"""Home Assistant platform adapter.

Listens on the HA WebSocket API; ``state_changed`` events become MessageEvents.
Outbound messages are delivered as HA persistent notifications.

Requires:
- aiohttp (already in messaging extras)
- HASS_TOKEN env var (Long-Lived Access Token)
- HASS_URL env var (default: http://homeassistant.local:8123)
"""

import asyncio
import json
import logging
import os
import time
import uuid
from datetime import datetime
from typing import Any, Dict, Optional, Set

try:
    import aiohttp
    AIOHTTP_AVAILABLE = True
except ImportError:
    AIOHTTP_AVAILABLE = False
    aiohttp = None  # type: ignore[assignment]

from gateway.config import Platform, PlatformConfig
from gateway.platforms.base import (
    gateway_trust_env,
    BasePlatformAdapter,
    MessageEvent,
    MessageType,
    SendResult,
)

from gateway.platforms._shared import get_scoped_secret as _get_scoped_secret


logger = logging.getLogger(__name__)


def check_ha_requirements() -> bool:
    """Check if Home Assistant runtime dependencies are available."""
    return AIOHTTP_AVAILABLE


def validate_ha_config(config: PlatformConfig) -> bool:
    """True when Home Assistant has enough credential config to connect."""
    return bool((getattr(config, "token", None) or _get_scoped_secret("HASS_TOKEN", "")).strip())


def _domain_of(entity_id: str) -> str:
    return entity_id.split(".")[0] if "." in entity_id else ""


def _on_off(val: str) -> str:
    return "on" if val == "on" else "off"


def _triggered(val: str) -> str:
    return "triggered" if val == "on" else "cleared"


class HomeAssistantAdapter(BasePlatformAdapter):
    """HA WebSocket adapter: ``state_changed`` events → MessageEvents, with
    domain/entity filtering and per-entity cooldowns against event floods."""

    MAX_MESSAGE_LENGTH = 4096
    _BACKOFF_STEPS = [5, 10, 30, 60]  # reconnect backoff (seconds)

    def __init__(self, config: PlatformConfig):
        super().__init__(config, Platform.HOMEASSISTANT)
        self._session: Optional["aiohttp.ClientSession"] = None
        self._ws: Optional["aiohttp.ClientWebSocketResponse"] = None
        self._rest_session: Optional["aiohttp.ClientSession"] = None
        self._listen_task: Optional[asyncio.Task] = None
        self._msg_id: int = 0

        extra = config.extra or {}
        url = extra.get("url") or os.getenv("HASS_URL", "http://homeassistant.local:8123")
        self._hass_url: str = url.rstrip("/")
        self._hass_token: str = config.token or _get_scoped_secret("HASS_TOKEN", "")

        self._watch_domains: Set[str] = set(extra.get("watch_domains", []))
        self._watch_entities: Set[str] = set(extra.get("watch_entities", []))
        self._ignore_entities: Set[str] = set(extra.get("ignore_entities", []))
        self._watch_all: bool = bool(extra.get("watch_all", False))
        self._cooldown_seconds: int = int(extra.get("cooldown_seconds", 30))
        self._last_event_time: Dict[str, float] = {}  # entity_id -> last event ts

    def _next_id(self) -> int:
        self._msg_id += 1
        return self._msg_id

    # -- Connection lifecycle -----------------------------------------------

    async def connect(self, *, is_reconnect: bool = False) -> bool:
        """Connect to HA WebSocket API and subscribe to events."""
        if not AIOHTTP_AVAILABLE:
            logger.warning("[%s] aiohttp not installed. Run: pip install aiohttp", self.name)
            return False
        if not self._hass_token:
            logger.warning("[%s] No HASS_TOKEN configured", self.name)
            return False

        try:
            if not await self._ws_connect():
                return False
            # Dedicated REST session for send() calls
            self._rest_session = aiohttp.ClientSession(
                timeout=aiohttp.ClientTimeout(total=30), trust_env=gateway_trust_env(),
            )
            if not self._watch_domains and not self._watch_entities and not self._watch_all:
                logger.warning(
                    "[%s] No watch_domains, watch_entities, or watch_all configured. "
                    "All state_changed events will be dropped. Configure filters in "
                    "your HA platform config to receive events.",
                    self.name,
                )
            self._listen_task = asyncio.create_task(self._listen_loop())
            self._running = True
            logger.info("[%s] Connected to %s", self.name, self._hass_url)
            self._wire_plugin_handlers(None)
            return True
        except Exception as e:
            logger.error("[%s] Failed to connect: %s", self.name, e)
            return False

    async def _ws_connect(self) -> bool:
        """Open the WebSocket, authenticate, and subscribe to ``state_changed``."""
        ws_url = self._hass_url.replace("https://", "wss://").replace("http://", "ws://")
        self._session = aiohttp.ClientSession(
            timeout=aiohttp.ClientTimeout(total=30), trust_env=gateway_trust_env(),
        )
        self._ws = await self._session.ws_connect(f"{ws_url}/api/websocket", heartbeat=30, timeout=30)

        msg = await self._ws.receive_json()
        if msg.get("type") != "auth_required":
            logger.error("Expected auth_required, got: %s", msg.get("type"))
            await self._cleanup_ws()
            return False

        await self._ws.send_json({"type": "auth", "access_token": self._hass_token})
        msg = await self._ws.receive_json()
        if msg.get("type") != "auth_ok":
            logger.error("Auth failed: %s", msg)
            await self._cleanup_ws()
            return False

        await self._ws.send_json({
            "id": self._next_id(),
            "type": "subscribe_events",
            "event_type": "state_changed",
        })
        msg = await self._ws.receive_json()
        if not msg.get("success"):
            logger.error("Failed to subscribe to events: %s", msg)
            await self._cleanup_ws()
            return False
        return True

    async def _cleanup_ws(self) -> None:
        if self._ws and not self._ws.closed:
            await self._ws.close()
        self._ws = None
        if self._session and not self._session.closed:
            await self._session.close()
        self._session = None

    async def disconnect(self) -> None:
        self._running = False
        if self._listen_task:
            self._listen_task.cancel()
            try:
                await self._listen_task
            except asyncio.CancelledError:
                pass
            self._listen_task = None

        await self._cleanup_ws()
        if self._rest_session and not self._rest_session.closed:
            await self._rest_session.close()
        self._rest_session = None
        logger.info("[%s] Disconnected", self.name)

    # -- Event listener -----------------------------------------------------

    async def _listen_loop(self) -> None:
        """Main event loop with automatic reconnection."""
        backoff_idx = 0
        while self._running:
            try:
                await self._read_events()
            except asyncio.CancelledError:
                return
            except Exception as e:
                logger.warning("[%s] WebSocket error: %s", self.name, e)

            if not self._running:
                return
            delay = self._BACKOFF_STEPS[min(backoff_idx, len(self._BACKOFF_STEPS) - 1)]
            logger.info("[%s] Reconnecting in %ds...", self.name, delay)
            await asyncio.sleep(delay)
            backoff_idx += 1

            try:
                await self._cleanup_ws()
                if await self._ws_connect():
                    backoff_idx = 0
                    logger.info("[%s] Reconnected", self.name)
            except Exception as e:
                logger.warning("[%s] Reconnection failed: %s", self.name, e)

    async def _read_events(self) -> None:
        """Read events from WebSocket until disconnected."""
        if self._ws is None or self._ws.closed:
            return
        async for ws_msg in self._ws:
            if ws_msg.type == aiohttp.WSMsgType.TEXT:
                try:
                    data = json.loads(ws_msg.data)
                    if data.get("type") == "event":
                        await self._handle_ha_event(data.get("event", {}))
                except json.JSONDecodeError:
                    logger.debug("Invalid JSON from HA WS: %s", ws_msg.data[:200])
            elif ws_msg.type in {aiohttp.WSMsgType.CLOSED, aiohttp.WSMsgType.ERROR}:
                break

    def _passes_filters(self, entity_id: str) -> bool:
        """Closed by default: requires watch_domains, watch_entities, or watch_all."""
        if entity_id in self._ignore_entities:
            return False
        if self._watch_domains or self._watch_entities:
            return _domain_of(entity_id) in self._watch_domains or entity_id in self._watch_entities
        return self._watch_all

    async def _handle_ha_event(self, event: Dict[str, Any]) -> None:
        """Process a state_changed event from Home Assistant."""
        event_data = event.get("data", {})
        entity_id: str = event_data.get("entity_id", "")
        if not entity_id or not self._passes_filters(entity_id):
            return

        now = time.time()
        if (now - self._last_event_time.get(entity_id, 0)) < self._cooldown_seconds:
            return
        self._last_event_time[entity_id] = now

        message = self._format_state_change(
            entity_id, event_data.get("old_state", {}), event_data.get("new_state", {}),
        )
        if not message:
            return

        source = self.build_source(
            chat_id="ha_events",
            chat_name="Home Assistant Events",
            chat_type="channel",
            user_id="homeassistant",
            user_name="Home Assistant",
        )
        await self.handle_message(MessageEvent(
            text=message,
            message_type=MessageType.TEXT,
            source=source,
            message_id=f"ha_{entity_id}_{int(now)}",
            timestamp=datetime.now(),
        ))

    @staticmethod
    def _format_state_change(
        entity_id: str,
        old_state: Dict[str, Any],
        new_state: Dict[str, Any],
    ) -> Optional[str]:
        """Convert a state_changed event into a human-readable description."""
        if not new_state:
            return None
        old_val = old_state.get("state", "unknown") if old_state else "unknown"
        new_val = new_state.get("state", "unknown")
        if old_val == new_val:
            return None

        attrs = new_state.get("attributes", {})
        name = attrs.get("friendly_name", entity_id)
        domain = _domain_of(entity_id)

        if domain == "climate":
            temp = attrs.get("current_temperature", "?")
            target = attrs.get("temperature", "?")
            return (
                f"[Home Assistant] {name}: HVAC mode changed from "
                f"'{old_val}' to '{new_val}' (current: {temp}, target: {target})"
            )
        if domain == "sensor":
            unit = attrs.get("unit_of_measurement", "")
            return f"[Home Assistant] {name}: changed from {old_val}{unit} to {new_val}{unit}"
        if domain == "binary_sensor":
            return f"[Home Assistant] {name}: {_triggered(new_val)} (was {_triggered(old_val)})"
        if domain in {"light", "switch", "fan"}:
            return f"[Home Assistant] {name}: turned {_on_off(new_val)}"
        if domain == "alarm_control_panel":
            return f"[Home Assistant] {name}: alarm state changed from '{old_val}' to '{new_val}'"
        return f"[Home Assistant] {name} ({entity_id}): changed from '{old_val}' to '{new_val}'"

    # -- Outbound messaging -------------------------------------------------

    async def send(
        self,
        chat_id: str,
        content: str,
        reply_to: Optional[str] = None,
        metadata: Optional[Dict[str, Any]] = None,
    ) -> SendResult:
        """Send a notification via HA REST API (persistent_notification.create).

        REST rather than the WebSocket, to avoid racing the listener loop that
        reads from the same WS connection.
        """
        url = f"{self._hass_url}/api/services/persistent_notification/create"
        headers = {"Authorization": f"Bearer {self._hass_token}", "Content-Type": "application/json"}
        payload = {"title": "Hermes Agent", "message": content[:self.MAX_MESSAGE_LENGTH]}

        async def _post(session) -> SendResult:
            async with session.post(
                url, headers=headers, json=payload, timeout=aiohttp.ClientTimeout(total=10),
            ) as resp:
                if resp.status < 300:
                    return SendResult(success=True, message_id=uuid.uuid4().hex[:12])
                body = await resp.text()
                return SendResult(success=False, error=f"HTTP {resp.status}: {body}")

        try:
            if self._rest_session:
                return await _post(self._rest_session)
            async with aiohttp.ClientSession(trust_env=gateway_trust_env()) as session:
                return await _post(session)
        except asyncio.TimeoutError:
            return SendResult(success=False, error="Timeout sending notification to HA")
        except Exception as e:
            return SendResult(success=False, error=str(e))

    async def get_chat_info(self, chat_id: str) -> Dict[str, Any]:
        return {"name": "Home Assistant Events", "type": "channel", "url": self._hass_url}


# -- Standalone (out-of-process) sender — cron deliver=homeassistant ---------


async def _standalone_send(
    pconfig,
    chat_id: str,
    message: str,
    *,
    thread_id: Optional[str] = None,
    media_files: Optional[list] = None,
    force_document: bool = False,
) -> Dict[str, Any]:
    """Send via the HA ``notify.notify`` service without a live gateway adapter.

    Token: ``pconfig.token`` then ``HASS_TOKEN``; URL: ``pconfig.extra["url"]``
    then ``HASS_URL``. ``thread_id``/``media_files``/``force_document`` are
    signature parity only — HA notifications have no threads or attachments.
    """
    if not AIOHTTP_AVAILABLE:
        return {"error": "aiohttp not installed. Run: pip install aiohttp"}

    extra = getattr(pconfig, "extra", {}) or {}
    hass_url = (extra.get("url") or os.getenv("HASS_URL", "")).rstrip("/")
    token = (getattr(pconfig, "token", None) or _get_scoped_secret("HASS_TOKEN", "")).strip()
    if not hass_url or not token:
        return {"error": "Home Assistant standalone send: HASS_URL and HASS_TOKEN must both be set"}

    url = f"{hass_url}/api/services/notify/notify"
    headers = {"Authorization": f"Bearer {token}", "Content-Type": "application/json"}
    payload = {"message": message, "target": chat_id}
    try:
        async with aiohttp.ClientSession(
            timeout=aiohttp.ClientTimeout(total=30), trust_env=gateway_trust_env(),
        ) as session:
            async with session.post(url, headers=headers, json=payload) as resp:
                if resp.status not in {200, 201}:
                    body = await resp.text()
                    return {"error": f"Home Assistant API error ({resp.status}): {body}"}
        return {"success": True, "platform": "homeassistant", "chat_id": chat_id}
    except asyncio.TimeoutError:
        return {"error": "Timeout sending notification to Home Assistant"}
    except Exception as e:
        return {"error": f"Home Assistant send failed: {e}"}


def _is_connected(config) -> bool:
    """Connected when ``HASS_TOKEN`` is set.

    Looked up via ``hermes_cli.gateway.get_env_value`` at call time so tests
    patching ``gateway_mod.get_env_value`` can suppress ambient env vars.
    """
    import hermes_cli.gateway as gateway_mod
    return bool((gateway_mod.get_env_value("HASS_TOKEN") or "").strip())


def _build_adapter(config):
    return HomeAssistantAdapter(config)


def register(ctx) -> None:
    """Plugin entry point — called by the Hermes plugin system."""
    ctx.register_platform(
        name="homeassistant",
        label="Home Assistant",
        adapter_factory=_build_adapter,
        check_fn=check_ha_requirements,
        validate_config=validate_ha_config,
        is_connected=_is_connected,
        required_env=["HASS_TOKEN"],
        install_hint="pip install aiohttp",
        standalone_sender_fn=_standalone_send,  # out-of-process cron delivery via notify.notify
        max_message_length=HomeAssistantAdapter.MAX_MESSAGE_LENGTH,
        emoji="🏠",
        allow_update_command=True,
    )