designPatternGuru/DesignPatternGuru/Flyweight/Flyweights/FlyweightFactory.cs

using Flyweight.Objects;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Flyweight.Flyweights
{
    internal class FlyweightFactory
    {
        private List<Tuple<Flyweight, string>> _flyweights = new List<Tuple<Flyweight, string>>();

        public FlyweightFactory(params Car[] args)
        {
            foreach (var elem in args)
            {
                _flyweights.Add(new Tuple<Flyweight, string>(new Flyweight(elem), GetKey(elem)));
            }
        }

        public string GetKey(Car car)
        {
            List<string> elements = new List<string>();

            elements.Add(car.Model);
            elements.Add(car.Color);
            elements.Add(car.Company);
            
            if (car.Owner != null && car.Number != null)
            {
                elements.Add(car.Number);
                elements.Add(car.Owner);
            }

            elements.Sort();

            return String.Join("_", elements);
        }

        public Flyweight GetFlyweight(Car sharedState)
        {
            string key = GetKey(sharedState);
            if (_flyweights.Where(t => t.Item2 == key).Count() == 0)
            {
                Console.WriteLine("FlyweightFactory: Can't find a flyweight, creating new one.");
                _flyweights.Add(new Tuple<Flyweight, string>(new Flyweight(sharedState), key));
            }
            else
            {
                Console.WriteLine("FlyweightFactory: Reusing existing flyweight.");
            }

            return _flyweights.Where(t => t.Item2 == key).FirstOrDefault().Item1;
        }

        public void ListFlyweights()
        {
            int count = _flyweights.Count;
            Console.WriteLine($"FlyweightFactory: I have {count} flyweights");
            foreach (var flyweight in _flyweights)
            {
                Console.WriteLine(flyweight.Item2);
            }
        }
    }
}