using System.Collections.Generic;
using UnityEngine;

namespace UnityExplorer.UI.CSharpConsole.Lexers
{
    public class StringLexer : Lexer
    {
        protected override Color HighlightColor => new Color(0.79f, 0.52f, 0.32f, 1.0f);

        public override IEnumerable<char> Delimiters => new[] { '"' };

        public override bool TryMatchCurrent(LexerBuilder lexer)
        {
            if (lexer.Current != '"')
                return false;

            if (lexer.Previous == '@')
            {
                // verbatim string, continue until un-escaped quote.
                while (!lexer.EndOfInput)
                {
                    lexer.Commit();
                    if (lexer.PeekNext() == '"')
                    {
                        lexer.Commit();
                        // possibly the end, check for escaped quotes.
                        // commit the character and flip the escape bool for each quote.
                        bool escaped = false;
                        while (lexer.PeekNext() == '"')
                        {
                            lexer.Commit();
                            escaped = !escaped;
                        }
                        // if the last quote wasnt escaped, that was the end of the string.
                        if (!escaped)
                            break;
                    }
                }
            }
            else
            {
                // normal string
                // continue until a quote which is not escaped, or end of input

                while (!lexer.EndOfInput)
                {
                    lexer.Commit();
                    if (lexer.PeekNext() == '"' && lexer.Previous != '\\')
                    {
                        lexer.Commit();
                        break;
                    }
                }
            }

            return true;
        }
    }
}