SharpVectors - SVG# Reloaded: An Introduction

// <developer>niklas@protocol7.com</developer>
// <completed>80</completed>

using System;
using System.Xml;
using System.Globalization;
using System.Text.RegularExpressions;

namespace SharpVectors.Dom.Css
{
	/// <summary>
	/// The CSSValue interface represents a simple or a complex value. A CSSValue object only occurs in a context of a CSS property
	/// </summary>
	public class CssValue : ICssValue
	{
		#region Static members
		private static string numberPattern = @"[\-\+]?[0-9]*\.?[0-9]+";
		public static string LengthUnitPattern = "(?<lengthUnit>in|cm|mm|px|em|ex|pc|pt|%)?";
		public static string AngleUnitPattern = "(?<angleUnit>deg|rad|grad)?";
		public static string LengthPattern = @"(?<lengthNumber>" + numberPattern + ")" + LengthUnitPattern;
		public static string AnglePattern = @"(?<angleNumber>" + numberPattern + ")" + AngleUnitPattern;

		private static string cssPrimValuePattern = @"^(?<primitiveValue>" 
			+ @"(?<func>(?<funcname>attr|url|counter|rect|rgb)\((?<funcvalue>[^\)]+)\))"
			+ @"|(?<length>" + LengthPattern + ")"
			+ @"|(?<angle>" + AnglePattern + ")"
			+ @"|(?<freqTimeNumber>(?<numberValue2>" + numberPattern + ")(?<unit2>Hz|kHz|in|s|ms|%)?)"
			+ @"|(?<string>[""'](?<stringvalue>(.|\n)*?)[""'])"
			+ @"|(?<colorIdent>([A-Za-z]+)|(\#[A-Fa-f0-9]{6})|(\#[A-Fa-f0-9]{3}))"
			+ @")";

		private static Regex reCssPrimitiveValue = new Regex(cssPrimValuePattern + "$");
		private static Regex reCssValueList = new Regex(cssPrimValuePattern + @"(\s*,\s*)+$");

		/// <summary>
		/// Detects what kind of value cssText contains and returns an instance of the correct CssValue class
		/// </summary>
		/// <param name="cssText">The text to parse for a CSS value</param>
		/// <param name="readOnly">Specifies if this instance is read-only</param>
		/// <returns>The correct type of CSS value</returns>
		static public CssValue GetCssValue(string cssText, bool readOnly)
		{
			if(cssText == "inherit")
			{
				// inherit
				return new CssValue(CssValueType.Inherit, cssText, readOnly);
			}
			else
			{
				Match match = reCssPrimitiveValue.Match(cssText);
				if(match.Success)
				{
					// single primitive value
					return CssPrimitiveValue.Create(match, readOnly);
				}
				
				match = reCssValueList.Match(cssText);
				if(match.Success)
				{
					// list of primitive values
					throw new NotImplementedException("Value lists not implemented");
				}
				else
				{
					// custom value
					return new CssValue(CssValueType.Custom, cssText, readOnly);
				}
			}
		}
		#endregion

		#region Constructors
		/// <summary>
		/// Constructor for CssValue
		/// </summary>
		/// <param name="type">The type of value</param>
		/// <param name="cssText">The entire content of the value</param>
		/// <param name="readOnly">Specifies if the instance is read-only</param>
		public CssValue(CssValueType type, string cssText, bool readOnly)
		{
			_cssText = cssText.Trim();
			_cssValueType = type;
			_readOnly = readOnly;
		}

		/// <summary>
		/// Only for internal use
		/// </summary>
		protected CssValue()
		{
			_readOnly = true;
		}
		#endregion

		#region Public methods
		public virtual CssValue GetAbsoluteValue(string propertyName, XmlElement elm)
		{
			return new CssAbsValue(this, propertyName, elm);
		}
		#endregion

		private bool _readOnly;
		public virtual bool ReadOnly
		{
			get
			{
				return _readOnly;
			}
		}

		#region ICssValue Members

		private string _cssText;
        protected CssValueType _cssValueType;

		/// <summary>
		/// A string representation of the current value.
		/// </summary>
		/// <exception cref="DomException">SYNTAX_ERR: Raised if the specified CSS string value has a syntax error (according to the attached property) or is unparsable.</exception>
		/// <exception cref="DomException">INVALID_MODIFICATION_ERR: Raised if the specified CSS string value represents a different type of values than the values allowed by the CSS property</exception>
		/// <exception cref="DomException">NO_MODIFICATION_ALLOWED_ERR: Raised if this value is readonly.</exception>
		public virtual string CssText
		{
			get
			{
				return _cssText;
			}
			set
			{
				if(ReadOnly)
				{
					throw new DomException(DomExceptionType.InvalidModificationErr, "The CssValue is read-only");
				}
				else
				{
					_cssText = value;
				}
			}
		}

		/// <summary>
		/// A code defining the type of the value as defined above
		/// </summary>
		public virtual CssValueType CssValueType
		{
			get
			{
				return _cssValueType;
			}
		}

		#endregion
	}
}