using System;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Threading.Tasks;
using NModbus.Data;
using NModbus.Message;

namespace NModbus.Device
{
	/// <summary>
	///     Modbus master device.
	/// </summary>
	public abstract class ModbusMaster : ModbusDevice, IModbusMaster
	{
		protected ModbusMaster(IModbusTransport transport)
				: base(transport)
		{
		}

		/// <summary>
		///    Reads from 1 to 2000 contiguous coils status.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of coils to read.</param>
		/// <returns>Coils status.</returns>
		public bool[] ReadCoils(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 2000);

			var request = new ReadCoilsInputsRequest(
					ModbusFunctionCodes.ReadCoils,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadDiscretes(request);
		}

		/// <summary>
		///    Asynchronously reads from 1 to 2000 contiguous coils status.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of coils to read.</param>
		/// <returns>A task that represents the asynchronous read operation.</returns>
		public Task<bool[]> ReadCoilsAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 2000);

			var request = new ReadCoilsInputsRequest(
					ModbusFunctionCodes.ReadCoils,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadDiscretesAsync(request);
		}

		/// <summary>
		///    Reads from 1 to 2000 contiguous discrete input status.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of discrete inputs to read.</param>
		/// <returns>Discrete inputs status.</returns>
		public bool[] ReadInputs(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 2000);

			var request = new ReadCoilsInputsRequest(
					ModbusFunctionCodes.ReadInputs,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadDiscretes(request);
		}

		/// <summary>
		///    Asynchronously reads from 1 to 2000 contiguous discrete input status.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of discrete inputs to read.</param>
		/// <returns>A task that represents the asynchronous read operation.</returns>
		public Task<bool[]> ReadInputsAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 2000);

			var request = new ReadCoilsInputsRequest(
					ModbusFunctionCodes.ReadInputs,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadDiscretesAsync(request);
		}

		/// <summary>
		///    Reads contiguous block of holding registers.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of holding registers to read.</param>
		/// <returns>Holding registers status.</returns>
		public ushort[] ReadHoldingRegisters(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 125);

			var request = new ReadHoldingInputRegistersRequest(
					ModbusFunctionCodes.ReadHoldingRegisters,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadRegisters(request);
		}

		/// <summary>
		///    Asynchronously reads contiguous block of holding registers.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of holding registers to read.</param>
		/// <returns>A task that represents the asynchronous read operation.</returns>
		public Task<ushort[]> ReadHoldingRegistersAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 125);

			var request = new ReadHoldingInputRegistersRequest(
					ModbusFunctionCodes.ReadHoldingRegisters,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadRegistersAsync(request);
		}

		/// <summary>
		///    Reads contiguous block of input registers.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of holding registers to read.</param>
		/// <returns>Input registers status.</returns>
		public ushort[] ReadInputRegisters(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 125);

			var request = new ReadHoldingInputRegistersRequest(
					ModbusFunctionCodes.ReadInputRegisters,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadRegisters(request);
		}

		/// <summary>
		///    Asynchronously reads contiguous block of input registers.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startAddress">Address to begin reading.</param>
		/// <param name="numberOfPoints">Number of holding registers to read.</param>
		/// <returns>A task that represents the asynchronous read operation.</returns>
		public Task<ushort[]> ReadInputRegistersAsync(byte slaveAddress, ushort startAddress, ushort numberOfPoints)
		{
			ValidateNumberOfPoints("numberOfPoints", numberOfPoints, 125);

			var request = new ReadHoldingInputRegistersRequest(
					ModbusFunctionCodes.ReadInputRegisters,
					slaveAddress,
					startAddress,
					numberOfPoints);

			return PerformReadRegistersAsync(request);
		}

		/// <summary>
		///    Writes a single coil value.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="coilAddress">Address to write value to.</param>
		/// <param name="value">Value to write.</param>
		public void WriteSingleCoil(byte slaveAddress, ushort coilAddress, bool value)
		{
			var request = new WriteSingleCoilRequestResponse(slaveAddress, coilAddress, value);
			Transport.UnicastMessage<WriteSingleCoilRequestResponse>(request);
		}

		/// <summary>
		///    Asynchronously writes a single coil value.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="coilAddress">Address to write value to.</param>
		/// <param name="value">Value to write.</param>
		/// <returns>A task that represents the asynchronous write operation.</returns>
		public Task WriteSingleCoilAsync(byte slaveAddress, ushort coilAddress, bool value)
		{
			var request = new WriteSingleCoilRequestResponse(slaveAddress, coilAddress, value);
			return PerformWriteRequestAsync<WriteSingleCoilRequestResponse>(request);
		}

		/// <summary>
		///    Writes a single holding register.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="registerAddress">Address to write.</param>
		/// <param name="value">Value to write.</param>
		public void WriteSingleRegister(byte slaveAddress, ushort registerAddress, ushort value)
		{
			var request = new WriteSingleRegisterRequestResponse(
					slaveAddress,
					registerAddress,
					value);
			Transport.UnicastMessage<WriteSingleRegisterRequestResponse>(request);
		}

		/// <summary>
		///    Asynchronously writes a single holding register.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="registerAddress">Address to write.</param>
		/// <param name="value">Value to write.</param>
		/// <returns>A task that represents the asynchronous write operation.</returns>
		public Task WriteSingleRegisterAsync(byte slaveAddress, ushort registerAddress, ushort value)
		{
			var request = new WriteSingleRegisterRequestResponse(
					slaveAddress,
					registerAddress,
					value);

			return PerformWriteRequestAsync<WriteSingleRegisterRequestResponse>(request);
		}

		/// <summary>
		///     Write a block of 1 to 123 contiguous 16 bit holding registers.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="startAddress">Address to begin writing values.</param>
		/// <param name="data">Values to write.</param>
		public void WriteMultipleRegisters(byte slaveAddress, ushort startAddress, ushort[] data)
		{
			ValidateData("data", data, 123);

			var request = new WriteMultipleRegistersRequest(
					slaveAddress,
					startAddress,
					new RegisterCollection(data));

			Transport.UnicastMessage<WriteMultipleRegistersResponse>(request);
		}

		/// <summary>
		///    Asynchronously writes a block of 1 to 123 contiguous registers.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="startAddress">Address to begin writing values.</param>
		/// <param name="data">Values to write.</param>
		/// <returns>A task that represents the asynchronous write operation.</returns>
		public Task WriteMultipleRegistersAsync(byte slaveAddress, ushort startAddress, ushort[] data)
		{
			ValidateData("data", data, 123);

			var request = new WriteMultipleRegistersRequest(
					slaveAddress,
					startAddress,
					new RegisterCollection(data));

			return PerformWriteRequestAsync<WriteMultipleRegistersResponse>(request);
		}

		/// <summary>
		///    Writes a sequence of coils.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="startAddress">Address to begin writing values.</param>
		/// <param name="data">Values to write.</param>
		public void WriteMultipleCoils(byte slaveAddress, ushort startAddress, bool[] data)
		{
			ValidateData("data", data, 1968);

			var request = new WriteMultipleCoilsRequest(
					slaveAddress,
					startAddress,
					new DiscreteCollection(data));

			Transport.UnicastMessage<WriteMultipleCoilsResponse>(request);
		}

		/// <summary>
		///    Asynchronously writes a sequence of coils.
		/// </summary>
		/// <param name="slaveAddress">Address of the device to write to.</param>
		/// <param name="startAddress">Address to begin writing values.</param>
		/// <param name="data">Values to write.</param>
		/// <returns>A task that represents the asynchronous write operation.</returns>
		public Task WriteMultipleCoilsAsync(byte slaveAddress, ushort startAddress, bool[] data)
		{
			ValidateData("data", data, 1968);

			var request = new WriteMultipleCoilsRequest(
					slaveAddress,
					startAddress,
					new DiscreteCollection(data));

			return PerformWriteRequestAsync<WriteMultipleCoilsResponse>(request);
		}

		/// <summary>
		///    Performs a combination of one read operation and one write operation in a single Modbus transaction.
		///    The write operation is performed before the read.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startReadAddress">Address to begin reading (Holding registers are addressed starting at 0).</param>
		/// <param name="numberOfPointsToRead">Number of registers to read.</param>
		/// <param name="startWriteAddress">Address to begin writing (Holding registers are addressed starting at 0).</param>
		/// <param name="writeData">Register values to write.</param>
		public ushort[] ReadWriteMultipleRegisters(
				byte slaveAddress,
				ushort startReadAddress,
				ushort numberOfPointsToRead,
				ushort startWriteAddress,
				ushort[] writeData)
		{
			ValidateNumberOfPoints("numberOfPointsToRead", numberOfPointsToRead, 125);
			ValidateData("writeData", writeData, 121);

			var request = new ReadWriteMultipleRegistersRequest(
					slaveAddress,
					startReadAddress,
					numberOfPointsToRead,
					startWriteAddress,
					new RegisterCollection(writeData));

			return PerformReadRegisters(request);
		}

		/// <summary>
		///    Asynchronously performs a combination of one read operation and one write operation in a single Modbus transaction.
		///    The write operation is performed before the read.
		/// </summary>
		/// <param name="slaveAddress">Address of device to read values from.</param>
		/// <param name="startReadAddress">Address to begin reading (Holding registers are addressed starting at 0).</param>
		/// <param name="numberOfPointsToRead">Number of registers to read.</param>
		/// <param name="startWriteAddress">Address to begin writing (Holding registers are addressed starting at 0).</param>
		/// <param name="writeData">Register values to write.</param>
		/// <returns>A task that represents the asynchronous operation.</returns>
		public Task<ushort[]> ReadWriteMultipleRegistersAsync(
				byte slaveAddress,
				ushort startReadAddress,
				ushort numberOfPointsToRead,
				ushort startWriteAddress,
				ushort[] writeData)
		{
			ValidateNumberOfPoints("numberOfPointsToRead", numberOfPointsToRead, 125);
			ValidateData("writeData", writeData, 121);

			var request = new ReadWriteMultipleRegistersRequest(
					slaveAddress,
					startReadAddress,
					numberOfPointsToRead,
					startWriteAddress,
					new RegisterCollection(writeData));

			return PerformReadRegistersAsync(request);
		}

		/// <summary>
		/// Write a file record to the device.
		/// </summary>
		/// <param name="slaveAdress">Address of device to write values to</param>
		/// <param name="fileNumber">The Extended Memory file number</param>
		/// <param name="startingAddress">The starting register address within the file</param>
		/// <param name="data">The data to be written</param>
		public void WriteFileRecord(byte slaveAdress, ushort fileNumber, ushort startingAddress, byte[] data)
		{
			ValidateMaxData("data", data, 244);
			var request = new WriteFileRecordRequest(slaveAdress, new FileRecordCollection(
					fileNumber, startingAddress, data));

			Transport.UnicastMessage<WriteFileRecordResponse>(request);
		}

		/// <summary>
		///    Executes the custom message.
		/// </summary>
		/// <typeparam name="TResponse">The type of the response.</typeparam>
		/// <param name="request">The request.</param>
		[SuppressMessage("Microsoft.Design", "CA1004:GenericMethodsShouldProvideTypeParameter")]
		[SuppressMessage("Microsoft.Usage", "CA2223:MembersShouldDifferByMoreThanReturnType")]
		public TResponse ExecuteCustomMessage<TResponse>(IModbusMessage request)
				where TResponse : IModbusMessage, new()
		{
			return Transport.UnicastMessage<TResponse>(request);
		}

		private static void ValidateData<T>(string argumentName, T[] data, int maxDataLength)
		{
			if (data == null)
			{
				throw new ArgumentNullException(nameof(data));
			}

			if (data.Length == 0 || data.Length > maxDataLength)
			{
				string msg = $"The length of argument {argumentName} must be between 1 and {maxDataLength} inclusive.";
				throw new ArgumentException(msg);
			}
		}

		private static void ValidateMaxData<T>(string argumentName, T[] data, int maxDataLength)
		{
			if (data == null)
			{
				throw new ArgumentNullException(nameof(data));
			}

			if (data.Length > maxDataLength)
			{
				string msg = $"The length of argument {argumentName} must not be greater than {maxDataLength}.";
				throw new ArgumentException(msg);
			}
		}

		private static void ValidateNumberOfPoints(string argumentName, ushort numberOfPoints, ushort maxNumberOfPoints)
		{
			if (numberOfPoints < 1 || numberOfPoints > maxNumberOfPoints)
			{
				string msg = $"Argument {argumentName} must be between 1 and {maxNumberOfPoints} inclusive.";
				throw new ArgumentException(msg);
			}
		}

		private bool[] PerformReadDiscretes(ReadCoilsInputsRequest request)
		{
			ReadCoilsInputsResponse response = Transport.UnicastMessage<ReadCoilsInputsResponse>(request);
			return response.Data.Take(request.NumberOfPoints).ToArray();
		}

		private Task<bool[]> PerformReadDiscretesAsync(ReadCoilsInputsRequest request)
		{
			return Task.Factory.StartNew(() => PerformReadDiscretes(request));
		}

		private ushort[] PerformReadRegisters(ReadHoldingInputRegistersRequest request)
		{
			ReadHoldingInputRegistersResponse response =
					Transport.UnicastMessage<ReadHoldingInputRegistersResponse>(request);

			return response.Data.Take(request.NumberOfPoints).ToArray();
		}

		private Task<ushort[]> PerformReadRegistersAsync(ReadHoldingInputRegistersRequest request)
		{
			return Task.Factory.StartNew(() => PerformReadRegisters(request));
		}

		private ushort[] PerformReadRegisters(ReadWriteMultipleRegistersRequest request)
		{
			ReadHoldingInputRegistersResponse response =
					Transport.UnicastMessage<ReadHoldingInputRegistersResponse>(request);

			return response.Data.Take(request.ReadRequest.NumberOfPoints).ToArray();
		}

		private Task<ushort[]> PerformReadRegistersAsync(ReadWriteMultipleRegistersRequest request)
		{
			return Task.Factory.StartNew(() => PerformReadRegisters(request));
		}

		private Task PerformWriteRequestAsync<T>(IModbusMessage request)
				where T : IModbusMessage, new()
		{
			return Task.Factory.StartNew(() => Transport.UnicastMessage<T>(request));
		}
	}
}