package services

import (
	"errors"
	"fmt"
	"strings"

	"attune-heart-therapy/internal/models"
	"attune-heart-therapy/internal/repositories"

	"github.com/go-playground/validator/v10"
)

// userService implements the UserService interface
type userService struct {
	userRepo            repositories.UserRepository
	jwtService          JWTService
	notificationService NotificationService
	validator           *validator.Validate
}

// NewUserService creates a new instance of UserService
func NewUserService(userRepo repositories.UserRepository, jwtService JWTService, notificationService NotificationService) UserService {
	return &userService{
		userRepo:            userRepo,
		jwtService:          jwtService,
		notificationService: notificationService,
		validator:           validator.New(),
	}
}

// Register creates a new user account with password hashing and validation
func (s *userService) Register(req RegisterRequest) (*models.User, error) {
	// Validate the request
	if err := s.validator.Struct(req); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Additional password validation
	if len(req.Password) < 8 {
		return nil, errors.New("password must be at least 8 characters long")
	}

	// Normalize email
	req.Email = strings.ToLower(strings.TrimSpace(req.Email))

	// Check if user already exists
	existingUser, err := s.userRepo.GetByEmail(req.Email)
	if err == nil && existingUser != nil {
		return nil, fmt.Errorf("user with email %s already exists", req.Email)
	}

	// Create new user
	user := &models.User{
		FirstName:   strings.TrimSpace(req.FirstName),
		LastName:    strings.TrimSpace(req.LastName),
		Email:       req.Email,
		Phone:       strings.TrimSpace(req.Phone),
		Location:    strings.TrimSpace(req.Location),
		DateOfBirth: req.DateOfBirth,
		IsAdmin:     false, // New users are not admin by default
	}

	// Hash the password
	if err := user.HashPassword(req.Password); err != nil {
		return nil, fmt.Errorf("failed to hash password: %w", err)
	}

	// Save user to database
	if err := s.userRepo.Create(user); err != nil {
		return nil, fmt.Errorf("failed to create user: %w", err)
	}

	// Send welcome email notification
	if err := s.notificationService.SendWelcomeEmail(user); err != nil {
		// Log the error but don't fail the registration
		fmt.Printf("Failed to send welcome email to %s: %v\n", user.Email, err)
	}

	// Clear password hash from response for security
	user.PasswordHash = ""

	return user, nil
}

// Login authenticates a user and returns user info with JWT token
func (s *userService) Login(email, password string) (*models.User, string, error) {
	// Validate input
	if email == "" {
		return nil, "", errors.New("email is required")
	}
	if password == "" {
		return nil, "", errors.New("password is required")
	}

	// Normalize email
	email = strings.ToLower(strings.TrimSpace(email))

	// Get user by email
	user, err := s.userRepo.GetByEmail(email)
	if err != nil {
		return nil, "", errors.New("invalid credentials")
	}

	// Check password
	if !user.CheckPassword(password) {
		return nil, "", errors.New("invalid credentials")
	}

	// Generate JWT token
	token, err := s.jwtService.GenerateToken(user.ID, user.Email, user.IsAdmin)
	if err != nil {
		return nil, "", fmt.Errorf("failed to generate token: %w", err)
	}

	// Clear password hash from response for security
	user.PasswordHash = ""

	return user, token, nil
}

// GetProfile retrieves user profile information by user ID
func (s *userService) GetProfile(userID uint) (*models.User, error) {
	if userID == 0 {
		return nil, errors.New("invalid user ID")
	}

	user, err := s.userRepo.GetByID(userID)
	if err != nil {
		return nil, fmt.Errorf("failed to get user profile: %w", err)
	}

	// Clear password hash from response for security
	user.PasswordHash = ""

	return user, nil
}

// UpdateProfile updates user profile information
func (s *userService) UpdateProfile(userID uint, req UpdateProfileRequest) (*models.User, error) {
	if userID == 0 {
		return nil, errors.New("invalid user ID")
	}

	// Validate the request
	if err := s.validator.Struct(req); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Get existing user
	user, err := s.userRepo.GetByID(userID)
	if err != nil {
		return nil, fmt.Errorf("failed to get user: %w", err)
	}

	// Update fields if provided
	if req.FirstName != "" {
		user.FirstName = strings.TrimSpace(req.FirstName)
	}
	if req.LastName != "" {
		user.LastName = strings.TrimSpace(req.LastName)
	}
	if req.Phone != "" {
		user.Phone = strings.TrimSpace(req.Phone)
	}
	if req.Location != "" {
		user.Location = strings.TrimSpace(req.Location)
	}
	if !req.DateOfBirth.IsZero() {
		user.DateOfBirth = req.DateOfBirth
	}

	// Update user in database
	if err := s.userRepo.Update(user); err != nil {
		return nil, fmt.Errorf("failed to update user: %w", err)
	}

	// Clear password hash from response for security
	user.PasswordHash = ""

	return user, nil
}

// CreateAdmin creates a new admin account with validation and password hashing
func (s *userService) CreateAdmin(req CreateAdminRequest) (*models.User, error) {
	// Validate the request
	if err := s.validator.Struct(req); err != nil {
		return nil, fmt.Errorf("validation failed: %w", err)
	}

	// Additional password validation
	if len(req.Password) < 8 {
		return nil, errors.New("password must be at least 8 characters long")
	}

	// Normalize email
	req.Email = strings.ToLower(strings.TrimSpace(req.Email))

	// Check if user already exists
	existingUser, err := s.userRepo.GetByEmail(req.Email)
	if err == nil && existingUser != nil {
		return nil, fmt.Errorf("user with email %s already exists", req.Email)
	}

	// Create new admin user
	user := &models.User{
		FirstName: strings.TrimSpace(req.FirstName),
		LastName:  strings.TrimSpace(req.LastName),
		Email:     req.Email,
		IsAdmin:   true, // Set admin flag
	}

	// Hash the password
	if err := user.HashPassword(req.Password); err != nil {
		return nil, fmt.Errorf("failed to hash password: %w", err)
	}

	// Save user to database
	if err := s.userRepo.Create(user); err != nil {
		return nil, fmt.Errorf("failed to create admin user: %w", err)
	}

	// Clear password hash from response for security
	user.PasswordHash = ""

	return user, nil
}