import atexit

from validitysensor.usb import usb
from validitysensor.tls import tls
from validitysensor.sensor import sensor
from validitysensor.sensor import reboot
from validitysensor.flash import read_tls_flash
from validitysensor.init_flash import init_flash
from validitysensor.upload_fwext import upload_fwext
from validitysensor.init_db import init_db

def close():
    if usb.dev is not None:
        # Send the reboot command before closing the device.
        # Without it the sensor seems to keep creating new TLS sessions and eventually runs out of memory.
        # The reboot command may fail if we're shutting down because the device is already gone.
        try:
            reboot()
        except RebootException:
            pass
        finally:
            usb.close()

def open_common():
    init_flash()
    usb.send_init()
    tls.parseTlsFlash(read_tls_flash())
    tls.open()
    upload_fwext()
    sensor.open()
    init_db()

    # We must register atexit only after we opened usb device, 
    # so that our atexit handler is called before pyusb's one and we can still talk to the device
    #
    # Don't attempt to autoreboot unless we finished initializing the sensor successfully.
    # Otherwise if there is a bug in initialization, we may end up in a loop constantly rebooting the device.
    atexit.register(close)

def open():
    usb.open()
    open_common()

def open_devpath(busnum, address):
    usb.open_devpath(busnum, address)
    open_common()