"""
Support for the Fitbit API.

For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/sensor.fitbit/
"""
import os
import json
import logging
import datetime
import time

import voluptuous as vol

from homeassistant.core import callback
from homeassistant.components.http import HomeAssistantView
from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.helpers.entity import Entity
from homeassistant.loader import get_component
from homeassistant.util import Throttle
import homeassistant.helpers.config_validation as cv

REQUIREMENTS = ['fitbit==0.2.3']

_CONFIGURING = {}
_LOGGER = logging.getLogger(__name__)

ATTR_ACCESS_TOKEN = 'access_token'
ATTR_REFRESH_TOKEN = 'refresh_token'
ATTR_CLIENT_ID = 'client_id'
ATTR_CLIENT_SECRET = 'client_secret'
ATTR_LAST_SAVED_AT = 'last_saved_at'

CONF_MONITORED_RESOURCES = 'monitored_resources'

DEPENDENCIES = ['http']

FITBIT_AUTH_CALLBACK_PATH = '/auth/fitbit/callback'
FITBIT_AUTH_START = '/auth/fitbit'
FITBIT_CONFIG_FILE = 'fitbit.conf'
FITBIT_DEFAULT_RESOURCES = ['activities/steps']

ICON = 'mdi:walk'

MIN_TIME_BETWEEN_UPDATES = datetime.timedelta(minutes=30)

DEFAULT_CONFIG = {
    'client_id': 'CLIENT_ID_HERE',
    'client_secret': 'CLIENT_SECRET_HERE'
}

FITBIT_RESOURCES_LIST = {
    'activities/activityCalories': 'cal',
    'activities/calories': 'cal',
    'activities/caloriesBMR': 'cal',
    'activities/distance': '',
    'activities/elevation': '',
    'activities/floors': 'floors',
    'activities/heart': 'bpm',
    'activities/minutesFairlyActive': 'minutes',
    'activities/minutesLightlyActive': 'minutes',
    'activities/minutesSedentary': 'minutes',
    'activities/minutesVeryActive': 'minutes',
    'activities/steps': 'steps',
    'activities/tracker/activityCalories': 'cal',
    'activities/tracker/calories': 'cal',
    'activities/tracker/distance': '',
    'activities/tracker/elevation': '',
    'activities/tracker/floors': 'floors',
    'activities/tracker/minutesFairlyActive': 'minutes',
    'activities/tracker/minutesLightlyActive': 'minutes',
    'activities/tracker/minutesSedentary': 'minutes',
    'activities/tracker/minutesVeryActive': 'minutes',
    'activities/tracker/steps': 'steps',
    'body/bmi': 'BMI',
    'body/fat': '%',
    'sleep/awakeningsCount': 'times awaken',
    'sleep/efficiency': '%',
    'sleep/minutesAfterWakeup': 'minutes',
    'sleep/minutesAsleep': 'minutes',
    'sleep/minutesAwake': 'minutes',
    'sleep/minutesToFallAsleep': 'minutes',
    'sleep/startTime': 'start time',
    'sleep/timeInBed': 'time in bed',
    'body/weight': ''
}

FITBIT_MEASUREMENTS = {
    'en_US': {
        'duration': 'ms',
        'distance': 'mi',
        'elevation': 'ft',
        'height': 'in',
        'weight': 'lbs',
        'body': 'in',
        'liquids': 'fl. oz.',
        'blood glucose': 'mg/dL',
    },
    'en_GB': {
        'duration': 'milliseconds',
        'distance': 'kilometers',
        'elevation': 'meters',
        'height': 'centimeters',
        'weight': 'stone',
        'body': 'centimeters',
        'liquids': 'milliliters',
        'blood glucose': 'mmol/L'
    },
    'metric': {
        'duration': 'milliseconds',
        'distance': 'kilometers',
        'elevation': 'meters',
        'height': 'centimeters',
        'weight': 'kilograms',
        'body': 'centimeters',
        'liquids': 'milliliters',
        'blood glucose': 'mmol/L'
    }
}

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
    vol.Optional(CONF_MONITORED_RESOURCES, default=FITBIT_DEFAULT_RESOURCES):
        vol.All(cv.ensure_list, [vol.In(FITBIT_RESOURCES_LIST)]),
})


def config_from_file(filename, config=None):
    """Small configuration file management function."""
    if config:
        # We"re writing configuration
        try:
            with open(filename, 'w') as fdesc:
                fdesc.write(json.dumps(config))
        except IOError as error:
            _LOGGER.error("Saving config file failed: %s", error)
            return False
        return config
    else:
        # We"re reading config
        if os.path.isfile(filename):
            try:
                with open(filename, 'r') as fdesc:
                    return json.loads(fdesc.read())
            except IOError as error:
                _LOGGER.error("Reading config file failed: %s", error)
                # This won"t work yet
                return False
        else:
            return {}


def request_app_setup(hass, config, add_devices, config_path,
                      discovery_info=None):
    """Assist user with configuring the Fitbit dev application."""
    configurator = get_component('configurator')

    # pylint: disable=unused-argument
    def fitbit_configuration_callback(callback_data):
        """Handle configuration updates."""
        config_path = hass.config.path(FITBIT_CONFIG_FILE)
        if os.path.isfile(config_path):
            config_file = config_from_file(config_path)
            if config_file == DEFAULT_CONFIG:
                error_msg = ("You didn't correctly modify fitbit.conf",
                             " please try again")
                configurator.notify_errors(_CONFIGURING['fitbit'], error_msg)
            else:
                setup_platform(hass, config, add_devices, discovery_info)
        else:
            setup_platform(hass, config, add_devices, discovery_info)

    start_url = "{}{}".format(hass.config.api.base_url,
                              FITBIT_AUTH_CALLBACK_PATH)

    description = """Please create a Fitbit developer app at
                       https://dev.fitbit.com/apps/new.
                       For the OAuth 2.0 Application Type choose Personal.
                       Set the Callback URL to {}.
                       They will provide you a Client ID and secret.
                       These need to be saved into the file located at: {}.
                       Then come back here and hit the below button.
                       """.format(start_url, config_path)

    submit = "I have saved my Client ID and Client Secret into fitbit.conf."

    _CONFIGURING['fitbit'] = configurator.request_config(
        hass, 'Fitbit', fitbit_configuration_callback,
        description=description, submit_caption=submit,
        description_image="/static/images/config_fitbit_app.png"
    )


def request_oauth_completion(hass):
    """Request user complete Fitbit OAuth2 flow."""
    configurator = get_component('configurator')
    if "fitbit" in _CONFIGURING:
        configurator.notify_errors(
            _CONFIGURING['fitbit'], "Failed to register, please try again.")

        return

    # pylint: disable=unused-argument
    def fitbit_configuration_callback(callback_data):
        """Handle configuration updates."""

    start_url = '{}{}'.format(hass.config.api.base_url, FITBIT_AUTH_START)

    description = "Please authorize Fitbit by visiting {}".format(start_url)

    _CONFIGURING['fitbit'] = configurator.request_config(
        hass, 'Fitbit', fitbit_configuration_callback,
        description=description,
        submit_caption="I have authorized Fitbit."
    )


def setup_platform(hass, config, add_devices, discovery_info=None):
    """Set up the Fitbit sensor."""
    config_path = hass.config.path(FITBIT_CONFIG_FILE)
    if os.path.isfile(config_path):
        config_file = config_from_file(config_path)
        if config_file == DEFAULT_CONFIG:
            request_app_setup(
                hass, config, add_devices, config_path, discovery_info=None)
            return False
    else:
        config_file = config_from_file(config_path, DEFAULT_CONFIG)
        request_app_setup(
            hass, config, add_devices, config_path, discovery_info=None)
        return False

    if "fitbit" in _CONFIGURING:
        get_component('configurator').request_done(_CONFIGURING.pop("fitbit"))

    import fitbit

    access_token = config_file.get(ATTR_ACCESS_TOKEN)
    refresh_token = config_file.get(ATTR_REFRESH_TOKEN)
    if None not in (access_token, refresh_token):
        authd_client = fitbit.Fitbit(config_file.get(ATTR_CLIENT_ID),
                                     config_file.get(ATTR_CLIENT_SECRET),
                                     access_token=access_token,
                                     refresh_token=refresh_token)

        if int(time.time()) - config_file.get(ATTR_LAST_SAVED_AT, 0) > 3600:
            authd_client.client.refresh_token()

        authd_client.system = authd_client.user_profile_get()["user"]["locale"]
        if authd_client.system != 'en_GB':
            if hass.config.units.is_metric:
                authd_client.system = 'metric'
            else:
                authd_client.system = 'en_US'

        dev = []
        for resource in config.get(CONF_MONITORED_RESOURCES):
            dev.append(FitbitSensor(
                authd_client, config_path, resource,
                hass.config.units.is_metric))
        add_devices(dev)

    else:
        oauth = fitbit.api.FitbitOauth2Client(
            config_file.get(ATTR_CLIENT_ID),
            config_file.get(ATTR_CLIENT_SECRET))

        redirect_uri = '{}{}'.format(hass.config.api.base_url,
                                     FITBIT_AUTH_CALLBACK_PATH)

        fitbit_auth_start_url, _ = oauth.authorize_token_url(
            redirect_uri=redirect_uri,
            scope=['activity', 'heartrate', 'nutrition', 'profile',
                   'settings', 'sleep', 'weight'])

        hass.http.register_redirect(FITBIT_AUTH_START, fitbit_auth_start_url)
        hass.http.register_view(FitbitAuthCallbackView(
            config, add_devices, oauth))

        request_oauth_completion(hass)


class FitbitAuthCallbackView(HomeAssistantView):
    """Handle OAuth finish callback requests."""

    requires_auth = False
    url = '/auth/fitbit/callback'
    name = 'auth:fitbit:callback'

    def __init__(self, config, add_devices, oauth):
        """Initialize the OAuth callback view."""
        self.config = config
        self.add_devices = add_devices
        self.oauth = oauth

    @callback
    def get(self, request):
        """Finish OAuth callback request."""
        from oauthlib.oauth2.rfc6749.errors import MismatchingStateError
        from oauthlib.oauth2.rfc6749.errors import MissingTokenError

        hass = request.app['hass']
        data = request.query

        response_message = """Fitbit has been successfully authorized!
        You can close this window now!"""

        if data.get('code') is not None:
            redirect_uri = '{}{}'.format(
                hass.config.api.base_url, FITBIT_AUTH_CALLBACK_PATH)

            try:
                self.oauth.fetch_access_token(data.get('code'), redirect_uri)
            except MissingTokenError as error:
                _LOGGER.error("Missing token: %s", error)
                response_message = """Something went wrong when
                attempting authenticating with Fitbit. The error
                encountered was {}. Please try again!""".format(error)
            except MismatchingStateError as error:
                _LOGGER.error("Mismatched state, CSRF error: %s", error)
                response_message = """Something went wrong when
                attempting authenticating with Fitbit. The error
                encountered was {}. Please try again!""".format(error)
        else:
            _LOGGER.error("Unknown error when authing")
            response_message = """Something went wrong when
                attempting authenticating with Fitbit.
                An unknown error occurred. Please try again!
                """

        html_response = """<html><head><title>Fitbit Auth</title></head>
        <body><h1>{}</h1></body></html>""".format(response_message)

        config_contents = {
            ATTR_ACCESS_TOKEN: self.oauth.token['access_token'],
            ATTR_REFRESH_TOKEN: self.oauth.token['refresh_token'],
            ATTR_CLIENT_ID: self.oauth.client_id,
            ATTR_CLIENT_SECRET: self.oauth.client_secret
        }
        if not config_from_file(hass.config.path(FITBIT_CONFIG_FILE),
                                config_contents):
            _LOGGER.error("Failed to save config file")

        hass.async_add_job(setup_platform, hass, self.config, self.add_devices)

        return html_response


class FitbitSensor(Entity):
    """Implementation of a Fitbit sensor."""

    def __init__(self, client, config_path, resource_type, is_metric):
        """Initialize the Fitbit sensor."""
        self.client = client
        self.config_path = config_path
        self.resource_type = resource_type
        pretty_resource = self.resource_type.replace('activities/', '')
        pretty_resource = pretty_resource.replace('/', ' ')
        pretty_resource = pretty_resource.title()
        if pretty_resource == 'Body Bmi':
            pretty_resource = 'BMI'
        elif pretty_resource == 'Heart':
            pretty_resource = 'Resting Heart Rate'
        self._name = pretty_resource
        unit_type = FITBIT_RESOURCES_LIST[self.resource_type]
        if unit_type == "":
            split_resource = self.resource_type.split('/')
            try:
                measurement_system = FITBIT_MEASUREMENTS[self.client.system]
            except KeyError:
                if is_metric:
                    measurement_system = FITBIT_MEASUREMENTS['metric']
                else:
                    measurement_system = FITBIT_MEASUREMENTS['en_US']
            unit_type = measurement_system[split_resource[-1]]
        self._unit_of_measurement = unit_type
        self._state = 0
        self.update()

    @property
    def name(self):
        """Return the name of the sensor."""
        return self._name

    @property
    def state(self):
        """Return the state of the sensor."""
        return self._state

    @property
    def unit_of_measurement(self):
        """Return the unit of measurement of this entity, if any."""
        return self._unit_of_measurement

    @property
    def icon(self):
        """Icon to use in the frontend, if any."""
        return ICON

    @Throttle(MIN_TIME_BETWEEN_UPDATES)
    def update(self):
        """Get the latest data from the Fitbit API and update the states."""
        container = self.resource_type.replace("/", "-")
        response = self.client.time_series(self.resource_type, period='7d')
        self._state = response[container][-1].get('value')
        if self.resource_type == 'activities/heart':
            self._state = response[container][-1]. \
                    get('value').get('restingHeartRate')
        config_contents = {
            ATTR_ACCESS_TOKEN: self.client.client.token['access_token'],
            ATTR_REFRESH_TOKEN: self.client.client.token['refresh_token'],
            ATTR_CLIENT_ID: self.client.client.client_id,
            ATTR_CLIENT_SECRET: self.client.client.client_secret,
            ATTR_LAST_SAVED_AT: int(time.time())
        }
        if not config_from_file(self.config_path, config_contents):
            _LOGGER.error("Failed to save config file")