using System;
using System.IO;
using System.Runtime.InteropServices;

using MatterHackers.TermiosH;

namespace MatterHackers.MatterControl.FrostedSerial
{
	[StructLayout(LayoutKind.Sequential, Pack=1)]
	public unsafe struct tDeviceInfo
	{
		public uint c_iflag;
		public uint c_oflag;
		public uint c_cflag;
		public uint c_lflag;

		public fixed byte c_cc[20];
		public uint c_ispeed;
		public uint c_ospeed;
	}

	class FrostedSerialPortStream : Stream, IFrostedSerialStream, IDisposable
    {
        int fd;
        int read_timeout;
        int write_timeout;
        bool disposed;

        [DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int open_serial(string portName);

		[DllImport("FrostedSerialHelper", SetLastError = true)]
		static extern int set_attributes (int fd, int baudRate, Parity parity, int dataBits, StopBits stopBits, Handshake handshake);

        public FrostedSerialPortStream(string portName, int baudRate, int dataBits, Parity parity, StopBits stopBits,
                bool dtrEnable, bool rtsEnable, Handshake handshake, int readTimeout, int writeTimeout,
                int readBufferSize, int writeBufferSize)
        {


			fd = open_serial(portName);
			if (fd == -1) {
				ThrowIOException ();
			}

            TryBaudRate(baudRate);

			int canSetAttributes = set_attributes (fd, baudRate, parity, dataBits, stopBits, handshake);

			if (canSetAttributes != 0)
			{
				throw new IOException(canSetAttributes.ToString()); // Probably Win32Exc for compatibility
			}

            read_timeout = readTimeout;
            write_timeout = writeTimeout;

            SetSignal(SerialSignal.Dtr, dtrEnable);

            if (handshake != Handshake.RequestToSend &&
                    handshake != Handshake.RequestToSendXOnXOff)
                SetSignal(SerialSignal.Rts, rtsEnable);
        }

		private int SetupBaudRate(int baudRate)
		{
			throw new NotImplementedException();
		}


		[DllImport("FrostedSerialHelper", SetLastError = true)]
		static extern int tcgetattr(int fd, tDeviceInfo newtio);

		private int TCGetAttribute(int fd, tDeviceInfo newtio)
		{
			int result = tcgetattr (fd, newtio);
			return result;
		}

		[DllImport("FrostedSerialHelper", SetLastError = true)]
		static extern int tcsetattr(int fd, uint optional_actions, tDeviceInfo newtio);

		private int TCSetAttribute(int fd, uint optional_actions, tDeviceInfo newtio)
		{
			return tcsetattr (fd, optional_actions, newtio);
		}

		private int CFSetISpeed(tDeviceInfo newtio, int baudRate)
		{
			newtio.c_ispeed = (uint)baudRate;
			return (int)newtio.c_ispeed;
		}

		private int CFSetOSpeed(tDeviceInfo newtio, int baudRate)
		{
			newtio.c_ospeed = (uint)baudRate;
			return (int)newtio.c_ospeed;
		}



		private bool SetFrostedAttributes(int fd, int baudRate, Parity parity, int dataBits, StopBits stopBits, Handshake handshake)
		{
			tDeviceInfo newtio = new tDeviceInfo ();
			if (TCGetAttribute (fd, newtio) == -1) {
				return false;
			}

			newtio.c_cflag |= (uint)(e_c_oflag.CLOCAL | e_c_oflag.CREAD);
			// there is no defenition for e_c_lflag.ECHOL that I can find. It was in the list of or'ed flags below
			unchecked 
			{
				newtio.c_lflag &= (uint)-(int)(e_c_lflag.ICANON | e_c_lflag.ECHO | e_c_lflag.ECHOE | e_c_lflag.ECHOK | e_c_lflag.ECHONL | e_c_lflag.ISIG | e_c_lflag.IEXTEN);
			}
			newtio.c_oflag &= (uint)(e_c_oflag.OPOST);
			newtio.c_iflag = (uint)e_c_iflag.IGNBRK;

			baudRate = SetupBaudRate (baudRate);

			unchecked {
				newtio.c_cflag &= (uint)-(uint)e_c_oflag.CSIZE;
			}

			switch (dataBits) 
			{
			case 5:
				newtio.c_cflag |= (uint)e_c_oflag.CS5;
				break;
			case 6:
				newtio.c_cflag |= (uint)e_c_oflag.CS6;
				break;
			case 7:
				newtio.c_cflag |= (uint)e_c_oflag.CS6;
				break;
			case 8:
			default:
				newtio.c_cflag |= (uint)e_c_oflag.CS8;
				break;
			}

			switch (stopBits) 
			{
			case StopBits.None:
				break;
			case StopBits.One:
				unchecked
				{
					newtio.c_cflag &= (uint)-(uint)e_c_oflag.CSTOPB;
				}
				break;
			case StopBits.Two:
				newtio.c_cflag |= (uint)e_c_oflag.CSTOPB;
				break;
			case StopBits.OnePointFive:
				break;
			}

			unchecked {
				newtio.c_iflag &= (uint)-(uint)(e_c_iflag.INPCK | e_c_iflag.ISTRIP);
			}

			switch (parity)
			{
				case Parity.None: /* None */
				newtio.c_cflag &= ~(uint)(e_c_oflag.PARENB | e_c_oflag.PARODD);
				break;

				case Parity.Odd: /* Odd */
				newtio.c_cflag |= (uint)(e_c_oflag.PARENB | e_c_oflag.PARODD);
				break;

				case Parity.Even: /* Even */
				newtio.c_cflag &= ~(uint)(e_c_oflag.PARODD);
				newtio.c_cflag |= (uint)(e_c_oflag.PARENB);
				break;

				case Parity.Mark: /* Mark */
				/* XXX unhandled */
				break;
				case Parity.Space: /* Space */
				/* XXX unhandled */
				break;
			}

			newtio.c_iflag &= ~(uint)(e_c_iflag.IXOFF | e_c_iflag.IXON);
#if CRTSCTS
			newtio.c_cflag &= ~CRTSCTS;
#endif //* def CRTSCTS */

			switch (handshake)
			{
				case Handshake.None: /* None */
				/* do nothing */
				break;
				case Handshake.RequestToSend: /* RequestToSend (RTS) */
#if CRTSCTS
				newtio.c_cflag |= CRTSCTS;
#endif //* def CRTSCTS */
				break;
				case Handshake.RequestToSendXOnXOff: /* RequestToSendXOnXOff (RTS + XON/XOFF) */
#if CRTSCTS
				newtio.c_cflag |= CRTSCTS;
#endif //* def CRTSCTS */
				/* fall through */
				case Handshake.XOnXOff: /* XOnXOff */
				newtio.c_iflag |= (uint)(e_c_iflag.IXOFF | e_c_iflag.IXON);
				break;
			}

			if (CFSetOSpeed (newtio, baudRate) < 0 || CFSetISpeed (newtio, baudRate) < 0 ||
			    TCSetAttribute (fd, (uint)e_tcsetaatr.TCSANOW, newtio) < 0)
			{
				return false;
			}
			else
			{
				return true;
			}

			//return set_attributes(fd, baudRate, parity, dataBits, sb, hs);
		}

        public override bool CanRead
        {
            get
            {
                return true;
            }
        }

        public override bool CanSeek
        {
            get
            {
                return false;
            }
        }

        public override bool CanWrite
        {
            get
            {
                return true;
            }
        }

        public override bool CanTimeout
        {
            get
            {
                return true;
            }
        }

        public override int ReadTimeout
        {
            get
            {
                return read_timeout;
            }
            set
            {
                if (value < 0 && value != FrostedSerialPort.InfiniteTimeout)
                    throw new ArgumentOutOfRangeException("value");

                read_timeout = value;
            }
        }

        public override int WriteTimeout
        {
            get
            {
                return write_timeout;
            }
            set
            {
                if (value < 0 && value != FrostedSerialPort.InfiniteTimeout)
                    throw new ArgumentOutOfRangeException("value");

                write_timeout = value;
            }
        }

        public override long Length
        {
            get
            {
                throw new NotSupportedException();
            }
        }

        public override long Position
        {
            get
            {
                throw new NotSupportedException();
            }
            set
            {
                throw new NotSupportedException();
            }
        }

        public override void Flush()
        {
            // If used, this _could_ flush the serial port
            // buffer (not the SerialPort class buffer)
        }

		[DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int read_serial(int fd, byte[] buffer, int offset, int count);


		[DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern bool poll_serial(int fd, out int error, int timeout);

        public override int Read([In, Out] byte[] buffer, int offset, int count)
        {
            CheckDisposed();
            if (buffer == null)
                throw new ArgumentNullException("buffer");
            if (offset < 0 || count < 0)
                throw new ArgumentOutOfRangeException("offset or count less than zero.");

            if (buffer.Length - offset < count)
                throw new ArgumentException("offset+count",
                                  "The size of the buffer is less than offset + count.");

            int error;
            bool poll_result = poll_serial(fd, out error, read_timeout);
            if (error == -1)
                ThrowIOException();

            if (!poll_result)
            {
                // see bug 79735   http://bugzilla.ximian.com/show_bug.cgi?id=79735
                // should the next line read: return -1; 
                throw new TimeoutException();
            }

            int result = read_serial(fd, buffer, offset, count);
            if (result == -1)
                ThrowIOException();
            return result;
        }

        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotSupportedException();
        }

        public override void SetLength(long value)
        {
            throw new NotSupportedException();
        }

		[DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int write_serial(int fd, byte[] buffer, int offset, int count, int timeout);

        public override void Write(byte[] buffer, int offset, int count)
        {
            CheckDisposed();
            if (buffer == null)
                throw new ArgumentNullException("buffer");

            if (offset < 0 || count < 0)
                throw new ArgumentOutOfRangeException();

            if (buffer.Length - offset < count)
                throw new ArgumentException("offset+count",
                                 "The size of the buffer is less than offset + count.");

            // FIXME: this reports every write error as timeout
            if (write_serial(fd, buffer, offset, count, write_timeout) < 0)
                throw new TimeoutException("The operation has timed-out");
        }

        protected override void Dispose(bool disposing)
        {
            if (disposed)
                return;

            disposed = true;
			if (close_serial (fd) != 0) 
			{
				//Don't do anything
			}
        }

        [DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int close_serial(int fd);

        public override void Close()
        {
            ((IDisposable)this).Dispose();
			
        }

        void IDisposable.Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        ~FrostedSerialPortStream()
        {
            Dispose(false);
        }

        void CheckDisposed()
        {
            if (disposed)
                throw new ObjectDisposedException(GetType().FullName);
        }

        

        public void SetAttributes(int baud_rate, Parity parity, int data_bits, StopBits sb, Handshake hs)
        {
			if (!SetFrostedAttributes(fd, baud_rate, parity, data_bits, sb, hs))
                ThrowIOException();
        }

        [DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int get_bytes_in_buffer(int fd, int input);

        public int BytesToRead
        {
            get
            {
                int result = get_bytes_in_buffer(fd, 1);
                if (result == -1)
                    ThrowIOException();
                return result;
            }
        }

        public int BytesToWrite
        {
            get
            {
                int result = get_bytes_in_buffer(fd, 0);
                if (result == -1)
                    ThrowIOException();
                return result;
            }
        }

        [DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int discard_buffer(int fd, bool inputBuffer);

        public void DiscardInBuffer()
        {
            if (discard_buffer(fd, true) != 0)
				ThrowIOException();
        }

        public void DiscardOutBuffer()
        {
            if (discard_buffer(fd, false) != 0)
                ThrowIOException();
        }

        [DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern SerialSignal get_signals(int fd, out int error);

        public SerialSignal GetSignals()
        {
            int error;
            SerialSignal signals = get_signals(fd, out error);
            if (error == -1)
                ThrowIOException();

            return signals;
        }

        [DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int set_signal(int fd, SerialSignal signal, bool value);

        public void SetSignal(SerialSignal signal, bool value)
        {
            if (signal < SerialSignal.Cd || signal > SerialSignal.Rts ||
                    signal == SerialSignal.Cd ||
                    signal == SerialSignal.Cts ||
                    signal == SerialSignal.Dsr)
                throw new Exception("Invalid internal value");

            if (set_signal(fd, signal, value) == -1)
                ThrowIOException();
        }

        [DllImport("FrostedSerialHelper", SetLastError = true)]
        static extern int breakprop(int fd);

        public void SetBreakState(bool value)
        {
            if (value)
                if (breakprop(fd) == -1)
                    ThrowIOException();
        }

        [DllImport("libc")]
        static extern IntPtr strerror(int errnum);

        static void ThrowIOException()
        {
            int errnum = Marshal.GetLastWin32Error();
            string error_message = Marshal.PtrToStringAnsi(strerror(errnum));

            throw new IOException(error_message);
        }

        [DllImport("FrostedSerialHelper")]
        static extern bool is_baud_rate_legal(int baud_rate);

        private void TryBaudRate(int baudRate)
        {
            if (!is_baud_rate_legal(baudRate))
            {
                // this kind of exception to be compatible with MSDN API
                throw new ArgumentOutOfRangeException("baudRate",
                    "Given baud rate is not supported on this platform.");
            }
        }
    }
}