"""Support for Modbus switches."""
from __future__ import annotations

from abc import ABC, abstractmethod
from datetime import timedelta
import logging
from typing import Any

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

from homeassistant.components.switch import PLATFORM_SCHEMA, SwitchEntity
from homeassistant.const import (
    CONF_ADDRESS,
    CONF_COMMAND_OFF,
    CONF_COMMAND_ON,
    CONF_NAME,
    CONF_SCAN_INTERVAL,
    CONF_SLAVE,
    CONF_SWITCHES,
    STATE_ON,
)
from homeassistant.core import HomeAssistant
from homeassistant.helpers import config_validation as cv
from homeassistant.helpers.event import async_track_time_interval
from homeassistant.helpers.restore_state import RestoreEntity
from homeassistant.helpers.typing import ConfigType

from .const import (
    CALL_TYPE_COIL,
    CALL_TYPE_REGISTER_HOLDING,
    CALL_TYPE_REGISTER_INPUT,
    CONF_COILS,
    CONF_HUB,
    CONF_INPUT_TYPE,
    CONF_REGISTER,
    CONF_REGISTER_TYPE,
    CONF_REGISTERS,
    CONF_STATE_OFF,
    CONF_STATE_ON,
    CONF_VERIFY_REGISTER,
    CONF_VERIFY_STATE,
    DEFAULT_HUB,
    DEFAULT_SCAN_INTERVAL,
    MODBUS_DOMAIN,
)
from .modbus import ModbusHub

_LOGGER = logging.getLogger(__name__)


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=CALL_TYPE_REGISTER_HOLDING): vol.In(
            [CALL_TYPE_REGISTER_HOLDING, CALL_TYPE_REGISTER_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(CALL_TYPE_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],
        }
    ),
)


async def async_setup_platform(
    hass: HomeAssistant, config: ConfigType, async_add_entities, discovery_info=None
):
    """Read configuration and create Modbus switches."""
    switches = []

    #  check for old config:
    if discovery_info is None:
        _LOGGER.warning(
            "Switch configuration is deprecated, will be removed in a future release"
        )
        discovery_info = {
            CONF_NAME: "no name",
            CONF_SWITCHES: [],
        }
        if CONF_COILS in config:
            discovery_info[CONF_SWITCHES].extend(config[CONF_COILS])
        if CONF_REGISTERS in config:
            discovery_info[CONF_SWITCHES].extend(config[CONF_REGISTERS])
        for entry in discovery_info[CONF_SWITCHES]:
            if CALL_TYPE_COIL in entry:
                entry[CONF_ADDRESS] = entry[CALL_TYPE_COIL]
                entry[CONF_INPUT_TYPE] = CALL_TYPE_COIL
                del entry[CALL_TYPE_COIL]
            if CONF_REGISTER in entry:
                entry[CONF_ADDRESS] = entry[CONF_REGISTER]
                del entry[CONF_REGISTER]
                if CONF_REGISTER_TYPE in entry:
                    entry[CONF_INPUT_TYPE] = entry[CONF_REGISTER_TYPE]
                    del entry[CONF_REGISTER_TYPE]
            if CONF_SCAN_INTERVAL not in entry:
                entry[CONF_SCAN_INTERVAL] = DEFAULT_SCAN_INTERVAL
        config = None

    for entry in discovery_info[CONF_SWITCHES]:
        if CONF_HUB in entry:
            # from old config!
            discovery_info[CONF_NAME] = entry[CONF_HUB]
        hub: ModbusHub = hass.data[MODBUS_DOMAIN][discovery_info[CONF_NAME]]
        if entry[CONF_INPUT_TYPE] == CALL_TYPE_COIL:
            switches.append(ModbusCoilSwitch(hub, entry))
        else:
            switches.append(ModbusRegisterSwitch(hub, entry))
    async_add_entities(switches)


class ModbusBaseSwitch(SwitchEntity, RestoreEntity, ABC):
    """Base class representing a Modbus switch."""

    def __init__(self, hub: ModbusHub, config: dict[str, Any]):
        """Initialize the switch."""
        self._hub: ModbusHub = hub
        self._name = config[CONF_NAME]
        self._slave = config.get(CONF_SLAVE)
        self._is_on = None
        self._available = True
        self._scan_interval = timedelta(seconds=config[CONF_SCAN_INTERVAL])

    async def async_added_to_hass(self):
        """Handle entity which will be added."""
        state = await self.async_get_last_state()
        if state:
            self._is_on = state.state == STATE_ON

        async_track_time_interval(
            self.hass, lambda arg: self._update(), self._scan_interval
        )

    @abstractmethod
    def _update(self):
        """Update the entity state."""

    @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 should_poll(self):
        """Return True if entity has to be polled for state.

        False if entity pushes its state to HA.
        """

        # Handle polling directly in this entity
        return False

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


class ModbusCoilSwitch(ModbusBaseSwitch, SwitchEntity):
    """Representation of a Modbus coil switch."""

    def __init__(self, hub: ModbusHub, config: dict[str, Any]):
        """Initialize the coil switch."""
        super().__init__(hub, config)
        self._coil = config[CONF_ADDRESS]

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

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

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

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

        if isinstance(result, (ModbusException, ExceptionResponse)):
            self._available = False
            return False

        self._available = True
        # bits[0] select the lowest bit in result,
        # is_on for a binary_sensor is true if the bit is 1
        # The other bits are not considered.
        return bool(result.bits[0] & 1)

    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._available = False
            return

        self._available = True


class ModbusRegisterSwitch(ModbusBaseSwitch, SwitchEntity):
    """Representation of a Modbus register switch."""

    def __init__(self, hub: ModbusHub, config: dict[str, Any]):
        """Initialize the register switch."""
        super().__init__(hub, config)
        self._register = config[CONF_ADDRESS]
        self._command_on = config[CONF_COMMAND_ON]
        self._command_off = config[CONF_COMMAND_OFF]
        self._state_on = config.get(CONF_STATE_ON, self._command_on)
        self._state_off = config.get(CONF_STATE_OFF, self._command_off)
        self._verify_state = config[CONF_VERIFY_STATE]
        self._verify_register = config.get(CONF_VERIFY_REGISTER, self._register)
        self._register_type = config[CONF_INPUT_TYPE]
        self._available = True
        self._is_on = None

    def turn_on(self, **kwargs):
        """Set switch on."""
        # Only holding register is writable
        if self._register_type == CALL_TYPE_REGISTER_HOLDING:
            self._write_register(self._command_on)
            if not self._verify_state:
                self._is_on = True
        self.schedule_update_ha_state()

    def turn_off(self, **kwargs):
        """Set switch off."""
        # Only holding register is writable
        if self._register_type == CALL_TYPE_REGISTER_HOLDING:
            self._write_register(self._command_off)
            if not self._verify_state:
                self._is_on = False
        self.schedule_update_ha_state()

    @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,
            )
        self.schedule_update_ha_state()

    def _read_register(self) -> int | None:
        try:
            if self._register_type == CALL_TYPE_REGISTER_INPUT:
                result = self._hub.read_input_registers(
                    self._slave, self._verify_register, 1
                )
            else:
                result = self._hub.read_holding_registers(
                    self._slave, self._verify_register, 1
                )
        except ConnectionException:
            self._available = False
            return

        if isinstance(result, (ModbusException, ExceptionResponse)):
            self._available = False
            return

        self._available = True

        return int(result.registers[0])

    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._available = False
            return

        self._available = True