Add multi-factor authentication modules (#15489)

* Get user after login flow finished

* Add multi factor authentication support

* Typings

homeassistant/auth/mfa_modules/insecure_example.py

@@ -0,0 +1,82 @@
+"""Example auth module."""
+import logging
+from typing import Any, Dict, Optional
+
+import voluptuous as vol
+
+from homeassistant.core import HomeAssistant
+
+from . import MultiFactorAuthModule, MULTI_FACTOR_AUTH_MODULES, \
+    MULTI_FACTOR_AUTH_MODULE_SCHEMA
+
+CONFIG_SCHEMA = MULTI_FACTOR_AUTH_MODULE_SCHEMA.extend({
+    vol.Required('data'): [vol.Schema({
+        vol.Required('user_id'): str,
+        vol.Required('pin'): str,
+    })]
+}, extra=vol.PREVENT_EXTRA)
+
+_LOGGER = logging.getLogger(__name__)
+
+
+@MULTI_FACTOR_AUTH_MODULES.register('insecure_example')
+class InsecureExampleModule(MultiFactorAuthModule):
+    """Example auth module validate pin."""
+
+    DEFAULT_TITLE = 'Insecure Personal Identify Number'
+
+    def __init__(self, hass: HomeAssistant, config: Dict[str, Any]) -> None:
+        """Initialize the user data store."""
+        super().__init__(hass, config)
+        self._data = config['data']
+
+    @property
+    def input_schema(self) -> vol.Schema:
+        """Validate login flow input data."""
+        return vol.Schema({'pin': str})
+
+    @property
+    def setup_schema(self) -> Optional[vol.Schema]:
+        """Validate async_setup_user input data."""
+        return vol.Schema({'pin': str})
+
+    async def async_setup_user(self, user_id: str, setup_data: Any) -> None:
+        """Set up user to use mfa module."""
+        # data shall has been validate in caller
+        pin = setup_data['pin']
+
+        for data in self._data:
+            if data['user_id'] == user_id:
+                # already setup, override
+                data['pin'] = pin
+                return
+
+        self._data.append({'user_id': user_id, 'pin': pin})
+
+    async def async_depose_user(self, user_id: str) -> None:
+        """Remove user from mfa module."""
+        found = None
+        for data in self._data:
+            if data['user_id'] == user_id:
+                found = data
+                break
+        if found:
+            self._data.remove(found)
+
+    async def async_is_user_setup(self, user_id: str) -> bool:
+        """Return whether user is setup."""
+        for data in self._data:
+            if data['user_id'] == user_id:
+                return True
+        return False
+
+    async def async_validation(
+            self, user_id: str, user_input: Dict[str, Any]) -> bool:
+        """Return True if validation passed."""
+        for data in self._data:
+            if data['user_id'] == user_id:
+                # user_input has been validate in caller
+                if data['pin'] == user_input['pin']:
+                    return True
+
+        return False