from pymodbus.client import ModbusTcpClient
from pymodbus.exceptions import ModbusIOException
from pymodbus.register_read_message import ReadHoldingRegistersResponse, ReadInputRegistersResponse
from pymodbus.payload import BinaryPayloadBuilder, BinaryPayloadDecoder
from pymodbus.constants import Endian

from loguru import logger
import sys
import logging
from time import sleep


class LocalModbusException(Exception):
  def __init__(self, msg='', cause=None):
    super().__init__(self)
    self.msg = msg
    self.cause = cause
  
  def __str__(self):
    return f"LocalModbusException: Msg:{self.msg}, Cause:{self.cause}"

class ModbusHandler:
  def __init__(self, config):
    self.config = config['modbus']
    self.client = ModbusTcpClient(self.config['gateway'])
    self.client.connect()

    
  def readRegister(self, typ, slave, addr):
    if typ == 'input':
      return self.readInputRegister(slave, addr)
    elif typ == 'holding':
      return self.readHoldingRegister(slave, addr)
    else:
      raise LocalModbusException('unsupported read type')

  def readInputRegister(self, slave, addr):
    res = self.client.read_input_registers(addr, 2, slave=slave)
    if (isinstance(res, ReadInputRegistersResponse)):
      v = BinaryPayloadDecoder.fromRegisters(res.registers, byteorder=Endian.BIG, wordorder=Endian.BIG).decode_32bit_float()
      return v
    elif (isinstance(res, LocalModbusException)):
      msg = f"Error: {type(res)}, Content: {res}"
      logger.warning(msg)
      raise LocalModbusException(msg=msg, cause=res)
    else:
      msg = f"Unknown type: {type(res)}, Content: {res}"
      logger.warning(msg)
      raise LocalModbusException(msg=msg)

  def readHoldingRegister(self, slave, addr):
    res = self.client.read_holding_registers(addr, 2, slave=slave)
    if (isinstance(res, ReadHoldingRegistersResponse)):
      v = res.registers
      return v
    elif (isinstance(res, LocalModbusException)):
      msg = f"Error: {type(res)}, Content: {res}"
      logger.warning(msg)
      raise LocalModbusException(msg=msg, cause=res)
    else:
      msg = f"Unknown type: {type(res)}, Content: {res}"
      logger.warning(msg)
      raise LocalModbusException(msg=msg)

  def writeCoil(self, slave, addr, value):
    res = self.client.write_coil(addr, value, slave=slave)
    logger.debug(f"write coil result {res}")
    return value


#client = ModbusTcpClient("172.16.2.42")
#registers = [
#  { "addr":0x0046, "name":"Frequency", "unit":"Hz" },
#  { "addr":0x0048, "name":"Import active energy", "unit":"kWh" },
#  { "addr":0x004a, "name":"Export active energy", "unit":"kWh" },
#  { "addr":0x004c, "name":"Import reactive energy", "unit":"kvarh" },
#  { "addr":0x004e, "name":"Export reactive energy", "unit":"kvarh" },
#  { "addr":0x000c, "name":"Active power", "unit":"W" },
#  { "addr":0x0058, "name":"Positive power", "unit":"W" },
#  { "addr":0x005c, "name":"Reverse power", "unit":"W" },
#  { "addr":0x0000, "name":"Voltage", "unit":"V" },
#  { "addr":0x0006, "name":"Current", "unit":"A" }
#]
#
#
#cnt = 0
#coilState = True
#per = 2
#while True:
#  try:
#    for reg in registers:
#      v = readInputRegister(client, reg['addr'])
#      logger.info(f"{reg['name']}: {v} {reg['unit']}")
#
#    cnt += 1
#    if ((cnt == per) == 0):
#      cnt = 0
#      coilState = not coilState
#      per = 2 if coilState else 10
#      logger.info(f"Write {coilState} to coil")
#      writeCoil(client, 0, coilState)
#
#
#
#    sleep(2)
#  except Exception as e:
#    logger.error(f"Caught exception: {str(e)}")