using System;
using System.Text.RegularExpressions;

namespace Algorithms.Strings
{
    /// <summary>
    ///     Palindrome a series of characters or a string that when reversed,
    ///     equals the original string.
    /// </summary>
    public static class Palindrome
    {
        /// <summary>
        ///     Function to check if a string is a palindrome.
        /// </summary>
        /// <param name="word">String being checked.</param>
        public static bool IsStringPalindrome(string word) =>
            TypifyString(word).Equals(TypifyString(ReverseString(word)));

        /// <summary>
        ///     Typify string to lower and remove white spaces.
        /// </summary>
        /// <param name="word">String to remove spaces.</param>
        /// <returns>Returns original string without spaces.</returns>
        private static string TypifyString(string word) =>
            Regex.Replace(word.ToLowerInvariant(), @"\s+", string.Empty);

        /// <summary>
        ///     Helper function that returns a reversed string inputed.
        /// </summary>
        /// <param name="s">String to be reversed.</param>
        /// <returns>Returns s reversed.</returns>
        private static string ReverseString(string s)
        {
            var arr = s.ToCharArray();
            Array.Reverse(arr);
            return new string(arr);
        }
    }
}
