Meum/Meum.Core/UserAddress.cs

using System.Net;

namespace Meum.Core;

public class UserAddress
{
    public readonly string Name;
    public readonly DnsEndPoint RegistrationServer;
    public readonly string Full;

    public UserAddress(string name, DnsEndPoint registrationServer)
    {
        Name = name;
        RegistrationServer = registrationServer;
        Full = $"{name}@{registrationServer}";
    }

    public UserAddress(string addrstr)
    {
        int at_index = addrstr.IndexOf('@');
        if(at_index == -1)
            throw new FormatException($"Invalid user address format '{addrstr}'");
        Full = addrstr;
        Name = addrstr.Substring(0, at_index);
        if(!ValidateName(Name))
            throw new FormatException($"Invalid user name '{Name}' in address '{addrstr}'");
        string serverstr = addrstr.Substring(at_index + 1);
        
        RegistrationServer = Network.ParseDnsEndPoint(serverstr);
    }

    public override string ToString() => Full;
    
    public override int GetHashCode() => ToString().GetHashCode();

    private static bool ValidateName(string? name)
    {
        if(string.IsNullOrEmpty(name))
            return false;
        foreach (char c in name)
        {
            if(!char.IsAsciiLetterOrDigit(c) && c != '.' && c != '-' && c != '_')
                return false;
        }
        
        return true;
    }
}