using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Xml.Serialization;

namespace MainServer
{
	public partial class Form1 : Form
	{
		//TcpListener listens for incoming TCP requests on port 5000
		TcpListener listener = new TcpListener(IPAddress.Parse("127.0.0.1"), 5000);		
		TcpClient client; //manage the incoming client requests		
		String clNo; //store the client number
		Dictionary<string, TcpClient> clientList = new Dictionary<string, TcpClient>(); // keep track of all clients		
		CancellationTokenSource cancellation = new CancellationTokenSource();

		//List object to store the chat messages
		List<string> chat = new List<string>();

		public Form1()
		{
			InitializeComponent();
		}

		private void btnStart_Click(object sender, EventArgs e)
		{
			//Resets the cancellation token when the server restarts
			cancellation = new CancellationTokenSource();		
			startServer();
		}

		public void updateUI(String m)
		{
			// update textbox with the received data
			this.Invoke((MethodInvoker)delegate
			{
				textBox1.AppendText("-" + m + Environment.NewLine);
			});
		}

		public async void startServer()
		{
			//Starts the TCP listener
			listener.Start();
			//Updates the UI showing server has started
			updateUI("Server Started at " + listener.LocalEndpoint);
			//Updates UI showing server is waiting for clients
			updateUI("Waiting for Clients");
			try
			{
				int counter = 0;
				while (true)
				{
					counter++;
					//Accepts incoming TCP connection 
					client = await Task.Run(() => listener.AcceptTcpClientAsync(), cancellation.Token);
				
					//Reads username
					byte[] name = new byte[50];
					NetworkStream stre = client.GetStream();
					stre.Read(name, 0, name.Length);
					String username = Encoding.ASCII.GetString(name);
					username = username.Substring(0, username.IndexOf("$"));

					clientList.Add(username, client); //Adds the client to the dictionary					
					listBox1.Items.Add(username); //Adds the username to the listbox					
					updateUI("Connected to user " + username + " - " + client.Client.RemoteEndPoint); // indicate client has connected					
					announce(username + " Joined ", username, false); //Sends message  to clients that a user has joined

					//Delays the task by 1 second, then sends the list of users to clients
					await Task.Delay(1000).ContinueWith(t => sendUsersList());

					//Starts new thread to receive data from client
					var c = new Thread(() => ServerReceive(client, username));
					c.Start();

				}
			}
			catch (Exception)
			{
				//Stops the TCP listener if theres an exception 
				listener.Stop();
			}

		}

		// broadcasts a message to all connected clients.
		public void announce(string msg, string uName, bool flag)
		{	
			try
			{
				foreach (var Item in clientList)
				{
					TcpClient broadcastSocket;
					broadcastSocket = (TcpClient)Item.Value;
					NetworkStream broadcastStream = broadcastSocket.GetStream();
					Byte[] broadcastBytes = null;

					if (flag)
					{
						// message with the username and message						
						chat.Add("gChat");
						chat.Add(uName + " says : " + msg);
						broadcastBytes = ObjectToByteArray(chat);
					}
					else
					{
						// message with the message content only					
						chat.Add("gChat");
						chat.Add(msg);
						broadcastBytes = ObjectToByteArray(chat);
					}

					// Send message to client
					broadcastStream.Write(broadcastBytes, 0, broadcastBytes.Length);
					broadcastStream.Flush();

					// Clear chat list for next message
					chat.Clear();
				}
			}
			catch (Exception er)
			{
				// Catch any exceptions 
			}
		}

		// converts a byte array to an object.
		public Object ByteArrayToObject(byte[] arrBytes)
		{
			using (var memStream = new MemoryStream())
			{
				var binForm = new BinaryFormatter();
				memStream.Write(arrBytes, 0, arrBytes.Length);
				memStream.Seek(0, SeekOrigin.Begin);
				var obj = binForm.Deserialize(memStream);
				return obj;
			}
		}

		// converts an object to a byte array.
		public byte[] ObjectToByteArray(Object obj)
		{
			BinaryFormatter bf = new BinaryFormatter();
			using (var ms = new MemoryStream())
			{
				bf.Serialize(ms, obj);
				return ms.ToArray();
			}
		}

		// handles receiving messages from client.
		public void ServerReceive(TcpClient clientn, String username)
		{
			byte[] data = new byte[1000];
			String text = null;

			// receive messages until the connection is closed --loop
			while (true)
			{
				try
				{
					// Get network stream for the client
					NetworkStream stream = clientn.GetStream();

					// Read message from client
					stream.Read(data, 0, data.Length);

					// Convert message from a byte array to a list of strings
					List<string> parts = (List<string>)ByteArrayToObject(data);

					// Check the first part of the message 
					switch (parts[0])
					{
						case "gChat":
							// Display message in text box on the server form
							this.Invoke((MethodInvoker)delegate
							{
								textBox1.Text += username + ": " + parts[1] + Environment.NewLine;
							});

							// Broadcast message to all clients
							announce(parts[1], username, true);
							break;
					}

					// Clear parts list for next message
					parts.Clear();
				}
				catch (Exception r)
				{
					updateUI("Client Disconnected: " + username);
					announce("Client Disconnected: " + username + "$", username, false);
					clientList.Remove(username);
					// removes the username from the list box
					this.Invoke((MethodInvoker)delegate
					{
						listBox1.Items.Remove(username);
					});
					// Send updated user list to clients
					sendUsersList();
					// Exit the method
					break;
				}
			}
		}

		private void btnServerStop_Click(object sender, EventArgs e)
		{
			try
			{
		
				listener.Stop();
				updateUI("Server Stopped");
				// Close all client connections
				foreach (var Item in clientList)
				{
					TcpClient broadcastSocket;
					broadcastSocket = (TcpClient)Item.Value;
					broadcastSocket.Close();
				}
			}
			catch (SocketException er)
			{

			}
  
		}

		private void disconnectToolStripMenuItem_Click(object sender, EventArgs e)
		{
			try
			{
				TcpClient workerSocket = null;

				// Get selected client's username from the list box
				String clientName = listBox1.GetItemText(listBox1.SelectedItem);
				// Find client in the dictionary using username
				workerSocket = (TcpClient)clientList.FirstOrDefault(x => x.Key == clientName).Value;
				// Close client connection
				workerSocket.Close();

			}
			catch (SocketException se)
			{
			}
		}

		public void sendUsersList()
		{
			try
			{			
				byte[] userList = new byte[1024]; // byte array to store user list data
				string[] clist = listBox1.Items.OfType<string>().ToArray(); // string array of current clients in the listBox control
				List<string> users = new List<string>(); // List to store user data

				// Add 'userList' to List
				users.Add("userList");

				// add all clients to list
				foreach (String name in clist)
				{
					users.Add(name);
				}

				// Convert List to byte array
				userList = ObjectToByteArray(users);

				// Send byte array to all clients in the clientList
				foreach (var Item in clientList)
				{
					TcpClient broadcastSocket;
					broadcastSocket = (TcpClient)Item.Value; // Retrieve the TcpClient object from the dictionary
					NetworkStream broadcastStream = broadcastSocket.GetStream(); // Retrieve the NetworkStream from the TcpClient object
					broadcastStream.Write(userList, 0, userList.Length); // Send the byte array to the client
					broadcastStream.Flush(); // Flush stream to ensure the data is sent immediately
					users.Clear(); // Clear the List for the next iteration
				}
			}
			catch (SocketException se)
			{
		
			}
		}

		private void textBox1_TextChanged(object sender, EventArgs e)
		{
			// scroll to the bottom of the textbox whenever text changes
			textBox1.SelectionStart = textBox1.TextLength;
			textBox1.ScrollToCaret();
		}

		private void textBox1_TextChanged_1(object sender, EventArgs e)
		{

		}
	}
}