package service

import (
	"baron-sso-backend/internal/domain"
	"baron-sso-backend/internal/repository"
	"context"
	"log/slog"
)

type UserGroupService interface {
	Create(ctx context.Context, group *domain.UserGroup) error
	Update(ctx context.Context, group *domain.UserGroup) error
	Delete(ctx context.Context, id string) error
	Get(ctx context.Context, id string) (*domain.UserGroup, error)
	List(ctx context.Context, tenantID string) ([]domain.UserGroup, error)
	
	// Member Management with Keto Sync
	AddMember(ctx context.Context, groupID, userID string) error
	RemoveMember(ctx context.Context, groupID, userID string) error
}

type userGroupService struct {
	repo        repository.UserGroupRepository
	userRepo    repository.UserRepository
	ketoService KetoService
}

func NewUserGroupService(repo repository.UserGroupRepository, userRepo repository.UserRepository, keto KetoService) UserGroupService {
	return &userGroupService{
		repo:        repo,
		userRepo:    userRepo,
		ketoService: keto,
	}
}

func (s *userGroupService) Create(ctx context.Context, group *domain.UserGroup) error {
	if err := s.repo.Create(ctx, group); err != nil {
		return err
	}

	// Keto: UserGroup:<id>#parent_tenant@Tenant:<tid>
	err := s.ketoService.CreateRelation(ctx, "UserGroup", group.ID, "parent_tenant", "Tenant:"+group.TenantID)
	if err != nil {
		slog.Error("Failed to create keto relation for user group", "error", err, "group_id", group.ID)
	}

	return nil
}

func (s *userGroupService) Update(ctx context.Context, group *domain.UserGroup) error {
	return s.repo.Update(ctx, group)
}

func (s *userGroupService) Delete(ctx context.Context, id string) error {
	// Optional: Delete relations in Keto before DB delete
	return s.repo.Delete(ctx, id)
}

func (s *userGroupService) Get(ctx context.Context, id string) (*domain.UserGroup, error) {
	group, err := s.repo.FindByID(ctx, id)
	if err != nil {
		return nil, err
	}

	// Fetch members from Keto
	tuples, err := s.ketoService.ListRelations(ctx, "UserGroup", group.ID, "members", "")
	if err != nil {
		slog.Error("Failed to fetch group members from keto", "error", err, "group_id", group.ID)
		// Return group without members rather than failing?
		// But if we fail here, we might hide partial failure. Let's log and proceed or return error?
		// For now, let's proceed with empty members to avoid blocking UI if keto is down?
		// No, SSOT is Keto. If Keto is down, we can't show members.
		// Returning error might be safer.
		return nil, err
	}

	var userIDs []string
	for _, t := range tuples {
		// SubjectID is like "User:uuid"
		if len(t.SubjectID) > 5 && t.SubjectID[:5] == "User:" {
			userIDs = append(userIDs, t.SubjectID[5:])
		}
	}

	if len(userIDs) > 0 {
		members, err := s.userRepo.FindByIDs(ctx, userIDs)
		if err != nil {
			slog.Error("Failed to fetch member details from db", "error", err)
			return nil, err
		}
		group.Members = members
	}

	return group, nil
}

func (s *userGroupService) List(ctx context.Context, tenantID string) ([]domain.UserGroup, error) {
	return s.repo.ListByTenantID(ctx, tenantID)
}

func (s *userGroupService) AddMember(ctx context.Context, groupID, userID string) error {
	// Keto: UserGroup:<groupID>#members@User:<userID>
	err := s.ketoService.CreateRelation(ctx, "UserGroup", groupID, "members", "User:"+userID)
	if err != nil {
		slog.Error("Failed to sync group membership to keto", "error", err, "group", groupID, "user", userID)
		return err
	}

	return nil
}

func (s *userGroupService) RemoveMember(ctx context.Context, groupID, userID string) error {
	// Keto: Delete relation
	err := s.ketoService.DeleteRelation(ctx, "UserGroup", groupID, "members", "User:"+userID)
	if err != nil {
		slog.Error("Failed to remove group membership from keto", "error", err, "group", groupID, "user", userID)
		return err
	}

	return nil
}