"""
Support Legacy API password auth provider.

It will be removed when auth system production ready
"""
import hmac
from typing import Any, Dict, Optional, cast

import voluptuous as vol

from homeassistant.components.http import HomeAssistantHTTP  # noqa: F401
from homeassistant.core import callback
from homeassistant.exceptions import HomeAssistantError

from . import AuthProvider, AUTH_PROVIDER_SCHEMA, AUTH_PROVIDERS, LoginFlow
from ..models import Credentials, UserMeta


USER_SCHEMA = vol.Schema({
    vol.Required('username'): str,
})


CONFIG_SCHEMA = AUTH_PROVIDER_SCHEMA.extend({
}, extra=vol.PREVENT_EXTRA)

LEGACY_USER_NAME = 'Legacy API password user'


class InvalidAuthError(HomeAssistantError):
    """Raised when submitting invalid authentication."""


@AUTH_PROVIDERS.register('legacy_api_password')
class LegacyApiPasswordAuthProvider(AuthProvider):
    """Example auth provider based on hardcoded usernames and passwords."""

    DEFAULT_TITLE = 'Legacy API Password'

    async def async_login_flow(self, context: Optional[Dict]) -> LoginFlow:
        """Return a flow to login."""
        return LegacyLoginFlow(self)

    @callback
    def async_validate_login(self, password: str) -> None:
        """Validate a username and password."""
        hass_http = getattr(self.hass, 'http', None)  # type: HomeAssistantHTTP

        if not hmac.compare_digest(hass_http.api_password.encode('utf-8'),
                                   password.encode('utf-8')):
            raise InvalidAuthError

    async def async_get_or_create_credentials(
            self, flow_result: Dict[str, str]) -> Credentials:
        """Return credentials for this login."""
        credentials = await self.async_credentials()
        if credentials:
            return credentials[0]

        return self.async_create_credentials({})

    async def async_user_meta_for_credentials(
            self, credentials: Credentials) -> UserMeta:
        """
        Return info for the user.

        Will be used to populate info when creating a new user.
        """
        return UserMeta(name=LEGACY_USER_NAME, is_active=True)


class LegacyLoginFlow(LoginFlow):
    """Handler for the login flow."""

    async def async_step_init(
            self, user_input: Optional[Dict[str, str]] = None) \
            -> Dict[str, Any]:
        """Handle the step of the form."""
        errors = {}

        hass_http = getattr(self.hass, 'http', None)
        if hass_http is None or not hass_http.api_password:
            return self.async_abort(
                reason='no_api_password_set'
            )

        if user_input is not None:
            try:
                cast(LegacyApiPasswordAuthProvider, self._auth_provider)\
                    .async_validate_login(user_input['password'])
            except InvalidAuthError:
                errors['base'] = 'invalid_auth'

            if not errors:
                return await self.async_finish({})

        return self.async_show_form(
            step_id='init',
            data_schema=vol.Schema({'password': str}),
            errors=errors,
        )