//
// ================
// Shared Resources
// ================
//
// This class is a container for all shared resources that may be needed
// by the drivers served by the Local Server. 
//
// NOTES:
//
//	* ALL DECLARATIONS MUST BE STATIC HERE!! INSTANCES OF THIS CLASS MUST NEVER BE CREATED!
//
// Written by:	Bob Denny	29-May-2007
// Modified by Chris Rowland and Peter Simpson to hamdle multiple hardware devices March 2011
//

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Windows.Forms;
using ASCOM.Utilities;
using ASCOM.Utilities.Interfaces;

namespace ASCOM.Meade.net
{
    /// <summary>
    /// The resources shared by all drivers and devices, in this example it's a serial port with a shared SendMessage method
    /// an idea for locking the message and handling connecting is given.
    /// In reality extensive changes will probably be needed.
    /// Multiple drivers means that several applications connect to the same hardware device, aka a hub.
    /// Multiple devices means that there are more than one instance of the hardware, such as two focusers.
    /// In this case there needs to be multiple instances of the hardware connector, each with it's own connection count.
    /// </summary>
    public static class SharedResources
    {
        // object used for locking to prevent multiple drivers accessing common code at the same time
        private static readonly object LockObject = new object();

        // Shared serial port. This will allow multiple drivers to use one single serial port.
        private static ISerial _sSharedSerial; // Shared serial port

        //
        // Public access to shared resources
        //

        #region single serial port connector

        //
        // this region shows a way that a single serial port could be connected to by multiple 
        // drivers.
        //
        // Connected is used to handle the connections to the port.
        //
        // SendMessage is a way that messages could be sent to the hardware without
        // conflicts between different drivers.
        //
        // All this is for a single connection, multiple connections would need multiple ports
        // and a way to handle connecting and disconnection from them - see the
        // multi driver handling section for ideas.
        //

        /// <summary>
        /// Shared serial port. Do not directly access this method.
        /// </summary>
        public static ISerial SharedSerial
        {
            get => _sSharedSerial ?? (_sSharedSerial = new Serial());
            set => _sSharedSerial = value;
        }

        public static void SendBlind(string message)
        {
            lock (LockObject)
            {
                SharedSerial.ClearBuffers();
                SharedSerial.Transmit(message);
            }
        }

        /// <summary>
        /// Example of a shared SendMessage method, the lock
        /// prevents different drivers tripping over one another.
        /// It needs error handling and assumes that the message will be sent unchanged
        /// and that the reply will always be terminated by a "#" character.
        /// </summary>
        /// <param name="message"></param>
        /// <returns></returns>
        public static string SendString(string message)
        {
            lock (LockObject)
            {
                SharedSerial.ClearBuffers();
                SharedSerial.Transmit(message);
                return SharedSerial.ReceiveTerminated("#").TrimEnd('#');
            }
        }

        public static string SendChar(string message)
        {
            lock (LockObject)
            {
                SharedSerial.ClearBuffers();
                SharedSerial.Transmit(message);
                return SharedSerial.ReceiveCounted(1);
            }
        }

        public static string ReadTerminated()
        {
            lock (LockObject)
            {
                return SharedSerial.ReceiveTerminated("#");
            }
        }

        public static void ReadCharacters(int throwAwayCharacters)
        {
            lock (LockObject)
            {
                SharedSerial.ReceiveCounted(throwAwayCharacters);
            }
        }

        #endregion

        #region Profile

        private const string DriverId = "ASCOM.MeadeGeneric.Telescope";

        // Constants used for Profile persistence
        private const string ComPortProfileName = "COM Port";
        private const string TraceStateProfileName = "Trace Level";
        private const string GuideRateProfileName = "Guide Rate Arc Seconds Per Second";
        private const string PrecisionProfileName = "Precision";

        public static void WriteProfile(ProfileProperties profileProperties)
        {
            lock (LockObject)
            {
                using (Profile driverProfile = new Profile())
                {
                    driverProfile.DeviceType = "Telescope";
                    driverProfile.WriteValue(DriverId, TraceStateProfileName, profileProperties.TraceLogger.ToString());
                    driverProfile.WriteValue(DriverId, ComPortProfileName, profileProperties.ComPort);
                    driverProfile.WriteValue(DriverId, GuideRateProfileName, profileProperties.GuideRateArcSecondsPerSecond.ToString(CultureInfo.CurrentCulture));
                    driverProfile.WriteValue(DriverId, PrecisionProfileName, profileProperties.Precision);
                }
            }
        }

        private const string ComPortDefault = "COM1";
        private const string TraceStateDefault = "false";
        private const string GuideRateProfileNameDefault = "10.077939"; //67% of sidereal rate
        private const string PrecisionDefault = "Unchanged";

        public static ProfileProperties ReadProfile()
        {
            lock (LockObject)
            {
                ProfileProperties profileProperties = new ProfileProperties();
                using (Profile driverProfile = new Profile())
                {
                    driverProfile.DeviceType = "Telescope";
                    profileProperties.ComPort = driverProfile.GetValue(DriverId, ComPortProfileName, string.Empty, ComPortDefault);
                    profileProperties.TraceLogger = Convert.ToBoolean(driverProfile.GetValue(DriverId, TraceStateProfileName, string.Empty, TraceStateDefault));
                    profileProperties.GuideRateArcSecondsPerSecond = double.Parse(driverProfile.GetValue(DriverId, GuideRateProfileName, string.Empty, GuideRateProfileNameDefault));
                    profileProperties.Precision = driverProfile.GetValue(DriverId, PrecisionProfileName, string.Empty, PrecisionDefault);
                }

                return profileProperties;
            }
        }

        #endregion

        #region SetupDialog

        public static void SetupDialog()
        {
            var profileProperties = ReadProfile();

            using (SetupDialogForm f = new SetupDialogForm())
            {
                f.SetProfile(profileProperties);

                if (IsConnected())
                {
                    f.SetReadOnlyMode();
                }

                var result = f.ShowDialog();
                if (result == DialogResult.OK)
                {
                    profileProperties = f.GetProfile();

                    WriteProfile(profileProperties); // Persist device configuration values to the ASCOM Profile store
                }
            }
        }

        #endregion
        
        #region Multi Driver handling

        public static string ProductName { get; private set; } = string.Empty;
        public static string FirmwareVersion { get; private set; } = string.Empty;

        // this section illustrates how multiple drivers could be handled,
        // it's for drivers where multiple connections to the hardware can be made and ensures that the
        // hardware is only disconnected from when all the connected devices have disconnected.

        // It is NOT a complete solution!  This is to give ideas of what can - or should be done.
        //
        // An alternative would be to move the hardware control here, handle connecting and disconnecting,
        // and provide the device with a suitable connection to the hardware.
        //
        /// <summary>
        /// dictionary carrying device connections.
        /// The Key is the connection number that identifies the device, it could be the COM port name,
        /// USB ID or IP Address, the Value is the DeviceHardware class
        /// </summary>
        private static readonly Dictionary<string, DeviceHardware> ConnectedDevices = new Dictionary<string, DeviceHardware>();

        private static readonly Dictionary<string, DeviceHardware> ConnectedDeviceIds = new Dictionary<string, DeviceHardware>();


        /// <summary>
        /// This is called in the driver Connect(true) property,
        /// it add the device id to the list of devices if it's not there and increments the device count.
        /// </summary>
        /// <param name="deviceId"></param>
        /// <param name="driverId"></param>
        public static ConnectionInfo Connect(string deviceId, string driverId)
        {
            lock (LockObject)
            {
                if (!ConnectedDevices.ContainsKey(deviceId))
                    ConnectedDevices.Add(deviceId, new DeviceHardware());
                
                if (!ConnectedDeviceIds.ContainsKey(driverId))
                    ConnectedDeviceIds.Add(driverId, new DeviceHardware());

                if (deviceId == "Serial")
                {
                    if (ConnectedDevices[deviceId].Count == 0)
                    {
                        var profileProperties = ReadProfile();
                        SharedSerial.PortName = profileProperties.ComPort;
                        SharedSerial.DTREnable = false;
                        SharedSerial.RTSEnable = false;
                        SharedSerial.DataBits = 8;
                        SharedSerial.StopBits = SerialStopBits.One;
                        SharedSerial.Parity = SerialParity.None;
                        SharedSerial.Speed = SerialSpeed.ps9600;
                        SharedSerial.Handshake = SerialHandshake.None;
                        SharedSerial.Connected = true;

                        try
                        {
                            ProductName = SendString(":GVP#");
                            FirmwareVersion = SendString(":GVN#");
                        }
                        catch (TimeoutException)
                        {
                            ProductName = TelescopeList.LX200CLASSIC;
                            FirmwareVersion = "Unknown";
                        }

                        if (ProductName == ":GVP")
                        {
                            //This means that the serial port is looping back what's been sent, something is very wrong.
                            SharedSerial.Connected = false;

                            throw new Exception("Serial port is looping back data, something is wrong with the hardware.");
                        }
                    }
                }
                else
                    throw new ArgumentException($"deviceId {deviceId} not currently supported");

                ConnectedDevices[deviceId].Count++; // increment the value
                ConnectedDeviceIds[driverId].Count++; // increment the value

                return new ConnectionInfo
                {
                    //Connections = ConnectedDevices[deviceId].Count,
                    SameDevice = ConnectedDeviceIds[driverId].Count
                };
            }
        }

        public static void Disconnect(string deviceId, string driverId)
        {
            lock (LockObject)
            {
                if (ConnectedDevices.ContainsKey(deviceId))
                {
                    ConnectedDevices[deviceId].Count--;
                    if (ConnectedDevices[deviceId].Count <= 0)
                    {
                        ConnectedDevices.Remove(deviceId);
                        if (deviceId == "Serial")
                        {
                            SharedSerial.Connected = false;
                        }
                    }
                }

                if (ConnectedDeviceIds.ContainsKey(driverId))
                {
                    ConnectedDeviceIds[driverId].Count--;
                }
            }
        }

        private static bool IsConnected()
        {
            foreach (var device in ConnectedDevices)
            {
                if (device.Value.Count > 0)
                    return true;
            }

            return false;
        }

        #endregion

        public static void Lock(Action action)
        {
            lock (LockObject)
            {
                action();
            }
        }

        public static T Lock<T>(Func<T> func)
        {
            lock (LockObject)
            {
                return func();
            }
        }

        /// <summary>
        /// Skeleton of a hardware class, all this does is hold a count of the connections,
        /// in reality extra code will be needed to handle the hardware in some way
        /// </summary>
        private class DeviceHardware
        {
            internal int Count { set; get; }

            internal DeviceHardware()
            {
                Count = 0;
            }
        }
    }
}