package service

import (
	"database/sql"
	"errors"
	"fmt"

	"devone.aplikasi.web.id/gitea/mario/go-ohif-proxy/internal/api/models"
	"devone.aplikasi.web.id/gitea/mario/go-ohif-proxy/internal/api/repository"
	"devone.aplikasi.web.id/gitea/mario/go-ohif-proxy/internal/database"
	"go.uber.org/zap"
)

var (
	ErrEmailExists    = errors.New("email already exists")
	ErrUserNotCreated = errors.New("failed to create user")
	ErrInvalidRole    = errors.New("invalid user role")
	ErrInvalidPatient = errors.New("invalid patient data")
	ErrInvalidDoctor  = errors.New("invalid doctor data")
	ErrTransaction    = errors.New("transaction error")
)

// RegisterRequest represents a user registration request
type RegisterRequest struct {
	Email    string                 `json:"email"`
	Password string                 `json:"password"`
	Name     string                 `json:"name"`
	Role     string                 `json:"role"` // "patient", "ref_doctor", "expertise_doctor", or "admin"
	Patient  *models.PatientDetails `json:"patient,omitempty"`
	Doctor   *models.DoctorDetails  `json:"doctor,omitempty"`
	Studies  []models.Study         `json:"studies,omitempty"` // Study records for patient
}

// RegisterService handles user registration
type RegisterService struct {
	userRepo    *repository.UserRepository
	patientRepo *repository.PatientRepository
	doctorRepo  *repository.DoctorRepository
	studyRepo   *repository.StudyRepository
	logger      *zap.Logger
}

// NewRegisterService creates a new register service
func NewRegisterService(logger *zap.Logger) *RegisterService {
	if logger == nil {
		// If no logger is provided, create a no-op logger
		logger = zap.NewNop()
	}

	return &RegisterService{
		userRepo:    repository.NewUserRepository(),
		patientRepo: repository.NewPatientRepository(),
		doctorRepo:  repository.NewDoctorRepository(),
		studyRepo:   repository.NewStudyRepository(),
		logger:      logger,
	}
}

// Register creates a new user with their associated role-specific data
func (s *RegisterService) Register(req *RegisterRequest) (*models.User, error) {
	// Validate role
	if req.Role != "patient" && req.Role != "ref_doctor" && req.Role != "expertise_doctor" && req.Role != "admin" {
		return nil, ErrInvalidRole
	}

	// Check role-specific data
	if req.Role == "patient" && (req.Patient == nil || req.Patient.PatientID == "" || req.Patient.DateOfBirth == "") {
		return nil, ErrInvalidPatient
	}

	if (req.Role == "ref_doctor" || req.Role == "expertise_doctor") && (req.Doctor == nil || req.Doctor.DoctorID == "") {
		return nil, ErrInvalidDoctor
	}

	// Check if email already exists - do this outside the transaction
	existingUser, err := s.userRepo.GetUserByEmail(req.Email)
	if err != nil && err != sql.ErrNoRows {
		return nil, fmt.Errorf("error checking existing user: %w", err)
	}

	if existingUser != nil {
		return nil, ErrEmailExists
	}

	// Start a transaction
	tx, err := database.DB.Beginx()
	if err != nil {
		s.logger.Error("Failed to begin transaction", zap.Error(err))
		return nil, fmt.Errorf("%w: failed to begin transaction", ErrTransaction)
	}

	// Ensure the transaction is rolled back if we return an error
	defer func() {
		if r := recover(); r != nil {
			s.logger.Error("Panic in transaction", zap.Any("recover", r))
			tx.Rollback()
			panic(r) // re-throw the panic after cleanup
		}
	}()

	// Create user
	newUser := &models.User{
		Email:    req.Email,
		Password: req.Password, // Will be hashed in repository
		Role:     req.Role,
		Name:     req.Name,
	}

	// Use the transaction for user creation
	if err := s.userRepo.CreateUserTx(tx, newUser); err != nil {
		s.logger.Error("Failed to create user", zap.Error(err), zap.String("email", req.Email))
		tx.Rollback()
		return nil, fmt.Errorf("error creating user: %w", err)
	}

	// Create role-specific data
	if req.Role == "patient" {
		err = s.patientRepo.CreatePatientTx(tx, req.Patient, newUser.ID)
		if err != nil {
			s.logger.Error("Failed to create patient", zap.Error(err), zap.String("patientID", req.Patient.PatientID))
			tx.Rollback()
			return nil, fmt.Errorf("error creating patient: %w", err)
		}

		// Create associated study records if provided
		if len(req.Studies) > 0 {
			for _, study := range req.Studies {
				if study.StudyInstanceUID == "" {
					continue // Skip studies without UIDs
				}

				err = s.studyRepo.CreateStudyTx(tx, req.Patient.PatientID, study)
				if err != nil {
					s.logger.Error("Failed to create study",
						zap.Error(err),
						zap.String("patientID", req.Patient.PatientID),
						zap.String("studyUID", study.StudyInstanceUID))
					tx.Rollback()
					return nil, fmt.Errorf("error creating study for patient: %w", err)
				}
			}
		}
	} else if req.Role == "ref_doctor" || req.Role == "expertise_doctor" {
		err = s.doctorRepo.CreateDoctorTx(tx, req.Doctor, newUser.ID)
		if err != nil {
			s.logger.Error("Failed to create doctor", zap.Error(err), zap.String("doctorID", req.Doctor.DoctorID))
			tx.Rollback()
			return nil, fmt.Errorf("error creating doctor: %w", err)
		}
	}

	// Commit the transaction
	if err := tx.Commit(); err != nil {
		s.logger.Error("Failed to commit transaction", zap.Error(err))
		tx.Rollback() // This is actually redundant as the transaction will be rolled back on failure
		return nil, fmt.Errorf("%w: failed to commit transaction", ErrTransaction)
	}

	s.logger.Info("Successfully registered new user",
		zap.String("email", req.Email),
		zap.String("role", req.Role),
		zap.String("userID", newUser.ID))

	return newUser, nil
}