using System;
using System.Threading;
using System.Device.Gpio;
using System.Device.Gpio.Drivers;
using System.Net;
using System.Net.Sockets;
using System.Text;

namespace BAT_UdpLedTestApp {

    internal class Program {
        public static GpioController Ctrl { get; set; }

        static void Main( string[] args ) {
            Console.WriteLine( "Application started!" );

            // Set up GPIO

            int gpioBank = 0;
            Console.WriteLine( "in Joystick() - create LibGpiodDriver" );
            LibGpiodDriver libGpiodDriver = new LibGpiodDriver( gpioBank );

            Console.WriteLine( "in Joystick() - create GpioController" );
            GpioController ctrl = new GpioController( PinNumberingScheme.Logical, libGpiodDriver );
            Ctrl = ctrl; // set in public property so joystick and leds can access it

            Thread t = new Thread( Run );
            // Background thread, ends when Main() ends
            t.IsBackground = false;
            t.Start();
            // Program ends, but Run-Thread keeps working
        }
        protected static void Run() {
            Joystick joystick = Joystick.GetInstance();
            Leds leds = Leds.GetInstance();
            JoystickButtons oldState = JoystickButtons.None;
            JoystickButtons newState;

            IPEndPoint ipEndpoint = new IPEndPoint(IPAddress.Any, 10001);
            UdpClient udpClient = new UdpClient(ipEndpoint);
            udpClient.Client.ReceiveTimeout = 100; // set timeout to 100ms
            byte[] data = new byte[1024];
            IPEndPoint sender = new IPEndPoint(IPAddress.Any, 0);

            Console.WriteLine("Waiting for clients...");
            while( true ) {
                // reset array
                data = Array.Empty<byte>();
                // try receive data
                try
                {
                    data = udpClient.Receive(ref sender);
                }
                catch (SocketException sockEx)
                {
                    // timeout = normal use case
                    if (sockEx.SocketErrorCode != SocketError.TimedOut)
                    {
                        throw;
                    }
                }

                // decode message, if any received => Handle it
                string receivedMessage = Encoding.ASCII.GetString(data, 0, data.Length);
                if(receivedMessage.Length > 0)
                {
                    Console.WriteLine("Message received from {0}:", sender.ToString());
                    Console.WriteLine(receivedMessage);

                    if(receivedMessage.StartsWith("led on"))
                    {
                        leds.Set( LedColor.Green, true );
                        ReplyMessage(udpClient, sender, "Led turned on");
                    }
                    else if(receivedMessage.StartsWith("led off"))
                    {
                        leds.Set( LedColor.Green, false );
                        ReplyMessage(udpClient, sender, "Led turned off");
                    }
                    else if(receivedMessage.StartsWith("joystick state"))
                    {
                        JoystickButtons state = joystick.State;
                        ReplyMessage(udpClient, sender, $"Current Joystick state: {state}");
                    }
                    else
                    {
                        ReplyMessage(udpClient, sender, "Unknown command");
                    }
                }

                // check if the joystick state changed, send to last sender
                newState = joystick.State;
                if( oldState != newState ) {
                    Console.WriteLine($"New Joystick state detected: {newState}");
                    ReplyMessage(udpClient, sender, $"New Joystick state: {newState}");
                    oldState = newState;
                }
                Thread.Sleep( 50 );
            }
        }
        
        public static void ReplyMessage(UdpClient client, IPEndPoint sender, string replyMessage)
        {
            // would lead to exception
            if(sender.Address == IPAddress.Any) { return; }

            // terminate message with LF
            string terminatedMessage = $"{replyMessage}\n";

            // send data
            byte[] data = new byte[1024];
            data = Encoding.ASCII.GetBytes(terminatedMessage);
            client.Send(data, data.Length, sender);
            Console.WriteLine($"Sent message: {replyMessage}");
        }        
    } // end class Program

} // end namespace