#!/usr/bin/env python3

from time import time
from binascii import hexlify
import enum
import struct
import zlib
import sys

import serial
from cobs import cobs


class CtrlPacketTypes(enum.Enum):
    RESET = 1
    ACK = 2
    RETRANSMIT = 3

def unpack_head(fmt, data):
    split = struct.calcsize(fmt)
    return *struct.unpack(fmt, data[:split]), data[split:]

def ctrl_packet(ptype, pid=0):
    return cobs.encode(struct.pack('BB', ptype.value, pid)) + b'\0'

ctrl_reset = lambda: ctrl_packet(CtrlPacketTypes.RESET)
ctrl_ack = lambda pid: ctrl_packet(CtrlPacketTypes.ACK, pid)
ctrl_retransmit = lambda pid: ctrl_packet(CtrlPacketTypes.RETRANSMIT, pid)


ser = serial.Serial('/dev/serial/by-id/usb-Silicon_Labs_CP2102_USB_to_UART_Bridge_Controller_0001-if00-port0', 250000, timeout=1.0)
ser.write(b'foobar'*32)
sys.exit(0)

log = []
ser.flushInput()
ser.write(ctrl_reset())
ser.flushOutput()
for _ in range(100):
    #ser.write(cobs.encode(b'\x01\xff') + b'\0')
    data = ser.read_until(b'\0')
    if not data or data[-1] != 0x00:
        #print(f'{time():>7.3f} Timeout: resetting')
        #ser.write(cobs.encode(b'\x01\xff') + b'\0') # reset
        continue

    crc32, payload = unpack_head('I', cobs.decode(data[:-1]))
    pid, seq, data = unpack_head('xBH', payload)
    ser.write(ctrl_ack(pid))
    ser.flushOutput()

    # Calculate byte-wise CRC32
    #our_crc = zlib.crc32(bytes(b for x in payload for b in (0, 0, 0, x)))
    our_crc = 0
    #log.append((time(), seq, crc32, our_crc, pid, data))

for time, seq, crc32, our_crc, pid, data in log:
    print(f'{time:>7.3f} {seq:05d} {crc32:08x} {our_crc:08x} {pid} {hexlify(data).decode()}')