"""
Outbound notification helpers — send messages to user channels proactively.

Channel config lives in home/{user}/channels.json:
  {
    "notification_channel": "email" | "nextcloud" | "google_chat",
    "notification_email":   "<override address — defaults to login email>",
    "nextcloud": {
      "url": "...", "bot_secret": "...", "notification_room": "<token>", ...
    },
    "google_chat": {
      "outbound_webhook": "https://chat.googleapis.com/v1/spaces/...", ...
    }
  }

If notification_channel is absent, defaults to "nextcloud" if configured.
"""
import asyncio
import hashlib
import hmac
import json
import logging
import secrets

import httpx

logger = logging.getLogger(__name__)


async def _send_nct_message(url: str, secret: str, room: str, message: str) -> None:
    """Post a message to a Nextcloud Talk room as the bot."""
    endpoint = f"{url}/ocs/v2.php/apps/spreed/api/v1/bot/{room}/message"
    random_str = secrets.token_hex(32)
    sig = hmac.new(
        secret.encode(),
        (random_str + message).encode("utf-8"),
        hashlib.sha256,
    ).hexdigest()
    body = json.dumps({"message": message}, ensure_ascii=False).encode("utf-8")

    try:
        async with httpx.AsyncClient() as client:
            resp = await client.post(
                endpoint,
                content=body,
                headers={
                    "Content-Type": "application/json",
                    "OCS-APIRequest": "true",
                    "X-Nextcloud-Talk-Bot-Random": random_str,
                    "X-Nextcloud-Talk-Bot-Signature": sig,
                },
                timeout=15,
            )
        if resp.status_code not in (200, 201):
            logger.warning("notify NCT %s → HTTP %d: %s", room, resp.status_code, resp.text[:200])
        else:
            logger.info("notify NCT → %s (%d chars)", room, len(message))
    except Exception as e:
        logger.error("notify NCT error: %s", e)


async def _notify_nct(nct: dict, message: str, username: str) -> None:
    room   = nct.get("notification_room", "").strip()
    url    = nct.get("url", "").rstrip("/")
    secret = nct.get("bot_secret", "")
    if not room:
        logger.debug("notify: NCT notification_room not set for %s — skipping", username)
        return
    if not url or not secret:
        logger.warning("notify: NCT config incomplete for %s (missing url or secret)", username)
        return
    await _send_nct_message(url, secret, room, message)


async def _notify_email(username: str, message: str, email_override: str | None = None) -> None:
    """Send notification via email. Address = override → google_email from auth.json."""
    from auth_utils import _read_auth
    from email_utils import send_email

    to_addr = email_override or _read_auth(username).get("google_email", "").strip()
    if not to_addr:
        logger.warning("notify: no email address for %s — set notification_email in channels.json", username)
        return

    ok = await asyncio.to_thread(
        send_email,
        to_email=to_addr,
        subject="Cortex",
        body_text=message,
        body_html=message.replace("\n", "<br>"),
    )
    if ok:
        logger.info("notify email → %s (%d chars)", to_addr, len(message))
    else:
        logger.warning("notify: email send failed for %s", username)


async def _notify_google_chat(webhook_url: str, message: str, username: str) -> None:
    """POST a message to a Google Chat space via incoming webhook."""
    body = json.dumps({"text": message}, ensure_ascii=False).encode("utf-8")
    try:
        async with httpx.AsyncClient() as client:
            resp = await client.post(
                webhook_url,
                content=body,
                headers={"Content-Type": "application/json"},
                timeout=15,
            )
        if resp.status_code not in (200, 201):
            logger.warning("notify Google Chat %s → HTTP %d: %s", username, resp.status_code, resp.text[:200])
        else:
            logger.info("notify Google Chat → %s (%d chars)", username, len(message))
    except Exception as e:
        logger.error("notify Google Chat error for %s: %s", username, e)


async def notify(username: str, message: str, channel: str | None = None) -> None:
    """Send a notification to the user's preferred outbound channel.

    Channel resolution order:
      1. `channel` parameter if provided
      2. `notification_channel` key in channels.json
      3. "nextcloud" if notification_room is configured
      4. Silent no-op

    Configure via home/{user}/channels.json — see module docstring.
    """
    from auth_utils import get_user_channels
    channels = get_user_channels(username)

    target = channel or channels.get("notification_channel", "").strip()
    if not target:
        # Auto-detect: nextcloud if a notification_room is set
        nct = channels.get("nextcloud", {})
        if nct.get("notification_room", "").strip():
            target = "nextcloud"
        else:
            return

    if target == "email":
        email_override = channels.get("notification_email", "").strip() or None
        await _notify_email(username, message, email_override=email_override)

    elif target == "nextcloud":
        nct = channels.get("nextcloud")
        if not nct:
            logger.debug("notify: nextcloud not configured for %s", username)
            return
        await _notify_nct(nct, message, username)

    elif target == "google_chat":
        gc = channels.get("google_chat", {})
        webhook = gc.get("outbound_webhook", "").strip()
        if not webhook:
            logger.debug("notify: google_chat outbound_webhook not set for %s", username)
            return
        await _notify_google_chat(webhook, message, username)

    else:
        logger.debug("notify: channel %r not supported for outbound (user %s)", target, username)