using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        foreach (var keyword in KeywordGroup.CreateFromRawString("Test　\"Hello World\" or1 OR or2 OR or or3 and1 and2"))

        {

            //Console.WriteLine(keyword);

            Console.WriteLine($"{keyword.CombineMode}: {string.Join(", ", keyword.Words)}");

        }

    }

}

​

internal record KeywordGroup(IEnumerable<KeywordItem> Words, CombineMode CombineMode, bool InQuotes)

{

    public static IEnumerable<KeywordGroup> CreateFromRawString(string? searchQuery)

    {

        if (searchQuery is not { Length: > 0 }) yield break;

​

        var matches = Regex.Matches(searchQuery, @"(?:[^\s""]+|""[^""]*"")+");

        var words = matches.Select(match => match.Value).ToArray();

​

        var combineMode = CombineMode.And;

        var wordsBuffer = new List<KeywordItem>();

        bool inQuotes = false;

        bool isBlock = false;

​

        foreach (var (current, index) in words.Select((x, i) => (x, i)))

        {

            var equalsOr = (string v) => v.Equals("OR", StringComparison.OrdinalIgnoreCase);

            if (current is not { Length: > 0 } || equalsOr(current))

                continue;

​

            inQuotes = Regex.IsMatch(current, @"""[^""]*""");

​

            var nextCombineMode =

                index + 1 < words.Length

                ? (equalsOr(words[index + 1]) ? CombineMode.OrElse : CombineMode.And)

                : combineMode;

            var currentWord = new KeywordItem(current.Trim('"'), inQuotes);

​

            if (combineMode == nextCombineMode)

            {

                wordsBuffer.Add(currentWord);

            }

            else if (!isBlock)

            {

                yield return new(wordsBuffer, combineMode, inQuotes);

                wordsBuffer = new() { currentWord };

                isBlock = true;

            }

            else

            {

                yield return new(wordsBuffer.Append(currentWord), combineMode, inQuotes);

                wordsBuffer = new();

                isBlock = false;

            }

​

            combineMode = nextCombineMode;

        }

​

        yield return new(wordsBuffer, combineMode, inQuotes);

    }

}

​

public record KeywordItem(string Value, bool InQuotes);

internal enum CombineMode

{

    And,

    OrElse

}

​