using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Web;
using System.Web.UI.WebControls;

namespace Extensions
{
	public static class StringExtensions
	{
		/// <summary>
		/// Returns the given string truncated to the specified length, suffixed with an elipses (...)
		/// </summary>
		/// <param name="input"></param>
		/// <param name="length">Maximum length of return string</param>
		/// <returns></returns>
		public static string Truncate(this string input, int length)
		{
			return Truncate(input, length, "...");
		}

		/// <summary>
		/// Returns the given string truncated to the specified length, suffixed with the given value
		/// </summary>
		/// <param name="input"></param>
		/// <param name="length">Maximum length of return string</param>
		/// <param name="suffix">The value to suffix the return value with (if truncation is performed)</param>
		/// <returns></returns>
		public static string Truncate(this string input, int length, string suffix)
		{
			if (input == null) return "";
			if (input.Length <= length) return input;

			if (suffix == null) suffix = "...";

			return input.Substring(0, length - suffix.Length) + suffix;
		}

		/// <summary>
		/// Splits a given string into an array based on character line breaks
		/// </summary>
		/// <param name="input"></param>
		/// <returns>String array, each containing one line</returns>
		public static string[] ToLineArray(this string input)
		{
			if (input == null) return new string[] { };
			return System.Text.RegularExpressions.Regex.Split(input, "\r\n");
		}

		/// <summary>
		/// Splits a given string into a strongly-typed list based on character line breaks
		/// </summary>
		/// <param name="input"></param>
		/// <returns>Strongly-typed string list, each containing one line</returns>
		public static List<string> ToLineList(this string input)
		{
			List<string> output = new List<string>();
			output.AddRange(input.ToLineArray());
			return output;
		}

		/// <summary>
		/// Replaces line breaks with self-closing HTML 'br' tags
		/// </summary>
		/// <param name="input"></param>
		/// <returns></returns>
		public static string ReplaceBreaksWithBR(this string input)
		{
			return string.Join("<br/>", input.ToLineArray());
		}

		/// <summary>
		/// Replaces any single apostrophes with two of the same
		/// </summary>
		/// <param name="input"></param>
		/// <returns>String</returns>
		public static string DoubleApostrophes(this string input)
		{
			return Regex.Replace(input, "'", "''");
		}

		/// <summary>
		/// Encodes the input string as HTML (converts special characters to entities)
		/// </summary>
		/// <param name="input"></param>
		/// <returns>HTML-encoded string</returns>
		public static string ToHTMLEncoded(this string input)
		{
			return HttpContext.Current.Server.HtmlEncode(input);
		}

		/// <summary>
		/// Encodes the input string as a URL (converts special characters to % codes)
		/// </summary>
		/// <param name="input"></param>
		/// <returns>URL-encoded string</returns>
		public static string ToURLEncoded(this string input)
		{
			return HttpContext.Current.Server.UrlEncode(input);
		}

		/// <summary>
		/// Decodes any HTML entities in the input string
		/// </summary>
		/// <param name="input"></param>
		/// <returns>String</returns>
		public static string FromHTMLEncoded(this string input)
		{
			return HttpContext.Current.Server.HtmlDecode(input);
		}

		/// <summary>
		/// Decodes any URL codes (% codes) in the input string
		/// </summary>
		/// <param name="input"></param>
		/// <returns>String</returns>
		public static string FromURLEncoded(this string input)
		{
			return HttpContext.Current.Server.UrlDecode(input);
		}

		/// <summary>
		/// Removes any HTML tags from the input string
		/// </summary>
		/// <param name="input"></param>
		/// <returns>String</returns>
		public static string StripHTML(this string input)
		{
			return Regex.Replace(input, @"<(style|script)[^<>]*>.*?</\1>|</?[a-z][a-z0-9]*[^<>]*>|<!--.*?-->", "");
		}
	}
}