feat: recurring expenses and reports

internal/service/budget.go

@@ -0,0 +1,169 @@
+package service
+
+import (
+	"fmt"
+	"time"
+
+	"git.juancwu.dev/juancwu/budgit/internal/model"
+	"git.juancwu.dev/juancwu/budgit/internal/repository"
+	"github.com/google/uuid"
+)
+
+type CreateBudgetDTO struct {
+	SpaceID   string
+	TagID     string
+	Amount    int
+	Period    model.BudgetPeriod
+	StartDate time.Time
+	EndDate   *time.Time
+	CreatedBy string
+}
+
+type UpdateBudgetDTO struct {
+	ID        string
+	TagID     string
+	Amount    int
+	Period    model.BudgetPeriod
+	StartDate time.Time
+	EndDate   *time.Time
+}
+
+type BudgetService struct {
+	budgetRepo repository.BudgetRepository
+}
+
+func NewBudgetService(budgetRepo repository.BudgetRepository) *BudgetService {
+	return &BudgetService{budgetRepo: budgetRepo}
+}
+
+func (s *BudgetService) CreateBudget(dto CreateBudgetDTO) (*model.Budget, error) {
+	if dto.Amount <= 0 {
+		return nil, fmt.Errorf("budget amount must be positive")
+	}
+
+	now := time.Now()
+	budget := &model.Budget{
+		ID:          uuid.NewString(),
+		SpaceID:     dto.SpaceID,
+		TagID:       dto.TagID,
+		AmountCents: dto.Amount,
+		Period:      dto.Period,
+		StartDate:   dto.StartDate,
+		EndDate:     dto.EndDate,
+		IsActive:    true,
+		CreatedBy:   dto.CreatedBy,
+		CreatedAt:   now,
+		UpdatedAt:   now,
+	}
+
+	if err := s.budgetRepo.Create(budget); err != nil {
+		return nil, err
+	}
+	return budget, nil
+}
+
+func (s *BudgetService) GetBudget(id string) (*model.Budget, error) {
+	return s.budgetRepo.GetByID(id)
+}
+
+func (s *BudgetService) GetBudgetsWithSpent(spaceID string, tags []*model.Tag) ([]*model.BudgetWithSpent, error) {
+	budgets, err := s.budgetRepo.GetBySpaceID(spaceID)
+	if err != nil {
+		return nil, err
+	}
+
+	tagMap := make(map[string]*model.Tag)
+	for _, t := range tags {
+		tagMap[t.ID] = t
+	}
+
+	result := make([]*model.BudgetWithSpent, 0, len(budgets))
+	for _, b := range budgets {
+		start, end := GetCurrentPeriodBounds(b.Period, time.Now())
+		spent, err := s.budgetRepo.GetSpentForBudget(spaceID, b.TagID, start, end)
+		if err != nil {
+			spent = 0
+		}
+
+		var percentage float64
+		if b.AmountCents > 0 {
+			percentage = float64(spent) / float64(b.AmountCents) * 100
+		}
+
+		var status model.BudgetStatus
+		switch {
+		case percentage > 100:
+			status = model.BudgetStatusOver
+		case percentage >= 75:
+			status = model.BudgetStatusWarning
+		default:
+			status = model.BudgetStatusOnTrack
+		}
+
+		bws := &model.BudgetWithSpent{
+			Budget:     *b,
+			SpentCents: spent,
+			Percentage: percentage,
+			Status:     status,
+		}
+
+		if tag, ok := tagMap[b.TagID]; ok {
+			bws.TagName = tag.Name
+			bws.TagColor = tag.Color
+		}
+
+		result = append(result, bws)
+	}
+	return result, nil
+}
+
+func (s *BudgetService) UpdateBudget(dto UpdateBudgetDTO) (*model.Budget, error) {
+	if dto.Amount <= 0 {
+		return nil, fmt.Errorf("budget amount must be positive")
+	}
+
+	existing, err := s.budgetRepo.GetByID(dto.ID)
+	if err != nil {
+		return nil, err
+	}
+
+	existing.TagID = dto.TagID
+	existing.AmountCents = dto.Amount
+	existing.Period = dto.Period
+	existing.StartDate = dto.StartDate
+	existing.EndDate = dto.EndDate
+	existing.UpdatedAt = time.Now()
+
+	if err := s.budgetRepo.Update(existing); err != nil {
+		return nil, err
+	}
+	return existing, nil
+}
+
+func (s *BudgetService) DeleteBudget(id string) error {
+	return s.budgetRepo.Delete(id)
+}
+
+func GetCurrentPeriodBounds(period model.BudgetPeriod, now time.Time) (time.Time, time.Time) {
+	switch period {
+	case model.BudgetPeriodWeekly:
+		weekday := int(now.Weekday())
+		if weekday == 0 {
+			weekday = 7
+		}
+		start := now.AddDate(0, 0, -(weekday - 1))
+		start = time.Date(start.Year(), start.Month(), start.Day(), 0, 0, 0, 0, now.Location())
+		end := start.AddDate(0, 0, 6)
+		end = time.Date(end.Year(), end.Month(), end.Day(), 23, 59, 59, 0, now.Location())
+		return start, end
+	case model.BudgetPeriodYearly:
+		start := time.Date(now.Year(), 1, 1, 0, 0, 0, 0, now.Location())
+		end := time.Date(now.Year(), 12, 31, 23, 59, 59, 0, now.Location())
+		return start, end
+	default: // monthly
+		start := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
+		end := start.AddDate(0, 1, -1)
+		end = time.Date(end.Year(), end.Month(), end.Day(), 23, 59, 59, 0, now.Location())
+		return start, end
+	}
+}