"""Support for Modbus switches."""
import logging
from typing import Optional

from pymodbus.exceptions import ConnectionException, ModbusException
from pymodbus.pdu import ExceptionResponse
import voluptuous as vol

from homeassistant.components.switch import PLATFORM_SCHEMA
from homeassistant.const import (
    CONF_COMMAND_OFF,
    CONF_COMMAND_ON,
    CONF_NAME,
    CONF_SLAVE,
    STATE_ON,
)
from homeassistant.helpers import config_validation as cv
from homeassistant.helpers.entity import ToggleEntity
from homeassistant.helpers.restore_state import RestoreEntity

from . import CONF_HUB, DEFAULT_HUB, DOMAIN as MODBUS_DOMAIN

_LOGGER = logging.getLogger(__name__)

CONF_COIL = "coil"
CONF_COILS = "coils"
CONF_REGISTER = "register"
CONF_REGISTER_TYPE = "register_type"
CONF_REGISTERS = "registers"
CONF_STATE_OFF = "state_off"
CONF_STATE_ON = "state_on"
CONF_VERIFY_REGISTER = "verify_register"
CONF_VERIFY_STATE = "verify_state"

DEFAULT_REGISTER_TYPE_HOLDING = "holding"
DEFAULT_REGISTER_TYPE_INPUT = "input"

REGISTERS_SCHEMA = vol.Schema(
    {
        vol.Required(CONF_COMMAND_OFF): cv.positive_int,
        vol.Required(CONF_COMMAND_ON): cv.positive_int,
        vol.Required(CONF_NAME): cv.string,
        vol.Required(CONF_REGISTER): cv.positive_int,
        vol.Optional(CONF_HUB, default=DEFAULT_HUB): cv.string,
        vol.Optional(CONF_REGISTER_TYPE, default=DEFAULT_REGISTER_TYPE_HOLDING): vol.In(
            [DEFAULT_REGISTER_TYPE_HOLDING, DEFAULT_REGISTER_TYPE_INPUT]
        ),
        vol.Optional(CONF_SLAVE): cv.positive_int,
        vol.Optional(CONF_STATE_OFF): cv.positive_int,
        vol.Optional(CONF_STATE_ON): cv.positive_int,
        vol.Optional(CONF_VERIFY_REGISTER): cv.positive_int,
        vol.Optional(CONF_VERIFY_STATE, default=True): cv.boolean,
    }
)

COILS_SCHEMA = vol.Schema(
    {
        vol.Required(CONF_COIL): cv.positive_int,
        vol.Required(CONF_NAME): cv.string,
        vol.Required(CONF_SLAVE): cv.positive_int,
        vol.Optional(CONF_HUB, default=DEFAULT_HUB): cv.string,
    }
)

PLATFORM_SCHEMA = vol.All(
    cv.has_at_least_one_key(CONF_COILS, CONF_REGISTERS),
    PLATFORM_SCHEMA.extend(
        {
            vol.Optional(CONF_COILS): [COILS_SCHEMA],
            vol.Optional(CONF_REGISTERS): [REGISTERS_SCHEMA],
        }
    ),
)


def setup_platform(hass, config, add_entities, discovery_info=None):
    """Read configuration and create Modbus devices."""
    switches = []
    if CONF_COILS in config:
        for coil in config[CONF_COILS]:
            hub_name = coil[CONF_HUB]
            hub = hass.data[MODBUS_DOMAIN][hub_name]
            switches.append(
                ModbusCoilSwitch(
                    hub, coil[CONF_NAME], coil[CONF_SLAVE], coil[CONF_COIL]
                )
            )
    if CONF_REGISTERS in config:
        for register in config[CONF_REGISTERS]:
            hub_name = register[CONF_HUB]
            hub = hass.data[MODBUS_DOMAIN][hub_name]

            switches.append(
                ModbusRegisterSwitch(
                    hub,
                    register[CONF_NAME],
                    register.get(CONF_SLAVE),
                    register[CONF_REGISTER],
                    register[CONF_COMMAND_ON],
                    register[CONF_COMMAND_OFF],
                    register[CONF_VERIFY_STATE],
                    register.get(CONF_VERIFY_REGISTER),
                    register[CONF_REGISTER_TYPE],
                    register.get(CONF_STATE_ON),
                    register.get(CONF_STATE_OFF),
                )
            )

    add_entities(switches)


class ModbusCoilSwitch(ToggleEntity, RestoreEntity):
    """Representation of a Modbus coil switch."""

    def __init__(self, hub, name, slave, coil):
        """Initialize the coil switch."""
        self._hub = hub
        self._name = name
        self._slave = int(slave) if slave else None
        self._coil = int(coil)
        self._is_on = None
        self._available = True

    async def async_added_to_hass(self):
        """Handle entity which will be added."""
        state = await self.async_get_last_state()
        if not state:
            return
        self._is_on = state.state == STATE_ON

    @property
    def is_on(self):
        """Return true if switch is on."""
        return self._is_on

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

    @property
    def available(self) -> bool:
        """Return True if entity is available."""
        return self._available

    def turn_on(self, **kwargs):
        """Set switch on."""
        self._write_coil(self._coil, True)

    def turn_off(self, **kwargs):
        """Set switch off."""
        self._write_coil(self._coil, False)

    def update(self):
        """Update the state of the switch."""
        self._is_on = self._read_coil(self._coil)

    def _read_coil(self, coil) -> Optional[bool]:
        """Read coil using the Modbus hub slave."""
        try:
            result = self._hub.read_coils(self._slave, coil, 1)
        except ConnectionException:
            self._set_unavailable()
            return

        if isinstance(result, (ModbusException, ExceptionResponse)):
            self._set_unavailable()
            return

        value = bool(result.bits[0])
        self._available = True

        return value

    def _write_coil(self, coil, value):
        """Write coil using the Modbus hub slave."""
        try:
            self._hub.write_coil(self._slave, coil, value)
        except ConnectionException:
            self._set_unavailable()
            return

        self._available = True

    def _set_unavailable(self):
        """Set unavailable state and log it as an error."""
        if not self._available:
            return

        _LOGGER.error(
            "No response from hub %s, slave %s, coil %s",
            self._hub.name,
            self._slave,
            self._coil,
        )
        self._available = False


class ModbusRegisterSwitch(ModbusCoilSwitch):
    """Representation of a Modbus register switch."""

    # pylint: disable=super-init-not-called
    def __init__(
        self,
        hub,
        name,
        slave,
        register,
        command_on,
        command_off,
        verify_state,
        verify_register,
        register_type,
        state_on,
        state_off,
    ):
        """Initialize the register switch."""
        self._hub = hub
        self._name = name
        self._slave = slave
        self._register = register
        self._command_on = command_on
        self._command_off = command_off
        self._verify_state = verify_state
        self._verify_register = verify_register if verify_register else self._register
        self._register_type = register_type
        self._available = True

        if state_on is not None:
            self._state_on = state_on
        else:
            self._state_on = self._command_on

        if state_off is not None:
            self._state_off = state_off
        else:
            self._state_off = self._command_off

        self._is_on = None

    def turn_on(self, **kwargs):
        """Set switch on."""

        # Only holding register is writable
        if self._register_type == DEFAULT_REGISTER_TYPE_HOLDING:
            self._write_register(self._command_on)
            if not self._verify_state:
                self._is_on = True

    def turn_off(self, **kwargs):
        """Set switch off."""

        # Only holding register is writable
        if self._register_type == DEFAULT_REGISTER_TYPE_HOLDING:
            self._write_register(self._command_off)
            if not self._verify_state:
                self._is_on = False

    @property
    def available(self) -> bool:
        """Return True if entity is available."""
        return self._available

    def update(self):
        """Update the state of the switch."""
        if not self._verify_state:
            return

        value = self._read_register()
        if value == self._state_on:
            self._is_on = True
        elif value == self._state_off:
            self._is_on = False
        elif value is not None:
            _LOGGER.error(
                "Unexpected response from hub %s, slave %s register %s, got 0x%2x",
                self._hub.name,
                self._slave,
                self._register,
                value,
            )

    def _read_register(self) -> Optional[int]:
        try:
            if self._register_type == DEFAULT_REGISTER_TYPE_INPUT:
                result = self._hub.read_input_registers(self._slave, self._register, 1)
            else:
                result = self._hub.read_holding_registers(
                    self._slave, self._register, 1
                )
        except ConnectionException:
            self._set_unavailable()
            return

        if isinstance(result, (ModbusException, ExceptionResponse)):
            self._set_unavailable()
            return

        value = int(result.registers[0])
        self._available = True

        return value

    def _write_register(self, value):
        """Write holding register using the Modbus hub slave."""
        try:
            self._hub.write_register(self._slave, self._register, value)
        except ConnectionException:
            self._set_unavailable()
            return

        self._available = True

    def _set_unavailable(self):
        """Set unavailable state and log it as an error."""
        if not self._available:
            return

        _LOGGER.error(
            "No response from hub %s, slave %s, register %s",
            self._hub.name,
            self._slave,
            self._register,
        )
        self._available = False