refactor(expenses): optimize expense aggregation queries for improved performance

apps/backend/src/modules/expenses/expenses.service.ts

@@ -146,38 +146,36 @@ export async function payExpense(id: number, data: z.infer<typeof payExpenseSche
 }
 
 export async function getMonthlyPayedTotal(year: number, month: number) {
-  const expenses = await prisma.expense.findMany({
+  const result = await prisma.expense.aggregate({
     where: { year, month, status: PaymentStatus.PAYED },
-    select: { amountPayed: true },
+    _sum: { amountPayed: true },
   });
-  const total = expenses.reduce((sum, e) => sum + Number(e.amountPayed ?? 0), 0);
-  return { total };
+  return { total: Number(result._sum.amountPayed ?? 0) };
 }
 
 export async function getMonthlyTotals(year: number, month: number) {
   const [payed, pending] = await Promise.all([
-    prisma.expense.findMany({
+    prisma.expense.aggregate({
       where: { year, month, status: PaymentStatus.PAYED },
-      select: { amountPayed: true },
+      _sum: { amountPayed: true },
     }),
-    prisma.expense.findMany({
+    prisma.expense.aggregate({
       where: { year, month, status: PaymentStatus.PENDING },
-      select: { amount: true },
+      _sum: { amount: true },
     }),
   ]);
   return {
-    payed: payed.reduce((sum, e) => sum + Number(e.amountPayed ?? 0), 0),
-    pending: pending.reduce((sum, e) => sum + Number(e.amount), 0),
+    payed: Number(payed._sum.amountPayed ?? 0),
+    pending: Number(pending._sum.amount ?? 0),
   };
 }
 
 export async function getTotalPending() {
-  const expenses = await prisma.expense.findMany({
+  const result = await prisma.expense.aggregate({
     where: { status: PaymentStatus.PENDING },
-    select: { amount: true },
+    _sum: { amount: true },
   });
-  const total = expenses.reduce((sum, e) => sum + Number(e.amount), 0);
-  return { total };
+  return { total: Number(result._sum.amount ?? 0) };
 }
 
 export async function generateExpensesForCurrentMonth() {