using System;
using System.Windows.Forms;
using System.Collections;


//中介者模式(Mediator)
//意圖
//    用一個中介對象來封裝一系列的對象交互。中介者使各對象不需要顯式地相互引用，從而使其耦合松散，而且可以獨立地改變它們之間的交互。
//適用性
//    1.一組對象以定義良好但是復雜的方式進行通信。產生的相互依賴關系結構混亂且難以理解。
//    2.一個對象引用其他很多對象并且直接與這些對象通信,導致難以復用該對象。
//    3.想定制一個分布在多個類中的行為，而又不想生成太多的子類。

namespace DesignPattern.MediatorRealWorld
{
    class MediatorRealWorld : AbstractPattern
    {
        public static void Run(TextBox tbInfo)
        {
            s_tbInfo = tbInfo;
            s_tbInfo.Text = "";

            // Create chatroom 
            Chatroom chatroom = new Chatroom();

             //Create participants and register them 
            Participant George = new Beatle("George");
            Participant Paul = new Beatle("Paul"); 
            Participant Ringo = new Beatle("Ringo"); 
            Participant John = new Beatle("John") ; 
            Participant Yoko = new NonBeatle("Yoko"); 

            chatroom.Register(George); 
            chatroom.Register(Paul); 
            chatroom.Register(Ringo); 
            chatroom.Register(John); 
            chatroom.Register(Yoko); 
            
            // Chatting participants 
            Yoko.Send ("John", "Hi John!"); 
            Paul.Send ("Ringo", "All you need is love"); 
            Ringo.Send("George", "My sweet Lord"); 
            Paul.Send ("John", "Can't buy me love"); 
            John.Send ("Yoko", "My sweet love") ; 
            
            // Wait for user 
            //Console.Read();
        }
    }
    
    // "Mediator" 
    abstract class AbstractChatroom 
    {
        public abstract void Register(Participant participant); 
        public abstract void Send( string from, string to, string message); 
    }
    
    // "ConcreteMediator" 
    class Chatroom : AbstractChatroom 
    {
        private Hashtable participants = new Hashtable(); 
        public override void Register(Participant participant)
        {
            if (participants[participant.Name] == null)
            { 
                participants[participant.Name] = participant; 
            }
            participant.Chatroom = this;
        }
        
        public override void Send(string from, string to, string message)
        {
            Participant pto = (Participant)participants[to]; 
            if (pto != null) 
            {
                pto.Receive(from, message); 
            }
        }
    }
    
    // "AbstractColleague" 
    class Participant 
    {
        private Chatroom chatroom; 
        private string name; 
        
        // Constructor 
        public Participant(string name) 
        {
            this.name = name;
        }
        
        // Properties 
        public string Name 
        {
            get{ return name; } 
        }
        public Chatroom Chatroom 
        {
            set{ chatroom = value; }
            get{ return chatroom; } 
        }
        public void Send(string to, string message)
        { 
            chatroom.Send(name, to, message); 
        }
        public virtual void Receive(string from, string message) 
        {
            DesignPattern.FormMain.OutputInfo("{0} to {1}: '{2}'", from, Name, message); 
        }
    }
    
    //" ConcreteColleague1" 
    class Beatle : Participant 
    {
        // Constructor 
        public Beatle(string name) : base(name) 
        {
        }
        public override void Receive(string from, string message) 
        {
            Console.Write("To a Beatle: "); 
            base.Receive(from, message); 
        }
    }
    
    //" ConcreteColleague2" 
    class NonBeatle : Participant 
    {
        // Constructor 
        public NonBeatle(string name) : base(name) 
        {
        }
        public override void Receive(string from, string message) 
        {
            Console.Write("To a non-Beatle: "); 
            base.Receive(from, message); 
        }
    }
}