core: Region selection for Tuya integration fails for non US region accounts. And getting "Invalid authentication"

The problem

Tuya integration doesn’t select REGION for uri based on country code, This causes “Invalid authentication” for non US accounts.

Environment

• Home Assistant Core release with the issue: homeassistant/raspberrypi3-homeassistant:2021.1.0
• Last working Home Assistant Core release (if known): homeassistant/raspberrypi3-homeassistant:2021.1.0
• Operating environment (OS/Container/Supervised/Core): raspberrypi3
• Integration causing this issue: Tuya
• Link to integration documentation on our website: https://www.home-assistant.io/integrations/tuya/

Traceback/Error logs

ipdb> s
> /srv/homeassistant/lib/python3.7/site-packages/tuyaha/tuyaapi.py(103)get_access_token()
    102         try:
--> 103             response = self._requestSession.post(
    104                 (TUYACLOUDURL + "/homeassistant/auth.do").format(SESSION.region),

ipdb> l 103
     98             self.discover_devices()
     99             return SESSION.devices
    100
    101     def get_access_token(self):
    102         try:
--> 103             response = self._requestSession.post(
    104                 (TUYACLOUDURL + "/homeassistant/auth.do").format(SESSION.region),
    105                 data={
    106                     "userName": SESSION.username,
    107                     "password": SESSION.password,
    108                     "countryCode": SESSION.countryCode,

ipdb> p SESSION.region
'us'

This causes to hit url https://px1.tuyaus.com/homeassistant/auth.do (US region url) instead of the right url https://px1.tuyaeu.com/homeassistant/auth.do (EU region url)

Additional information

The patch requires some way to manage region at tuyaha API, I have created an issue at their end as well. tuyaha/issues/68

In order to reproduce.

Smartlife App

• Install Smartlife app
• Signup and use the country as “United Arab Emirates”
• Lets say you signed up using “xyzab@mailinator.com” and password “Xyz123”
• Once you entered the verification code that you received at email account you will be signed in.
• Try signing out from the Smartlife app and Sign in again. It works very well.

Home Assistant

• Goto Configuration > Integrations > Add integration > Tuya
• Enter below configuration

username: xyzab@mailinator.com
password: Xyz123
countrycode: 971
app: smart life

• This will always show as “Invalid authentication” even though your password is correct.

Underlying problem

Ideally the URL for tuya should be intelligently selected based on country code. Or we should have a new column for REGION in the input. Lack of region selection causes to hit url https://px1.tuyaus.com/homeassistant/auth.do (US region url) instead of the right url https://px1.tuyaeu.com/homeassistant/auth.do (EU region url)

Work around

If you are desperately trying to connect your devices and you don’t have time to wait for the patch, Delete existing account in another country, create an account in country “United States”

Please note that If you have an account with apple integration / google integration, it might not work very well with home assistant integration