using System;

using System.Collections.Generic;

using System.Linq;

using System.Reflection;

​

public class Program

{

    public static void Main()

    {

        // sử dụng giống enum

        var emp1 = EmployeeTypes.FullTime;

        // convert value sang enum

        var emp2 = EmployeeTypes.FromValue<EmployeeTypes>(2);

        // convert name sang enum

        var emp3 = EmployeeTypes.FromDisplayName<EmployeeTypes>("Intern");

        Console.WriteLine(emp1.Id);

    }

}

public class EmployeeTypes : Enumeration

{

    public static EmployeeTypes FullTime = new EmployeeTypes(1, "FullTime");

    public static EmployeeTypes PartTime = new EmployeeTypes(2, "PartTime");

    public static EmployeeTypes Intern = new EmployeeTypes(3, "Intern");

​

    public EmployeeTypes() : base() { }

    public EmployeeTypes(int id, string name) : base(id, name) { }

}

​

public abstract class Enumeration : IComparable

{

    public string Name { get; set; }

​

    public int Id { get; set; }

​

    protected Enumeration() { }

​

    protected Enumeration(int id, string name)

    {

        Id = id;

        Name = name;

    }

    public int CompareTo(object other) => Id.CompareTo(((Enumeration)other).Id);

    public override string ToString() => Name;

​

    public static IEnumerable<T> GetAll<T>() where T : Enumeration

    {

        var fields = typeof(T).GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly);

​

        return fields.Select(f => f.GetValue(null)).Cast<T>();

    }

    public static T FromValue<T>(int value) where T : Enumeration

    {

        var matchingItem = Parse<T, int>(value, "value", item => item.Id == value);

        return matchingItem;

    }

​

    public static T FromDisplayName<T>(string displayName) where T : Enumeration

    {

        var matchingItem = Parse<T, string>(displayName, "display name", item => item.Name == displayName);

        return matchingItem;

    }

​

    private static T Parse<T, K>(K value, string description, Func<T, bool> predicate) where T : Enumeration

    {

        var matchingItem = GetAll<T>().FirstOrDefault(predicate);

​

        if (matchingItem == null)

                throw new InvalidOperationException($"'{value}' is not a valid {description} in {typeof(T)}");

​

        return matchingItem;

    }

}

​