fix: how monthly total is calculated (#98)

Author: npv12

frontend/components/custom/CategoryAnalytics/CategoryAnalytics.tsx

@@ -133,7 +133,7 @@ export function CategoryAnalytics({ data }: CategoryAnalyticsProps) {
         <CardContent className="space-y-6">
           {/* Horizontal Progress Bar */}
           <div className="space-y-4">
-            <div className="h-4 bg-gray-200 rounded-full overflow-hidden">
+            <div className="h-4 rounded-full overflow-hidden">
               {categoriesWithPercentages.map((category) => (
                 <div
                   key={category.category_id}

frontend/components/custom/Dashboard/MonthlyAnalyticsCard.tsx

@@ -4,7 +4,12 @@ import { useMonthlyAnalytics } from "@/components/hooks/useAnalytics";
 import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
 import { Skeleton } from "@/components/ui/skeleton";
 import { formatCurrency } from "@/lib/utils";
-import { CalendarIcon, TrendingDownIcon, TrendingUpIcon } from "lucide-react";
+import {
+  ArrowRightLeftIcon,
+  CalendarIcon,
+  TrendingDownIcon,
+  TrendingUpIcon,
+} from "lucide-react";
 import { useRef, useState } from "react";
 
 interface MonthlyData {
@@ -215,9 +220,12 @@ export function MonthlyAnalyticsCard() {
 
                   {/* Net Amount */}
                   <div className="flex items-center justify-between p-2 bg-blue-50 dark:bg-blue-950/20 rounded-lg">
-                    <span className="text-xs font-medium text-blue-700 dark:text-blue-400">
-                      Net Flow
-                    </span>
+                    <div className="flex items-center gap-2">
+                      <ArrowRightLeftIcon className="h-3 w-3 text-blue-600" />
+                      <span className="text-xs font-medium text-blue-700 dark:text-blue-400">
+                        Net Flow
+                      </span>
+                    </div>
                     <span className="text-xs font-semibold text-blue-800 dark:text-blue-300">
                       {formatCurrency(item.data.total_amount)}
                     </span>

server/internal/api/controller/analytics_controller_test.go

@@ -1074,10 +1074,9 @@ var _ = Describe("AnalyticsController", func() {
 			Expect(hasAmount).To(BeTrue())
 			Expect(totalAmount).To(BeAssignableToTypeOf(float64(0)))
 
-			// Verify values are non-negative (business logic check)
 			Expect(totalIncome.(float64)).To(BeNumerically(">=", 0))
 			Expect(totalExpenses.(float64)).To(BeNumerically(">=", 0))
-			Expect(totalAmount.(float64)).To(BeNumerically(">=", 0))
+			Expect(totalAmount.(float64)).To(BeNumerically("==", totalIncome.(float64)-totalExpenses.(float64)))
 		})
 
 		It("should return different results for different users", func() {

server/internal/repository/analytics_repository.go

@@ -209,9 +209,7 @@ func (r *AnalyticsRepository) GetMonthlyAnalytics(ctx context.Context, userId in
 	if err != nil {
 		return nil, err
 	}
-
-	// Calculate total amount (income + expenses, treating income as positive)
-	totalAmount := totalIncome + totalExpenses
+	totalAmount := totalIncome - totalExpenses
 
 	return &models.MonthlyAnalyticsResponse{
 		TotalIncome:   totalIncome,

server/internal/service/analytics_service.go

@@ -155,11 +155,5 @@ func (s *AnalyticsService) GetMonthlyAnalytics(ctx context.Context, userId int64
 		return nil, fmt.Errorf("end date must be after or equal to start date")
 	}
 
-	// Call repository to get the analytics
-	analytics, err := s.analyticsRepo.GetMonthlyAnalytics(ctx, userId, startDate, endDate)
-	if err != nil {
-		return nil, fmt.Errorf("failed to get monthly analytics: %w", err)
-	}
-
-	return analytics, nil
+	return s.analyticsRepo.GetMonthlyAnalytics(ctx, userId, startDate, endDate)
 }

server/internal/service/analytics_service_test.go

@@ -837,7 +837,6 @@ var _ = Describe("AnalyticsService", func() {
 			It("should return error", func() {
 				_, err := analyticsService.GetMonthlyAnalytics(ctx, userId, startDate, endDate)
 				Expect(err).To(HaveOccurred())
-				Expect(err.Error()).To(ContainSubstring("failed to get monthly analytics"))
 			})
 		})