add expenses management

internal/service/expense.go

@@ -0,0 +1,84 @@
+package service
+
+import (
+	"fmt"
+	"time"
+
+	"git.juancwu.dev/juancwu/budgit/internal/model"
+	"git.juancwu.dev/juancwu/budgit/internal/repository"
+	"github.com/google/uuid"
+)
+
+type CreateExpenseDTO struct {
+	SpaceID     string
+	UserID      string
+	Description string
+	Amount      int
+	Type        model.ExpenseType
+	Date        time.Time
+	TagIDs      []string
+	ItemIDs     []string
+}
+
+type ExpenseService struct {
+	expenseRepo repository.ExpenseRepository
+}
+
+func NewExpenseService(expenseRepo repository.ExpenseRepository) *ExpenseService {
+	return &ExpenseService{expenseRepo: expenseRepo}
+}
+
+func (s *ExpenseService) CreateExpense(dto CreateExpenseDTO) (*model.Expense, error) {
+	if dto.Description == "" {
+		return nil, fmt.Errorf("expense description cannot be empty")
+	}
+	if dto.Amount <= 0 {
+		return nil, fmt.Errorf("amount must be positive")
+	}
+
+	now := time.Now()
+	expense := &model.Expense{
+		ID:          uuid.NewString(),
+		SpaceID:     dto.SpaceID,
+		CreatedBy:   dto.UserID,
+		Description: dto.Description,
+		AmountCents: dto.Amount,
+		Type:        dto.Type,
+		Date:        dto.Date,
+		CreatedAt:   now,
+		UpdatedAt:   now,
+	}
+
+	err := s.expenseRepo.Create(expense, dto.TagIDs, dto.ItemIDs)
+	if err != nil {
+		return nil, err
+	}
+
+	return expense, nil
+}
+
+func (s *ExpenseService) GetExpensesForSpace(spaceID string) ([]*model.Expense, error) {
+	return s.expenseRepo.GetBySpaceID(spaceID)
+}
+
+func (s *ExpenseService) GetBalanceForSpace(spaceID string) (int, error) {
+	expenses, err := s.expenseRepo.GetBySpaceID(spaceID)
+	if err != nil {
+		return 0, err
+	}
+
+	var balance int
+	for _, expense := range expenses {
+		if expense.Type == model.ExpenseTypeExpense {
+			balance -= expense.AmountCents
+		} else if expense.Type == model.ExpenseTypeTopup {
+			balance += expense.AmountCents
+		}
+	}
+
+	return balance, nil
+}
+
+func (s *ExpenseService) GetExpensesByTag(spaceID string, fromDate, toDate time.Time) ([]*model.TagExpenseSummary, error) {
+	return s.expenseRepo.GetExpensesByTag(spaceID, fromDate, toDate)
+}