"""
APNS Notification platform.

For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/notify.apns/
"""
import logging
import os

import voluptuous as vol

from homeassistant.helpers.event import track_state_change
from homeassistant.config import load_yaml_config_file
from homeassistant.components.notify import (
    ATTR_TARGET, ATTR_DATA, BaseNotificationService, DOMAIN, PLATFORM_SCHEMA)
from homeassistant.const import CONF_NAME, CONF_PLATFORM, ATTR_NAME
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers import template as template_helper

REQUIREMENTS = ['apns2==0.3.0']

APNS_DEVICES = 'apns.yaml'
CONF_CERTFILE = 'cert_file'
CONF_TOPIC = 'topic'
CONF_SANDBOX = 'sandbox'
DEVICE_TRACKER_DOMAIN = 'device_tracker'
SERVICE_REGISTER = 'apns_register'

ATTR_PUSH_ID = 'push_id'

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
    vol.Required(CONF_PLATFORM): 'apns',
    vol.Required(CONF_NAME): cv.string,
    vol.Required(CONF_CERTFILE): cv.isfile,
    vol.Required(CONF_TOPIC): cv.string,
    vol.Optional(CONF_SANDBOX, default=False): cv.boolean,
})

REGISTER_SERVICE_SCHEMA = vol.Schema({
    vol.Required(ATTR_PUSH_ID): cv.string,
    vol.Optional(ATTR_NAME): cv.string,
})


def get_service(hass, config, discovery_info=None):
    """Return push service."""
    name = config.get(CONF_NAME)
    cert_file = config.get(CONF_CERTFILE)
    topic = config.get(CONF_TOPIC)
    sandbox = config.get(CONF_SANDBOX)

    service = ApnsNotificationService(hass, name, topic, sandbox, cert_file)
    hass.services.register(
        DOMAIN, 'apns_{}'.format(name), service.register,
        schema=REGISTER_SERVICE_SCHEMA)
    return service


class ApnsDevice:
    """
    The APNS Device class.

    Stores information about a device that is registered for push
    notifications.
    """

    def __init__(self, push_id, name, tracking_device_id=None, disabled=False):
        """Initialize APNS Device."""
        self.device_push_id = push_id
        self.device_name = name
        self.tracking_id = tracking_device_id
        self.device_disabled = disabled

    @property
    def push_id(self):
        """Return the  APNS id for the device."""
        return self.device_push_id

    @property
    def name(self):
        """Return the friendly name for the device."""
        return self.device_name

    @property
    def tracking_device_id(self):
        """
        Return the device Id.

        The id of a device that is tracked by the device
        tracking component.
        """
        return self.tracking_id

    @property
    def full_tracking_device_id(self):
        """
        Return the fully qualified device id.

        The full id of a device that is tracked by the device
        tracking component.
        """
        return '{}.{}'.format(DEVICE_TRACKER_DOMAIN, self.tracking_id)

    @property
    def disabled(self):
        """Return the state of the service."""
        return self.device_disabled

    def disable(self):
        """Disable the device from receiving notifications."""
        self.device_disabled = True

    def __eq__(self, other):
        """Return the comparison."""
        if isinstance(other, self.__class__):
            return self.push_id == other.push_id and self.name == other.name
        return NotImplemented

    def __ne__(self, other):
        """Return the comparison."""
        return not self.__eq__(other)


def _write_device(out, device):
    """Write a single device to file."""
    attributes = []
    if device.name is not None:
        attributes.append(
            'name: {}'.format(device.name))
    if device.tracking_device_id is not None:
        attributes.append(
            'tracking_device_id: {}'.format(device.tracking_device_id))
    if device.disabled:
        attributes.append('disabled: True')

    out.write(device.push_id)
    out.write(": {")
    if attributes:
        separator = ", "
        out.write(separator.join(attributes))

    out.write("}\n")


class ApnsNotificationService(BaseNotificationService):
    """Implement the notification service for the APNS service."""

    def __init__(self, hass, app_name, topic, sandbox, cert_file):
        """Initialize APNS application."""
        self.hass = hass
        self.app_name = app_name
        self.sandbox = sandbox
        self.certificate = cert_file
        self.yaml_path = hass.config.path(app_name + '_' + APNS_DEVICES)
        self.devices = {}
        self.device_states = {}
        self.topic = topic
        if os.path.isfile(self.yaml_path):
            self.devices = {
                str(key): ApnsDevice(
                    str(key),
                    value.get('name'),
                    value.get('tracking_device_id'),
                    value.get('disabled', False)
                )
                for (key, value) in
                load_yaml_config_file(self.yaml_path).items()
            }

        tracking_ids = [
            device.full_tracking_device_id
            for (key, device) in self.devices.items()
            if device.tracking_device_id is not None
        ]
        track_state_change(
            hass, tracking_ids, self.device_state_changed_listener)

    def device_state_changed_listener(self, entity_id, from_s, to_s):
        """
        Listen for sate change.

        Track device state change if a device has a tracking id specified.
        """
        self.device_states[entity_id] = str(to_s.state)

    def write_devices(self):
        """Write all known devices to file."""
        with open(self.yaml_path, 'w+') as out:
            for _, device in self.devices.items():
                _write_device(out, device)

    def register(self, call):
        """Register a device to receive push messages."""
        push_id = call.data.get(ATTR_PUSH_ID)

        device_name = call.data.get(ATTR_NAME)
        current_device = self.devices.get(push_id)
        current_tracking_id = None if current_device is None \
            else current_device.tracking_device_id

        device = ApnsDevice(push_id, device_name, current_tracking_id)

        if current_device is None:
            self.devices[push_id] = device
            with open(self.yaml_path, 'a') as out:
                _write_device(out, device)
            return True

        if device != current_device:
            self.devices[push_id] = device
            self.write_devices()

        return True

    def send_message(self, message=None, **kwargs):
        """Send push message to registered devices."""
        from apns2.client import APNsClient
        from apns2.payload import Payload
        from apns2.errors import Unregistered

        apns = APNsClient(
            self.certificate,
            use_sandbox=self.sandbox,
            use_alternative_port=False)

        device_state = kwargs.get(ATTR_TARGET)
        message_data = kwargs.get(ATTR_DATA)

        if message_data is None:
            message_data = {}

        if isinstance(message, str):
            rendered_message = message
        elif isinstance(message, template_helper.Template):
            rendered_message = message.render()
        else:
            rendered_message = ''

        payload = Payload(
            alert=rendered_message,
            badge=message_data.get('badge'),
            sound=message_data.get('sound'),
            category=message_data.get('category'),
            custom=message_data.get('custom', {}),
            content_available=message_data.get('content_available', False))

        device_update = False

        for push_id, device in self.devices.items():
            if not device.disabled:
                state = None
                if device.tracking_device_id is not None:
                    state = self.device_states.get(
                        device.full_tracking_device_id)

                if device_state is None or state == str(device_state):
                    try:
                        apns.send_notification(
                            push_id, payload, topic=self.topic)
                    except Unregistered:
                        logging.error("Device %s has unregistered", push_id)
                        device_update = True
                        device.disable()

        if device_update:
            self.write_devices()

        return True