"""Config flow to configure the Ambient PWS component."""
import voluptuous as vol

from homeassistant import config_entries
from homeassistant.const import CONF_API_KEY
from homeassistant.core import callback
from homeassistant.helpers import aiohttp_client

from .const import CONF_APP_KEY, DOMAIN


@callback
def configured_instances(hass):
    """Return a set of configured Ambient PWS instances."""
    return set(
        entry.data[CONF_APP_KEY]
        for entry in hass.config_entries.async_entries(DOMAIN))


@config_entries.HANDLERS.register(DOMAIN)
class AmbientStationFlowHandler(config_entries.ConfigFlow):
    """Handle an Ambient PWS config flow."""

    VERSION = 1
    CONNECTION_CLASS = config_entries.CONN_CLASS_CLOUD_PUSH

    async def _show_form(self, errors=None):
        """Show the form to the user."""
        data_schema = vol.Schema({
            vol.Required(CONF_API_KEY): str,
            vol.Required(CONF_APP_KEY): str,
        })

        return self.async_show_form(
            step_id='user',
            data_schema=data_schema,
            errors=errors if errors else {},
        )

    async def async_step_import(self, import_config):
        """Import a config entry from configuration.yaml."""
        return await self.async_step_user(import_config)

    async def async_step_user(self, user_input=None):
        """Handle the start of the config flow."""
        from aioambient import Client
        from aioambient.errors import AmbientError

        if not user_input:
            return await self._show_form()

        if user_input[CONF_APP_KEY] in configured_instances(self.hass):
            return await self._show_form({CONF_APP_KEY: 'identifier_exists'})

        session = aiohttp_client.async_get_clientsession(self.hass)
        client = Client(
            user_input[CONF_API_KEY], user_input[CONF_APP_KEY], session)

        try:
            devices = await client.api.get_devices()
        except AmbientError:
            return await self._show_form({'base': 'invalid_key'})

        if not devices:
            return await self._show_form({'base': 'no_devices'})

        # The Application Key (which identifies each config entry) is too long
        # to show nicely in the UI, so we take the first 12 characters (similar
        # to how GitHub does it):
        return self.async_create_entry(
            title=user_input[CONF_APP_KEY][:12], data=user_input)