PatternObserver

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

namespace Events
{
    class Program
    {
        static void Main(string[] args)
        {
            WeatherData weatherData = new WeatherData();
            CurrentConditionsDisplay currentConditionsDisplay = new CurrentConditionsDisplay(weatherData);
            HeatIndexDisplay heatIndexDisplay = new HeatIndexDisplay(weatherData);

            weatherData.SetMessurements(80, 65, 30.4f);
            Console.WriteLine();
            weatherData.SetMessurements(20, 325, 30.4f);
            Console.WriteLine();
            weatherData.SetMessurements(520, 785, 30.4f);

            Console.ReadKey();
        }
    }

    class HeatIndexDisplay : IObserver, IDisplayElement
    {
        private float _heatIndex;
        private ISubject _weatherData;

        public HeatIndexDisplay(ISubject weatherData)
        {
            _weatherData = weatherData;
            weatherData.registerObserver(this);
        }
        public void Display()
        {
            Console.WriteLine("Ощущается как: " + _heatIndex);
        }

        public void Update(float temperature, float humidity, float pressure)
        {
            _heatIndex = -42.379f + 2.04901523f * temperature + 10.14333127f * humidity -
                0.22475541f * temperature * humidity - 0.00683783f * temperature * temperature -
                0.5481717f * humidity * humidity + 0.0122874f * temperature * temperature * humidity +
                0.00085282f * temperature * humidity * humidity - 0.000000199f * temperature * temperature *
                humidity * humidity;
            Display();
        }
    }

    class CurrentConditionsDisplay : IObserver, IDisplayElement
    {
        private float _temperature;
        private float _humidity;
        private ISubject _weatherData;
        public CurrentConditionsDisplay(ISubject weatherData)
        {
            _weatherData = weatherData;
            weatherData.registerObserver(this);
        }

        public void Display()
        {
            Console.WriteLine("Текущая погода: \nTemperature: " + _temperature +
                              "\nHumidity: " + _humidity + "%");
        }

        public void Update(float temperature, float humidity, float pressure)
        {
            _temperature = temperature;
            _humidity = humidity;
            Display();
        }
    }

    interface IObserver
    {
        void Update(float temperature, float humidity, float pressure);
    }

    interface ISubject
    {
        void registerObserver(IObserver observer);
        void removeObserver(IObserver observer);
        void notifyObservers();
    }

    interface IDisplayElement
    {
        void Display();
    }

    class WeatherData : ISubject
    {
        private IObserver[] _observers = new IObserver[0];
        private float _temperature;
        private float _humidity;
        private float _pressure;

        public void notifyObservers()
        {
            foreach (var observer in _observers)
            {
                observer.Update(_temperature, _humidity, _pressure);
            }
        }

        public void registerObserver(IObserver observer)
        {
            IObserver[] newObservers = new IObserver[_observers.Length + 1];
            for(int i = 0; i < _observers.Length; i++)
            {
                newObservers[i] = _observers[i];
            }
            newObservers[newObservers.Length - 1] = observer;
            _observers = newObservers;
        }

        public void removeObserver(IObserver observer)
        {
            int indexRemove = 0;
            for (int i = 0; i < _observers.Length; i++)
            {
                if(_observers[i] == observer)
                {
                    indexRemove = i;
                }
            }

            IObserver[] newObservers = new IObserver[_observers.Length - 1];
            int index = 0;
            for (int i = 0; i < newObservers.Length; i++)
            {
                if(index == indexRemove)
                {
                    index++;
                }
                newObservers[i] = _observers[i];
                index++;
            }
            _observers = newObservers;
        }

        public void MessurementChanged()
        {
            notifyObservers();
        }

        public void SetMessurements(float temperature, float humidity, float pressure)
        {
            _temperature = temperature;
            _humidity = humidity;
            _pressure = pressure;
            MessurementChanged();
        }
    }
}