using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        // Create from string. Ex SOAP request. Like Enum.Parse()

        //var mailClass = MailClass.FromName("Priority");

        //var mailClass = MailClass.FromName("FirstClass");

        // Create from known value

        var mailClass = MailClass.Express;

        // ToString

        Console.WriteLine("As string: {0}", mailClass);

        // Is it FirstClass

        Console.WriteLine("Is FirstClass: {0}", mailClass == MailClass.FirstClass);

        // Is it Priority

        Console.WriteLine("Is Priority: {0}", mailClass == MailClass.Priority);

        // Is it greater than Priority

        Console.WriteLine("Is > FirstClass: {0}", mailClass > MailClass.FirstClass);

        // Is it FedEx (Dynamic value)

        Console.WriteLine("Is FedEx: {0}", mailClass == MailClass.FromName("fedex_standard_overnight"));

        // Cast to integer

        Console.WriteLine("As integer: {0}", (int)mailClass);

        // Cast from integer

        Console.WriteLine("From integer: {0}", (MailClass)300);

        /*

        switch(mailClass)

        {

            case MailClass.Priority:

                Console.WriteLine("Priority");

                break;

        }

        */

    }

}

​

public struct MailClass

{   

    private readonly string _name;

    private readonly int _value;

    // Known Values

    public static MailClass FirstClass { get; private set; }

    public static MailClass Priority { get; private set; }

    public static MailClass Express { get; private set; }

    private static List<MailClass> _mailClasses;

    private MailClass(string name, int value)

    {

        _name = name;

        _value = value;

    }

    static MailClass()

    {

        _mailClasses = new List<MailClass>();

        // Known Values

        FirstClass = new MailClass("FirstClass", 0);

        _mailClasses.Add(FirstClass);

        Priority = new MailClass("Priority", 1);

        _mailClasses.Add(Priority);

        Express = new MailClass("Express", 2);

        _mailClasses.Add(Express);

        // Dynamic Values

        _mailClasses.Add(new MailClass("fedex_standard_overnight", 300));   // values should come from the database

    }

    public static MailClass FromName(string name)

    {

        return _mailClasses.FirstOrDefault(m => m._name == name);

    }

    public static MailClass FromValue(int value)

    {

        return _mailClasses.FirstOrDefault(m => m._value == value);

    }

    public override string ToString()

    {

        return _name;

    }

    public static bool operator == (MailClass x, MailClass y) 

    {

        return x._value == y._value;

    }

    public static bool operator != (MailClass x, MailClass y) 

    {

        return x._value != y._value;

    }

    public static bool operator > (MailClass x, MailClass y) 

    {

        return x._value > y._value;

    }

    public static bool operator < (MailClass x, MailClass y) 

    {

        return x._value < y._value;

    }

    public static bool operator >= (MailClass x, MailClass y) 

    {

        return x._value >= y._value;

    }

    public static bool operator <= (MailClass x, MailClass y) 

    {

        return x._value <= y._value;

    }

    public static explicit operator MailClass(int value)

    {

        return FromValue(value);

    }

    public static explicit operator int(MailClass mailClass)

    {

        return mailClass._value;

    }

    public override bool Equals(object obj)

    {

        return obj is MailClass other && _value == other._value;

    }

    public override int GetHashCode()

    {

        return _value.GetHashCode();

    }

}