using Microsoft.Win32;
using System;
using System.Diagnostics;
using System.IO.Ports;
using System.Text;
using System.Timers;
using System.Windows.Forms;

namespace MeetingClock
{
    public class MeetingClockManager
    {
        private const string MTC = "MTC";

        public enum MeetingClockState
        {
            NotInitialized,
            NoComPort,
            Disconnected,
            Connected
        }

        public MeetingClockState State { get; private set; } = MeetingClockState.NotInitialized;
        public string Version { get; private set; }
        public string Port { 
            get 
            {
                if (this.serialPort != null && this.serialPort.IsOpen)
                {
                    return this.serialPort.PortName;
                }
                return "";
            }
        }

        public delegate void MeetingClockStateChangeHandler(MeetingClockManager manager, MeetingClockState oldState, MeetingClockState newState);
        public event MeetingClockStateChangeHandler StateChanged;

        private System.Timers.Timer startTimer;
        private System.Timers.Timer checkTimer;
        private BluetoothManager bluetoothManager;
        private SerialPort serialPort;

        public MeetingClockManager(BluetoothManager bluetoothManager)
        {
            this.NewSerialPort();

            this.startTimer = new System.Timers.Timer(1000);
            this.startTimer.AutoReset = false;
            this.startTimer.Elapsed += ConnectTimer_Elapsed;

            this.checkTimer = new System.Timers.Timer(30000);
            this.checkTimer.AutoReset = false;
            this.checkTimer.Elapsed += CheckTimer_Elapsed;
            this.checkTimer.Start();

            this.bluetoothManager = bluetoothManager;
            this.bluetoothManager.StateChanged += BluetoothManager_StateChanged;
        }

        private void NewSerialPort() {
            lock (this) {
                if (this.serialPort != null)
                {
                    try
                    {
                        this.serialPort.Close();
                    }
                    catch (Exception)
                    {
                        // ignored
                    }
                }
                this.serialPort = new SerialPort();
                this.serialPort.BaudRate = 9600;
                this.serialPort.Parity = Parity.None;
                this.serialPort.DataBits = 8;
                this.serialPort.StopBits = StopBits.One;
                this.serialPort.Encoding = Encoding.GetEncoding("iso8859-1");
                this.serialPort.ReadTimeout = 5000;
                this.serialPort.WriteTimeout = 5000;
            }
        }

        private void BluetoothManager_StateChanged(BluetoothManager manager, BluetoothManager.BluetoothState oldState, BluetoothManager.BluetoothState newState)
        {
            switch (newState)
            {
                case BluetoothManager.BluetoothState.On:
                    this.startTimer.Start();
                    break;
                default:
                    this.Disconnect();
                    break;
            }
        }

        private void ConnectTimer_Elapsed(object sender, ElapsedEventArgs e)
        {
            this.Connect();
        }

        private void Connect()
        {
            lock (this)
            {
                if (this.State == MeetingClockState.Connected && this.serialPort.IsOpen)
                {
                    Debug.WriteLine("Meeting clock already connected. Not trying to connect again.");
                    return;
                }

                string[] portNames = SerialPort.GetPortNames();
                if (portNames.Length == 0)
                {
                    Debug.WriteLine("No COM ports are available at the moment.");
                    this.ChangeState(MeetingClockState.NoComPort);
                    return;
                }

                this.ChangeState(MeetingClockState.Disconnected);
                this.NewSerialPort();

                foreach (string portName in portNames)
                {
                    Debug.WriteLine(String.Format("Trying to connect to {0}", portName));
                    try
                    {
                        this.serialPort.PortName = portName;
                        this.serialPort.Open();

                        if (this.Handshake())
                        {
                            Debug.WriteLine(String.Format("Successfully connected to meeting clock {0} on port {1}", this.Version, portName));
                            this.Adjust();
                            this.ScrollText("");
                            this.NextDate(DateTime.Now.AddMinutes(-5));
                            this.ChangeState(MeetingClockState.Connected);
                            return;
                        }
                        else
                        {
                            Debug.WriteLine(String.Format("Failed to connect to meeting clock on port {0}. Invalid Handshake.", portName));
                        }
                    }
                    catch (Exception exception)
                    {
                        Debug.WriteLine(String.Format("Failed to connect to meeting clock on port {0}. {1}", portName, exception.Message));
                    }

                    this.Disconnect();
                }
            }
        }

        private void Disconnect()
        {
            lock (this)
            {
                if (this.serialPort.IsOpen)
                {
                    Debug.WriteLine(String.Format("Closing connection on port {0}", this.serialPort.PortName));
                    try
                    {
                        this.serialPort.Close();
                    }
                    catch (Exception)
                    {
                        // ignored
                    }
                }
                
                this.ChangeState(MeetingClockState.Disconnected);
                this.NewSerialPort();
            }
        }

        private bool Handshake()
        {
            string rx = this.SendAndReceive(MTC);
            
            if (rx == null)
            {
                return false;
            }

            if (rx.StartsWith(MTC))
            {
                this.Version = rx.Substring(MTC.Length).Trim();
                return true;
            }

            return false;
        }

        public void Adjust()
        {
            this.SendAndReceive(String.Format("ADJ {0}", DateTime.Now.ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ss")));
        }

        private string SendAndReceive(string tx)
        {
            lock (this)
            {
                try
                {
                    if (this.serialPort.IsOpen)
                    {
                        Debug.WriteLine(String.Format(">>> {0}", tx));
                        this.serialPort.WriteLine(tx);
                        string rx = this.serialPort.ReadLine().Trim();
                        Debug.WriteLine(String.Format("<<< {0}", rx));
                        return rx;
                    }
                }
                catch (Exception exception)
                {
                    Debug.WriteLine(String.Format("Failed to send/receiv on port {0}. {1}", this.serialPort.PortName, exception.Message));
                    this.Disconnect();
                }

                return null;
            }
        }

        private void ChangeState(MeetingClockState newState)
        {
            MeetingClockState oldState = this.State;
            this.State = newState;

            if (newState != oldState)
            {
                Debug.WriteLine("Meeting Clock state change detected. Old state: {0}, new state {1}.", oldState, newState);

                if (this.StateChanged != null)
                {
                    this.StateChanged(this, oldState, newState);
                }
            }
        }

        private void CheckTimer_Elapsed(object sender, ElapsedEventArgs e)
        {
            if (this.serialPort.IsOpen)
            {
                if (!this.Handshake())
                {
                    this.Disconnect();
                }
            } 
            else if (this.bluetoothManager.State == BluetoothManager.BluetoothState.On)
            {
                this.Connect();
            }

            this.checkTimer.Start();
        }

        public void Stop()
        {
            this.Disconnect();
            this.checkTimer.Stop();
            this.startTimer.Stop();
        }

        public int? GetTimeInterval()
        {
            try
            {
                string rx = this.SendAndReceive("GET TI").Substring(7);
                return int.Parse(rx);
            }
            catch (Exception)
            {
                return null;
            }
        }

        public void SetTimeInterval(int value)
        {
            try
            {
                this.SendAndReceive("SET TI " + value);
            }
            catch (Exception)
            {
            }
        }

        public int? GetDateInterval()
        {
            try
            {
                string rx = this.SendAndReceive("GET DI").Substring(7);
                return int.Parse(rx);
            }
            catch (Exception)
            {
                return null;
            }
        }

        public void SetDateInterval(int value)
        {
            try
            {
                this.SendAndReceive("SET DI " + value);
            }
            catch (Exception)
            {
            }
        }

        public int? GetTemperatureInterval()
        {
            try
            {
                string rx = this.SendAndReceive("GET CI").Substring(7);
                return int.Parse(rx);
            }
            catch (Exception)
            {
                return null;
            }
        }
        public void SetTemperatureInterval(int value)
        {
            try
            {
                this.SendAndReceive("SET CI " + value);
            }
            catch (Exception)
            {
            }
        }

        public int? GetBrightness()
        {
            try
            {
                string rx = this.SendAndReceive("GET IN").Substring(7);
                return int.Parse(rx);
            }
            catch (Exception)
            {
                return null;
            }
        }

        public int? GetScrollSpeed()
        {
            try
            {
                string rx = this.SendAndReceive("GET SS").Substring(7);
                return int.Parse(rx);
            }
            catch (Exception)
            {
                return null;
            }
        }

        public int? GetScrollWait()
        {
            try
            {
                string rx = this.SendAndReceive("GET SW").Substring(7);
                return int.Parse(rx);
            }
            catch (Exception)
            {
                return null;
            }
        }

        public void SetBrightness(int value)
        {
            try
            {
                this.SendAndReceive("SET IN " + value);
            }
            catch (Exception)
            {
            }
        }

        public void SetScrollSpeed(int value)
        {
            try
            {
                this.SendAndReceive("SET SS " + value);
            }
            catch (Exception)
            {
            }
        }

        public void SetScrollWait(int value)
        {
            try
            {
                this.SendAndReceive("SET SW " + value);
            }
            catch (Exception)
            {
            }
        }

        public void ScrollText(string value)
        {
            try
            {
                this.SendAndReceive("SCR " + value);
            }
            catch (Exception)
            {
            }
        }

        public bool? GetDateEnabled()
        {
            try
            {
                string rx = this.SendAndReceive("GET DE").Substring(7);
                return int.Parse(rx) > 0;
            }
            catch (Exception)
            {
                return null;
            }
        }

        public void SetDateEnabled(bool value)
        {
            try
            {
                this.SendAndReceive("SET DE " + (value ? "1" : "0"));
            }
            catch (Exception)
            {
            }
        }

        public bool? GetTemperatureEnabled()
        {
            try
            {
                string rx = this.SendAndReceive("GET CE").Substring(7);
                return int.Parse(rx) > 0;
            }
            catch (Exception)
            {
                return null;
            }
        }

        public void SetTemperatureEnabled(bool value)
        {
            try
            {
                this.SendAndReceive("SET CE " + (value ? "1" : "0"));
            }
            catch (Exception)
            {
            }
        }

        internal void NextDate(DateTime value)
        {
            try
            {
                this.SendAndReceive("NXT " + value.ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ss"));
            }
            catch (Exception)
            {
            }
        }
    }
}