from __future__ import annotations

import asyncio
from collections.abc import Callable, Coroutine
import contextlib
from dataclasses import dataclass
from functools import partial
import json
import logging
from pathlib import Path
import threading
from typing import Any

from esphome.storage_json import ignored_devices_storage_path

from ..zeroconf import DiscoveredImport
from .dns import DNSCache
from .entries import DashboardEntries
from .settings import DashboardSettings
from .status.mdns import MDNSStatus
from .status.ping import PingStatus

_LOGGER = logging.getLogger(__name__)

IGNORED_DEVICES_STORAGE_PATH = "ignored-devices.json"

MDNS_BOOTSTRAP_TIME = 7.5


@dataclass
class Event:
    """Dashboard Event."""

    event_type: str
    data: dict[str, Any]


class EventBus:
    """Dashboard event bus."""

    def __init__(self) -> None:
        """Initialize the Dashboard event bus."""
        self._listeners: dict[str, set[Callable[[Event], None]]] = {}

    def async_add_listener(
        self, event_type: str, listener: Callable[[Event], None]
    ) -> Callable[[], None]:
        """Add a listener to the event bus."""
        self._listeners.setdefault(event_type, set()).add(listener)
        return partial(self._async_remove_listener, event_type, listener)

    def _async_remove_listener(
        self, event_type: str, listener: Callable[[Event], None]
    ) -> None:
        """Remove a listener from the event bus."""
        self._listeners[event_type].discard(listener)

    def async_fire(self, event_type: str, event_data: dict[str, Any]) -> None:
        """Fire an event."""
        event = Event(event_type, event_data)

        _LOGGER.debug("Firing event: %s", event)

        for listener in self._listeners.get(event_type, set()):
            listener(event)


class ESPHomeDashboard:
    """Class that represents the dashboard."""

    __slots__ = (
        "bus",
        "entries",
        "loop",
        "import_result",
        "stop_event",
        "ping_request",
        "mqtt_ping_request",
        "mdns_status",
        "settings",
        "dns_cache",
        "_background_tasks",
        "ignored_devices",
        "_ping_status_task",
    )

    def __init__(self) -> None:
        """Initialize the ESPHomeDashboard."""
        self.bus = EventBus()
        self.entries: DashboardEntries | None = None
        self.loop: asyncio.AbstractEventLoop | None = None
        self.import_result: dict[str, DiscoveredImport] = {}
        self.stop_event = threading.Event()
        self.ping_request: asyncio.Event | None = None
        self.mqtt_ping_request = threading.Event()
        self.mdns_status: MDNSStatus | None = None
        self.settings = DashboardSettings()
        self.dns_cache = DNSCache()
        self._background_tasks: set[asyncio.Task] = set()
        self.ignored_devices: set[str] = set()
        self._ping_status_task: asyncio.Task | None = None

    async def async_setup(self) -> None:
        """Setup the dashboard."""
        self.loop = asyncio.get_running_loop()
        self.ping_request = asyncio.Event()
        self.entries = DashboardEntries(self)
        await self.loop.run_in_executor(None, self.load_ignored_devices)

    def load_ignored_devices(self) -> None:
        storage_path = Path(ignored_devices_storage_path())
        try:
            with storage_path.open("r", encoding="utf-8") as f_handle:
                data = json.load(f_handle)
                self.ignored_devices = set(data.get("ignored_devices", set()))
        except FileNotFoundError:
            pass

    def save_ignored_devices(self) -> None:
        storage_path = Path(ignored_devices_storage_path())
        with storage_path.open("w", encoding="utf-8") as f_handle:
            json.dump(
                {"ignored_devices": sorted(self.ignored_devices)}, indent=2, fp=f_handle
            )

    def _async_start_ping_status(self, ping_status: PingStatus) -> None:
        self._ping_status_task = asyncio.create_task(ping_status.async_run())

    async def async_run(self) -> None:
        """Run the dashboard."""
        settings = self.settings
        mdns_task: asyncio.Task | None = None
        await self.entries.async_update_entries()

        mdns_status = MDNSStatus(self)
        ping_status = PingStatus(self)
        start_ping_timer: asyncio.TimerHandle | None = None

        self.mdns_status = mdns_status
        if mdns_status.async_setup():
            mdns_task = asyncio.create_task(mdns_status.async_run())
            # Start ping MDNS_BOOTSTRAP_TIME seconds after startup to ensure
            # MDNS has had a chance to resolve the devices
            start_ping_timer = self.loop.call_later(
                MDNS_BOOTSTRAP_TIME, self._async_start_ping_status, ping_status
            )
        else:
            # If mDNS is not available, start the ping status immediately
            self._async_start_ping_status(ping_status)

        if settings.status_use_mqtt:
            from .status.mqtt import MqttStatusThread

            status_thread_mqtt = MqttStatusThread(self)
            status_thread_mqtt.start()

        try:
            await asyncio.Event().wait()
        finally:
            _LOGGER.info("Shutting down...")
            self.stop_event.set()
            self.ping_request.set()
            if start_ping_timer:
                start_ping_timer.cancel()
            if self._ping_status_task:
                self._ping_status_task.cancel()
                self._ping_status_task = None
            if mdns_task:
                mdns_task.cancel()
            if settings.status_use_mqtt:
                status_thread_mqtt.join()
                self.mqtt_ping_request.set()
            for task in self._background_tasks:
                task.cancel()
                with contextlib.suppress(asyncio.CancelledError):
                    await task
            await asyncio.sleep(0)

    def async_create_background_task(
        self, coro: Coroutine[Any, Any, Any]
    ) -> asyncio.Task:
        """Create a background task."""
        task = self.loop.create_task(coro)
        task.add_done_callback(self._background_tasks.discard)
        return task


DASHBOARD = ESPHomeDashboard()