////////////////////////////////////////////////////////////////////////////////////////////////////
// file:	Extensions\StringExtensions.cs
//
// summary:	Implements the string extensions class
////////////////////////////////////////////////////////////////////////////////////////////////////

using System;
using System.Linq;
using System.Security.Cryptography;

namespace TVLib.Extensions
{
    ////////////////////////////////////////////////////////////////////////////////////////////////////
    /// <summary>   String extensions. </summary>
    ///
    /// <remarks>   Mike Gardner 12/05/16. </remarks>
    ////////////////////////////////////////////////////////////////////////////////////////////////////
    public static class StringExtensions
    {
        #region ENUMERATIONS

        ////////////////////////////////////////////////////////////////////////////////////////////////////
        /// <summary>   Values that represent random string contents. </summary>
        ///
        /// <remarks>   Mike Gardner 12/05/16. </remarks>
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        public enum RandomStringContent : long
        {
            /// <summary>   An enum constant representing the alpha option. </summary>
            LettersOnly = 0,

            /// <summary>   An enum constant representing the numeric option. </summary>
            DigitsOnly = 1,

            /// <summary>   An enum constant representing the alphanumeric option. </summary>
            AlphaNumeric = 2
        }

        #endregion

        #region CONSTANTS

        /// <summary>   The alpha numeric characters. </summary>
        private const string kAlphaNumericCharacters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

        /// <summary>   The digit characters. </summary>
        private const string kDigitCharacters = "0123456789";

        /// <summary>   The letter characters. </summary>
        private const string kLetterCharacters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

        #endregion

        #region ALL OTHER MEMBERS

        ////////////////////////////////////////////////////////////////////////////////////////////////////
        /// <summary>
        /// Remove all escape sequences from a string and replace them with a specified character. By
        /// default, the character is nothing.
        /// </summary>
        ///
        /// <remarks>   Mike Gardner 12/09/16. </remarks>
        ///
        /// <param name="text">         Text to sanitize. </param>
        /// <param name="replacement">  (Optional) Character used to replace each escape sequence. </param>
        ///
        /// <returns>   Null on error. </returns>
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        public static string RemoveEscapeSequences(this string text, string replacement = "")
        {
            if (string.IsNullOrEmpty(text))
            {
                return null;
            }

            var cleaned = text.Replace("\a", replacement)  // Warning
                              .Replace("\b", replacement)  // BACKSPACE
                              .Replace("\f", replacement)  // Form-feed
                              .Replace("\n", replacement)  // Line reverse
                              .Replace("\r", replacement)  // Carriage return
                              .Replace("\t", replacement)  // Horizontal tab
                              .Replace("\v", replacement)  // Vertical tab
                              .Replace("\'", replacement)  // Single quote
                              .Replace("\"", replacement)  // Double quote
                              .Replace("\\", replacement); // Backslash
            //.Replace ("\?", replacement); // Literal question mark

            return cleaned;
        }

        ////////////////////////////////////////////////////////////////////////////////////////////////////
        /// <summary>   A string extension method that converts a text "boolean" to a boolean. </summary>
        ///
        /// <remarks>   Mike Gardner 12/12/16. </remarks>
        ///
        /// <param name="text"> Text to sanitize. </param>
        ///
        /// <returns>   A boolean value or null on error. </returns>
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        public static bool? ToBoolean(this string text)
        {
            if (text.Equals("Yes") || text.Equals("True") || text.Equals("Y") || text.Equals("T")) return true;

            if (text.Equals("No") || text.Equals("False") || text.Equals("N") || text.Equals("F")) return false;

            return null;
        }

        ////////////////////////////////////////////////////////////////////////////////////////////////////
        /// <summary>   Generates a random string of a desired length. </summary>
        ///
        /// <remarks>
        /// Mike Gardner 12/05/16. The random string is not guaranteed to be unique.
        /// </remarks>
        ///
        /// <exception cref="ArgumentOutOfRangeException">  Thrown when one or more arguments are outside
        ///                                                 the required range. </exception>
        ///
        /// <param name="content">  The content. </param>
        /// <param name="length">   (Optional) The length. </param>
        ///
        /// <returns>   The random string, or null on error. </returns>
        ////////////////////////////////////////////////////////////////////////////////////////////////////
        public static string GenerateRandomString(RandomStringContent content, uint length = 10)
        {
            var permittedCharacters = string.Empty;

            switch (content)
            {
                case RandomStringContent.LettersOnly:
                    permittedCharacters = kLetterCharacters;
                    break;
                case RandomStringContent.DigitsOnly:
                    permittedCharacters = kDigitCharacters;
                    break;
                case RandomStringContent.AlphaNumeric:
                    permittedCharacters = kAlphaNumericCharacters;
                    break;
                default:
                    throw new ArgumentOutOfRangeException(nameof(content), content, null);
            }

            return new string(
                              Enumerable
                                  // Permitted characters and length
                                 .Repeat(permittedCharacters, (int) length)
                                 .Select(
                                         s =>
                                         {
                                             var cryptoResult = new byte[4];
                                             new RNGCryptoServiceProvider()
                                                .GetBytes(cryptoResult);
                                             return
                                                 s[
                                                   new Random(
                                                              BitConverter
                                                                 .ToInt32(
                                                                          cryptoResult,
                                                                          0))
                                                      .Next(s.Length)];
                                         }).ToArray());
        }

        #endregion
    }
}