Automatically Minify, Combine, Compress, and Cache *.js and *.css Files in your ASP.NET Project

using System;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;

namespace CssJscriptOptimizer.Minifiers
{
	public static class CssMinifier
	{
		public static int AppendReplacement(this Match match, StringBuilder sb, string input, string replacement, int index)
		{
			var preceding = input.Substring(index, match.Index - index);

			sb.Append(preceding);
			sb.Append(replacement);

			return match.Index + match.Length;
		}

		public static void AppendTail(this Match match, StringBuilder sb, string input, int index)
		{
			sb.Append(input.Substring(index));
		}

		public static uint ToUInt32(this ValueType instance)
		{
			return Convert.ToUInt32(instance);
		}

		public static string RegexReplace(this string input, string pattern, string replacement)
		{
			return Regex.Replace(input, pattern, replacement);
		}

		public static string RegexReplace(this string input, string pattern, string replacement, RegexOptions options)
		{
			return Regex.Replace(input, pattern, replacement, options);
		}

		public static string Fill(this string format, params object[] args)
		{
			return String.Format(format, args);
		}

		public static string RemoveRange(this string input, int startIndex, int endIndex)
		{
			return input.Remove(startIndex, endIndex - startIndex);
		}

		public static bool EqualsIgnoreCase(this string left, string right)
		{
			return String.Compare(left, right, true) == 0;
		}

		public static string ToHexString(this int value)
		{
			var sb = new StringBuilder();
			var input = value.ToString();

			foreach (char digit in input)
			{
				sb.Append("{0:x2}".Fill(digit.ToUInt32()));
			}

			return sb.ToString();
		}

		#region YUI Compressor's CssMin originally written by Isaac Schlueter

		/// <summary>
		/// Minifies CSS.
		/// </summary>
		/// <param name="css">The CSS content to minify.</param>
		/// <returns>Minified CSS content.</returns>
		public static string CssMinify(this string css)
		{
			return CssMinify(css, 0);
		}

		/// <summary>
		/// Minifies CSS with a column width maximum.
		/// </summary>
		/// <param name="css">The CSS content to minify.</param>
		/// <param name="columnWidth">The maximum column width.</param>
		/// <returns>Minified CSS content.</returns>
		public static string CssMinify(this string css, int columnWidth)
		{
			css = css.RemoveCommentBlocks();
			css = css.RegexReplace("\\s+", " ");
			css = css.RegexReplace("\"\\\\\"}\\\\\"\"", "___PSEUDOCLASSBMH___");
			css = css.RemovePrecedingSpaces();
			css = css.RegexReplace("([!{}:;>+\\(\\[,])\\s+", "$1");
			css = css.RegexReplace("([^;\\}])}", "$1;}");
			css = css.RegexReplace("([\\s:])(0)(px|em|%|in|cm|mm|pc|pt|ex)", "$1$2");
			css = css.RegexReplace(":0 0 0 0;", ":0;");
			css = css.RegexReplace(":0 0 0;", ":0;");
			css = css.RegexReplace(":0 0;", ":0;");
			css = css.RegexReplace("background-position:0;", "background-position:0 0;");
			css = css.RegexReplace("(:|\\s)0+\\.(\\d+)", "$1.$2");
			css = css.ShortenRgbColors();
			css = css.ShortenHexColors();
			css = css.RegexReplace("[^\\}]+\\{;\\}", "");

			if (columnWidth > 0)
			{
				css = css.BreakLines(columnWidth);
			}

			css = css.RegexReplace("___PSEUDOCLASSBMH___", "\"\\\\\"}\\\\\"\"");
			css = css.Trim();

			return css;
		}

		private static string RemoveCommentBlocks(this string input)
		{
			var startIndex = 0;
			var endIndex = 0;
			var iemac = false;

			startIndex = input.IndexOf(@"/*", startIndex);
			while (startIndex >= 0)
			{
				endIndex = input.IndexOf(@"*/", startIndex + 2);
				if (endIndex >= startIndex + 2)
				{
					if (input[endIndex - 1] == '\\')
					{
						startIndex = endIndex + 2;
						iemac = true;
					}
					else if (iemac)
					{
						startIndex = endIndex + 2;
						iemac = false;
					}
					else
					{
						input = input.RemoveRange(startIndex, endIndex + 2);
					}
				}
				startIndex = input.IndexOf(@"/*", startIndex);
			}

			return input;
		}

		private static string ShortenRgbColors(this string css)
		{
			var sb = new StringBuilder();
			Regex p = new Regex("rgb\\s*\\(\\s*([0-9,\\s]+)\\s*\\)");
			Match m = p.Match(css);

			int index = 0;
			while (m.Success)
			{
				string[] colors = m.Groups[1].Value.Split(',');
				StringBuilder hexcolor = new StringBuilder("#");

				foreach (string color in colors)
				{
					int val = Int32.Parse(color);
					if (val < 16)
					{
						hexcolor.Append("0");
					}
					hexcolor.Append(val.ToHexString());
				}

				index = m.AppendReplacement(sb, css, hexcolor.ToString(), index);
				m = m.NextMatch();
			}

			m.AppendTail(sb, css, index);
			return sb.ToString();
		}

		private static string ShortenHexColors(this string css)
		{
			var sb = new StringBuilder();
			Regex p = new Regex("([^\"'=\\s])(\\s*)#([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])([0-9a-fA-F])");
			Match m = p.Match(css);

			int index = 0;
			while (m.Success)
			{
				if (m.Groups[3].Value.EqualsIgnoreCase(m.Groups[4].Value) &&
					m.Groups[5].Value.EqualsIgnoreCase(m.Groups[6].Value) &&
					m.Groups[7].Value.EqualsIgnoreCase(m.Groups[8].Value))
				{
					var replacement = String.Concat(m.Groups[1].Value, m.Groups[2].Value, "#", m.Groups[3].Value, m.Groups[5].Value, m.Groups[7].Value);
					index = m.AppendReplacement(sb, css, replacement, index);
				}
				else
				{
					index = m.AppendReplacement(sb, css, m.Value, index);
				}

				m = m.NextMatch();
			}

			m.AppendTail(sb, css, index);
			return sb.ToString();
		}

		private static string RemovePrecedingSpaces(this string css)
		{
			var sb = new StringBuilder();
			Regex p = new Regex("(^|\\})(([^\\{:])+:)+([^\\{]*\\{)");
			Match m = p.Match(css);

			int index = 0;
			while (m.Success)
			{
				var s = m.Value;
				s = s.RegexReplace(":", "___PSEUDOCLASSCOLON___");

				index = m.AppendReplacement(sb, css, s, index);
				m = m.NextMatch();
			}
			m.AppendTail(sb, css, index);

			var result = sb.ToString();
			result = result.RegexReplace("\\s+([!{};:>+\\(\\)\\],])", "$1");
			result = result.RegexReplace("___PSEUDOCLASSCOLON___", ":");

			return result;
		}

		private static string BreakLines(this string css, int columnWidth)
		{
			int i = 0;
			int start = 0;

			var sb = new StringBuilder(css);
			while (i < sb.Length)
			{
				var c = sb[i++];
				if (c == '}' && i - start > columnWidth)
				{
					sb.Insert(i, '\n');
					start = i;
				}
			}
			return sb.ToString();
		}
		#endregion

	}
}