HatShop.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace RegularExam
{
    internal class HatShop
    {
        private string name;
        private List<Hat> hats;

        public HatShop(string name)
        {
            Name = name;
            hats = new List<Hat>();
        }

        public string Name
        {
            get { return name; }
            set
            {
                if (value.Length < 6)
                {
                    throw new ArgumentException("Invalid hat shop name!");
                }
                name = value;
            }
        }

        public void AddHat(Hat Hat)
        {
            this.hats.Add(Hat);
        }

        public bool SellHat(Hat Hat)
        {
            foreach (Hat checkHat in this.hats)
            {
                if (checkHat.Type == Hat.Type && checkHat.Color == Hat.Color && checkHat.Price == Hat.Price)
                {
                    this.hats.Remove(checkHat);
                    return true;
                }
            }
            return false;
        }

        public double CalculateTotalPrice()
        {
            return this.hats.Select(e => e.Price).Sum();
        }

        public Hat GetHatWithHighestPrice()
        {
            return this.hats.OrderByDescending(e => e.Price).First();
        }

        public Hat GetHatWithLowestPrice()
        {
            return this.hats.OrderBy(e => e.Price).First();
        }

        public void RenameHatShop(string newName)
        {
            Name = newName;
        }

        public void SellAllHats()
        {
            this.hats.Clear();
        }

        public override string ToString()
        {
            var sb = new StringBuilder();

            if (this.hats.Count() > 0)
            {
                sb.Append($"Hat shop {name} has {this.hats.Count} hat/s:\n");
                sb.Append(string.Join("\n", this.hats));
            }
            else
            {
                sb.Append($"Hat shop {name} has no available hats.");

            }
            return sb.ToString();
        }
    }
}