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

namespace ConsoleApp1
{
    /// <summary>
    /// 观察者模式(接口实现)
    /// </summary>
    internal class guanchazhe_jieko
    {
        // 主题接口
        public interface ISubject
        {
            void RegisterObserver(IObserver observer);
            void RemoveObserver(IObserver observer);
            void NotifyObservers();
            string GetState();
            void SetState(string state);
        }

        // 观察者接口
        public interface IObserver
        {
            void Update(string message);
        }

        // 主题类
        public class ConcreteSubject : ISubject
        {
            private readonly List<IObserver> _observers = new List<IObserver>();
            private string _subjectState;

            public void RegisterObserver(IObserver observer)
            {
                _observers.Add(observer);
            }

            public void RemoveObserver(IObserver observer)
            {
                _observers.Remove(observer);
            }

            public void NotifyObservers()
            {
                foreach (var observer in _observers)
                {
                    observer.Update(_subjectState);
                }
            }

            // 主题状态的设置和获取方法
            public string GetState()
            {
                return _subjectState;
            }

            public void SetState(string state)
            {
                _subjectState = state;
            }
        }

        // 观察者类
        public class ConcreteObserver : IObserver
        {
            private string _name;
            private string _observerState;

            public ConcreteObserver(string name)
            {
                this._name = name;
            }

            public void Update(string message)
            {
                _observerState = message;
                Console.WriteLine("Observer {0} received message: {1}", _name, _observerState);
            }
        }
    }
}