('parent_id', $parentId);
+            }
+
+            if ($invoiceId !== null) {
+                $builder->where('invoice_id', $invoiceId);
+            }
+
             if ($schoolYear !== null && $schoolYear !== '') {
                 $builder->where('school_year', $schoolYear);
             }
 
             $rows = $builder->get()->map(fn ($row) => (array) $row)->all();
-            foreach ($rows as $row) {
-                $amount = (float) ($row['amount'] ?? 0);
-                $type = strtolower((string) ($row['charge_type'] ?? 'add'));
-                $amount = $type === 'deduct' ? -abs($amount) : abs($amount);
-                $additionalSubtotal += $amount;
-            }
         } catch (\Throwable $e) {
-            Log::warning('Failed to sum additional charges.', ['error' => $e->getMessage()]);
+            Log::warning('Failed to load additional charges.', ['error' => $e->getMessage()]);
+        }
+
+        return $rows;
+    }
+
+    /**
+     * @param array<int, array{charge_type?: string, amount?: float|int|string}> $rows
+     */
+    private function sumAdditionalChargeRows(array $rows): float
+    {
+        $additionalSubtotal = 0.0;
+
+        foreach ($rows as $row) {
+            $amount = (float) ($row['amount'] ?? 0);
+            $type = strtolower((string) ($row['charge_type'] ?? 'add'));
+
+            if (in_array($type, ['deduct', 'previous'], true)) {
+                $amount = -abs($amount);
+            } else {
+                $amount = abs($amount);
+            }
+
+            $additionalSubtotal += $amount;
         }
 
         return round($additionalSubtotal, 2);