// <developer>niklas@protocol7.com</developer>
// <completed>75</completed>

using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace SharpVectors.Dom.Stylesheets
{
	/// <summary>
	/// The MediaList interface provides the abstraction of an ordered collection of media, without defining or constraining how this collection is implemented. An empty list is the same as a list that contains the medium "all".
	/// The items in the MediaList are accessible via an integral index, starting from 0.
	/// </summary>
	public sealed class MediaList : IMediaList
	{
		private static Regex splitter = new Regex(@"\s*,\s*");

		#region Constructors
		public MediaList() : this(String.Empty)
		{
		}

		public MediaList(string val)
		{
			_parseString(val);
		}
		#endregion

		private void _parseString(string mediaText)
		{
			mediaText = mediaText.Trim();
			if(mediaText.Length > 0)
			{
				string[] ms = splitter.Split(mediaText);
				foreach(string m in ms)
				{
					AppendMedium(m);
				}
			}
		}

		private void _clear()
		{
			medias.Clear();
		}

		#region Public methods
		/// <summary>
		/// Compares this MediaList with another and see if the second fits this
		/// </summary>
		/// <param name="inMedia">The MediaList to compare</param>
		/// <returns>True if this list fits the specified</returns>
		public bool Matches(MediaList inMedia)
		{
			if(inMedia.Length == 0) return false;
			else if(Length == 0 || containsAll)
			{
				// is empty or this list contains "all"
				return true;
			}
			else
			{
				for(ulong i = 0; i<inMedia.Length; i++)
				{
					if (medias.Contains(inMedia[i])) 
                        return true;
				}
			}
			return false;
		}

		#endregion

		#region Private fields
		private bool containsAll = false;	//speeds up matching if the list contains "all"
        private List<string> medias = new List<string>();
		#endregion

		#region Implementation of IMediaList
		/// <summary>
		/// Adds the medium newMedium to the end of the list. If the newMedium is already used, it is first removed.
		/// </summary>
		/// <param name="newMedium">The new medium to add.</param>
		/// <exception cref="DomException">INVALID_CHARACTER_ERR: If the medium contains characters that are invalid in the underlying style language.</exception>
		/// <exception cref="DomException">NO_MODIFICATION_ALLOWED_ERR: Raised if this media list is readonly.</exception>
		public void AppendMedium(string newMedium)
		{
			if (newMedium.Length > 0)
			{
				medias.Remove(newMedium);
				medias.Add(newMedium);
				if (newMedium.Equals("all")) 
                    containsAll = true;
			}
		}

		/// <summary>
		/// Deletes the medium indicated by oldMedium from the list.
		/// </summary>
		/// <param name="oldMedium">The medium to delete in the media list.</param>
		/// <exception cref="DomException">NOT_FOUND_ERR: Raised if oldMedium is not in the list.</exception>
		/// <exception cref="DomException">NO_MODIFICATION_ALLOWED_ERR: Raised if this media list is readonly.</exception>
		public void DeleteMedium(string oldMedium)
		{
			if(oldMedium == "all") containsAll = false;
			medias.Remove(oldMedium);
		}

		/// <summary>
		/// The number of media in the list. The range of valid media is 0 to length-1 inclusive.
		/// </summary>
		public ulong Length
		{
			get
			{
				return (ulong)medias.Count;
			}
		}

		/// <summary>
		/// The parsable textual representation of the media list. This is a comma-separated list of media.
		/// </summary>
		/// <exception cref="DomException">SYNTAX_ERR: Raised if the specified string value has a syntax error and is unparsable.</exception>
		/// <exception cref="DomException">NO_MODIFICATION_ALLOWED_ERR: Raised if this media list is readonly.</exception>
		public string MediaText
		{
			get
			{
				string result = String.Empty;
				foreach(string media in medias)
				{
					result += media + ",";
				}
				if(result.Length > 0)
				{
					result = result.Substring(0, result.Length-1);
				}
				return result;
			}
			set
			{
				_clear();
				_parseString(value);
			}
		}

		/// <summary>
		/// Returns the indexth in the list. If index is greater than or equal to the number of media in the list, this returns null.
		/// </summary>
		public string this[ulong index]
		{
			get
			{
				return (index < Length) ? medias[(int)index] : null;
			}
		}

		#endregion
	}
}