//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="StepDataTokenReader"
// Project: StgSharp
// AuthorGroup: Nitload Space
// Copyright (c) Nitload Space. All rights reserved.
//     
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//     
// -----------------------------------------------------------------------
// -----------------------------------------------------------------------
using StgSharp.Model.Step;
using StgSharp.Script;
using StgSharp.Script.Express;

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;

namespace StgSharp.Model.Step
{
    public partial class StepDataTokenReader : IScriptTokenReader
    {

        private ExpTokenReader _reader;

        private HashSet<string> tokenHash = [ "T", "F", "UNSPECIFIED" ];
        private Queue<Token> _cache = new Queue<Token>();
        private StepDataSectionTransmitter _transmitter;

        public StepDataTokenReader(StepDataSectionTransmitter transmitter)
        {
            _reader = new ExpTokenReader(transmitter);
            _reader.TokenReaderPreProcessor = new TokenPreReader();
            _transmitter = transmitter;
        }

        public bool IsEmpty
        {
            get
            {
                if (_reader.IsEmpty) {
                    return !_transmitter.IsWriting;
                }
                return false;
            }
        }

        public Token ReadToken()
        {
            return _reader.ReadToken();
        }

        public bool TryReadToken(out Token t)
        {
            return _reader.TryReadToken(out t);
        }

        private partial class TokenPreReader : ExpTokenReaderPreProcessor
        {

            private static Regex
                _nextHashtagSymbolPattern = GetEntityTagSymbolPattern(),
                _nextEnumPattern = GetNextEnumPattern(),
                _stringPattern = GetStringPattern();

            public override bool Process(string codeLine, int line, ref int current, out Token t)
            {
                ReadOnlySpan<char> chars = codeLine.AsSpan(current);
                char c = chars[0];
                Match match;
                switch (c)
                {
                    case '#':
                        match = _nextHashtagSymbolPattern.Match(codeLine, current);
                        if (match.Success)
                        {
                            int begin = match.Groups["token"].Index;
                            int end = match.Groups["end"].Index;
                            int rest = match.Groups["rest"].Index;
                            current = rest;
                            t = new(
                                ExpressCompile.PoolString(chars[0..(end - begin)]), line,
                                begin, TokenFlag.Member);
                            return true;
                        }
                        break;
                    case '.':
                        match = _nextEnumPattern.Match(codeLine, current);
                        if (match.Success)
                        {
                            int begin = match.Groups["token"].Index;
                            int end = match.Groups["end"].Index;
                            int rest = match.Groups["rest"].Index;
                            current = rest;
                            t = new Token(
                                match.Groups["token"].Value, line, begin, TokenFlag.Enum);
                            return true;
                        }
                        break;
                    case '$':
                        t = new Token("$", line, current, TokenFlag.Member);
                        current++;
                        return true;
                    case '*':
                        t = new Token("*", line, current, TokenFlag.Member);
                        current++;
                        return true;
                    case '\'':
                        match = _stringPattern.Match(codeLine, current);
                        if (match.Success)
                        {
                            int begin = match.Groups["token"].Index;
                            int end = match.Groups["end"].Index;
                            int rest = match.Groups["rest"].Index;
                            current = rest;
                            string value = chars.Slice(1, (end - begin - 1)).ToString();
                            if (string.IsNullOrWhiteSpace(value)) {
                                value = string.Empty;
                            }
                            t = new Token(value, line, begin, TokenFlag.String);
                            return true;
                        }
                        break;
                    default:
                        break;
                }
                t = Token.Empty;
                return false;
            }

            [GeneratedRegex(@"(?<token>#[0-9A-Za-z]+)(?<end>\s*?)(?<rest>\S|$)", RegexOptions.Singleline)]
            private static partial Regex GetEntityTagSymbolPattern();

            [GeneratedRegex(@"(?<token>\.[A-Za-z_]+\.)(?<end>\s*)(?<rest>\S*)", RegexOptions.Singleline)]
            private static partial Regex GetNextEnumPattern();

            [GeneratedRegex(@"(?<token>')(?>\\\\|''|(?!')[^'])*(?<end>')\s*?(?<rest>\S|$)", RegexOptions.Singleline)]
            private static partial Regex GetStringPattern();

        }

    }
}