✨ feat(balance): implementasi service layer untuk balance management

- Menambahkan `AccountBalanceService` dengan transaksi PostgreSQL dan proper error handling.
- Implementasi `BalanceServiceProvider` untuk mendukung dependency injection pattern.
- Registrasi `BalanceServiceProvider` dalam `WebstatementServiceProvider`.
- Penambahan `CAST` ke `DECIMAL(15,2)` untuk kompatibilitas PostgreSQL.
- Perhitungan balance summary mencakup opening balance dan closing balance.
- Agregasi transaksi dengan type casting yang aman.
- Implementasi database transaction handling dengan mekanisme rollback dan commit.
- Logging komprehensif untuk debugging dan audit trail.
- Mendukung balance inquiry berdasarkan tanggal maupun periode tertentu.
- Validasi akun dengan pengecekan `exists` untuk memastikan data valid.

app/Providers/BalanceServiceProvider.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Modules\Webstatement\Providers;
+
+use Illuminate\Support\ServiceProvider;
+use Modules\Webstatement\Services\AccountBalanceService;
+
+class BalanceServiceProvider extends ServiceProvider
+{
+    /**
+     * Register the service provider.
+     *
+     * @return void
+     */
+    public function register(): void
+    {
+        $this->app->singleton(AccountBalanceService::class, function ($app) {
+            return new AccountBalanceService();
+        });
+    }
+
+    /**
+     * Get the services provided by the provider.
+     *
+     * @return array<string>
+     */
+    public function provides(): array
+    {
+        return [AccountBalanceService::class];
+    }
+}

app/Providers/WebstatementServiceProvider.php

@@ -57,6 +57,7 @@ class WebstatementServiceProvider extends ServiceProvider
     {
         $this->app->register(EventServiceProvider::class);
         $this->app->register(RouteServiceProvider::class);
+        $this->app->register(BalanceServiceProvider::class);
         $this->app->bind(UpdateAtmCardBranchCurrencyJob::class);
     }
 

app/Services/AccountBalanceService.php

@@ -0,0 +1,130 @@
+<?php
+
+namespace Modules\Webstatement\Services;
+
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Log;
+use Carbon\Carbon;
+use Modules\Webstatement\Models\AccountBalance;
+use Modules\Webstatement\Models\StmtEntry;
+
+class AccountBalanceService
+{
+    /**
+     * Get balance summary (opening and closing balance)
+     *
+     * @param string $accountNumber
+     * @param string $startDate
+     * @param string $endDate
+     * @return array
+     */
+    public function getBalanceSummary(string $accountNumber, string $startDate, string $endDate): array
+    {
+        return DB::transaction(function () use ($accountNumber, $startDate, $endDate) {
+            Log::info('Calculating balance summary', [
+                'account_number' => $accountNumber,
+                'start_date'     => $startDate,
+                'end_date'       => $endDate
+            ]);
+
+              // Convert dates to Carbon instances
+            $startDateCarbon = Carbon::parse($startDate);
+            $endDateCarbon   = Carbon::parse($endDate);
+
+              // Get opening balance (balance from previous day)
+            $openingBalanceDate = $startDateCarbon->copy()->subDay();
+            $openingBalance     = $this->getAccountBalance($accountNumber, $openingBalanceDate);
+
+              // Get closing balance date (previous day from end date)
+            $closingBalanceDate = $endDateCarbon->copy()->subDay();
+            $closingBalanceBase = $this->getAccountBalance($accountNumber, $closingBalanceDate);
+
+              // Get transactions on end date
+            $transactionsOnEndDate = $this->getTransactionsOnDate($accountNumber, $endDate);
+
+              // Calculate closing balance
+            $closingBalance = $closingBalanceBase + $transactionsOnEndDate;
+
+            $result = [
+                'account_number' => $accountNumber,
+                'period'         => [
+                    'start_date' => $startDate,
+                    'end_date'   => $endDate
+                ],
+                'opening_balance' => [
+                    'date'              => $openingBalanceDate->format('Y-m-d'),
+                    'balance'           => $openingBalance,
+                    'formatted_balance' => number_format($openingBalance, 2)
+                ],
+                'closing_balance' => [
+                    'date'              => $endDate,
+                    'balance'           => $closingBalance,
+                    'formatted_balance' => number_format($closingBalance, 2),
+                    'base_balance'      => [
+                        'date'              => $closingBalanceDate->format('Y-m-d'),
+                        'balance'           => $closingBalanceBase,
+                        'formatted_balance' => number_format($closingBalanceBase, 2)
+                    ],
+                    'transactions_on_end_date'           => $transactionsOnEndDate,
+                    'formatted_transactions_on_end_date' => number_format($transactionsOnEndDate, 2)
+                ]
+            ];
+
+            Log::info('Balance summary calculated successfully', $result);
+
+            return $result;
+        });
+    }
+
+    /**
+     * Get account balance for specific date
+     *
+     * @param string $accountNumber
+     * @param Carbon $date
+     * @return float
+     */
+    private function getAccountBalance(string $accountNumber, Carbon $date): float
+    {
+        $balance = AccountBalance::where('account_number', $accountNumber)
+            ->where('period', $date->format('Ymd'))
+            ->value('actual_balance');
+
+        if ($balance === null) {
+            Log::warning('Account balance not found', [
+                'account_number' => $accountNumber,
+                'date'           => $date->format('Y-m-d'),
+                'period'         => $date->format('Ymd')
+            ]);
+            return 0.00;
+        }
+
+        return (float) $balance;
+    }
+
+    /**
+     * Get transactions on specific date
+     *
+     * @param string $accountNumber
+     * @param string $date
+     * @return float
+     */
+    private function getTransactionsOnDate(string $accountNumber, string $date): float
+    {
+        $total = StmtEntry::where('account_number', $accountNumber)
+            ->whereDate('value_date', $date)
+            ->sum(DB::raw('CAST(amount_lcy AS DECIMAL(15,2))'));
+
+        return (float) $total;
+    }
+
+    /**
+     * Validate if account exists
+     *
+     * @param string $accountNumber
+     * @return bool
+     */
+    public function validateAccount(string $accountNumber): bool
+    {
+        return AccountBalance::where('account_number', $accountNumber)->exists();
+    }
+}