"""ChannelService — manages the lifecycle of all IM channels."""

from __future__ import annotations

import logging
import os
from typing import Any

from app.channels.base import Channel
from app.channels.manager import DEFAULT_GATEWAY_URL, DEFAULT_LANGGRAPH_URL, ChannelManager
from app.channels.message_bus import MessageBus
from app.channels.store import ChannelStore

logger = logging.getLogger(__name__)

# Channel name → import path for lazy loading
_CHANNEL_REGISTRY: dict[str, str] = {
    "discord": "app.channels.discord:DiscordChannel",
    "feishu": "app.channels.feishu:FeishuChannel",
    "slack": "app.channels.slack:SlackChannel",
    "telegram": "app.channels.telegram:TelegramChannel",
    "wechat": "app.channels.wechat:WechatChannel",
    "wecom": "app.channels.wecom:WeComChannel",
}

_CHANNELS_LANGGRAPH_URL_ENV = "DEER_FLOW_CHANNELS_LANGGRAPH_URL"
_CHANNELS_GATEWAY_URL_ENV = "DEER_FLOW_CHANNELS_GATEWAY_URL"


def _resolve_service_url(config: dict[str, Any], config_key: str, env_key: str, default: str) -> str:
    value = config.pop(config_key, None)
    if isinstance(value, str) and value.strip():
        return value
    env_value = os.getenv(env_key, "").strip()
    if env_value:
        return env_value
    return default


class ChannelService:
    """Manages the lifecycle of all configured IM channels.

    Reads configuration from ``config.yaml`` under the ``channels`` key,
    instantiates enabled channels, and starts the ChannelManager dispatcher.
    """

    def __init__(self, channels_config: dict[str, Any] | None = None) -> None:
        self.bus = MessageBus()
        self.store = ChannelStore()
        config = dict(channels_config or {})
        langgraph_url = _resolve_service_url(config, "langgraph_url", _CHANNELS_LANGGRAPH_URL_ENV, DEFAULT_LANGGRAPH_URL)
        gateway_url = _resolve_service_url(config, "gateway_url", _CHANNELS_GATEWAY_URL_ENV, DEFAULT_GATEWAY_URL)
        default_session = config.pop("session", None)
        channel_sessions = {name: channel_config.get("session") for name, channel_config in config.items() if isinstance(channel_config, dict)}
        self.manager = ChannelManager(
            bus=self.bus,
            store=self.store,
            langgraph_url=langgraph_url,
            gateway_url=gateway_url,
            default_session=default_session if isinstance(default_session, dict) else None,
            channel_sessions=channel_sessions,
        )
        self._channels: dict[str, Any] = {}  # name -> Channel instance
        self._config = config
        self._running = False

    @classmethod
    def from_app_config(cls) -> ChannelService:
        """Create a ChannelService from the application config."""
        from deerflow.config.app_config import get_app_config

        config = get_app_config()
        channels_config = {}
        # extra fields are allowed by AppConfig (extra="allow")
        extra = config.model_extra or {}
        if "channels" in extra:
            channels_config = extra["channels"]
        return cls(channels_config=channels_config)

    async def start(self) -> None:
        """Start the manager and all enabled channels."""
        if self._running:
            return

        await self.manager.start()

        for name, channel_config in self._config.items():
            if not isinstance(channel_config, dict):
                continue
            if not channel_config.get("enabled", False):
                logger.info("Channel %s is disabled, skipping", name)
                continue

            await self._start_channel(name, channel_config)

        self._running = True
        logger.info("ChannelService started with channels: %s", list(self._channels.keys()))

    async def stop(self) -> None:
        """Stop all channels and the manager."""
        for name, channel in list(self._channels.items()):
            try:
                await channel.stop()
                logger.info("Channel %s stopped", name)
            except Exception:
                logger.exception("Error stopping channel %s", name)
        self._channels.clear()

        await self.manager.stop()
        self._running = False
        logger.info("ChannelService stopped")

    async def restart_channel(self, name: str) -> bool:
        """Restart a specific channel. Returns True if successful."""
        if name in self._channels:
            try:
                await self._channels[name].stop()
            except Exception:
                logger.exception("Error stopping channel %s for restart", name)
            del self._channels[name]

        config = self._config.get(name)
        if not config or not isinstance(config, dict):
            logger.warning("No config for channel %s", name)
            return False

        return await self._start_channel(name, config)

    async def _start_channel(self, name: str, config: dict[str, Any]) -> bool:
        """Instantiate and start a single channel."""
        import_path = _CHANNEL_REGISTRY.get(name)
        if not import_path:
            logger.warning("Unknown channel type: %s", name)
            return False

        try:
            from deerflow.reflection import resolve_class

            channel_cls = resolve_class(import_path, base_class=None)
        except Exception:
            logger.exception("Failed to import channel class for %s", name)
            return False

        try:
            channel = channel_cls(bus=self.bus, config=config)
            await channel.start()
            self._channels[name] = channel
            logger.info("Channel %s started", name)
            return True
        except Exception:
            logger.exception("Failed to start channel %s", name)
            return False

    def get_status(self) -> dict[str, Any]:
        """Return status information for all channels."""
        channels_status = {}
        for name in _CHANNEL_REGISTRY:
            config = self._config.get(name, {})
            enabled = isinstance(config, dict) and config.get("enabled", False)
            running = name in self._channels and self._channels[name].is_running
            channels_status[name] = {
                "enabled": enabled,
                "running": running,
            }
        return {
            "service_running": self._running,
            "channels": channels_status,
        }

    def get_channel(self, name: str) -> Channel | None:
        """Return a running channel instance by name when available."""
        return self._channels.get(name)


# -- singleton access -------------------------------------------------------

_channel_service: ChannelService | None = None


def get_channel_service() -> ChannelService | None:
    """Get the singleton ChannelService instance (if started)."""
    return _channel_service


async def start_channel_service() -> ChannelService:
    """Create and start the global ChannelService from app config."""
    global _channel_service
    if _channel_service is not None:
        return _channel_service
    _channel_service = ChannelService.from_app_config()
    await _channel_service.start()
    return _channel_service


async def stop_channel_service() -> None:
    """Stop the global ChannelService."""
    global _channel_service
    if _channel_service is not None:
        await _channel_service.stop()
        _channel_service = None
