using System;
using System.Collections.Generic;
namespace sharp.parser
{
	public class LexerPathSegment
	{
		public CharGroup CharGroup { get; private set; }
		public bool MayFinish { get; set; }

		public LexerPathSegment[] Followers { get { return followers.ToArray(); } }
		private List<LexerPathSegment> followers = new List<LexerPathSegment>();

		public LexerPathSegment(){
			this.CharGroup = null;
		}

		public LexerPathSegment(LexerPathSegment follower)
		{
			this.CharGroup = null;
			this.AddFollower(follower);
		}

		public LexerPathSegment(CharGroup charGroup)
		{
			this.CharGroup = charGroup;
		}

		public LexerPathSegment(char[] chars){
			this.CharGroup = new CharGroup(chars);
		}

		public LexerPathSegment(char ch)
		{
			this.CharGroup = new CharGroup(ch);
		}

		public LexerPathSegment(char first,char last)
		{
			this.CharGroup = new CharGroup(first,last);
		}

		public LexerPathSegment(CharGroup charGroup,bool mayFinish)
		{
			this.CharGroup = charGroup;
			this.MayFinish = mayFinish;
		}

		public LexerPathSegment(char[] chars,bool mayFinish)
		{
			this.CharGroup = new CharGroup(chars);
			this.MayFinish = mayFinish;
		}

		public LexerPathSegment(char ch,bool mayFinish)
		{
			this.CharGroup = new CharGroup(ch);
			this.MayFinish = mayFinish;
		}

		public LexerPathSegment(char first, char last,bool mayFinish)
		{
			this.CharGroup = new CharGroup(first, last);
			this.MayFinish = mayFinish;
		}

		public LexerPathSegment(CharGroup charGroup, LexerPathSegment follower)
		{
			this.CharGroup = charGroup;
			this.AddFollower(follower);
		}

		public LexerPathSegment(char[] chars, LexerPathSegment follower)
		{
			this.CharGroup = new CharGroup(chars);
            this.AddFollower(follower);
		}

		public LexerPathSegment(char ch, LexerPathSegment follower)
		{
			this.CharGroup = new CharGroup(ch);
            this.AddFollower(follower);
		}

		public LexerPathSegment(char first, char last, LexerPathSegment follower)
		{
			this.CharGroup = new CharGroup(first, last);
            this.AddFollower(follower);
		}



		public void AddFollower(LexerPathSegment path, params LexerPathSegment[] paths)
		{
			AddFollower(path);
			foreach (LexerPathSegment p in paths)
			{
				AddFollower(p);
			}
		}
		public void AddFollower(LexerPathSegment path)
		{
			followers.Add(path);
		}

		public void RemoveFollower(LexerPathSegment path)
		{
			followers.Remove(path);
		}

		public int walk(CharBuffer buffer){

			if (this.CharGroup == null){

				foreach (LexerPathSegment next in followers){
					int n = next.walk(buffer);
					if (n > 0){
						return n;
					}
				}

				return -1;
			}

			if (MayFinish && buffer.EndOfBuffer()){
				return 1;
			}

			if (this.CharGroup.Contains(buffer.Current)){
				buffer.MoveNext();

				foreach (LexerPathSegment next in followers){
					int n = next.walk(buffer);
					if (n > 0){
						buffer.MoveBack();
						return n + 1;
					}
				}
				buffer.MoveBack();

				if (MayFinish){
					return 1;
				}
			}
			return -1;
		}

	}
}