the-biergarten-app/web/backend/Features/Features.Users/Commands/Authentication/RegisterUser/RegisterUserValidator.cs

using FluentValidation;

namespace Features.Auth.Commands.Authentication.RegisterUser;

/// <summary>
///     Validates the field-level constraints on <see cref="RegisterUserCommand" />: username format and
///     length, name lengths, email format, minimum age of 19, and password complexity.
/// </summary>
public class RegisterUserValidator : AbstractValidator<RegisterUserCommand>
{
    public RegisterUserValidator()
    {
        RuleFor(x => x.Username)
            .NotEmpty()
            .WithMessage("Username is required")
            .Length(3, 64)
            .WithMessage("Username must be between 3 and 64 characters")
            .Matches("^[a-zA-Z0-9._-]+$")
            .WithMessage(
                "Username can only contain letters, numbers, dots, underscores, and hyphens"
            );

        RuleFor(x => x.FirstName)
            .NotEmpty()
            .WithMessage("First name is required")
            .MaximumLength(128)
            .WithMessage("First name cannot exceed 128 characters");

        RuleFor(x => x.LastName)
            .NotEmpty()
            .WithMessage("Last name is required")
            .MaximumLength(128)
            .WithMessage("Last name cannot exceed 128 characters");

        RuleFor(x => x.Email)
            .NotEmpty()
            .WithMessage("Email is required")
            .EmailAddress()
            .WithMessage("Invalid email format")
            .MaximumLength(128)
            .WithMessage("Email cannot exceed 128 characters");

        RuleFor(x => x.DateOfBirth)
            .NotEmpty()
            .WithMessage("Date of birth is required")
            .LessThan(DateTime.Today.AddYears(-19))
            .WithMessage("You must be at least 19 years old to register");

        RuleFor(x => x.Password)
            .NotEmpty()
            .WithMessage("Password is required")
            .MinimumLength(8)
            .WithMessage("Password must be at least 8 characters")
            .Matches("[A-Z]")
            .WithMessage("Password must contain at least one uppercase letter")
            .Matches("[a-z]")
            .WithMessage("Password must contain at least one lowercase letter")
            .Matches("[0-9]")
            .WithMessage("Password must contain at least one number")
            .Matches("[^a-zA-Z0-9]")
            .WithMessage("Password must contain at least one special character");
    }
}