refactor to use app package instead of service

refactor app to be composable

internal/app/statistics.go

@@ -0,0 +1,37 @@
+package app
+
+import (
+	"context"
+	"errors"
+
+	"github.com/LazyBachelor/LazyPM/internal/models"
+	"github.com/LazyBachelor/LazyPM/internal/storage"
+)
+
+type StatisticsService struct {
+	storage *storage.Storage[models.Statistics]
+}
+
+func NewStatisticsService(storage *storage.Storage[models.Statistics]) (*StatisticsService, error) {
+	if err := storage.Init(); err != nil {
+		return nil, err
+	}
+	return &StatisticsService{
+		storage: storage,
+	}, nil
+}
+
+func (s *StatisticsService) Load(ctx context.Context) error {
+	return s.storage.Load()
+}
+
+func (s *StatisticsService) Save(ctx context.Context) error {
+	return s.storage.Save()
+}
+
+func (s *StatisticsService) GetStatistics() (models.Statistics, error) {
+	if s.storage.Data == nil {
+		return models.Statistics{}, errors.New("statistics data not initialized")
+	}
+	return *s.storage.Data, nil
+}