from serial import Serial
import struct

class ModbusRTU(object):

	#class for master querry
	class MasterQuerryClass(object):
		def __init__(self,data):
			self.SlaveAdress    =  data[0]
			self.Function       =  data[1]
			self.StartingAdress =  data[2] + data[3]
			self.NoRegisters    =  data[4] + data[5]
			self.ErrorCheck     =  data[6] + data[7]
			self.CorrectMessage = self.CRC(self.ErrorCheck,data[:-2])

	#class for a slave response
	class SlaveResponse(object):
		def __init__(data):
			self.SlaveAdress    =  data[0]
			self.Function       =  data[1]
			self.ByteCount      =  data[2]
			self.Data           =  data[2:self.ByteCount]
			self.ErrorCheck     =  data[sef.ByteCount+2:sef.ByteCount+4]
			self.CorrectMessage = CRC(self.ErrorCheck,data[:-2])

	def __init__(self):
		self.SlaveData      = []
		self.Connection     = [1]
		self.SlaveID        = [10]

	#Starts slave mode with preset settings
	def SlaveMode(self,ID):
		print("Slave mode initated")
		self.SlaveID = ID

		#if there is no connection object, it returns to command selection
		if self.Connection == "":
			print("No valid COM port specified, use 'scp' command to specify port")
			print("Press Enter to return to command selection")
			input()
			CommandHandler()

		print("Waiting for message")
		rawmessage = self.Connection.read(size = 8)		#reads the raw message
		print("message got")
		print(message)#debug

		message = self.MasterQuerryClass(message)       #constructs the message class

		print(message.SlaveAdress)#debug
		print(self.SlaveID)#debug

		#if the CRC is broken, it discards the message
		if  not message.CorrectMessage:
			print("Malformatted message")

		#if the ID is the slave's id the it proceeds
		if message.SlaveAdress == self.SlaveID:
			print("Modbus message recved")
			if SlaveData[0] == message.Function:
				serial.write(self.SlaveData[1])
			else:
				print("Unknown function")
		SlaveMode(self,ID)

	#friendly help screen
	def Help(self):
		print("scp port                                           : Set Communication Port, i.e COM3/COM4...")
		print("ssm slaveadress                                    : Set Slave mode, Turn on the slave mode with previously set function")
		print("smq slaveadress function startadress noregisters   : Send MasterQuerry, Sends a querry to the bus")
		print("asf functioncode data                              : Add Slave Function, adds a function to the slave")
		print("rsf functioncode                                   : Remove Slave Function, removes a slave function")
		print("Press Enter to return to command selection")
		input()
		self.CommandHandler()

	#sets a single slave function
	def SetSlaveFunction(self,command):
		command = command.split(" ")
		adress = int(command[1].strip()).to_bytes(1, byteorder='big')
		data   = int(command[2].strip()).to_bytes(int(len(command[2].strip())/2),byteorder='big')
		self.SlaveFunction = (adress, data)
		print(self.SlaveFunction)
		self.CommandHandler()

	def MasterQuerry(self,querry):

	# if there is no existing connection, it returns to selection screen
		if self.Connection == "":
			print("No valid COM port specified, use 'scp' command to specify port")
			print("Press Enter to return to command selection")
			input()
			self.CommandHandler()

		querry = querry.split(" ")		#splitting the querry to bytes
		querry = querry[1:]
		for byte in querry:
			try:
				print(struct.pack('<B',int(byte)))
				self.Connection.write(struct.pack('<B',int(byte)))

	#if the sending fails it returns to command selection
			except:
				print("Unable to send mondbus request")
				print("Press Enter to return to command selection")
				input()
				self.CommandHandler()
		self.CommandHandler()
	def CRC(CRC,Data):

		return True

	def SetCommPort(self,command):
		command = command.split(" ")
		print(command[1])
		try:
			self.Connection = Serial(port = command[1] , baudrate = 9600)
		except:
			print("Can't open port, use 'scp' to specify a valid port")
			print("No valid COM port specified, use 'scp' command to specify port")
			print("Press Enter to return to command selection")
			raise
		input()
		self.CommandHandler()


	def CommandHandler(self):
		print("Python RTU Modbus master/slave by Tamás Miseta")
		print("Specify a command, type 'help' for the list of avalible commands")
		command = input()
		print(command[:4])
		if command[:3] == "ssm":
			self.SlaveMode(command)
		if command[:3] == "smq":
			self.MasterQuerry(command)
		if command[:3] == "asf":
			self.SetSlaveFunction(command)
		if command[:3] == "scp":
			self.SetCommPort(command)
		if command[:4] == "help":
			self.Help()


ModbusConnection = ModbusRTU()
ModbusConnection.CommandHandler()