"""Support for MQTT discovery."""

from __future__ import annotations

import asyncio
from collections import deque
import functools
import logging
import re
import time
from typing import TYPE_CHECKING, Any

from homeassistant.config_entries import ConfigEntry
from homeassistant.const import CONF_DEVICE, CONF_PLATFORM
from homeassistant.core import HassJobType, HomeAssistant, callback
from homeassistant.data_entry_flow import FlowResultType
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.dispatcher import (
    async_dispatcher_connect,
    async_dispatcher_send,
)
from homeassistant.helpers.service_info.mqtt import MqttServiceInfo
from homeassistant.helpers.typing import DiscoveryInfoType
from homeassistant.loader import async_get_mqtt
from homeassistant.util.json import json_loads_object
from homeassistant.util.signal_type import SignalTypeFormat

from .. import mqtt
from .abbreviations import ABBREVIATIONS, DEVICE_ABBREVIATIONS, ORIGIN_ABBREVIATIONS
from .const import (
    ATTR_DISCOVERY_HASH,
    ATTR_DISCOVERY_PAYLOAD,
    ATTR_DISCOVERY_TOPIC,
    CONF_AVAILABILITY,
    CONF_ORIGIN,
    CONF_TOPIC,
    DOMAIN,
    SUPPORTED_COMPONENTS,
)
from .models import DATA_MQTT, MqttOriginInfo, ReceiveMessage
from .schemas import MQTT_ORIGIN_INFO_SCHEMA
from .util import async_forward_entry_setup_and_setup_discovery

ABBREVIATIONS_SET = set(ABBREVIATIONS)
DEVICE_ABBREVIATIONS_SET = set(DEVICE_ABBREVIATIONS)
ORIGIN_ABBREVIATIONS_SET = set(ORIGIN_ABBREVIATIONS)

_LOGGER = logging.getLogger(__name__)

TOPIC_MATCHER = re.compile(
    r"(?P<component>\w+)/(?:(?P<node_id>[a-zA-Z0-9_-]+)/)"
    r"?(?P<object_id>[a-zA-Z0-9_-]+)/config"
)

MQTT_DISCOVERY_UPDATED: SignalTypeFormat[MQTTDiscoveryPayload] = SignalTypeFormat(
    "mqtt_discovery_updated_{}_{}"
)
MQTT_DISCOVERY_NEW: SignalTypeFormat[MQTTDiscoveryPayload] = SignalTypeFormat(
    "mqtt_discovery_new_{}_{}"
)
MQTT_DISCOVERY_DONE: SignalTypeFormat[Any] = SignalTypeFormat(
    "mqtt_discovery_done_{}_{}"
)

TOPIC_BASE = "~"


class MQTTDiscoveryPayload(dict[str, Any]):
    """Class to hold and MQTT discovery payload and discovery data."""

    discovery_data: DiscoveryInfoType


def clear_discovery_hash(hass: HomeAssistant, discovery_hash: tuple[str, str]) -> None:
    """Clear entry from already discovered list."""
    hass.data[DATA_MQTT].discovery_already_discovered.discard(discovery_hash)


def set_discovery_hash(hass: HomeAssistant, discovery_hash: tuple[str, str]) -> None:
    """Add entry to already discovered list."""
    hass.data[DATA_MQTT].discovery_already_discovered.add(discovery_hash)


@callback
def async_log_discovery_origin_info(
    message: str, discovery_payload: MQTTDiscoveryPayload, level: int = logging.INFO
) -> None:
    """Log information about the discovery and origin."""
    if not _LOGGER.isEnabledFor(level):
        # bail early if logging is disabled
        return
    if CONF_ORIGIN not in discovery_payload:
        _LOGGER.log(level, message)
        return
    origin_info: MqttOriginInfo = discovery_payload[CONF_ORIGIN]
    sw_version_log = ""
    if sw_version := origin_info.get("sw_version"):
        sw_version_log = f", version: {sw_version}"
    support_url_log = ""
    if support_url := origin_info.get("support_url"):
        support_url_log = f", support URL: {support_url}"
    _LOGGER.log(
        level,
        "%s from external application %s%s%s",
        message,
        origin_info["name"],
        sw_version_log,
        support_url_log,
    )


@callback
def _replace_abbreviations(
    payload: Any | dict[str, Any],
    abbreviations: dict[str, str],
    abbreviations_set: set[str],
) -> None:
    """Replace abbreviations in an MQTT discovery payload."""
    if not isinstance(payload, dict):
        return
    for key in abbreviations_set.intersection(payload):
        payload[abbreviations[key]] = payload.pop(key)


@callback
def _replace_all_abbreviations(discovery_payload: Any | dict[str, Any]) -> None:
    """Replace all abbreviations in an MQTT discovery payload."""

    _replace_abbreviations(discovery_payload, ABBREVIATIONS, ABBREVIATIONS_SET)

    if CONF_ORIGIN in discovery_payload:
        _replace_abbreviations(
            discovery_payload[CONF_ORIGIN],
            ORIGIN_ABBREVIATIONS,
            ORIGIN_ABBREVIATIONS_SET,
        )

    if CONF_DEVICE in discovery_payload:
        _replace_abbreviations(
            discovery_payload[CONF_DEVICE],
            DEVICE_ABBREVIATIONS,
            DEVICE_ABBREVIATIONS_SET,
        )

    if CONF_AVAILABILITY in discovery_payload:
        for availability_conf in cv.ensure_list(discovery_payload[CONF_AVAILABILITY]):
            _replace_abbreviations(availability_conf, ABBREVIATIONS, ABBREVIATIONS_SET)


@callback
def _replace_topic_base(discovery_payload: dict[str, Any]) -> None:
    """Replace topic base in MQTT discovery data."""
    base = discovery_payload.pop(TOPIC_BASE)
    for key, value in discovery_payload.items():
        if isinstance(value, str) and value:
            if value[0] == TOPIC_BASE and key.endswith("topic"):
                discovery_payload[key] = f"{base}{value[1:]}"
            if value[-1] == TOPIC_BASE and key.endswith("topic"):
                discovery_payload[key] = f"{value[:-1]}{base}"
    if discovery_payload.get(CONF_AVAILABILITY):
        for availability_conf in cv.ensure_list(discovery_payload[CONF_AVAILABILITY]):
            if not isinstance(availability_conf, dict):
                continue
            if topic := str(availability_conf.get(CONF_TOPIC)):
                if topic[0] == TOPIC_BASE:
                    availability_conf[CONF_TOPIC] = f"{base}{topic[1:]}"
                if topic[-1] == TOPIC_BASE:
                    availability_conf[CONF_TOPIC] = f"{topic[:-1]}{base}"


@callback
def _valid_origin_info(discovery_payload: MQTTDiscoveryPayload) -> bool:
    """Parse and validate origin info from a single component discovery payload."""
    if CONF_ORIGIN not in discovery_payload:
        return True
    try:
        MQTT_ORIGIN_INFO_SCHEMA(discovery_payload[CONF_ORIGIN])
    except Exception as exc:  # noqa:BLE001
        _LOGGER.warning(
            "Unable to parse origin information from discovery message: %s, got %s",
            exc,
            discovery_payload[CONF_ORIGIN],
        )
        return False
    return True


async def async_start(  # noqa: C901
    hass: HomeAssistant, discovery_topic: str, config_entry: ConfigEntry
) -> None:
    """Start MQTT Discovery."""
    mqtt_data = hass.data[DATA_MQTT]
    platform_setup_lock: dict[str, asyncio.Lock] = {}

    @callback
    def _async_add_component(discovery_payload: MQTTDiscoveryPayload) -> None:
        """Add a component from a discovery message."""
        discovery_hash = discovery_payload.discovery_data[ATTR_DISCOVERY_HASH]
        component, discovery_id = discovery_hash
        message = f"Found new component: {component} {discovery_id}"
        async_log_discovery_origin_info(message, discovery_payload)
        mqtt_data.discovery_already_discovered.add(discovery_hash)
        async_dispatcher_send(
            hass, MQTT_DISCOVERY_NEW.format(component, "mqtt"), discovery_payload
        )

    async def _async_component_setup(
        component: str, discovery_payload: MQTTDiscoveryPayload
    ) -> None:
        """Perform component set up."""
        async with platform_setup_lock.setdefault(component, asyncio.Lock()):
            if component not in mqtt_data.platforms_loaded:
                await async_forward_entry_setup_and_setup_discovery(
                    hass, config_entry, {component}
                )
        _async_add_component(discovery_payload)

    @callback
    def async_discovery_message_received(msg: ReceiveMessage) -> None:  # noqa: C901
        """Process the received message."""
        mqtt_data.last_discovery = msg.timestamp
        payload = msg.payload
        topic = msg.topic
        topic_trimmed = topic.replace(f"{discovery_topic}/", "", 1)

        if not (match := TOPIC_MATCHER.match(topic_trimmed)):
            if topic_trimmed.endswith("config"):
                _LOGGER.warning(
                    (
                        "Received message on illegal discovery topic '%s'. The topic"
                        " contains "
                        "not allowed characters. For more information see "
                        "https://www.home-assistant.io/integrations/mqtt/#discovery-topic"
                    ),
                    topic,
                )
            return

        component, node_id, object_id = match.groups()

        if component not in SUPPORTED_COMPONENTS:
            _LOGGER.warning("Integration %s is not supported", component)
            return

        if payload:
            try:
                discovery_payload = MQTTDiscoveryPayload(json_loads_object(payload))
            except ValueError:
                _LOGGER.warning("Unable to parse JSON %s: '%s'", object_id, payload)
                return
            _replace_all_abbreviations(discovery_payload)
            if not _valid_origin_info(discovery_payload):
                return
            if TOPIC_BASE in discovery_payload:
                _replace_topic_base(discovery_payload)
        else:
            discovery_payload = MQTTDiscoveryPayload({})

        # If present, the node_id will be included in the discovered object id
        discovery_id = f"{node_id} {object_id}" if node_id else object_id
        discovery_hash = (component, discovery_id)

        if discovery_payload:
            # Attach MQTT topic to the payload, used for debug prints
            setattr(
                discovery_payload,
                "__configuration_source__",
                f"MQTT (topic: '{topic}')",
            )
            discovery_data = {
                ATTR_DISCOVERY_HASH: discovery_hash,
                ATTR_DISCOVERY_PAYLOAD: discovery_payload,
                ATTR_DISCOVERY_TOPIC: topic,
            }
            setattr(discovery_payload, "discovery_data", discovery_data)

            discovery_payload[CONF_PLATFORM] = "mqtt"

        if discovery_hash in mqtt_data.discovery_pending_discovered:
            pending = mqtt_data.discovery_pending_discovered[discovery_hash]["pending"]
            pending.appendleft(discovery_payload)
            _LOGGER.debug(
                "Component has already been discovered: %s %s, queuing update",
                component,
                discovery_id,
            )
            return

        async_process_discovery_payload(component, discovery_id, discovery_payload)

    @callback
    def async_process_discovery_payload(
        component: str, discovery_id: str, payload: MQTTDiscoveryPayload
    ) -> None:
        """Process the payload of a new discovery."""

        _LOGGER.debug("Process discovery payload %s", payload)
        discovery_hash = (component, discovery_id)

        already_discovered = discovery_hash in mqtt_data.discovery_already_discovered
        if (
            already_discovered or payload
        ) and discovery_hash not in mqtt_data.discovery_pending_discovered:
            discovery_pending_discovered = mqtt_data.discovery_pending_discovered

            @callback
            def discovery_done(_: Any) -> None:
                pending = discovery_pending_discovered[discovery_hash]["pending"]
                _LOGGER.debug("Pending discovery for %s: %s", discovery_hash, pending)
                if not pending:
                    discovery_pending_discovered[discovery_hash]["unsub"]()
                    discovery_pending_discovered.pop(discovery_hash)
                else:
                    payload = pending.pop()
                    async_process_discovery_payload(component, discovery_id, payload)

            discovery_pending_discovered[discovery_hash] = {
                "unsub": async_dispatcher_connect(
                    hass,
                    MQTT_DISCOVERY_DONE.format(*discovery_hash),
                    discovery_done,
                ),
                "pending": deque([]),
            }

        if component not in mqtt_data.platforms_loaded and payload:
            # Load component first
            config_entry.async_create_task(
                hass, _async_component_setup(component, payload)
            )
        elif already_discovered:
            # Dispatch update
            message = f"Component has already been discovered: {component} {discovery_id}, sending update"
            async_log_discovery_origin_info(message, payload, logging.DEBUG)
            async_dispatcher_send(
                hass, MQTT_DISCOVERY_UPDATED.format(*discovery_hash), payload
            )
        elif payload:
            _async_add_component(payload)
        else:
            # Unhandled discovery message
            async_dispatcher_send(
                hass, MQTT_DISCOVERY_DONE.format(*discovery_hash), None
            )

    mqtt_data.discovery_unsubscribe = [
        mqtt.async_subscribe_internal(
            hass,
            topic,
            async_discovery_message_received,
            0,
            job_type=HassJobType.Callback,
        )
        for topic in (
            f"{discovery_topic}/+/+/config",
            f"{discovery_topic}/+/+/+/config",
        )
    ]

    mqtt_data.last_discovery = time.monotonic()
    mqtt_integrations = await async_get_mqtt(hass)
    integration_unsubscribe = mqtt_data.integration_unsubscribe

    async def async_integration_message_received(
        integration: str, msg: ReceiveMessage
    ) -> None:
        """Process the received message."""
        if TYPE_CHECKING:
            assert mqtt_data.data_config_flow_lock
        key = f"{integration}_{msg.subscribed_topic}"

        # Lock to prevent initiating many parallel config flows.
        # Note: The lock is not intended to prevent a race, only for performance
        async with mqtt_data.data_config_flow_lock:
            # Already unsubscribed
            if key not in integration_unsubscribe:
                return

            data = MqttServiceInfo(
                topic=msg.topic,
                payload=msg.payload,
                qos=msg.qos,
                retain=msg.retain,
                subscribed_topic=msg.subscribed_topic,
                timestamp=msg.timestamp,
            )
            result = await hass.config_entries.flow.async_init(
                integration, context={"source": DOMAIN}, data=data
            )
            if (
                result
                and result["type"] == FlowResultType.ABORT
                and result["reason"]
                in ("already_configured", "single_instance_allowed")
            ):
                integration_unsubscribe.pop(key)()

    integration_unsubscribe.update(
        {
            f"{integration}_{topic}": mqtt.async_subscribe_internal(
                hass,
                topic,
                functools.partial(async_integration_message_received, integration),
                0,
                job_type=HassJobType.Coroutinefunction,
            )
            for integration, topics in mqtt_integrations.items()
            for topic in topics
        }
    )


async def async_stop(hass: HomeAssistant) -> None:
    """Stop MQTT Discovery."""
    mqtt_data = hass.data[DATA_MQTT]
    for unsub in mqtt_data.discovery_unsubscribe:
        unsub()
    mqtt_data.discovery_unsubscribe = []
    for key, unsub in list(mqtt_data.integration_unsubscribe.items()):
        unsub()
        mqtt_data.integration_unsubscribe.pop(key)