"""Tracks devices by sending a ICMP echo request (ping)."""
import asyncio
from datetime import timedelta
from functools import partial
import logging
import subprocess
import sys

from icmplib import multiping
import voluptuous as vol

from homeassistant import const, util
from homeassistant.components.device_tracker import PLATFORM_SCHEMA
from homeassistant.components.device_tracker.const import (
    CONF_SCAN_INTERVAL,
    SCAN_INTERVAL,
    SOURCE_TYPE_ROUTER,
)
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.event import async_track_point_in_utc_time
from homeassistant.util.async_ import gather_with_concurrency
from homeassistant.util.process import kill_subprocess

from . import async_get_next_ping_id
from .const import DOMAIN, ICMP_TIMEOUT, PING_ATTEMPTS_COUNT, PING_PRIVS, PING_TIMEOUT

_LOGGER = logging.getLogger(__name__)

PARALLEL_UPDATES = 0
CONF_PING_COUNT = "count"
CONCURRENT_PING_LIMIT = 6

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {
        vol.Required(const.CONF_HOSTS): {cv.slug: cv.string},
        vol.Optional(CONF_PING_COUNT, default=1): cv.positive_int,
    }
)


class HostSubProcess:
    """Host object with ping detection."""

    def __init__(self, ip_address, dev_id, hass, config, privileged):
        """Initialize the Host pinger."""
        self.hass = hass
        self.ip_address = ip_address
        self.dev_id = dev_id
        self._count = config[CONF_PING_COUNT]
        if sys.platform == "win32":
            self._ping_cmd = ["ping", "-n", "1", "-w", "1000", ip_address]
        else:
            self._ping_cmd = ["ping", "-n", "-q", "-c1", "-W1", ip_address]

    def ping(self):
        """Send an ICMP echo request and return True if success."""
        with subprocess.Popen(
            self._ping_cmd, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL
        ) as pinger:
            try:
                pinger.communicate(timeout=1 + PING_TIMEOUT)
                return pinger.returncode == 0
            except subprocess.TimeoutExpired:
                kill_subprocess(pinger)
                return False

            except subprocess.CalledProcessError:
                return False

    def update(self) -> bool:
        """Update device state by sending one or more ping messages."""
        failed = 0
        while failed < self._count:  # check more times if host is unreachable
            if self.ping():
                return True
            failed += 1

        _LOGGER.debug("No response from %s failed=%d", self.ip_address, failed)
        return False


async def async_setup_scanner(hass, config, async_see, discovery_info=None):
    """Set up the Host objects and return the update function."""

    privileged = hass.data[DOMAIN][PING_PRIVS]
    ip_to_dev_id = {ip: dev_id for (dev_id, ip) in config[const.CONF_HOSTS].items()}
    interval = config.get(
        CONF_SCAN_INTERVAL,
        timedelta(seconds=len(ip_to_dev_id) * config[CONF_PING_COUNT]) + SCAN_INTERVAL,
    )
    _LOGGER.debug(
        "Started ping tracker with interval=%s on hosts: %s",
        interval,
        ",".join(ip_to_dev_id.keys()),
    )

    if privileged is None:
        hosts = [
            HostSubProcess(ip, dev_id, hass, config, privileged)
            for (dev_id, ip) in config[const.CONF_HOSTS].items()
        ]

        async def async_update(now):
            """Update all the hosts on every interval time."""
            results = await gather_with_concurrency(
                CONCURRENT_PING_LIMIT,
                *[hass.async_add_executor_job(host.update) for host in hosts],
            )
            await asyncio.gather(
                *[
                    async_see(dev_id=host.dev_id, source_type=SOURCE_TYPE_ROUTER)
                    for idx, host in enumerate(hosts)
                    if results[idx]
                ]
            )

    else:

        async def async_update(now):
            """Update all the hosts on every interval time."""
            responses = await hass.async_add_executor_job(
                partial(
                    multiping,
                    ip_to_dev_id.keys(),
                    count=PING_ATTEMPTS_COUNT,
                    timeout=ICMP_TIMEOUT,
                    privileged=privileged,
                    id=async_get_next_ping_id(hass, len(ip_to_dev_id)),
                )
            )
            _LOGGER.debug("Multiping responses: %s", responses)
            await asyncio.gather(
                *[
                    async_see(dev_id=dev_id, source_type=SOURCE_TYPE_ROUTER)
                    for idx, dev_id in enumerate(ip_to_dev_id.values())
                    if responses[idx].is_alive
                ]
            )

    async def _async_update_interval(now):
        try:
            await async_update(now)
        finally:
            if not hass.is_stopping:
                async_track_point_in_utc_time(
                    hass, _async_update_interval, util.dt.utcnow() + interval
                )

    await _async_update_interval(None)
    return True