package auth

import (
	"context"
	"errors"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/google/uuid"
	"veza-backend-api/internal/models"
	"veza-backend-api/internal/services" // Added import for services
	"veza-backend-api/internal/workers"

	"go.uber.org/zap"
	"golang.org/x/crypto/bcrypt"
	"gorm.io/gorm"

	"veza-backend-api/internal/validators" // Import the validators package
)

type AuthService struct {
	db                       *gorm.DB
	logger                   *zap.Logger
	JWTService               *services.JWTService               // Changed to pointer
	emailVerificationService *services.EmailVerificationService // Changed to pointer
	refreshTokenService      *services.RefreshTokenService      // Changed to pointer
	passwordResetService     *services.PasswordResetService     // Added for password reset
	emailValidator           *validators.EmailValidator
	passwordValidator        *validators.PasswordValidator
	passwordService          *services.PasswordService // Changed to pointer
	emailService             *services.EmailService    // Changed to pointer
	jobWorker                *workers.JobWorker        // Job worker pour envoi d'emails asynchrones
}

func NewAuthService(
	db *gorm.DB,
	emailValidator *validators.EmailValidator,
	passwordValidator *validators.PasswordValidator,
	passwordService *services.PasswordService, // Changed to pointer
	jwtService *services.JWTService, // Changed to pointer
	refreshTokenService *services.RefreshTokenService, // Changed to pointer
	emailVerificationService *services.EmailVerificationService, // Changed to pointer
	passwordResetService *services.PasswordResetService, // Added for password reset
	emailService *services.EmailService, // Changed to pointer
	jobWorker *workers.JobWorker, // Job worker pour emails asynchrones
	logger *zap.Logger,
) *AuthService {
	return &AuthService{
		db:                       db,
		logger:                   logger,
		JWTService:               jwtService,
		emailVerificationService: emailVerificationService,
		refreshTokenService:      refreshTokenService,
		passwordResetService:     passwordResetService,
		emailValidator:           emailValidator,
		passwordValidator:        passwordValidator,
		passwordService:          passwordService,
		emailService:             emailService,
		jobWorker:                jobWorker,
	}
}

// GetUserByUsername récupère un utilisateur par son nom d'utilisateur
func (s *AuthService) GetUserByUsername(ctx context.Context, username string) (*models.User, error) {
	var user models.User
	if err := s.db.WithContext(ctx).Where("username = ?", username).First(&user).Error; err != nil {
		return nil, err
	}
	return &user, nil
}

// Refresh est un alias pour RefreshToken
func (s *AuthService) Refresh(ctx context.Context, refreshToken string) (*models.TokenPair, error) {
	return s.RefreshToken(ctx, refreshToken)
}

func (s *AuthService) Register(ctx context.Context, email, username, password string) (*models.User, error) {
	s.logger.Info("Attempting to register new user", zap.String("email", email))

	// Valider l'email
	if err := s.emailValidator.Validate(email); err != nil {
		s.logger.Warn("Registration failed: invalid email", zap.String("email", email), zap.Error(err))
		return nil, errors.New("invalid email: " + err.Error())
	}

	// Valider le mot de passe
	passwordStrength, err := s.passwordValidator.Validate(password)
	if err != nil || !passwordStrength.Valid { // Vérifiez également si la force n'est pas suffisante
		s.logger.Warn("Registration failed: weak password", zap.String("email", email), zap.Error(err))
		// Si l'erreur est nil mais pas valide, utilisez les détails de la force
		if err == nil {
			err = errors.New("weak password: " + strings.Join(passwordStrength.Details, ", "))
		}
		return nil, errors.New("weak password: " + err.Error())
	}

	// Hacher le mot de passe
	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		s.logger.Error("Failed to hash password", zap.Error(err))
		return nil, err
	}

	// Créer l'utilisateur dans la base de données
	user := &models.User{
		ID:           uuid.New(), // Générer un nouvel UUID
		Email:        email,
		Username:     username,
		Slug:         strings.ToLower(username),
		PasswordHash: string(hashedPassword),
		// IsVerified: false par défaut
	}

	if err := s.db.WithContext(ctx).Create(user).Error; err != nil {
		// PostgreSQL error code 23505 is unique_violation
		// We check for specific constraint names if possible, or fallback to generic "duplicate"
		errMsg := err.Error()
		if strings.Contains(errMsg, "users_email_key") || strings.Contains(errMsg, "idx_users_email") {
			s.logger.Warn("Registration failed: email already exists", zap.String("email", email))
			return nil, services.ErrUserAlreadyExists
		}
		if strings.Contains(errMsg, "users_username_key") || strings.Contains(errMsg, "idx_users_username") {
			s.logger.Warn("Registration failed: username already exists", zap.String("username", username))
			// We can return the same error or a more specific one if needed
			return nil, errors.New("username already exists")
		}
		if strings.Contains(errMsg, "users_slug_key") || strings.Contains(errMsg, "idx_users_slug") {
			s.logger.Warn("Registration failed: slug collision", zap.String("slug", user.Slug))
			// In a real robust system, we would retry with a suffix here
			// For now, fail explicitly so the user knows
			return nil, errors.New("username unavailable (slug collision)")
		}
		
		// Fallback for generic unique constraint
		if strings.Contains(errMsg, "unique constraint") || strings.Contains(errMsg, "duplicate key") {
			s.logger.Warn("Registration failed: unique constraint violation", zap.Error(err))
			return nil, services.ErrUserAlreadyExists
		}
		
		s.logger.Error("Failed to create user in database", zap.Error(err))
		return nil, err
	}

	// Générer le token de vérification d'email
	token, err := s.emailVerificationService.GenerateToken()
	if err != nil {
		s.logger.Error("Failed to generate email verification token", zap.Error(err))
		return user, fmt.Errorf("failed to generate verification token: %w", err)
	}

	// Stocker le token
	if err := s.emailVerificationService.StoreToken(user.ID, user.Email, token); err != nil {
		s.logger.Error("Failed to store email verification token", zap.Error(err))
		return user, fmt.Errorf("failed to store verification token: %w", err)
	}

	// Envoyer l'email de vérification (simulation pour l'instant)
	s.logger.Info("Sending verification email",
		zap.String("email", user.Email),
		zap.String("token", token),
		zap.String("user_id", user.ID.String()))

	s.logger.Info("User registered successfully", zap.String("user_id", user.ID.String()))
	return user, nil
}

func (s *AuthService) Login(ctx context.Context, email, password string, rememberMe bool) (*models.User, *models.TokenPair, error) {
	s.logger.Info("Attempting login", zap.String("email", email))

	var user models.User
	if err := s.db.WithContext(ctx).Where("email = ?", email).First(&user).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			s.logger.Warn("Login failed: user not found", zap.String("email", email))
			return nil, nil, errors.New("invalid credentials")
		}
		s.logger.Error("Database error during login", zap.Error(err), zap.String("email", email))
		return nil, nil, err
	}

	if err := bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(password)); err != nil {
		s.logger.Warn("Login failed: invalid password", zap.String("email", email))
		return nil, nil, errors.New("invalid credentials")
	}

	if !user.IsVerified {
		s.logger.Warn("Login failed: email not verified", zap.String("email", email))
		return nil, nil, errors.New("email not verified")
	}

	// Générer les tokens JWT
	accessToken, err := s.JWTService.GenerateAccessToken(&user)
	if err != nil {
		s.logger.Error("Failed to generate access token", zap.Error(err), zap.String("user_id", user.ID.String()))
		return nil, nil, fmt.Errorf("failed to generate access token: %w", err)
	}

	refreshTokenTTL := s.JWTService.Config.RefreshTokenTTL
	if rememberMe {
		refreshTokenTTL = s.JWTService.Config.RememberMeRefreshTokenTTL // Assurez-vous que ce champ existe dans models.JWTConfig
	}
	refreshToken, err := s.JWTService.GenerateRefreshToken(&user)
	if err != nil {
		s.logger.Error("Failed to generate refresh token", zap.Error(err), zap.String("user_id", user.ID.String()))
		return nil, nil, fmt.Errorf("failed to generate refresh token: %w", err)
	}

	// Stocker le refresh token en base
	if err := s.refreshTokenService.Store(user.ID, refreshToken, refreshTokenTTL); err != nil {
		s.logger.Error("Failed to store refresh token", zap.Error(err), zap.String("user_id", user.ID.String()))
		return nil, nil, fmt.Errorf("failed to store refresh token: %w", err)
	}

	s.logger.Info("User logged in successfully", zap.String("user_id", user.ID.String()))

	return &user, &models.TokenPair{
		AccessToken:  accessToken,
		RefreshToken: refreshToken,
		ExpiresIn:    int(s.JWTService.Config.AccessTokenTTL.Seconds()),
	}, nil
}

func (s *AuthService) RefreshToken(ctx context.Context, refreshToken string) (*models.TokenPair, error) {
	claims, err := s.JWTService.ValidateToken(refreshToken)
	if err != nil {
		s.logger.Warn("Invalid refresh token format", zap.Error(err))
		return nil, errors.New("invalid refresh token")
	}

	if !claims.IsRefresh {
		s.logger.Warn("Token is not a refresh token")
		return nil, errors.New("invalid token type")
	}

	if err := s.refreshTokenService.Validate(claims.UserID, refreshToken); err != nil {
		s.logger.Warn("Refresh token invalid or revoked", zap.Error(err))
		return nil, errors.New("invalid or revoked refresh token")
	}

	var user models.User
	if err := s.db.WithContext(ctx).First(&user, claims.UserID).Error; err != nil {
		s.logger.Error("User not found for refresh token", zap.Error(err))
		return nil, errors.New("user not found")
	}

	newAccessToken, err := s.JWTService.GenerateAccessToken(&user)
	if err != nil {
		s.logger.Error("Failed to generate new access token", zap.Error(err))
		return nil, err
	}

	newRefreshToken, err := s.JWTService.GenerateRefreshToken(&user)
	if err != nil {
		s.logger.Error("Failed to generate new refresh token", zap.Error(err))
		return nil, err
	}

	if err := s.refreshTokenService.Rotate(user.ID, refreshToken, newRefreshToken, s.JWTService.Config.RefreshTokenTTL); err != nil {
		s.logger.Error("Failed to rotate refresh token", zap.Error(err))
		return nil, err
	}

	return &models.TokenPair{
		AccessToken:  newAccessToken,
		RefreshToken: newRefreshToken,
		ExpiresIn:    int(s.JWTService.Config.AccessTokenTTL.Seconds()),
	}, nil
}

func (s *AuthService) VerifyEmail(ctx context.Context, token string) error {
	userID, err := s.emailVerificationService.VerifyToken(token)
	if err != nil {
		s.logger.Warn("Email verification failed", zap.Error(err))
		return err
	}

	if err := s.db.WithContext(ctx).Model(&models.User{}).Where("id = ?", userID).Update("is_verified", true).Error; err != nil {
		s.logger.Error("Failed to update user verification status", zap.Error(err))
		return err
	}

	if err := s.emailVerificationService.InvalidateOldTokens(userID); err != nil {
		s.logger.Warn("Failed to invalidate old verification tokens", zap.Error(err))
	}

	s.logger.Info("Email verified successfully", zap.String("user_id", userID.String()))
	return nil
}

func (s *AuthService) ResendVerificationEmail(ctx context.Context, email string) error {
	var user models.User
	if err := s.db.WithContext(ctx).Where("email = ?", email).First(&user).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return nil
		}
		return err
	}

	if user.IsVerified {
		return errors.New("email already verified")
	}

	if err := s.emailVerificationService.InvalidateOldTokens(user.ID); err != nil {
		s.logger.Error("Failed to invalidate old tokens", zap.Error(err))
	}

	token, err := s.emailVerificationService.GenerateToken()
	if err != nil {
		return err
	}

	if err := s.emailVerificationService.StoreToken(user.ID, user.Email, token); err != nil {
		return err
	}

	s.logger.Info("Resending verification email",
		zap.String("email", user.Email),
		zap.String("token", token),
		zap.String("user_id", user.ID.String()))

	return nil
}

func (s *AuthService) Logout(ctx context.Context, userID uuid.UUID, refreshToken string) error {
	// Valider le refresh token
	claims, err := s.JWTService.ValidateToken(refreshToken)
	if err != nil {
		s.logger.Warn("Invalid refresh token during logout", zap.Error(err), zap.String("user_id", userID.String()))
		return nil // Ne pas retourner d'erreur pour ne pas bloquer le logout côté UI
	}

	if claims.UserID != userID {
		s.logger.Warn("User ID mismatch for logout request", zap.String("requested_user_id", userID.String()), zap.String("token_user_id", claims.UserID.String()))
		return errors.New("user ID mismatch")
	}

	if err := s.refreshTokenService.Revoke(claims.UserID, refreshToken); err != nil {
		s.logger.Error("Failed to revoke refresh token during logout", zap.Error(err), zap.String("user_id", userID.String()))
		return err
	}

	s.logger.Info("User logged out successfully", zap.String("user_id", userID.String()))
	return nil
}

func (s *AuthService) InvalidateAllUserSessions(ctx context.Context, userID uuid.UUID, sessionService interface {
	RevokeAllUserSessions(ctx context.Context, userID uuid.UUID) (int64, error)
}) error {
	if err := s.refreshTokenService.RevokeAll(userID); err != nil {
		s.logger.Error("Failed to revoke all refresh tokens", zap.Error(err))
		return err
	}

	if sessionService != nil {
		count, err := sessionService.RevokeAllUserSessions(ctx, userID)
		if err != nil {
			s.logger.Error("Failed to revoke user sessions", zap.Error(err))
		} else {
			s.logger.Info("Revoked user sessions", zap.Int64("count", count), zap.String("user_id", userID.String()))
		}
	}

	s.logger.Info("All user sessions invalidated", zap.String("user_id", userID.String()))
	return nil
}

// MIGRATION UUID: userID migré vers uuid.UUID
func (s *AuthService) AdminVerifyUser(ctx context.Context, userID uuid.UUID) error {
	result := s.db.WithContext(ctx).Model(&models.User{}).Where("id = ?", userID).Update("is_verified", true)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return errors.New("user not found")
	}

	_ = s.emailVerificationService.InvalidateOldTokens(userID)

	s.logger.Info("User verified by admin", zap.String("user_id", userID.String()))
	return nil
}

// MIGRATION UUID: userID migré vers uuid.UUID
func (s *AuthService) AdminBlockUser(ctx context.Context, userID uuid.UUID) error {
	if err := s.refreshTokenService.RevokeAll(userID); err != nil {
		return err
	}

	s.logger.Info("User blocked by admin", zap.String("user_id", userID.String()))
	return nil
}

func (s *AuthService) RequestPasswordReset(ctx context.Context, email string) error {
	var user models.User
	if err := s.db.WithContext(ctx).Where("email = ?", email).First(&user).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			// Return nil to prevent email enumeration - always return success
			return nil
		}
		return err
	}

	// Invalidate old tokens for this user
	if err := s.passwordResetService.InvalidateOldTokens(user.ID); err != nil {
		s.logger.Warn("Failed to invalidate old password reset tokens",
			zap.String("user_id", user.ID.String()),
			zap.Error(err),
		)
		// Continue anyway, not critical
	}

	// Generate new reset token
	token, err := s.passwordResetService.GenerateToken()
	if err != nil {
		s.logger.Error("Failed to generate password reset token",
			zap.String("user_id", user.ID.String()),
			zap.Error(err),
		)
		return fmt.Errorf("failed to generate reset token: %w", err)
	}

	// Store token in database
	if err := s.passwordResetService.StoreToken(user.ID, token); err != nil {
		s.logger.Error("Failed to store password reset token",
			zap.String("user_id", user.ID.String()),
			zap.Error(err),
		)
		return fmt.Errorf("failed to store reset token: %w", err)
	}

	// Send password reset email via job worker (asynchrone)
	if s.jobWorker != nil {
		// Construire l'URL de reset
		baseURL := os.Getenv("FRONTEND_URL")
		if baseURL == "" {
			baseURL = "http://localhost:5173"
		}
		resetURL := fmt.Sprintf("%s/reset-password?token=%s", baseURL, token)

		// Préparer les données du template
		templateData := map[string]interface{}{
			"Username": user.Username,
			"ResetURL": resetURL,
		}

		// Enqueue le job d'email avec template
		s.jobWorker.EnqueueEmailJobWithTemplate(
			user.Email,
			"Reset your Veza password",
			"password_reset",
			templateData,
		)

		s.logger.Info("Password reset email job enqueued",
			zap.String("user_id", user.ID.String()),
			zap.String("email", user.Email),
		)
	} else {
		// Fallback sur l'ancien système si job worker non disponible
		s.logger.Warn("Job worker not available, using direct email service")
		if err := s.emailService.SendPasswordResetEmail(user.ID, user.Email, token); err != nil {
			s.logger.Error("Failed to send password reset email",
				zap.String("user_id", user.ID.String()),
				zap.String("email", user.Email),
				zap.Error(err),
			)
		}
	}

	s.logger.Info("Password reset requested successfully",
		zap.String("email", email),
		zap.String("user_id", user.ID.String()),
		zap.String("token_preview", token[:min(len(token), 8)]+"..."),
	)
	return nil
}

func (s *AuthService) ResetPassword(ctx context.Context, token, newPassword string) error {
	// Verify the reset token
	userID, err := s.passwordResetService.VerifyToken(token)
	if err != nil {
		s.logger.Warn("Password reset token verification failed",
			zap.String("token_preview", token[:min(len(token), 8)]+"..."),
			zap.Error(err),
		)
		return fmt.Errorf("invalid or expired token: %w", err)
	}

	// Validate password strength
	if err := s.passwordService.ValidatePassword(newPassword); err != nil {
		s.logger.Warn("Password validation failed during reset",
			zap.String("user_id", userID.String()),
			zap.Error(err),
		)
		return fmt.Errorf("invalid password: %w", err)
	}

	// Update password using PasswordService
	if err := s.passwordService.UpdatePassword(userID, newPassword); err != nil {
		s.logger.Error("Failed to update password during reset",
			zap.String("user_id", userID.String()),
			zap.Error(err),
		)
		return fmt.Errorf("failed to update password: %w", err)
	}

	// Mark token as used
	if err := s.passwordResetService.MarkTokenAsUsed(token); err != nil {
		// Log but don't fail - password is already updated
		s.logger.Warn("Failed to mark password reset token as used",
			zap.String("user_id", userID.String()),
			zap.String("token_preview", token[:min(len(token), 8)]+"..."),
			zap.Error(err),
		)
	}

	// Invalidate all user sessions (revoke refresh tokens)
	if err := s.refreshTokenService.RevokeAll(userID); err != nil {
		s.logger.Warn("Failed to revoke refresh tokens after password reset",
			zap.String("user_id", userID.String()),
			zap.Error(err),
		)
		// Don't fail - password is already updated
	}

	s.logger.Info("Password reset completed successfully",
		zap.String("user_id", userID.String()),
	)
	return nil
}

// MIGRATION UUID: userID migré vers uuid.UUID
func (s *AuthService) ChangePassword(ctx context.Context, userID uuid.UUID, currentPassword, newPassword string) error {
	var user models.User
	if err := s.db.WithContext(ctx).First(&user, userID).Error; err != nil {
		return err
	}

	if err := bcrypt.CompareHashAndPassword([]byte(user.PasswordHash), []byte(currentPassword)); err != nil {
		return errors.New("invalid current password")
	}

	hashedPassword, err := bcrypt.GenerateFromPassword([]byte(newPassword), bcrypt.DefaultCost)
	if err != nil {
		return err
	}

	if err := s.db.WithContext(ctx).Model(&user).Update("password_hash", string(hashedPassword)).Error; err != nil {
		return err
	}

	if err := s.refreshTokenService.RevokeAll(userID); err != nil {
		s.logger.Warn("Failed to revoke refresh tokens after password change", zap.Error(err))
	}

	s.logger.Info("Password changed successfully", zap.String("user_id", userID.String()))
	return nil
}

func (s *AuthService) ValidateAccessToken(tokenString string) (*models.CustomClaims, error) {
	return s.JWTService.ValidateToken(tokenString)
}

func (s *AuthService) UpdateLastLogin(ctx context.Context, userID uuid.UUID) error {
	return s.db.WithContext(ctx).Model(&models.User{}).
		Where("id = ?", userID).
		Update("last_login_at", time.Now()).Error
}

// min returns the minimum of two integers (helper function)
func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}