#!/bin/python3

import argparse
import sys
import os

# Create a parser
parser = argparse.ArgumentParser(description='Patch a M10 firmware for specific frequenc.\nThis is for M10 based on MSP430F233.')
parser.add_argument('--verbose', action='store_true', help='Print the details', default=False)

# Lecture du binaire
subparsers = parser.add_subparsers()
p_readbin = subparsers.add_parser("readbin", help='Read the binary file')
p_readbin.add_argument('--input', type=str, help='Input file')
p_readbin.set_defaults(func="readbin")

# Ecriture du binaire
p_writebin = subparsers.add_parser("writebin", help='Write the binary file')
p_writebin.set_defaults(func="writebin")
p_writebin.add_argument('--input', type=str, help='Input file')
p_writebin.add_argument('--output', type=str, help='Output file')
p_writebin.add_argument('--frequency', type=int, help='Frequency in Hz')

args = parser.parse_args()
if not hasattr(args, 'func'):
  print('error: arguments are required\n'
        'use --help for more information',
        file=sys.stderr)
  sys.exit(os.EX_USAGE)

if args.func == "writebin" and args.verbose:
  print("Writing the binary file")
  print("File : " + args.input)
  print("Output : " + args.output)
  print("Frequency : " + str(args.frequency))

def hex_to_freq(hex_value):
  inverted_hex_value = hex(int(hex_value[4:6] + hex_value[2:4] + hex_value[0:2], 16))
  shifted_bin_value = bin(int(inverted_hex_value, 16) >> 2)
  if args.verbose:
    print("Binary value : \t\t" + bin(int(inverted_hex_value, 16)))
    print("Binary value shifted : \t" + str(shifted_bin_value))
  return int(shifted_bin_value, 2) / 512

# function to convert frequence to hex
# Coded on 20 bits in binary format.
def freq_to_hex(freq_base):
  freq=freq_base/1000
  if args.verbose:
    print("Frequency: " + str(freq) + "Hz")
    print("freq * 512 = " + str(freq*512))
    print("arrondu freq * 512 = " + str(int(freq*512)))
    print("binary : " + str(bin(int(freq*512))))
    print("binare + 01 : " + str(bin(int(freq*512)) + "01"))
    print("binary str : " + str(bin(int(freq*512)) + "01").replace("0b",""))

  value = str(hex(int(str(bin(int(freq*512)) + "01").replace("0b",""),2)))[2:]
  print("hex value calculated : 0x" + value)

  # invert the value
  # draft and dirty value flip-flop
  value1="0" + value[0:1]
  value2=value[1:3]
  value3=value[3:5]
  if args.verbose:
    print("value : " + value)
    print ("value1 : " + value1 + " value2 : " + value2 + " value3 : " + value3)
    print("hex value inverted : 0x" + value3 + value2 + value1)
  return value3 + value2 + value1

def write_output_line(line):
  # write the output line
  with open(args.output, 'a') as f_out:
    f_out.write(line)
    f_out.close()

def fix_checksum(line):
  print("Fixing the checksum")
  # calculate the checksum
  checksum = 0

  print("Checksum : \n" + line)
  byte1 = hex(int(line[1:3], 16))
  byte2 = hex(int(line[3:5], 16))
  byte3 = hex(int(line[5:7], 16))
  byte4 = hex(int(line[7:9], 16))
  byte5 = hex(int(line[9:11], 16))
  byte6 = hex(int(line[11:13], 16))
  byte7 = hex(int(line[13:15], 16))
  byte8 = hex(int(line[15:17], 16))
  byte9 = hex(int(line[17:19], 16))
  byte10 = hex(int(line[19:21], 16))
  byte11 = hex(int(line[21:23], 16))
  byte12 = hex(int(line[23:25], 16))
  byte13 = hex(int(line[25:27], 16))
  byte14 = hex(int(line[27:29], 16))
  byte15 = hex(int(line[29:31], 16))
  byte16 = hex(int(line[31:33], 16))
  byte17 = hex(int(line[33:35], 16))
  byte18 = hex(int(line[35:37], 16))
  byte19 = hex(int(line[37:39], 16))
  byte20 = hex(int(line[39:41], 16))

  # checksum intel hex format
  checksum = 0x100 - (int(byte1, 16) + int(byte2, 16) + int(byte3, 16) + int(byte4, 16) + int(byte5, 16) + int(byte6, 16) + int(byte7, 16) + int(byte8, 16) + int(byte9, 16) + int(byte10, 16) + int(byte11, 16) + int(byte12, 16) + int(byte13, 16) + int(byte14, 16) + int(byte15, 16) + int(byte16, 16) + int(byte17, 16) + int(byte18, 16) + int(byte19, 16) + int(byte20, 16)) % 0x100
  print("Checksum : " + str(hex(checksum)))

  return checksum


# check if the input file exists
try:
  with open(args.input, 'rb') as f:
    pass

except FileNotFoundError:
  print(f'Error: {args.input} does not exist')
  exit(1)

if args.func == "readbin":
  print("")
  print("Reading the frequency value for M10...")
  # print each line of the input file
  with open(args.input, 'rb') as f:
    for line in f:
      if ":10101000" in line.decode('utf-8'):
        if args.verbose:
          print("Found the frequency sequence in Hex Intel format : " + line.decode('utf-8')[9:15])
        print("Frequency read : " + str(hex_to_freq(line.decode('utf-8')[9:15])))
        exit(0)

if args.func == "writebin":
  if os.path.exists(args.output):
    os.remove(args.output)

  with open(args.output, 'wb') as f_new:
    f_new.close()


  print("Calculating the frequency "+ str(args.frequency) +"Hz value for M10...")

  # print each line of the input file
  with open(args.input, 'rb') as f_in:
    for line in f_in:
      if ":10101000" in line.decode('utf-8'):
        if args.verbose:
          print("Found the frequency line like this : " + str(line))
          print("Frequency sequence in Hex Intel format : " + line.decode('utf-8')[9:15])
        print("Actual frequency value : " + str(hex_to_freq(line.decode('utf-8')[9:15])) + "Hz")
        new_freq = freq_to_hex(args.frequency)
        print("New frequency value : " + str(args.frequency) + "Hz")

        # replace the frequency value
        new_line = line.decode('utf-8').replace(line.decode('utf-8')[9:15], new_freq).upper()
        print("New line : " + new_line)
        #replace two last bytes with the checksum
        new_line = new_line[0:41] + str(hex(fix_checksum(new_line)))[2:].upper() + "\n"
        print("New line with checksum : " + new_line)
        write_output_line(new_line)
        
      else:
        write_output_line(line.decode('utf-8'))
    f_in.close()