package domain

import (
	"fmt"
	"regexp"
	"time"

	"git.nakama.town/fmartingr/hako/internal/auth/store"
	"git.nakama.town/fmartingr/hako/internal/dependencies"
	"git.nakama.town/fmartingr/hako/internal/model"
	"github.com/google/uuid"
	"golang.org/x/crypto/bcrypt"
)

var emailRegex = regexp.MustCompile(`^[a-zA-Z0-9._%+\-]+@[a-zA-Z0-9.\-]+\.[a-zA-Z]{2,}$`)

// AuthDomain handles business logic for authentication
type AuthDomain struct {
	deps model.Dependencies
}

// NewAuthDomain creates a new AuthDomain
func NewAuthDomain(deps model.Dependencies) model.AuthDomain {
	return &AuthDomain{deps: deps}
}

// getDeps returns the concrete dependencies implementation
func (d *AuthDomain) getDeps() *dependencies.Dependencies {
	return d.deps.(*dependencies.Dependencies)
}

// Login authenticates a user and returns a JWT token
func (d *AuthDomain) Login(email, password string) (*model.User, *model.Token, error) {
	deps := d.getDeps()
	// Find user by email
	storeUser, err := deps.UserStore.FindByEmail(email)
	if err != nil {
		return nil, nil, fmt.Errorf("invalid credentials")
	}

	// Convert to domain user
	user := convertUser(storeUser)

	// Verify password
	if !d.VerifyPassword(user, password) {
		return nil, nil, fmt.Errorf("invalid credentials")
	}

	// Get JWT service from dependencies
	jwtService := deps.GetJWTService()
	if jwtService == nil {
		return nil, nil, fmt.Errorf("JWT service not available")
	}

	// Generate JWT token with user's role
	tokenString, expiresAt, err := jwtService.GenerateTokenWithRole(user.ID, user.Email, user.Role)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to generate token: %w", err)
	}

	token := &model.Token{
		Token:     tokenString,
		ExpiresAt: expiresAt,
	}

	return user, token, nil
}

// VerifyPassword verifies a password against a user's password hash
func (d *AuthDomain) VerifyPassword(user *model.User, password string) bool {
	err := bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(password))
	return err == nil
}

// CreateUser creates a new user with hashed password and specified role
func (d *AuthDomain) CreateUser(email, password, role string) (*model.User, error) {
	deps := d.getDeps()

	if !d.isValidEmail(email) {
		return nil, fmt.Errorf("invalid email format")
	}

	if len(password) < 8 {
		return nil, fmt.Errorf("password must be at least 8 characters")
	}

	if role == "" {
		role = "user"
	}
	if role != "user" && role != "admin" {
		return nil, fmt.Errorf("role must be 'user' or 'admin'")
	}

	// Check if user already exists
	_, err := deps.UserStore.FindByEmail(email)
	if err == nil {
		return nil, fmt.Errorf("user with this email already exists")
	}

	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		return nil, fmt.Errorf("failed to hash password: %w", err)
	}

	user := model.NewUserWithRole(email, string(hashedPassword), role)

	storeUser := convertUserToStore(user)
	if err := deps.UserStore.Create(storeUser); err != nil {
		return nil, fmt.Errorf("failed to create user: %w", err)
	}

	return user, nil
}

// ListUsers returns all users
func (d *AuthDomain) ListUsers() ([]*model.User, error) {
	deps := d.getDeps()
	storeUsers, err := deps.UserStore.List()
	if err != nil {
		return nil, fmt.Errorf("failed to list users: %w", err)
	}

	users := make([]*model.User, len(storeUsers))
	for i, su := range storeUsers {
		users[i] = convertUser(su)
	}
	return users, nil
}

// GetUser returns a user by ID
func (d *AuthDomain) GetUser(id string) (*model.User, error) {
	deps := d.getDeps()
	uid, err := uuid.Parse(id)
	if err != nil {
		return nil, fmt.Errorf("invalid user ID")
	}

	storeUser, err := deps.UserStore.FindByID(uid)
	if err != nil {
		return nil, fmt.Errorf("user not found")
	}

	return convertUser(storeUser), nil
}

// UpdateUser updates a user's email and role
func (d *AuthDomain) UpdateUser(id, email, role string) (*model.User, error) {
	deps := d.getDeps()
	uid, err := uuid.Parse(id)
	if err != nil {
		return nil, fmt.Errorf("invalid user ID")
	}

	if !d.isValidEmail(email) {
		return nil, fmt.Errorf("invalid email format")
	}

	if role != "user" && role != "admin" {
		return nil, fmt.Errorf("role must be 'user' or 'admin'")
	}

	// Fetch existing user
	storeUser, err := deps.UserStore.FindByID(uid)
	if err != nil {
		return nil, fmt.Errorf("user not found")
	}

	// Check email uniqueness (allow keeping the same email)
	if email != storeUser.Email {
		existing, err := deps.UserStore.FindByEmail(email)
		if err == nil && existing.ID != uid {
			return nil, fmt.Errorf("email already in use")
		}
	}

	storeUser.Email = email
	storeUser.Role = role
	storeUser.UpdatedAt = time.Now()

	if err := deps.UserStore.Update(storeUser); err != nil {
		return nil, fmt.Errorf("failed to update user: %w", err)
	}

	return convertUser(storeUser), nil
}

// UpdateUserPassword changes a user's password
func (d *AuthDomain) UpdateUserPassword(id, password string) error {
	deps := d.getDeps()
	uid, err := uuid.Parse(id)
	if err != nil {
		return fmt.Errorf("invalid user ID")
	}

	if len(password) < 8 {
		return fmt.Errorf("password must be at least 8 characters")
	}

	storeUser, err := deps.UserStore.FindByID(uid)
	if err != nil {
		return fmt.Errorf("user not found")
	}

	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		return fmt.Errorf("failed to hash password: %w", err)
	}

	storeUser.PasswordHash = string(hashedPassword)
	storeUser.UpdatedAt = time.Now()

	if err := deps.UserStore.Update(storeUser); err != nil {
		return fmt.Errorf("failed to update password: %w", err)
	}

	return nil
}

// DeleteUser deletes a user by ID
func (d *AuthDomain) DeleteUser(id string) error {
	deps := d.getDeps()
	uid, err := uuid.Parse(id)
	if err != nil {
		return fmt.Errorf("invalid user ID")
	}

	if err := deps.UserStore.Delete(uid); err != nil {
		return fmt.Errorf("failed to delete user: %w", err)
	}

	return nil
}

// isValidEmail validates email format
func (d *AuthDomain) isValidEmail(email string) bool {
	return emailRegex.MatchString(email)
}

// Helper conversion functions
func convertUser(su *store.User) *model.User {
	if su == nil {
		return nil
	}
	// Default role to "user" if not set
	role := su.Role
	if role == "" {
		role = "user"
	}
	return &model.User{
		ID:           su.ID,
		Email:        su.Email,
		PasswordHash: su.PasswordHash,
		Role:         role,
		CreatedAt:    su.CreatedAt,
		UpdatedAt:    su.UpdatedAt,
	}
}

func convertUserToStore(du *model.User) *store.User {
	if du == nil {
		return nil
	}
	return &store.User{
		ID:           du.ID,
		Email:        du.Email,
		PasswordHash: du.PasswordHash,
		Role:         du.Role,
		CreatedAt:    du.CreatedAt,
		UpdatedAt:    du.UpdatedAt,
	}
}