Update auth document (#52)

* Update auth_auth_provider.md

* Update auth_auth_provider.md

* Create auth_auth_module.md

* Update en.json

* Update sidebars.json

* Update auth_auth_module.md

* Update auth_auth_provider.md

* Update auth_auth_module.md

* Update auth_auth_module.md

docs/auth_auth_module.md

@@ -0,0 +1,55 @@
+---
+title: "Multi-factor Authentication Modules"
+---
+
+Multi-factor Authentication Modules are used in conjunction with [Authentication Provider](auth_auth_provider.html) to provide a fully configurable authentication framework. Each MFA module may provide one multi-factor authentication function. User can enable mulitple mfa module, but can only select one module in login process.
+
+## Defining an mfa auth module
+
+> We currently only support built-in mfa auth modules. Support for custom auth modules might arrive in the future.
+
+Multi-facor Auth modules are defined in `homeassistant/auth/mfa_modules/<name of module>.py`. The auth module will need to provide an implementation of the `MultiFactorAuthModule` class.
+
+For an example of a fully implemented auth module, please see [insecure_example.py](https://github.com/home-assistant/home-assistant/blob/dev/homeassistant/auth/mfa_modules/insecure_example.py).
+
+Multi-factor Auth modules shall extend the following methods of `MultiFactorAuthModule` class.
+
+| method | Required | Description
+| ------ | -------- | -----------
+| `@property def input_schema(self)` | Yes | Return a schema defined the user input form.
+| `@property def setup_schema(self)` | No | Return a schema defined the setup input form.
+| `async def async_setup_user(self, user_id, setup_data)` | Yes | Set up user for use this auth module.
+| `async def async_depose_user(self, user_id)` | Yes | Remove user information from this auth module.
+| `async def async_is_user_setup(self, user_id)` | Yes | Return whether user is set up.
+| `async def async_validation(self, user_id, user_input)` | Yes | Given a user_id and user input, return valiidation result.
+
+## Workflow
+
+To use a MFA auth module, user has to be created first, then call `AuthManager.async_enable_user_mfa` to setup.
+
+> TODO: draw a diagram
+
+User == select auth provider ==> LoginFlow.init == input/validate username/password ==> LoginFlow.finish ==> if user enabled mfa ==> LoginFlow.select_mfa_module ==> LoginFlow.mfa == input/validate MFA code ==> LoginFlow.finish ==> Done
+
+## Configuration example
+
+```yaml
+# configuration.xml
+homeassistant:
+  auth_providers:
+    - type: homeassistant
+    - type: legacy_api_password
+  auth_mfa_modules:
+    - type: totp
+    - type: insecure_example
+      users: [{'user_id': 'a_32_bytes_length_user_id', 'pin': '123456'}]
+auth:        
+```
+
+In this example, user will first select from `homeassistant` or `legacy_api_password` auth provider. For `homeassistant` auth provider, user will first input username/password, if that user enabled both `totp` and `insecure_example`, then user need select one auth module, then input Google Authenticator code or input pin code base on the selection.
+
+> insecure_example is only for demo purpose, please do not use it in production.
+
+## Validation session
+
+Not like auth provider, auth module use session to manage the validation. After auth provider validated, mfa module will create a validation session, include an experiation time and user_id from auth provider validate result. Mutli-factor auth moudle will not only verify the user input, and also verify the session is not experied. The validatoin session data storges in login flow instance.

docs/auth_auth_provider.md

@@ -10,15 +10,33 @@ Once an authentication provider has confirmed the identity of a user, it will pa
 
 > We currently only support built-in auth providers. Support for custom auth providers might arrive in the future.
 
-Auth providers are defined in `homeassistant/auth_providers/<name of provider>.py`. The auth provider module will need to provide an implementation of the `AuthProvider` class and contain a credential flow. This flow is what asks user for information and validates it.
+Auth providers are defined in `homeassistant/auth/providers/<name of provider>.py`. The auth provider module will need to provide an implementation of the `AuthProvider` class and `LoginFlow` class, it is what asks user for information and validates it base on `data_entry_flow`.
 
 For an example of a fully implemented auth provider, please see [insecure_example.py](https://github.com/home-assistant/home-assistant/blob/dev/homeassistant/auth/providers/insecure_example.py).
 
-Auth providers can extend the following methods.
+Auth providers shall extend the following methods of `AuthProvider` class.
 
 | method | Required | Description
 | ------ | -------- | -----------
-| async def async_credential_flow(self) | Yes | Return an instance of the credential flow for a user to identify itself.
-| async def async_get_or_create_credentials(self, flow_result) | Yes | Given the result of a credential flow, return a credentials object. This can either be an existing one or a new one.
-| async def async_initialize(self) | No | Callback callled once before interacting with the auth provider for the first time.
+| async def async_login_flow(self) | Yes | Return an instance of the login flow for a user to identify itself.
+| async def async_get_or_create_credentials(self, flow_result) | Yes | Given the result of a login flow, return a credentials object. This can either be an existing one or a new one.
 | async def async_user_meta_for_credentials(credentials) | No | Callback called Home Assistant is going to create a user from a Credentials object. Can be used to populate extra fields for the user.
+
+Auth providers shall extend the following methods of `LoginFlow` class.
+
+| method | Required | Description
+| ------ | -------- | -----------
+| async def async_step_init(self, user_input=None) | Yes | Handle the login form, see more detail in below.
+
+## async_step_init of LoginFlow
+
+> We may change this inteface in near future.
+
+`LoginFlow` extends `data_entry_flow.FlowHandler`. The first step of data entry flow is hard coded as `init`, so each flow has to implement `async_step_init` method. The pattern of `async_step_init` likes following pseudo-code:
+
+```python
+async def async_step_init(self, user_input=None):
+    return self.async_show_form(step_id='init', data_schema='some schema to construct ui form') if user_input is None
+    return self.async_show_form(step_id='init', errors) if user_input is invalid
+    return await self.async_finish(username) if user_input is valid
+```

website/i18n/en.json

@@ -18,6 +18,7 @@
     "asyncio_working_with_async": "Working with Async",
     "auth_api": "Authentication API",
     "API": "API",
+    "auth_auth_module": "Authentication Modules",
     "auth_auth_provider": "Authentication Providers",
     "auth_index": "Authentication",
     "config_entries_config_flow_handler": "Config Flow Handlers",

website/sidebars.json

@@ -25,7 +25,8 @@
     "Authentication": [
       "auth_index",
       "auth_api",
-      "auth_auth_provider"
+      "auth_auth_provider",
+      "auth_auth_module"
     ],
     "Configuration.yaml": [
       "configuration_yaml_index"