GildedRose-Refactoring-Kata/csharpcore/GildedRose/GildedRose.cs

using System.Collections.Generic;

namespace GildedRoseKata;

public class GildedRose
{
    private readonly IList<Item> _items;
    const int MinQuality = 0;
    const int MaxQuality = 50;

    public GildedRose(IList<Item> items)
    {
        _items = items;
    }

    public void UpdateQuality()
    {
        foreach (var item in _items)
        {
            DailyItemUpdate(item);
        }
    }

    private static bool IsLegendaryItem(Item item) => item.Name.ToLower().Contains("sulfuras");

    private static bool IsBackstagePassesItem(Item item) => item.Name.ToLower().Contains("backstage passes");

    private static bool IsBetterWithAgeItem(Item item) => item.Name.ToLower().Equals("aged brie");
    
    
    
    
    private void DailyItemUpdate(Item item)
    {
        if (!IsBetterWithAgeItem(item) && !IsBackstagePassesItem(item))
        {
            if (item.Quality > MinQuality)
            {
                if (!IsLegendaryItem(item))
                {
                    item.Quality = item.Quality - 1;
                }
            }
        }
        else
        {
            if (item.Quality < MaxQuality)
            {
                item.Quality = item.Quality + 1;

                if (IsBackstagePassesItem(item))
                {
                    if (item.SellIn < 11)
                    {
                        if (item.Quality < MaxQuality)
                        {
                            item.Quality = item.Quality + 1;
                        }
                    }

                    if (item.SellIn < 6)
                    {
                        if (item.Quality < MaxQuality)
                        {
                            item.Quality = item.Quality + 1;
                        }
                    }
                }
            }
        }

        if (!IsLegendaryItem(item))
        {
            item.SellIn = item.SellIn - 1;
        }

        if (item.SellIn < 0)
        {
            if (!IsBetterWithAgeItem(item))
            {
                if (!IsBackstagePassesItem(item))
                {
                    if (item.Quality > MinQuality)
                    {
                        if (!IsLegendaryItem(item))
                        {
                            item.Quality = item.Quality - 1;
                        }
                    }
                }
                else
                {
                    item.Quality = item.Quality - item.Quality;
                }
            }
            else
            {
                if (item.Quality < MaxQuality)
                {
                    item.Quality = item.Quality + 1;
                }
            }
        }
    }
}