# -*- coding: utf-8 -*-
"""
homeassistant.components.sensor.rpi_gpio
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allows to configure a binary state sensor using RPi GPIO.
Note: To use RPi GPIO, Home Assistant must be run as root.

sensor:
  platform: rpi_gpio
  pull_mode: "UP"
  value_high: "Active"
  value_low: "Inactive"
  ports:
    11: PIR Office
    12: PIR Bedroom

Variables:

pull_mode
*Optional
The internal pull to use (UP or DOWN). Default is UP.

value_high
*Optional
The value of the sensor when the port is HIGH. Default is "HIGH".

value_low
*Optional
The value of the sensor when the port is LOW. Default is "LOW".

bouncetime
*Optional
The time in milliseconds for port debouncing. Default is 50ms.

ports
*Required
An array specifying the GPIO ports to use and the name to use in the frontend.

"""

import logging
from homeassistant.helpers.entity import Entity
try:
    import RPi.GPIO as GPIO
except ImportError:
    GPIO = None
from homeassistant.const import (DEVICE_DEFAULT_NAME,
                                 EVENT_HOMEASSISTANT_START,
                                 EVENT_HOMEASSISTANT_STOP)

DEFAULT_PULL_MODE = "UP"
DEFAULT_VALUE_HIGH = "HIGH"
DEFAULT_VALUE_LOW = "LOW"
DEFAULT_BOUNCETIME = 50

REQUIREMENTS = ['RPi.GPIO>=0.5.11']
_LOGGER = logging.getLogger(__name__)


# pylint: disable=unused-argument
def setup_platform(hass, config, add_devices, discovery_info=None):
    """ Sets up the Raspberry PI GPIO ports. """
    if GPIO is None:
        _LOGGER.error('RPi.GPIO not available. rpi_gpio ports ignored.')
        return

    GPIO.setmode(GPIO.BCM)

    sensors = []
    pull_mode = config.get('pull_mode', DEFAULT_PULL_MODE)
    value_high = config.get('value_high', DEFAULT_VALUE_HIGH)
    value_low = config.get('value_low', DEFAULT_VALUE_LOW)
    bouncetime = config.get('bouncetime', DEFAULT_BOUNCETIME)
    ports = config.get('ports')
    for port_num, port_name in ports.items():
        sensors.append(RPiGPIOSensor(
            port_name, port_num, pull_mode,
            value_high, value_low, bouncetime))
    add_devices(sensors)

    def cleanup_gpio(event):
        """ Stuff to do before stop home assistant. """
        # pylint: disable=no-member
        GPIO.cleanup()

    def prepare_gpio(event):
        """ Stuff to do when home assistant starts. """
        hass.bus.listen_once(EVENT_HOMEASSISTANT_STOP, cleanup_gpio)

    hass.bus.listen_once(EVENT_HOMEASSISTANT_START, prepare_gpio)


class RPiGPIOSensor(Entity):
    """ Sets up the Raspberry PI GPIO ports. """
    def __init__(self, port_name, port_num, pull_mode,
                 value_high, value_low, bouncetime):
        self._name = port_name
        self._port = port_num
        self._pull = GPIO.PUD_DOWN if pull_mode=="DOWN" else GPIO.PUD_UP
        self._vhigh = value_high
        self._vlow = value_low
        self._bouncetime = bouncetime
        GPIO.setup(self._port, GPIO.IN, pull_up_down=self._pull)
        self._state = self._vhigh if GPIO.input(self._port) else self._vlow

        def edge_callback(channel):
            """ port changed state """
            self._state = self._vhigh if GPIO.input(channel) else self._vlow
            self.update_ha_state()

        GPIO.add_event_detect(
            self._port,
            GPIO.BOTH,
            callback=edge_callback,
            bouncetime=self._bouncetime)

    @property
    def should_poll(self):
        """ No polling needed """
        return False

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

    @property
    def state(self):
        """ Returns the state of the entity. """
        return self._state