using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace BitStrap
{
	public static class EmailHelper
	{
		private const string emailPattern = "^([0-9a-zA-Z]([\\+\\-_\\.][0-9a-zA-Z]+)*)+@(([0-9a-zA-Z][-\\w]*[0-9a-zA-Z]*\\.)+[a-zA-Z0-9]{2,17})$";

		private static ICollection<string> emailProviders;

		static EmailHelper()
		{
			emailProviders = new HashSet<string>();
			emailProviders.Add("gmail.com");
			emailProviders.Add("hotmail.com");
			emailProviders.Add("yahoo.com");
			emailProviders.Add("live.com");
			emailProviders.Add("icloud.com");
			emailProviders.Add("me.com");
			emailProviders.Add("outlook.com");
		}

		public static bool IsEmail(string text)
		{
			return Regex.IsMatch(text, "^([0-9a-zA-Z]([\\+\\-_\\.][0-9a-zA-Z]+)*)+@(([0-9a-zA-Z][-\\w]*[0-9a-zA-Z]*\\.)+[a-zA-Z0-9]{2,17})$");
		}

		public static bool IsMistyped(string email, out string correctEmail)
		{
			if (!IsEmail(email))
			{
				correctEmail = null;
				return true;
			}
			correctEmail = email;
			int num = email.IndexOf('@') + 1;
			int num2 = email.IndexOf('.', num);
			int num3 = email.IndexOf('.', num2 + 1);
			if (num3 < 0)
			{
				num3 = email.Length;
			}
			num2 = num3 - num;
			string source = email.Substring(num, num2);
			string value = null;
			int num4 = 6;
			foreach (string emailProvider in emailProviders)
			{
				int num5 = source.Distance(emailProvider);
				if (num5 == 0)
				{
					return false;
				}
				if (num5 < num4)
				{
					num4 = num5;
					value = emailProvider;
				}
			}
			if (!string.IsNullOrEmpty(value))
			{
				correctEmail = email.Remove(num, num2).Insert(num, value);
				return true;
			}
			return false;
		}
	}
}