feat: migrate auth module to modular domain pattern

internal/auth/service/service.go

@@ -0,0 +1,57 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"mal/internal/domain"
+	"time"
+
+	"github.com/google/uuid"
+	"golang.org/x/crypto/bcrypt"
+)
+
+type authService struct {
+	repo domain.AuthRepository
+}
+
+func NewAuthService(repo domain.AuthRepository) domain.AuthService {
+	return &authService{repo: repo}
+}
+
+func (s *authService) Login(ctx context.Context, username, password string) (*domain.Session, error) {
+	user, err := s.repo.GetUserByUsername(ctx, username)
+	if err != nil {
+		return nil, err
+	}
+	if user == nil {
+		return nil, errors.New("invalid credentials")
+	}
+
+	if err := bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(password)); err != nil {
+		return nil, errors.New("invalid credentials")
+	}
+
+	sessionID := uuid.New().String()
+	return s.repo.CreateSession(ctx, user.ID, sessionID)
+}
+
+func (s *authService) ValidateSession(ctx context.Context, sessionID string) (*domain.User, error) {
+	session, err := s.repo.GetSession(ctx, sessionID)
+	if err != nil {
+		return nil, err
+	}
+	if session == nil {
+		return nil, errors.New("session not found")
+	}
+
+	if session.ExpiresAt.Before(time.Now()) {
+		_ = s.repo.DeleteSession(ctx, sessionID)
+		return nil, errors.New("session expired")
+	}
+
+	return s.repo.GetUserByID(ctx, session.UserID)
+}
+
+func (s *authService) Logout(ctx context.Context, sessionID string) error {
+	return s.repo.DeleteSession(ctx, sessionID)
+}