// -----------------------------------------------------------------------------
// file="RegexAnalyzer.SourceGen"
// Project: StgSharp
// Copyright (c) Nitload.
// SPDX-License-Identifier: MIT
// -----------------------------------------------------------------------------

using Microsoft.CodeAnalysis;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace StgSharp.RegularAnalysis.Text
{
    public partial class RegexAnalyzer
    {

        internal static StringBuilder GenerateSource(
                                      List<RegexIR> ir
        )
        {
            StringBuilder sb = new();
            List<StringBuilder> sub_match_list = [];

            ReadOnlySpan<RegexIR> source = CollectionsMarshal.AsSpan(ir);
            RegexIR[] window = new RegexIR[8];
            Span<RegexIR> scan_win = window;

            _ = sb.AppendLine(@"public abstract MatchResult Match(ReadOnlySpan<char> text)")//
                  .AppendLine(@"{");

            int index = 0;
            do
            {
                int count = int.Min(8, source.Length - index);
                source.Slice(index, count).CopyTo(scan_win);
            } while (index < ir.Count);

            foreach (StringBuilder _sub in sub_match_list)
            {
                _ = sb.AppendLine()                     //
                      .Append(_sub);
            }

            return sb;
            /*
            int TryGenerateMatch(
                Span<RegexIR> scan_win,
                StringBuilder sb
            )
            {
                if (scan_win[0] is RegexMatchSeqIR seq) {
                    _ = sb.AppendLine(string.Empty);
                }
            }
            /**/
        }

    }
}