using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using Learn.Models;

namespace Learn.Parsers;

public class RawParser : ItemParser
{
    private string ParseSeasonFromCN(string season)
    {
        if (int.TryParse(season, out _)) return season;
        
        switch (season)
        {
            case "零": return "0";
            case "一": return "1";
            case "二": return "2";
            case "三": return "3";
            case "四": return "4";
            case "五": return "5";
            case "六": return "6";
            case "七": return "7";
            case "八": return "8";
            case "九": return "9";
        }
        return season;
    }
    
    
    private (string, string) SplitTitleAndSeason(string rawTitle)
    {
        var match1 = Regex.Match(rawTitle, @"第(.+)季");
        if (match1.Success)
        {
            var seasonStr = match1.Groups[0].Value.Trim();
            var season = ParseSeasonFromCN(match1.Groups[1].Value.Trim());
            var title = rawTitle.Replace(seasonStr, "").Trim();
            return (title, season);
        }
        
        var match2 = Regex.Match(rawTitle, @"[Ss]eason *(\d+)");
        if (match2.Success)
        {
            var seasonStr = match1.Groups[0].Value.Trim();
            var season = int.Parse(match1.Groups[1].Value.Trim()).ToString();
            var title = rawTitle.Replace(seasonStr, "").Trim();
            return (title, season);
        }

        return (rawTitle, null);
    }

    private void SimplifyMatches(List<string> matches)
    {
        matches.RemoveAll(match => string.IsNullOrEmpty(match.Trim()));
        matches.RemoveAll(match => Regex.Match(match.Trim(), @"\d+[Pp]$").Success);
    }

    private List<string> GetParts(string name)
    {
        var matches = Regex.Matches(name, @"[^\[\]_【】]+").Select(match => match.Value).ToList();
        SimplifyMatches(matches);
        return matches;
    }
    
    private bool TryParseRawTitle(Item item, out string rawTitle)
    {
        rawTitle = null;
        var name = item.Name();
        var matches = GetParts(name);
        
        if (matches.Count == 0) return false;

        if (matches.Count == 1)
        {
            rawTitle = matches[0];
        }
        else
        {
            rawTitle = matches[1];
        }
        
        (rawTitle, _) = SplitTitleAndSeason(rawTitle);
        return true;
    }

    private bool TryParseSeason(Item item, out string season)
    {
        season = null;
        var name = item.Name();
        var matches = GetParts(name);
        
        if (matches.Count == 0) return false;

        if (matches.Count == 1)
        {
            (_, season) = SplitTitleAndSeason(matches[0]);
            if (!string.IsNullOrEmpty(season)) return true;
        }
        else
        {
            (_, season) = SplitTitleAndSeason(matches[1]);
            if (!string.IsNullOrEmpty(season)) return true;
        }
        
        return false;
    }

    private bool TryParseGroup(Item item, out string group)
    {
        group = null;
        var name = item.Name();
        var matches = GetParts(name);

        if (matches.Count <= 1) return false;
        group = matches[0];
        return true;
    }
    
    private delegate bool FieldParser(Item item, out string result);
    
    private bool TryParseField(TreeNode node, FieldParser fieldParser, out string result)
    {
        result = null;
        if (node.Info == null) return false;
        if (!fieldParser(node.Info, out var fieldValue)) return false;
        var parsed = new List<string>();
        foreach (var child in node.Children)
        {
            if (fieldParser(child.Info, out var childFieldValue))
            {
                parsed.Add(childFieldValue);
            }
        }
        
        var totalCount = parsed.Count;
        if (totalCount == 0)
        {
            result = fieldValue;
            return true;
        }
        
        var maxGroupCount = parsed.GroupBy(value => value)
            .Select(group => group.Count())
            .Max();

        if (maxGroupCount > totalCount / 2)
        {
            result = fieldValue;
            return true;
        }

        return false;
    }

    private void DoParse(TreeNode node, FieldParser fieldParser, string fieldName)
    {
        var queue = new Queue<TreeNode>();
        queue.Enqueue(node);
        while (queue.Count > 0)
        {
            var current = queue.Dequeue();
            if (TryParseField(current, fieldParser, out var fieldValue))
            {
                current.Info.Info.TryAdd(fieldName, fieldValue);
            }
            else
            {
                foreach (var child in current.Children)
                {
                    queue.Enqueue(child);
                }
            }
        }
    }
    
    public async Task Parse(TreeNode node)
    {
        DoParse(node, TryParseRawTitle, ItemFields.Key_RawTitle);
        DoParse(node, TryParseSeason, ItemFields.Key_Season);
        DoParse(node, TryParseGroup, ItemFields.Key_Group);
    }
}