Add expense analytics

internal/processor/expense_processor.go

@@ -19,6 +19,7 @@ type ExpenseProcessor interface {
 	DeleteExpense(ctx context.Context, id, organizationID uuid.UUID) error
 	GetExpenseByID(ctx context.Context, id, organizationID uuid.UUID) (*models.ExpenseResponse, error)
 	ListExpenses(ctx context.Context, organizationID uuid.UUID, filters map[string]interface{}, page, limit int) ([]*models.ExpenseResponse, int, error)
+	GetExpenseAnalytics(ctx context.Context, req *models.ExpenseAnalyticsRequest) (*models.ExpenseAnalyticsResponse, error)
 }
 
 type ExpenseProcessorImpl struct {
@@ -221,3 +222,70 @@ func (p *ExpenseProcessorImpl) ListExpenses(ctx context.Context, organizationID
 
 	return expenseResponses, totalPages, nil
 }
+
+func (p *ExpenseProcessorImpl) GetExpenseAnalytics(ctx context.Context, req *models.ExpenseAnalyticsRequest) (*models.ExpenseAnalyticsResponse, error) {
+	if req.DateFrom.After(req.DateTo) {
+		return nil, fmt.Errorf("date_from cannot be after date_to")
+	}
+
+	if req.GroupBy == "" {
+		req.GroupBy = "day"
+	}
+
+	result, err := p.expenseRepo.GetAnalytics(ctx, req.OrganizationID, req.OutletID, req.DateFrom, req.DateTo, req.GroupBy)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get expense analytics: %w", err)
+	}
+
+	data := make([]models.ExpenseAnalyticsData, len(result.Data))
+	for i, item := range result.Data {
+		data[i] = models.ExpenseAnalyticsData{
+			Date:         item.Date,
+			Expenses:     item.Expenses,
+			ExpenseCount: item.ExpenseCount,
+			Tax:          item.Tax,
+			Items:        item.Items,
+			Categories:   item.Categories,
+		}
+	}
+
+	categoryData := make([]models.ExpenseAnalyticsCategoryData, len(result.CategoryData))
+	for i, item := range result.CategoryData {
+		categoryData[i] = models.ExpenseAnalyticsCategoryData{
+			ChartOfAccountID:   item.ChartOfAccountID,
+			ChartOfAccountName: item.ChartOfAccountName,
+			TotalAmount:        item.TotalAmount,
+			ExpenseCount:       item.ExpenseCount,
+			ItemCount:          item.ItemCount,
+		}
+	}
+
+	itemData := make([]models.ExpenseAnalyticsItemData, len(result.ItemData))
+	for i, item := range result.ItemData {
+		itemData[i] = models.ExpenseAnalyticsItemData{
+			Item:         item.Item,
+			TotalAmount:  item.TotalAmount,
+			ExpenseCount: item.ExpenseCount,
+			ItemCount:    item.ItemCount,
+		}
+	}
+
+	return &models.ExpenseAnalyticsResponse{
+		OrganizationID: req.OrganizationID,
+		OutletID:       req.OutletID,
+		DateFrom:       req.DateFrom,
+		DateTo:         req.DateTo,
+		GroupBy:        req.GroupBy,
+		Summary: models.ExpenseAnalyticsSummary{
+			TotalExpenses:       result.Summary.TotalExpenses,
+			TotalExpenseCount:   result.Summary.TotalExpenseCount,
+			TotalTax:            result.Summary.TotalTax,
+			AverageExpenseValue: result.Summary.AverageExpenseValue,
+			TotalCategories:     result.Summary.TotalCategories,
+			TotalItems:          result.Summary.TotalItems,
+		},
+		Data:         data,
+		CategoryData: categoryData,
+		ItemData:     itemData,
+	}, nil
+}