Add expense analytics

internal/contract/expense_contract.go

@@ -91,3 +91,55 @@ type ListExpenseResponse struct {
 	Limit      int               `json:"limit"`
 	TotalPages int               `json:"total_pages"`
 }
+
+type ExpenseAnalyticsRequest struct {
+	OutletID *string `form:"outlet_id,omitempty"`
+	DateFrom string  `form:"date_from" validate:"required"`
+	DateTo   string  `form:"date_to" validate:"required"`
+	GroupBy  string  `form:"group_by,default=day" validate:"omitempty,oneof=day hour week month"`
+}
+
+type ExpenseAnalyticsResponse struct {
+	OrganizationID uuid.UUID                      `json:"organization_id"`
+	OutletID       *uuid.UUID                     `json:"outlet_id,omitempty"`
+	DateFrom       time.Time                      `json:"date_from"`
+	DateTo         time.Time                      `json:"date_to"`
+	GroupBy        string                         `json:"group_by"`
+	Summary        ExpenseAnalyticsSummary        `json:"summary"`
+	Data           []ExpenseAnalyticsData         `json:"data"`
+	CategoryData   []ExpenseAnalyticsCategoryData `json:"category_data"`
+	ItemData       []ExpenseAnalyticsItemData     `json:"item_data"`
+}
+
+type ExpenseAnalyticsSummary struct {
+	TotalExpenses       float64 `json:"total_expenses"`
+	TotalExpenseCount   int64   `json:"total_expense_count"`
+	TotalTax            float64 `json:"total_tax"`
+	AverageExpenseValue float64 `json:"average_expense_value"`
+	TotalCategories     int64   `json:"total_categories"`
+	TotalItems          int64   `json:"total_items"`
+}
+
+type ExpenseAnalyticsData struct {
+	Date         time.Time `json:"date"`
+	Expenses     float64   `json:"expenses"`
+	ExpenseCount int64     `json:"expense_count"`
+	Tax          float64   `json:"tax"`
+	Items        int64     `json:"items"`
+	Categories   int64     `json:"categories"`
+}
+
+type ExpenseAnalyticsCategoryData struct {
+	ChartOfAccountID   uuid.UUID `json:"chart_of_account_id"`
+	ChartOfAccountName string    `json:"chart_of_account_name"`
+	TotalAmount        float64   `json:"total_amount"`
+	ExpenseCount       int64     `json:"expense_count"`
+	ItemCount          int64     `json:"item_count"`
+}
+
+type ExpenseAnalyticsItemData struct {
+	Item         string  `json:"item"`
+	TotalAmount  float64 `json:"total_amount"`
+	ExpenseCount int64   `json:"expense_count"`
+	ItemCount    int64   `json:"item_count"`
+}

internal/entities/expense.go

@@ -28,6 +28,46 @@ type Expense struct {
 	Items        []ExpenseItem `gorm:"foreignKey:ExpenseID" json:"items,omitempty"`
 }
 
+type ExpenseAnalytics struct {
+	Summary      ExpenseAnalyticsSummary
+	Data         []ExpenseAnalyticsData
+	CategoryData []ExpenseAnalyticsCategoryData
+	ItemData     []ExpenseAnalyticsItemData
+}
+
+type ExpenseAnalyticsSummary struct {
+	TotalExpenses       float64
+	TotalExpenseCount   int64
+	TotalTax            float64
+	AverageExpenseValue float64
+	TotalCategories     int64
+	TotalItems          int64
+}
+
+type ExpenseAnalyticsData struct {
+	Date         time.Time
+	Expenses     float64
+	ExpenseCount int64
+	Tax          float64
+	Items        int64
+	Categories   int64
+}
+
+type ExpenseAnalyticsCategoryData struct {
+	ChartOfAccountID   uuid.UUID
+	ChartOfAccountName string
+	TotalAmount        float64
+	ExpenseCount       int64
+	ItemCount          int64
+}
+
+type ExpenseAnalyticsItemData struct {
+	Item         string
+	TotalAmount  float64
+	ExpenseCount int64
+	ItemCount    int64
+}
+
 func (e *Expense) BeforeCreate(tx *gorm.DB) error {
 	if e.ID == uuid.Nil {
 		e.ID = uuid.New()

internal/handler/expense_handler.go

@@ -199,3 +199,31 @@ func (h *ExpenseHandler) ListExpenses(c *gin.Context) {
 
 	util.HandleResponse(c.Writer, c.Request, expenseResponse, "ExpenseHandler::ListExpenses")
 }
+
+func (h *ExpenseHandler) GetExpenseAnalytics(c *gin.Context) {
+	ctx := c.Request.Context()
+	contextInfo := appcontext.FromGinContext(ctx)
+
+	var req contract.ExpenseAnalyticsRequest
+	if err := c.ShouldBindQuery(&req); err != nil {
+		logger.FromContext(ctx).WithError(err).Error("ExpenseHandler::GetExpenseAnalytics -> request binding failed")
+		validationResponseError := contract.NewResponseError(constants.MalformedFieldErrorCode, constants.RequestEntity, err.Error())
+		util.HandleResponse(c.Writer, c.Request, contract.BuildErrorResponse([]*contract.ResponseError{validationResponseError}), "ExpenseHandler::GetExpenseAnalytics")
+		return
+	}
+
+	if contextInfo.OutletID != uuid.Nil {
+		outletID := contextInfo.OutletID.String()
+		req.OutletID = &outletID
+	} else if outletID := c.Query("outlet_id"); outletID != "" {
+		req.OutletID = &outletID
+	}
+
+	expenseResponse := h.expenseService.GetExpenseAnalytics(ctx, contextInfo, &req)
+	if expenseResponse.HasErrors() {
+		errorResp := expenseResponse.GetErrors()[0]
+		logger.FromContext(ctx).WithError(errorResp).Error("ExpenseHandler::GetExpenseAnalytics -> Failed to get expense analytics from service")
+	}
+
+	util.HandleResponse(c.Writer, c.Request, expenseResponse, "ExpenseHandler::GetExpenseAnalytics")
+}

internal/models/expense.go

@@ -118,3 +118,56 @@ type ListExpenseResponse struct {
 	Limit      int                `json:"limit"`
 	TotalPages int                `json:"total_pages"`
 }
+
+type ExpenseAnalyticsRequest struct {
+	OrganizationID uuid.UUID  `json:"organization_id"`
+	OutletID       *uuid.UUID `json:"outlet_id,omitempty"`
+	DateFrom       time.Time  `json:"date_from"`
+	DateTo         time.Time  `json:"date_to"`
+	GroupBy        string     `json:"group_by"`
+}
+
+type ExpenseAnalyticsResponse struct {
+	OrganizationID uuid.UUID                      `json:"organization_id"`
+	OutletID       *uuid.UUID                     `json:"outlet_id,omitempty"`
+	DateFrom       time.Time                      `json:"date_from"`
+	DateTo         time.Time                      `json:"date_to"`
+	GroupBy        string                         `json:"group_by"`
+	Summary        ExpenseAnalyticsSummary        `json:"summary"`
+	Data           []ExpenseAnalyticsData         `json:"data"`
+	CategoryData   []ExpenseAnalyticsCategoryData `json:"category_data"`
+	ItemData       []ExpenseAnalyticsItemData     `json:"item_data"`
+}
+
+type ExpenseAnalyticsSummary struct {
+	TotalExpenses       float64 `json:"total_expenses"`
+	TotalExpenseCount   int64   `json:"total_expense_count"`
+	TotalTax            float64 `json:"total_tax"`
+	AverageExpenseValue float64 `json:"average_expense_value"`
+	TotalCategories     int64   `json:"total_categories"`
+	TotalItems          int64   `json:"total_items"`
+}
+
+type ExpenseAnalyticsData struct {
+	Date         time.Time `json:"date"`
+	Expenses     float64   `json:"expenses"`
+	ExpenseCount int64     `json:"expense_count"`
+	Tax          float64   `json:"tax"`
+	Items        int64     `json:"items"`
+	Categories   int64     `json:"categories"`
+}
+
+type ExpenseAnalyticsCategoryData struct {
+	ChartOfAccountID   uuid.UUID `json:"chart_of_account_id"`
+	ChartOfAccountName string    `json:"chart_of_account_name"`
+	TotalAmount        float64   `json:"total_amount"`
+	ExpenseCount       int64     `json:"expense_count"`
+	ItemCount          int64     `json:"item_count"`
+}
+
+type ExpenseAnalyticsItemData struct {
+	Item         string  `json:"item"`
+	TotalAmount  float64 `json:"total_amount"`
+	ExpenseCount int64   `json:"expense_count"`
+	ItemCount    int64   `json:"item_count"`
+}

internal/processor/analytics_processor_test.go

@@ -61,6 +61,9 @@ func (expenseRepositoryStub) Delete(context.Context, uuid.UUID) error         {
 func (expenseRepositoryStub) List(context.Context, uuid.UUID, map[string]interface{}, int, int) ([]*entities.Expense, int64, error) {
 	return nil, 0, nil
 }
+func (expenseRepositoryStub) GetAnalytics(context.Context, uuid.UUID, *uuid.UUID, time.Time, time.Time, string) (*entities.ExpenseAnalytics, error) {
+	return nil, nil
+}
 func (expenseRepositoryStub) CreateItem(context.Context, *entities.ExpenseItem) error { return nil }
 func (expenseRepositoryStub) DeleteItemsByExpenseID(context.Context, uuid.UUID) error { return nil }
 

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
+}

internal/processor/expense_processor_test.go

@@ -3,6 +3,7 @@ package processor
 import (
 	"context"
 	"testing"
+	"time"
 
 	"apskel-pos-be/internal/entities"
 	"apskel-pos-be/internal/models"
@@ -14,6 +15,7 @@ import (
 type expenseRepositoryCaptureStub struct {
 	createdExpense *entities.Expense
 	createdItems   []*entities.ExpenseItem
+	analytics      *entities.ExpenseAnalytics
 }
 
 func (s *expenseRepositoryCaptureStub) Create(_ context.Context, expense *entities.Expense) error {
@@ -44,6 +46,9 @@ func (*expenseRepositoryCaptureStub) Delete(context.Context, uuid.UUID) error
 func (*expenseRepositoryCaptureStub) List(context.Context, uuid.UUID, map[string]interface{}, int, int) ([]*entities.Expense, int64, error) {
 	return nil, 0, nil
 }
+func (s *expenseRepositoryCaptureStub) GetAnalytics(context.Context, uuid.UUID, *uuid.UUID, time.Time, time.Time, string) (*entities.ExpenseAnalytics, error) {
+	return s.analytics, nil
+}
 func (s *expenseRepositoryCaptureStub) CreateItem(_ context.Context, item *entities.ExpenseItem) error {
 	if item.ID == uuid.Nil {
 		item.ID = uuid.New()
@@ -134,3 +139,68 @@ func TestExpenseProcessorCreatePersistsProvidedStatus(t *testing.T) {
 	require.Equal(t, "approved", repo.createdExpense.Status)
 	require.Equal(t, "approved", resp.Status)
 }
+
+func TestExpenseProcessorGetExpenseAnalyticsDefaultsGroupByAndMapsResponse(t *testing.T) {
+	coaID := uuid.New()
+	outletID := uuid.New()
+	now := time.Date(2026, 5, 1, 0, 0, 0, 0, time.UTC)
+	repo := &expenseRepositoryCaptureStub{
+		analytics: &entities.ExpenseAnalytics{
+			Summary: entities.ExpenseAnalyticsSummary{
+				TotalExpenses:       100000,
+				TotalExpenseCount:   2,
+				TotalTax:            10000,
+				AverageExpenseValue: 50000,
+				TotalCategories:     1,
+				TotalItems:          2,
+			},
+			Data: []entities.ExpenseAnalyticsData{
+				{
+					Date:         now,
+					Expenses:     100000,
+					ExpenseCount: 2,
+					Tax:          10000,
+					Items:        2,
+					Categories:   1,
+				},
+			},
+			CategoryData: []entities.ExpenseAnalyticsCategoryData{
+				{
+					ChartOfAccountID:   coaID,
+					ChartOfAccountName: "Operational",
+					TotalAmount:        100000,
+					ExpenseCount:       2,
+					ItemCount:          2,
+				},
+			},
+			ItemData: []entities.ExpenseAnalyticsItemData{
+				{
+					Item:         "Cleaning supplies",
+					TotalAmount:  100000,
+					ExpenseCount: 2,
+					ItemCount:    2,
+				},
+			},
+		},
+	}
+	p := NewExpenseProcessorImpl(repo)
+
+	resp, err := p.GetExpenseAnalytics(context.Background(), &models.ExpenseAnalyticsRequest{
+		OrganizationID: uuid.New(),
+		OutletID:       &outletID,
+		DateFrom:       now,
+		DateTo:         now,
+	})
+
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+	require.Equal(t, "day", resp.GroupBy)
+	require.Equal(t, &outletID, resp.OutletID)
+	require.Equal(t, float64(100000), resp.Summary.TotalExpenses)
+	require.Len(t, resp.Data, 1)
+	require.Equal(t, int64(2), resp.Data[0].ExpenseCount)
+	require.Len(t, resp.CategoryData, 1)
+	require.Equal(t, coaID, resp.CategoryData[0].ChartOfAccountID)
+	require.Len(t, resp.ItemData, 1)
+	require.Equal(t, "Cleaning supplies", resp.ItemData[0].Item)
+}

internal/processor/expense_repository.go

@@ -3,6 +3,7 @@ package processor
 import (
 	"apskel-pos-be/internal/entities"
 	"context"
+	"time"
 
 	"github.com/google/uuid"
 )
@@ -14,6 +15,7 @@ type ExpenseRepository interface {
 	Update(ctx context.Context, expense *entities.Expense) error
 	Delete(ctx context.Context, id uuid.UUID) error
 	List(ctx context.Context, organizationID uuid.UUID, filters map[string]interface{}, limit, offset int) ([]*entities.Expense, int64, error)
+	GetAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, groupBy string) (*entities.ExpenseAnalytics, error)
 	CreateItem(ctx context.Context, item *entities.ExpenseItem) error
 	DeleteItemsByExpenseID(ctx context.Context, expenseID uuid.UUID) error
 }

internal/repository/expense_repository.go

@@ -114,6 +114,138 @@ func (r *ExpenseRepositoryImpl) List(ctx context.Context, organizationID uuid.UU
 	return expenses, total, err
 }
 
+func (r *ExpenseRepositoryImpl) GetAnalytics(ctx context.Context, organizationID uuid.UUID, outletID *uuid.UUID, dateFrom, dateTo time.Time, groupBy string) (*entities.ExpenseAnalytics, error) {
+	var summary entities.ExpenseAnalyticsSummary
+
+	summaryQuery := r.db.WithContext(ctx).
+		Table("expenses e").
+		Select(`
+			COALESCE(SUM(e.total), 0) as total_expenses,
+			COUNT(e.id) as total_expense_count,
+			COALESCE(SUM(e.tax), 0) as total_tax,
+			COALESCE(AVG(e.total), 0) as average_expense_value
+		`).
+		Where("e.organization_id = ?", organizationID).
+		Where("e.status = ?", "approved").
+		Where("e.transaction_date >= ? AND e.transaction_date <= ?", dateFrom, dateTo)
+	if outletID != nil {
+		summaryQuery = summaryQuery.Where("e.outlet_id = ?", *outletID)
+	}
+	if err := summaryQuery.Scan(&summary).Error; err != nil {
+		return nil, err
+	}
+
+	countsQuery := r.db.WithContext(ctx).
+		Table("expense_items ei").
+		Select(`
+			COUNT(ei.id) as total_items,
+			COUNT(DISTINCT ei.chart_of_account_id) as total_categories
+		`).
+		Joins("JOIN expenses e ON ei.expense_id = e.id").
+		Where("e.organization_id = ?", organizationID).
+		Where("e.status = ?", "approved").
+		Where("e.transaction_date >= ? AND e.transaction_date <= ?", dateFrom, dateTo)
+	if outletID != nil {
+		countsQuery = countsQuery.Where("e.outlet_id = ?", *outletID)
+	}
+	if err := countsQuery.Scan(&summary).Error; err != nil {
+		return nil, err
+	}
+
+	dateFormat := "DATE_TRUNC('day', e.transaction_date)"
+	switch groupBy {
+	case "hour":
+		dateFormat = "DATE_TRUNC('hour', e.transaction_date)"
+	case "week":
+		dateFormat = "DATE_TRUNC('week', e.transaction_date)"
+	case "month":
+		dateFormat = "DATE_TRUNC('month', e.transaction_date)"
+	}
+
+	var data []entities.ExpenseAnalyticsData
+	dataQuery := r.db.WithContext(ctx).
+		Table("expenses e").
+		Select(`
+			`+dateFormat+` as date,
+			COALESCE(SUM(e.total), 0) as expenses,
+			COUNT(e.id) as expense_count,
+			COALESCE(SUM(e.tax), 0) as tax,
+			COALESCE(SUM(item_counts.items), 0) as items,
+			COALESCE(SUM(item_counts.categories), 0) as categories
+		`).
+		Joins(`LEFT JOIN (
+			SELECT expense_id, COUNT(id) as items, COUNT(DISTINCT chart_of_account_id) as categories
+			FROM expense_items
+			GROUP BY expense_id
+		) item_counts ON item_counts.expense_id = e.id`).
+		Where("e.organization_id = ?", organizationID).
+		Where("e.status = ?", "approved").
+		Where("e.transaction_date >= ? AND e.transaction_date <= ?", dateFrom, dateTo).
+		Group(dateFormat).
+		Order(dateFormat)
+	if outletID != nil {
+		dataQuery = dataQuery.Where("e.outlet_id = ?", *outletID)
+	}
+	if err := dataQuery.Scan(&data).Error; err != nil {
+		return nil, err
+	}
+
+	var categoryData []entities.ExpenseAnalyticsCategoryData
+	categoryQuery := r.db.WithContext(ctx).
+		Table("expense_items ei").
+		Select(`
+			COALESCE(parent_coa.id, coa.id) as chart_of_account_id,
+			COALESCE(parent_coa.name, coa.name, 'Lain-lain') as chart_of_account_name,
+			COALESCE(SUM(ei.amount), 0) as total_amount,
+			COUNT(DISTINCT e.id) as expense_count,
+			COUNT(ei.id) as item_count
+		`).
+		Joins("JOIN expenses e ON ei.expense_id = e.id").
+		Joins("JOIN chart_of_accounts coa ON ei.chart_of_account_id = coa.id").
+		Joins("LEFT JOIN chart_of_accounts parent_coa ON coa.parent_id = parent_coa.id").
+		Where("e.organization_id = ?", organizationID).
+		Where("e.status = ?", "approved").
+		Where("e.transaction_date >= ? AND e.transaction_date <= ?", dateFrom, dateTo).
+		Group("COALESCE(parent_coa.id, coa.id), COALESCE(parent_coa.name, coa.name, 'Lain-lain')").
+		Order("total_amount DESC")
+	if outletID != nil {
+		categoryQuery = categoryQuery.Where("e.outlet_id = ?", *outletID)
+	}
+	if err := categoryQuery.Scan(&categoryData).Error; err != nil {
+		return nil, err
+	}
+
+	var itemData []entities.ExpenseAnalyticsItemData
+	itemQuery := r.db.WithContext(ctx).
+		Table("expense_items ei").
+		Select(`
+			COALESCE(NULLIF(ei.item, ''), ei.description, coa.name) as item,
+			COALESCE(SUM(ei.amount), 0) as total_amount,
+			COUNT(DISTINCT e.id) as expense_count,
+			COUNT(ei.id) as item_count
+		`).
+		Joins("JOIN expenses e ON ei.expense_id = e.id").
+		Joins("JOIN chart_of_accounts coa ON ei.chart_of_account_id = coa.id").
+		Where("e.organization_id = ?", organizationID).
+		Where("e.status = ?", "approved").
+		Where("e.transaction_date >= ? AND e.transaction_date <= ?", dateFrom, dateTo).
+		Group("COALESCE(NULLIF(ei.item, ''), ei.description, coa.name)").
+		Order("total_amount DESC")
+	if outletID != nil {
+		itemQuery = itemQuery.Where("e.outlet_id = ?", *outletID)
+	}
+	if err := itemQuery.Scan(&itemData).Error; err != nil {
+		return nil, err
+	}
+
+	return &entities.ExpenseAnalytics{
+		Summary:      summary,
+		Data:         data,
+		CategoryData: categoryData,
+		ItemData:     itemData,
+	}, nil
+}
+
 func (r *ExpenseRepositoryImpl) CreateItem(ctx context.Context, item *entities.ExpenseItem) error {
 	return r.db.WithContext(ctx).Create(item).Error
 }

internal/router/router.go

@@ -451,6 +451,7 @@ func (r *Router) addAppRoutes(rg *gin.Engine) {
 			{
 				expenses.POST("", r.expenseHandler.CreateExpense)
 				expenses.GET("", r.expenseHandler.ListExpenses)
+				expenses.GET("/analytics", r.expenseHandler.GetExpenseAnalytics)
 				expenses.GET("/:id", r.expenseHandler.GetExpense)
 				expenses.PUT("/:id", r.expenseHandler.UpdateExpense)
 				expenses.DELETE("/:id", r.expenseHandler.DeleteExpense)

internal/service/expense_service.go

@@ -19,6 +19,7 @@ type ExpenseService interface {
 	DeleteExpense(ctx context.Context, apctx *appcontext.ContextInfo, id uuid.UUID) *contract.Response
 	GetExpenseByID(ctx context.Context, apctx *appcontext.ContextInfo, id uuid.UUID) *contract.Response
 	ListExpenses(ctx context.Context, apctx *appcontext.ContextInfo, req *contract.ListExpenseRequest) *contract.Response
+	GetExpenseAnalytics(ctx context.Context, apctx *appcontext.ContextInfo, req *contract.ExpenseAnalyticsRequest) *contract.Response
 }
 
 type ExpenseServiceImpl struct {
@@ -126,3 +127,24 @@ func (s *ExpenseServiceImpl) ListExpenses(ctx context.Context, apctx *appcontext
 
 	return contract.BuildSuccessResponse(response)
 }
+
+func (s *ExpenseServiceImpl) GetExpenseAnalytics(ctx context.Context, apctx *appcontext.ContextInfo, req *contract.ExpenseAnalyticsRequest) *contract.Response {
+	modelReq, err := transformer.ExpenseAnalyticsRequestToModel(req)
+	if err != nil {
+		errorResp := contract.NewResponseError(constants.MalformedFieldErrorCode, constants.ExpenseServiceEntity, err.Error())
+		return contract.BuildErrorResponse([]*contract.ResponseError{errorResp})
+	}
+
+	modelReq.OrganizationID = apctx.OrganizationID
+	if apctx.OutletID != uuid.Nil {
+		modelReq.OutletID = &apctx.OutletID
+	}
+
+	response, err := s.expenseProcessor.GetExpenseAnalytics(ctx, modelReq)
+	if err != nil {
+		errorResp := contract.NewResponseError(constants.InternalServerErrorCode, constants.ExpenseServiceEntity, err.Error())
+		return contract.BuildErrorResponse([]*contract.ResponseError{errorResp})
+	}
+
+	return contract.BuildSuccessResponse(transformer.ExpenseAnalyticsModelToContract(response))
+}

internal/transformer/expense_transformer.go

@@ -3,6 +3,7 @@ package transformer
 import (
 	"apskel-pos-be/internal/contract"
 	"apskel-pos-be/internal/models"
+	"apskel-pos-be/internal/util"
 )
 
 func CreateExpenseRequestToModel(req *contract.CreateExpenseRequest) *models.CreateExpenseRequest {
@@ -134,3 +135,81 @@ func ExpenseModelResponsesToResponses(expenses []*models.ExpenseResponse) []cont
 	}
 	return responses
 }
+
+func ExpenseAnalyticsRequestToModel(req *contract.ExpenseAnalyticsRequest) (*models.ExpenseAnalyticsRequest, error) {
+	dateFrom, dateTo, err := util.ParseDateRangeToJakartaTime(req.DateFrom, req.DateTo)
+	if err != nil {
+		return nil, err
+	}
+
+	modelReq := &models.ExpenseAnalyticsRequest{
+		OutletID: parseOutletID(req.OutletID),
+		GroupBy:  req.GroupBy,
+	}
+	if dateFrom != nil {
+		modelReq.DateFrom = *dateFrom
+	}
+	if dateTo != nil {
+		modelReq.DateTo = *dateTo
+	}
+
+	return modelReq, nil
+}
+
+func ExpenseAnalyticsModelToContract(resp *models.ExpenseAnalyticsResponse) *contract.ExpenseAnalyticsResponse {
+	if resp == nil {
+		return nil
+	}
+
+	data := make([]contract.ExpenseAnalyticsData, len(resp.Data))
+	for i, item := range resp.Data {
+		data[i] = contract.ExpenseAnalyticsData{
+			Date:         item.Date,
+			Expenses:     item.Expenses,
+			ExpenseCount: item.ExpenseCount,
+			Tax:          item.Tax,
+			Items:        item.Items,
+			Categories:   item.Categories,
+		}
+	}
+
+	categoryData := make([]contract.ExpenseAnalyticsCategoryData, len(resp.CategoryData))
+	for i, item := range resp.CategoryData {
+		categoryData[i] = contract.ExpenseAnalyticsCategoryData{
+			ChartOfAccountID:   item.ChartOfAccountID,
+			ChartOfAccountName: item.ChartOfAccountName,
+			TotalAmount:        item.TotalAmount,
+			ExpenseCount:       item.ExpenseCount,
+			ItemCount:          item.ItemCount,
+		}
+	}
+
+	itemData := make([]contract.ExpenseAnalyticsItemData, len(resp.ItemData))
+	for i, item := range resp.ItemData {
+		itemData[i] = contract.ExpenseAnalyticsItemData{
+			Item:         item.Item,
+			TotalAmount:  item.TotalAmount,
+			ExpenseCount: item.ExpenseCount,
+			ItemCount:    item.ItemCount,
+		}
+	}
+
+	return &contract.ExpenseAnalyticsResponse{
+		OrganizationID: resp.OrganizationID,
+		OutletID:       resp.OutletID,
+		DateFrom:       resp.DateFrom,
+		DateTo:         resp.DateTo,
+		GroupBy:        resp.GroupBy,
+		Summary: contract.ExpenseAnalyticsSummary{
+			TotalExpenses:       resp.Summary.TotalExpenses,
+			TotalExpenseCount:   resp.Summary.TotalExpenseCount,
+			TotalTax:            resp.Summary.TotalTax,
+			AverageExpenseValue: resp.Summary.AverageExpenseValue,
+			TotalCategories:     resp.Summary.TotalCategories,
+			TotalItems:          resp.Summary.TotalItems,
+		},
+		Data:         data,
+		CategoryData: categoryData,
+		ItemData:     itemData,
+	}
+}