//
// Sample code for book "C# in Front Office" (ISBN/EAN13: 144215358X / 9781442153585)
//
// Code is provided as it is and without any guarentee. Using this code for both
// personal and commercial purpose is permitted if the original source of this
// code is included.
//
// Author email: greenwich2greenwich@gmail.com
// Book website: http://book.greenwich2greenwich.com/CsInFrontOffice/
// Code Example: http://book.greenwich2greenwich.com/Examples/
//
using System;
using System.Reflection;

/// <summary>
/// Enum related utility methods. Its beauty is intuitive user interface.
/// 
/// By comparison, in C++, usually a lengthy if-elif-elif-...-else or a switch-case structure is required.
/// Even though such code can be wrapped into a macro or a a fancy template class,such approach is not very
/// natural. Also it typically will require some additional efforts when defining an enum.
/// 
/// See section 7.8 in the book.
/// </summary>
class MyEnumUtil
{
  #region String2Enum
  /// <summary>
  /// Converts a string to an Enum. 
  /// 
  /// If you are using VS2003 which does not support generics, see the next method.
  /// </summary>
  /// <typeparam name="Type_">Enum type</typeparam>
  /// <param name="value_">a String</param>
  /// <returns>An Enum value, throw if failed</returns>
  public static Type_ String2Enum<Type_>(String value_)
  {
    foreach (FieldInfo fi in typeof(Type_).GetFields())
    {
      if (fi.Name == value_)
      {
        return (Type_)fi.GetValue(null);
      }
    }
    throw new Exception(string.Format("Can't convert {0} to {1}", value_, typeof(Type_)));
  }

  /// <summary>
  /// Converts a String to Enum (VS2003 version). The previous method is preferred if you are using higher version. 
  /// </summary>
  /// <param name="type_"></param>
  /// <param name="value_"></param>
  /// <returns></returns>
  public static object String2Enum(Type type_, String value_)
  {
    foreach (FieldInfo fi in type_.GetFields())
    {
      if (fi.Name == value_)
      {
        return fi.GetValue(null);
      }
    }
    throw new Exception(string.Format("Can't convert {0} to {1}", value_, type_.GetType()));
  }
  #endregion
}

class Test
{
  enum CityEnum { NYC, LDN, SHA };

  static void Main(string[] args)
  {
    CityEnum city1 = MyEnumUtil.String2Enum<CityEnum>("SHA");                   // VS2005/2008 version
    CityEnum city2 = (CityEnum)MyEnumUtil.String2Enum(typeof(CityEnum), "NYC"); // VS2003 version

    Console.WriteLine(String.Format("city1 = {0}", city1.ToString()));  // also serve as an example of coverting
    Console.WriteLine(String.Format("city2 = {0}", city2.ToString()));  // Enum to string
  }
}