import os
import binascii


def _generate_data_bytes(boarduuid, mac0, mac1):
    data = bytearray()
    data += (2029785358).to_bytes(4, 'big')  # magicid --> 0x78FC110E
    data += bytearray([0, 0, 0, 0])  # crc32 = 0
    data += bytearray(boarduuid + "\0",
                      'ascii')  # uuid --> 'c0846c8a-5fa5-11ea-8576-f8b156ac62d7' and \0 at the end
    data += binascii.unhexlify(mac0.replace(':', ''))  # mac0 --> 'f8:b1:56:ac:62:d7'
    if mac1 is not None:
        data += binascii.unhexlify(mac1.replace(':', ''))  # mac1 --> 'f8:b1:56:ac:62:d7'
    else:
        data += bytearray([0, 0, 0, 0, 0, 0])  # mac1 --> 0:0:0:0:0:0
    # calculate crc
    crc = (binascii.crc32(data, 0)).to_bytes(4, 'big')
    data[4:8] = crc
    return data


def _generate_output_data(data_rx):
    boarduuid = data_rx[8:45].decode()
    mac0 = binascii.hexlify(data_rx[45:51]).decode()
    mac1 = binascii.hexlify(data_rx[51:57]).decode()
    smac0 = ':'.join(mac0[i:i + 2] for i in range(0, len(mac0), 2))
    smac1 = ':'.join(mac1[i:i + 2] for i in range(0, len(mac1), 2))
    eepromdata = "UUID:" + boarduuid + " MAC0:" + smac0 + " MAC1:" + smac1

    return eepromdata


# returns exitcode and data saved into eeprom
def flash_eeprom(eeprompath, boarduuid, mac0, mac1=None):
    print("Start programming Eeprom...")
    # check if eeprompath is correct
    if os.path.isfile(eeprompath):
        # create u-boot data struct
        data = _generate_data_bytes(boarduuid, mac0, mac1)
        # write into eeprom and read back
        f = open(eeprompath, "r+b")
        f.write(data)
        f.seek(0)
        data_rx = f.read(57)
        for i in range(57):
            if data_rx[i] != data[i]:
                print("Error while programming eeprom memory.")
                return 1, None
        print("Eeprom programmed succesfully.")
        # generated eeprom read data
        eepromdata = _generate_output_data(data_rx)
        return 0, eepromdata
    else:
        print("Eeprom memory not found.")
        return 1, None