"""Provides an HTTP API for mobile_app."""
import uuid
from typing import Dict

from aiohttp.web import Response, Request

from homeassistant.auth.util import generate_secret
from homeassistant.components.cloud import (async_create_cloudhook,
                                            async_remote_ui_url,
                                            CloudNotAvailable)
from homeassistant.components.http import HomeAssistantView
from homeassistant.components.http.data_validator import RequestDataValidator
from homeassistant.const import (HTTP_CREATED, CONF_WEBHOOK_ID)

from homeassistant.loader import get_component

from .const import (ATTR_APP_COMPONENT, ATTR_DEVICE_ID,
                    ATTR_SUPPORTS_ENCRYPTION, CONF_CLOUDHOOK_URL,
                    CONF_REMOTE_UI_URL, CONF_SECRET,
                    CONF_USER_ID, DOMAIN, ERR_INVALID_COMPONENT,
                    REGISTRATION_SCHEMA)

from .helpers import error_response, supports_encryption


class RegistrationsView(HomeAssistantView):
    """A view that accepts registration requests."""

    url = '/api/mobile_app/registrations'
    name = 'api:mobile_app:register'

    @RequestDataValidator(REGISTRATION_SCHEMA)
    async def post(self, request: Request, data: Dict) -> Response:
        """Handle the POST request for registration."""
        hass = request.app['hass']

        if ATTR_APP_COMPONENT in data:
            component = get_component(hass, data[ATTR_APP_COMPONENT])
            if component is None:
                fmt_str = "{} is not a valid component."
                msg = fmt_str.format(data[ATTR_APP_COMPONENT])
                return error_response(ERR_INVALID_COMPONENT, msg)

            if (hasattr(component, 'DEPENDENCIES') is False or
                    (hasattr(component, 'DEPENDENCIES') and
                     DOMAIN not in component.DEPENDENCIES)):
                fmt_str = "{} is not compatible with mobile_app."
                msg = fmt_str.format(data[ATTR_APP_COMPONENT])
                return error_response(ERR_INVALID_COMPONENT, msg)

        webhook_id = generate_secret()

        if hass.components.cloud.async_active_subscription():
            data[CONF_CLOUDHOOK_URL] = \
                await async_create_cloudhook(hass, webhook_id)

        data[ATTR_DEVICE_ID] = str(uuid.uuid4()).replace("-", "")

        data[CONF_WEBHOOK_ID] = webhook_id

        if data[ATTR_SUPPORTS_ENCRYPTION] and supports_encryption():
            from nacl.secret import SecretBox

            data[CONF_SECRET] = generate_secret(SecretBox.KEY_SIZE)

        data[CONF_USER_ID] = request['hass_user'].id

        ctx = {'source': 'registration'}
        await hass.async_create_task(
            hass.config_entries.flow.async_init(DOMAIN, context=ctx,
                                                data=data))

        remote_ui_url = None
        try:
            remote_ui_url = async_remote_ui_url(hass)
        except CloudNotAvailable:
            pass

        return self.json({
            CONF_CLOUDHOOK_URL: data.get(CONF_CLOUDHOOK_URL),
            CONF_REMOTE_UI_URL: remote_ui_url,
            CONF_SECRET: data.get(CONF_SECRET),
            CONF_WEBHOOK_ID: data[CONF_WEBHOOK_ID],
        }, status_code=HTTP_CREATED)