//-----------------------------------------------------------------------
// -----------------------------------------------------------------------
// file="RegexInterpreter.IROptimize"
// Project: StgSharp
// AuthorGroup: Nitload
// Copyright (c) Nitload. 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 System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

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

        internal static RegexInfo ScanAndOptimizeIR(
                                  List<RegexIR> baseIR,
                                  out List<RegexIR> optIR
        )
        {
            int index = 0;
            List<RegexIR> optimizedIR = new(baseIR.Count);
            List<RegexIR> segment = [];
            RegexInfo info = new();
            do
            {
                // TODO scan and opt here
                OptimizeIR(baseIR, ref index, segment, info);
                optimizedIR.AddRange(segment);
                index++;
            } while (index < baseIR.Count);
            optIR = optimizedIR;
            return info;
        }

        private static void OptimizeDot(
                            RegexCountSetIR root,
                            List<RegexIR> ir,
                            ref int index,
                            List<RegexIR> optimizedIR,
                            RegexInfo info
        )
        {
            int next = index + 1;
            if (next >= ir.Count)
            {
                optimizedIR.Clear();
                optimizedIR.Add(root);
                return;
            }
            RegexIR nextIR = ir[next];
            if (nextIR.Command == RegexIRCommand.Match_Seq)
            {
                // opt .*abc style
                RegexFindSeqIR find = new((nextIR as RegexMatchSeqIR)!.Pattern);
                optimizedIR.Add(find);
                info.MinLength += find.Pattern.Length;
                return;
            } else { }
        }

        private static void OptimizeIR(
                            List<RegexIR> ir,
                            ref int index,
                            List<RegexIR> optimizedIR,
                            RegexInfo info
        )
        {
            optimizedIR.Clear();

            // TODO optimize here
            RegexIR root = ir[index];
            switch (root.Command)
            {
                case RegexIRCommand.Count_Set:
                    RegexCountSetIR count = (root as RegexCountSetIR)!;
                    if (count.CharSet == ".")
                    {
                        // opt for .+ / .* / .{}    pattern
                        OptimizeDot(count, ir, ref index, optimizedIR, info);
                    }
                    break;
                case RegexIRCommand.Match_Seq:
                    info.MinLength += (root as RegexMatchSeqIR)!.Pattern.Length;
                    optimizedIR.Add(root);
                    break;
                default:
                    optimizedIR.Add(root);
                    break;
            }
        }

        internal class RegexInfo
        {

            public int MinLength { get; set; }

            public int TryDepth { get; set; }

        }

    }
}