"""Helpers for listening to events."""
import functools as ft
from datetime import timedelta

from ..core import HomeAssistant, callback
from ..const import (
    ATTR_NOW, EVENT_STATE_CHANGED, EVENT_TIME_CHANGED, MATCH_ALL)
from ..util import dt as dt_util
from ..util.async import run_callback_threadsafe

# PyLint does not like the use of threaded_listener_factory
# pylint: disable=invalid-name


def threaded_listener_factory(async_factory):
    """Convert an async event helper to a threaded one."""
    @ft.wraps(async_factory)
    def factory(*args, **kwargs):
        """Call async event helper safely."""
        hass = args[0]

        if not isinstance(hass, HomeAssistant):
            raise TypeError('First parameter needs to be a hass instance')

        async_remove = run_callback_threadsafe(
            hass.loop, ft.partial(async_factory, *args, **kwargs)).result()

        def remove():
            """Threadsafe removal."""
            run_callback_threadsafe(hass.loop, async_remove).result()

        return remove

    return factory


@callback
def async_track_state_change(hass, entity_ids, action, from_state=None,
                             to_state=None):
    """Track specific state changes.

    entity_ids, from_state and to_state can be string or list.
    Use list to match multiple.

    Returns a function that can be called to remove the listener.

    Must be run within the event loop.
    """
    from_state = _process_state_match(from_state)
    to_state = _process_state_match(to_state)

    # Ensure it is a lowercase list with entity ids we want to match on
    if entity_ids == MATCH_ALL:
        pass
    elif isinstance(entity_ids, str):
        entity_ids = (entity_ids.lower(),)
    else:
        entity_ids = tuple(entity_id.lower() for entity_id in entity_ids)

    @callback
    def state_change_listener(event):
        """The listener that listens for specific state changes."""
        if entity_ids != MATCH_ALL and \
           event.data.get('entity_id') not in entity_ids:
            return

        if event.data.get('old_state') is not None:
            old_state = event.data['old_state'].state
        else:
            old_state = None

        if event.data.get('new_state') is not None:
            new_state = event.data['new_state'].state
        else:
            new_state = None

        if _matcher(old_state, from_state) and _matcher(new_state, to_state):
            hass.async_run_job(action, event.data.get('entity_id'),
                               event.data.get('old_state'),
                               event.data.get('new_state'))

    return hass.bus.async_listen(EVENT_STATE_CHANGED, state_change_listener)


track_state_change = threaded_listener_factory(async_track_state_change)


@callback
def async_track_template(hass, template, action, variables=None):
    """Add a listener that track state changes with template condition."""
    from . import condition

    # Local variable to keep track of if the action has already been triggered
    already_triggered = False

    @callback
    def template_condition_listener(entity_id, from_s, to_s):
        """Check if condition is correct and run action."""
        nonlocal already_triggered
        template_result = condition.async_template(hass, template, variables)

        # Check to see if template returns true
        if template_result and not already_triggered:
            already_triggered = True
            hass.async_run_job(action, entity_id, from_s, to_s)
        elif not template_result:
            already_triggered = False

    return async_track_state_change(
        hass, template.extract_entities(), template_condition_listener)


track_template = threaded_listener_factory(async_track_template)


@callback
def async_track_point_in_time(hass, action, point_in_time):
    """Add a listener that fires once after a specific point in time."""
    utc_point_in_time = dt_util.as_utc(point_in_time)

    @callback
    def utc_converter(utc_now):
        """Convert passed in UTC now to local now."""
        hass.async_run_job(action, dt_util.as_local(utc_now))

    return async_track_point_in_utc_time(hass, utc_converter,
                                         utc_point_in_time)


track_point_in_time = threaded_listener_factory(async_track_point_in_time)


@callback
def async_track_point_in_utc_time(hass, action, point_in_time):
    """Add a listener that fires once after a specific point in UTC time."""
    # Ensure point_in_time is UTC
    point_in_time = dt_util.as_utc(point_in_time)

    @callback
    def point_in_time_listener(event):
        """Listen for matching time_changed events."""
        now = event.data[ATTR_NOW]

        if now < point_in_time or hasattr(point_in_time_listener, 'run'):
            return

        # Set variable so that we will never run twice.
        # Because the event bus might have to wait till a thread comes
        # available to execute this listener it might occur that the
        # listener gets lined up twice to be executed. This will make
        # sure the second time it does nothing.
        point_in_time_listener.run = True
        async_unsub()

        hass.async_run_job(action, now)

    async_unsub = hass.bus.async_listen(EVENT_TIME_CHANGED,
                                        point_in_time_listener)

    return async_unsub


track_point_in_utc_time = threaded_listener_factory(
    async_track_point_in_utc_time)


@callback
def async_track_time_interval(hass, action, interval):
    """Add a listener that fires repetitively at every timedelta interval."""
    remove = None

    def next_interval():
        """Return the next interval."""
        return dt_util.utcnow() + interval

    @callback
    def interval_listener(now):
        """Called when when the interval has elapsed."""
        nonlocal remove
        remove = async_track_point_in_utc_time(
            hass, interval_listener, next_interval())
        hass.async_run_job(action, now)

    remove = async_track_point_in_utc_time(
        hass, interval_listener, next_interval())

    def remove_listener():
        """Remove interval listener."""
        remove()

    return remove_listener


track_time_interval = threaded_listener_factory(async_track_time_interval)


@callback
def async_track_sunrise(hass, action, offset=None):
    """Add a listener that will fire a specified offset from sunrise daily."""
    from homeassistant.components import sun
    offset = offset or timedelta()
    remove = None

    def next_rise():
        """Return the next sunrise."""
        next_time = sun.next_rising_utc(hass) + offset

        while next_time < dt_util.utcnow():
            next_time = next_time + timedelta(days=1)

        return next_time

    @callback
    def sunrise_automation_listener(now):
        """Called when it's time for action."""
        nonlocal remove
        remove = async_track_point_in_utc_time(
            hass, sunrise_automation_listener, next_rise())
        hass.async_run_job(action)

    remove = async_track_point_in_utc_time(
        hass, sunrise_automation_listener, next_rise())

    def remove_listener():
        """Remove sunset listener."""
        remove()

    return remove_listener


track_sunrise = threaded_listener_factory(async_track_sunrise)


@callback
def async_track_sunset(hass, action, offset=None):
    """Add a listener that will fire a specified offset from sunset daily."""
    from homeassistant.components import sun
    offset = offset or timedelta()
    remove = None

    def next_set():
        """Return next sunrise."""
        next_time = sun.next_setting_utc(hass) + offset

        while next_time < dt_util.utcnow():
            next_time = next_time + timedelta(days=1)

        return next_time

    @callback
    def sunset_automation_listener(now):
        """Called when it's time for action."""
        nonlocal remove
        remove = async_track_point_in_utc_time(
            hass, sunset_automation_listener, next_set())
        hass.async_run_job(action)

    remove = async_track_point_in_utc_time(
        hass, sunset_automation_listener, next_set())

    def remove_listener():
        """Remove sunset listener."""
        remove()

    return remove_listener


track_sunset = threaded_listener_factory(async_track_sunset)


@callback
def async_track_utc_time_change(hass, action, year=None, month=None, day=None,
                                hour=None, minute=None, second=None,
                                local=False):
    """Add a listener that will fire if time matches a pattern."""
    # We do not have to wrap the function with time pattern matching logic
    # if no pattern given
    if all(val is None for val in (year, month, day, hour, minute, second)):
        @callback
        def time_change_listener(event):
            """Fire every time event that comes in."""
            hass.async_run_job(action, event.data[ATTR_NOW])

        return hass.bus.async_listen(EVENT_TIME_CHANGED, time_change_listener)

    pmp = _process_time_match
    year, month, day = pmp(year), pmp(month), pmp(day)
    hour, minute, second = pmp(hour), pmp(minute), pmp(second)

    @callback
    def pattern_time_change_listener(event):
        """Listen for matching time_changed events."""
        now = event.data[ATTR_NOW]

        if local:
            now = dt_util.as_local(now)
        mat = _matcher

        # pylint: disable=too-many-boolean-expressions
        if mat(now.year, year) and \
           mat(now.month, month) and \
           mat(now.day, day) and \
           mat(now.hour, hour) and \
           mat(now.minute, minute) and \
           mat(now.second, second):

            hass.async_run_job(action, now)

    return hass.bus.async_listen(EVENT_TIME_CHANGED,
                                 pattern_time_change_listener)


track_utc_time_change = threaded_listener_factory(async_track_utc_time_change)


@callback
def async_track_time_change(hass, action, year=None, month=None, day=None,
                            hour=None, minute=None, second=None):
    """Add a listener that will fire if UTC time matches a pattern."""
    return async_track_utc_time_change(hass, action, year, month, day, hour,
                                       minute, second, local=True)


track_time_change = threaded_listener_factory(async_track_time_change)


def _process_state_match(parameter):
    """Wrap parameter in a tuple if it is not one and returns it."""
    if parameter is None or parameter == MATCH_ALL:
        return MATCH_ALL
    elif isinstance(parameter, str) or not hasattr(parameter, '__iter__'):
        return (parameter,)
    else:
        return tuple(parameter)


def _process_time_match(parameter):
    """Wrap parameter in a tuple if it is not one and returns it."""
    if parameter is None or parameter == MATCH_ALL:
        return MATCH_ALL
    elif isinstance(parameter, str) and parameter.startswith('/'):
        return parameter
    elif isinstance(parameter, str) or not hasattr(parameter, '__iter__'):
        return (parameter,)
    else:
        return tuple(parameter)


def _matcher(subject, pattern):
    """Return True if subject matches the pattern.

    Pattern is either a tuple of allowed subjects or a `MATCH_ALL`.
    """
    if isinstance(pattern, str) and pattern.startswith('/'):
        try:
            return subject % float(pattern.lstrip('/')) == 0
        except ValueError:
            return False

    return MATCH_ALL == pattern or subject in pattern
