using AngleSharp.Dom;
using Sony.Filtr.Core.SpotifyCharts.Data;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Sony.Filtr.Core.SpotifyCharts.Extensions
{
    public static class SpotifyChartHTMLExtensions
    {
        public static IEnumerable<ChartItemCsv> ToChartItems(this IDocument document)
        {
            if (document == null) { return Enumerable.Empty<ChartItemCsv>(); }

            var cssSelector = "table.chart-table tr";

            var trs = document.QuerySelectorAll(cssSelector);

            var items = new List<ChartItemCsv>();

            if (trs != null)
            {
                foreach (var tr in trs)
                {
                    var item = tr.ToChartItem();
                    if (item != null)
                    {
                        items.Add(item);
                    }
                }
            }

            return items;
        }

        public static ChartItemCsv ToChartItem(this IElement tr)
        {
            var item = new ChartItemCsv();

            tr
                .AddLinkAndId(item)
                .AddStreams(item)
                .AddTrackPosition(item)
                .AddTrackNameAndArtist(item);

            return item.ReturnItemIfValidOrNULL();
        }

        private static ChartItemCsv ReturnItemIfValidOrNULL(this ChartItemCsv item)
        {
            if (!String.IsNullOrWhiteSpace(item.ArtistName) && !String.IsNullOrWhiteSpace(item.TrackName) && !String.IsNullOrWhiteSpace(item.TrackUrl) && !String.IsNullOrWhiteSpace(item.TrackId))
            {
                return item;
            }

            return null;
        }

        private static IElement AddLinkAndId(this IElement tr, ChartItemCsv item)
        {
            var anchor = tr.QuerySelector("td.chart-table-image a");

            if (anchor != null)
            {
                var trackLink = anchor.GetAttribute("href");
                if (!String.IsNullOrWhiteSpace(trackLink))
                {
                    item.TrackUrl = trackLink;

                    var uri = new Uri(trackLink);
                    if (uri.Segments != null && uri.Segments.Length == 3 && uri.Segments[1].ToLower() == "track/")
                    {
                        item.TrackId = uri.Segments[2];
                    }
                }
            }

            return tr;
        }

        private static Regex NonDigitRegex = new Regex(@"[^\d]");
        private static IElement AddStreams(this IElement tr, ChartItemCsv item)
        {
            var streamsTD = tr.QuerySelector("td.chart-table-streams");

            if (streamsTD != null)
            {
                if (Int32.TryParse(NonDigitRegex.Replace(streamsTD.InnerHtml, ""), out int streams))
                {
                    item.NumberOfStreams = streams;
                }
            }

            return tr;
        }

        private static IElement AddTrackPosition(this IElement tr, ChartItemCsv item)
        {
            var positionTD = tr.QuerySelector("td.chart-table-position");

            if (positionTD != null)
            {
                if (Int32.TryParse(positionTD.InnerHtml, out int position))
                {
                    item.Position = position;
                }
            }

            return tr;
        }

        private static Regex ArtistNameRegex = new Regex("^by (.+)$", RegexOptions.IgnoreCase);
        private static IElement AddTrackNameAndArtist(this IElement tr, ChartItemCsv item)
        {
            var trackTD = tr.QuerySelector("td.chart-table-track");

            if (trackTD != null)
            {
                var nameStrong = trackTD.QuerySelector("strong");
                if (nameStrong != null)
                {
                    item.TrackName = System.Net.WebUtility.HtmlDecode(nameStrong.InnerHtml);
                }

                var artistSpan = trackTD.QuerySelector("span");
                if (artistSpan != null)
                {
                    var match = ArtistNameRegex.Match(artistSpan.InnerHtml);
                    if (match.Success)
                    {
                        item.ArtistName = System.Net.WebUtility.HtmlDecode(match.Groups[1].Value.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries)[0]);
                    }
                }
            }

            return tr;
        }
    }
}