"""Config flow for DSMR integration."""
from __future__ import annotations

import asyncio
from functools import partial
import logging
import os
from typing import Any

from async_timeout import timeout
from dsmr_parser import obis_references as obis_ref
from dsmr_parser.clients.protocol import create_dsmr_reader, create_tcp_dsmr_reader
import serial
import serial.tools.list_ports
import voluptuous as vol

from homeassistant import config_entries, core, exceptions
from homeassistant.const import CONF_HOST, CONF_PORT, CONF_TYPE
from homeassistant.core import callback

from .const import (
    CONF_DSMR_VERSION,
    CONF_SERIAL_ID,
    CONF_SERIAL_ID_GAS,
    CONF_TIME_BETWEEN_UPDATE,
    DEFAULT_TIME_BETWEEN_UPDATE,
    DOMAIN,
)

_LOGGER = logging.getLogger(__name__)

CONF_MANUAL_PATH = "Enter Manually"


class DSMRConnection:
    """Test the connection to DSMR and receive telegram to read serial ids."""

    def __init__(self, host, port, dsmr_version):
        """Initialize."""
        self._host = host
        self._port = port
        self._dsmr_version = dsmr_version
        self._telegram = {}
        if dsmr_version == "5L":
            self._equipment_identifier = obis_ref.LUXEMBOURG_EQUIPMENT_IDENTIFIER
        else:
            self._equipment_identifier = obis_ref.EQUIPMENT_IDENTIFIER

    def equipment_identifier(self):
        """Equipment identifier."""
        if self._equipment_identifier in self._telegram:
            dsmr_object = self._telegram[self._equipment_identifier]
            return getattr(dsmr_object, "value", None)

    def equipment_identifier_gas(self):
        """Equipment identifier gas."""
        if obis_ref.EQUIPMENT_IDENTIFIER_GAS in self._telegram:
            dsmr_object = self._telegram[obis_ref.EQUIPMENT_IDENTIFIER_GAS]
            return getattr(dsmr_object, "value", None)

    async def validate_connect(self, hass: core.HomeAssistant) -> bool:
        """Test if we can validate connection with the device."""

        def update_telegram(telegram):
            if self._equipment_identifier in telegram:
                self._telegram = telegram
                transport.close()

        if self._host is None:
            reader_factory = partial(
                create_dsmr_reader,
                self._port,
                self._dsmr_version,
                update_telegram,
                loop=hass.loop,
            )
        else:
            reader_factory = partial(
                create_tcp_dsmr_reader,
                self._host,
                self._port,
                self._dsmr_version,
                update_telegram,
                loop=hass.loop,
            )

        try:
            transport, protocol = await asyncio.create_task(reader_factory())
        except (serial.serialutil.SerialException, OSError):
            _LOGGER.exception("Error connecting to DSMR")
            return False

        if transport:
            try:
                async with timeout(30):
                    await protocol.wait_closed()
            except asyncio.TimeoutError:
                # Timeout (no data received), close transport and return True (if telegram is empty, will result in CannotCommunicate error)
                transport.close()
                await protocol.wait_closed()
        return True


async def _validate_dsmr_connection(hass: core.HomeAssistant, data):
    """Validate the user input allows us to connect."""
    conn = DSMRConnection(data.get(CONF_HOST), data[CONF_PORT], data[CONF_DSMR_VERSION])

    if not await conn.validate_connect(hass):
        raise CannotConnect

    equipment_identifier = conn.equipment_identifier()
    equipment_identifier_gas = conn.equipment_identifier_gas()

    # Check only for equipment identifier in case no gas meter is connected
    if equipment_identifier is None:
        raise CannotCommunicate

    info = {
        CONF_SERIAL_ID: equipment_identifier,
        CONF_SERIAL_ID_GAS: equipment_identifier_gas,
    }

    return info


class DSMRFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
    """Handle a config flow for DSMR."""

    VERSION = 1

    def __init__(self):
        """Initialize flow instance."""
        self._dsmr_version = None

    @staticmethod
    @callback
    def async_get_options_flow(config_entry):
        """Get the options flow for this handler."""
        return DSMROptionFlowHandler(config_entry)

    def _abort_if_host_port_configured(
        self,
        port: str,
        host: str = None,
        updates: dict[Any, Any] | None = None,
        reload_on_update: bool = True,
    ):
        """Test if host and port are already configured."""
        for entry in self._async_current_entries():
            if entry.data.get(CONF_HOST) == host and entry.data[CONF_PORT] == port:
                if updates is not None:
                    changed = self.hass.config_entries.async_update_entry(
                        entry, data={**entry.data, **updates}
                    )
                    if (
                        changed
                        and reload_on_update
                        and entry.state
                        in (
                            config_entries.ConfigEntryState.LOADED,
                            config_entries.ConfigEntryState.SETUP_RETRY,
                        )
                    ):
                        self.hass.async_create_task(
                            self.hass.config_entries.async_reload(entry.entry_id)
                        )
                return self.async_abort(reason="already_configured")

        return None

    async def async_step_user(self, user_input=None):
        """Step when user initializes a integration."""
        errors = {}
        if user_input is not None:
            user_selection = user_input[CONF_TYPE]
            if user_selection == "Serial":
                return await self.async_step_setup_serial()

            return await self.async_step_setup_network()

        list_of_types = ["Serial", "Network"]

        schema = vol.Schema({vol.Required(CONF_TYPE): vol.In(list_of_types)})
        return self.async_show_form(step_id="user", data_schema=schema, errors=errors)

    async def async_step_setup_network(self, user_input=None):
        """Step when setting up network configuration."""
        errors = {}

        if user_input is not None:
            data = await self.async_validate_dsmr(user_input, errors)

            if not errors:
                return self.async_create_entry(
                    title=f"{data[CONF_HOST]}:{data[CONF_PORT]}", data=data
                )

        schema = vol.Schema(
            {
                vol.Required(CONF_HOST): str,
                vol.Required(CONF_PORT): int,
                vol.Required(CONF_DSMR_VERSION): vol.In(["2.2", "4", "5", "5B", "5L"]),
            }
        )
        return self.async_show_form(
            step_id="setup_network",
            data_schema=schema,
            errors=errors,
        )

    async def async_step_setup_serial(self, user_input=None):
        """Step when setting up serial configuration."""
        errors = {}

        if user_input is not None:
            user_selection = user_input[CONF_PORT]
            if user_selection == CONF_MANUAL_PATH:
                self._dsmr_version = user_input[CONF_DSMR_VERSION]
                return await self.async_step_setup_serial_manual_path()

            dev_path = await self.hass.async_add_executor_job(
                get_serial_by_id, user_selection
            )

            validate_data = {
                CONF_PORT: dev_path,
                CONF_DSMR_VERSION: user_input[CONF_DSMR_VERSION],
            }

            data = await self.async_validate_dsmr(validate_data, errors)

            if not errors:
                return self.async_create_entry(title=data[CONF_PORT], data=data)

        ports = await self.hass.async_add_executor_job(serial.tools.list_ports.comports)
        list_of_ports = {}
        for port in ports:
            list_of_ports[
                port.device
            ] = f"{port}, s/n: {port.serial_number or 'n/a'}" + (
                f" - {port.manufacturer}" if port.manufacturer else ""
            )
        list_of_ports[CONF_MANUAL_PATH] = CONF_MANUAL_PATH

        schema = vol.Schema(
            {
                vol.Required(CONF_PORT): vol.In(list_of_ports),
                vol.Required(CONF_DSMR_VERSION): vol.In(["2.2", "4", "5", "5B", "5L"]),
            }
        )
        return self.async_show_form(
            step_id="setup_serial",
            data_schema=schema,
            errors=errors,
        )

    async def async_step_setup_serial_manual_path(self, user_input=None):
        """Select path manually."""
        errors = {}

        if user_input is not None:
            validate_data = {
                CONF_PORT: user_input[CONF_PORT],
                CONF_DSMR_VERSION: self._dsmr_version,
            }

            data = await self.async_validate_dsmr(validate_data, errors)

            if not errors:
                return self.async_create_entry(title=data[CONF_PORT], data=data)

        schema = vol.Schema({vol.Required(CONF_PORT): str})
        return self.async_show_form(
            step_id="setup_serial_manual_path",
            data_schema=schema,
            errors=errors,
        )

    async def async_validate_dsmr(self, input_data, errors):
        """Validate dsmr connection and create data."""
        data = input_data

        try:
            info = await _validate_dsmr_connection(self.hass, data)

            data = {**data, **info}

            await self.async_set_unique_id(info[CONF_SERIAL_ID])
            self._abort_if_unique_id_configured()
        except CannotConnect:
            errors["base"] = "cannot_connect"
        except CannotCommunicate:
            errors["base"] = "cannot_communicate"

        return data

    async def async_step_import(self, import_config=None):
        """Handle the initial step."""
        host = import_config.get(CONF_HOST)
        port = import_config[CONF_PORT]

        status = self._abort_if_host_port_configured(port, host, import_config)
        if status is not None:
            return status

        try:
            info = await _validate_dsmr_connection(self.hass, import_config)
        except CannotConnect:
            return self.async_abort(reason="cannot_connect")
        except CannotCommunicate:
            return self.async_abort(reason="cannot_communicate")

        if host is not None:
            name = f"{host}:{port}"
        else:
            name = port

        data = {**import_config, **info}

        await self.async_set_unique_id(info[CONF_SERIAL_ID])
        self._abort_if_unique_id_configured(data)

        return self.async_create_entry(title=name, data=data)


class DSMROptionFlowHandler(config_entries.OptionsFlow):
    """Handle options."""

    def __init__(self, config_entry):
        """Initialize options flow."""
        self.config_entry = config_entry

    async def async_step_init(self, user_input=None):
        """Manage the options."""
        if user_input is not None:
            return self.async_create_entry(title="", data=user_input)

        return self.async_show_form(
            step_id="init",
            data_schema=vol.Schema(
                {
                    vol.Optional(
                        CONF_TIME_BETWEEN_UPDATE,
                        default=self.config_entry.options.get(
                            CONF_TIME_BETWEEN_UPDATE, DEFAULT_TIME_BETWEEN_UPDATE
                        ),
                    ): vol.All(vol.Coerce(int), vol.Range(min=0)),
                }
            ),
        )


def get_serial_by_id(dev_path: str) -> str:
    """Return a /dev/serial/by-id match for given device if available."""
    by_id = "/dev/serial/by-id"
    if not os.path.isdir(by_id):
        return dev_path

    for path in (entry.path for entry in os.scandir(by_id) if entry.is_symlink()):
        if os.path.realpath(path) == dev_path:
            return path
    return dev_path


class CannotConnect(exceptions.HomeAssistantError):
    """Error to indicate we cannot connect."""


class CannotCommunicate(exceptions.HomeAssistantError):
    """Error to indicate we cannot connect."""