using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Net;

public class Program

{

    public static void Main()

    {

        var gigs = new Dictionary<(string artist, DateTime date, string city), List<string>>();

        var endDate = new DateTime(2022, 12, 05);

​

        for (int i = 1; ; i++)

        {

            Console.WriteLine($"{i}. Date:{(gigs.Any() ? gigs.Max(x => x.Key.date) : DateTime.Today)} Count:{gigs.Count}");

            var wb = new WebClient();

            var url = @"https://www.koncertomania.pl/koncerty";

            if (i > 1)

            {

                url += "-strona-" + i;

            }

            url += ".html";

            var page = wb.DownloadString(url);

            if (!BrowseGigs(gigs, page, endDate))

            {

                break;

            }

        }

        foreach(var gig in gigs)

        {

            Console.Write($"{gig.Key.artist} / {gig.Key.date.ToShortDateString()} / {gig.Key.city}");

            if (gig.Value.Count > 1)

            {

                Console.Write($" [{string.Join(", ", gig.Value)}]");

            }

            Console.WriteLine();

        }

        Console.WriteLine("Koniec");

    }

    private static bool BrowseGigs(Dictionary<(string artist, DateTime date, string city), List<string>> gigs, string page, DateTime maxDate)

    {

        using (var reader = new StringReader(page))

        {

            var doc = new HtmlAgilityPack.HtmlDocument();

            doc.LoadHtml(page);

            var resultList = doc.DocumentNode.SelectSingleNode("//div [@id='result-list']");

            foreach (var node in resultList.SelectNodes("div [@class='vevent res-item']/div [@class='desc-cnt']|div [@class='vevent res-item odd']/div [@class='desc-cnt']"))

            {

                var summary = node.SelectSingleNode("abbr [@class='summary']");

                var dateNode = node.SelectSingleNode("p [@class='start date concert-when']/span [@class='dtstart']");

                var date = DateTime.Parse(dateNode.InnerText, new System.Globalization.CultureInfo("pl-PL"));

                if (date > maxDate)

                {

                    return false;

                }

                var city = node.SelectSingleNode("abbr [@class='location']/abbr [@class='locality']/p [@class='concert-where']/a").InnerText;

                var artistList = summary.SelectNodes("p [@class='concert-who']/a").Select(x => x.InnerText).ToList();

                foreach (var artist in artistList)

                {

                    if (!gigs.ContainsKey((artist, date, city)))

                    {

                        gigs[(artist, date, city)] = artistList;

                    }

                }

            }

        }

​

        return true;

    }

}