using System;
using System.Collections.Generic;
using System.Reflection.Metadata.Ecma335;
using System.Text;

namespace ln.parse.tokenizer
{
    public class Tokenizer
    {
        List<TokenMatcher> tokenMatchers = new List<TokenMatcher>();

        public Tokenizer()
        {
        }

        public Tokenizer Add(TokenMatcher tokenMatcher) { tokenMatchers.Add(tokenMatcher); return this; }
        public Tokenizer Remove(TokenMatcher tokenMatcher) { tokenMatchers.Remove(tokenMatcher); return this; }

        public Token[] Parse(string source) => Parse(new SourceBuffer(source));
        public Token[] Parse(SourceBuffer sourceBuffer)
        {
            List<Token> tokens = new List<Token>();

            while (sourceBuffer.LinearPosition < sourceBuffer.Length)
            {
                Token token = null;

                foreach (TokenMatcher tokenMatcher in tokenMatchers)
                {
                    if (tokenMatcher.Match(sourceBuffer, out token))
                        break;
                }

                if (token == null)
                    throw new FormatException(String.Format("invalid token at {0}",sourceBuffer.TextPosition));

                tokens.Add(token);
                sourceBuffer.LinearPosition += token.Length;
            }
            
            return tokens.ToArray();
        }


        public static Tokenizer CreateDefaultTokenizer() =>
                new Tokenizer()
                .Add(TokenMatcher.WHITESPACE)
                .Add(TokenMatcher.FLOAT)
                .Add(TokenMatcher.INTEGER)
                .Add(TokenMatcher.STRING)
                .Add(TokenMatcher.OPERATOR)
                .Add(TokenMatcher.BRACKET);
    }
}