chatelet/nostr/service.py

"""Nostr I/O for Chatelet: sign + publish outbound events, and subscribe to
inbound availability queries — over the `nostrclient` extension's relay
manager, in-process (the spirekeeper pattern, aiolabs/spirekeeper
nostr_publish.py + tasks.py).

Signing + NIP-44 go through `lnbits.core.signers.resolve_signer`: the
operator account's signer produces the signature and (for encrypted events)
the NIP-44 ciphertext. No nsec is read here — works with a server-signing /
NIP-46 bunker signer. A LocalSigner can `sign_event` but its `nip44_encrypt`
raises (bunker-forward by design), so **public** events (listing 30402,
calendar 31923, availability 22001) publish today, while **encrypted** events
(reservation 30078) soft-fail with a clear log until a bunker lands (lnbits
#18). Everything degrades gracefully: no operator onboarded, nostrclient not
installed, or signer can't encrypt → publish is skipped, never crashes the
booking flow (which stands on its own over HTTP/RPC).
"""

import asyncio
import json
import time

from loguru import logger

from .. import crud, services
from ..models import Booking, Room
from . import events, giftwrap
from .kinds import KIND_AVAILABILITY_QUERY

try:
    from lnbits.core.crud import get_account
    from lnbits.core.signers import resolve_signer
    from lnbits.core.signers.base import SignerUnavailableError

    _SIGNER_AVAILABLE = True
except ImportError:  # pre-signer lnbits — Nostr layer soft-disables
    _SIGNER_AVAILABLE = False

_AVAILABILITY_SUB_ID = "chatelet_availability_query"
_POLL_INTERVAL_S = 1.0
_BACKOFF_S = 30


class _NostrclientUnavailable(Exception):
    """nostrclient extension not importable; caller backs off and retries."""


def _nostrclient():
    try:
        from nostrclient.router import (  # type: ignore[import-not-found]
            NostrRouter,
            nostr_client,
        )
    except ImportError as exc:
        raise _NostrclientUnavailable() from exc
    return NostrRouter, nostr_client


# --- signer -----------------------------------------------------------------


async def _operator_signer():
    """(account, signer) for the configured operator, or (None, None) if the
    Nostr layer is unavailable / no operator onboarded."""
    if not _SIGNER_AVAILABLE:
        return None, None
    settings = await crud.get_or_create_settings()
    if not settings.operator_id:
        logger.debug("chatelet: no operator_id configured; skipping publish")
        return None, None
    account = await get_account(settings.operator_id)
    if not account or not account.pubkey:
        logger.warning("chatelet: operator account has no Nostr pubkey; skipping")
        return None, None
    return account, resolve_signer(account)


# --- outbound: sign + publish -----------------------------------------------


async def _sign_and_publish(unsigned: dict, *, encrypt_to: str | None = None) -> str | None:
    """Encrypt (if `encrypt_to`), sign as the operator, and publish via
    nostrclient. Returns the event id, or None on any soft-fail."""
    _account, signer = await _operator_signer()
    if not signer:
        return None

    if encrypt_to:
        try:
            unsigned["content"] = await signer.nip44_encrypt(
                unsigned.get("content", ""), encrypt_to
            )
        except SignerUnavailableError as exc:
            logger.warning(
                f"chatelet: cannot NIP-44 encrypt kind={unsigned.get('kind')} "
                f"(needs bunker/server-signing signer, lnbits#18): {exc}"
            )
            return None

    unsigned["created_at"] = int(time.time())  # part of the event-id hash
    try:
        signed = await signer.sign_event(unsigned)
    except SignerUnavailableError as exc:
        logger.warning(f"chatelet: signer cannot sign kind={unsigned.get('kind')}: {exc}")
        return None
    if not signed:
        return None
    return _publish_signed(signed)


def _publish_signed(signed: dict) -> str | None:
    """Publish an already-signed event via nostrclient. Returns the event id,
    or None if nostrclient isn't installed."""
    try:
        _, nostr_client = _nostrclient()
    except _NostrclientUnavailable:
        logger.warning(
            "chatelet: nostrclient extension not installed; publish skipped. "
            "Install + activate nostrclient to reach relays."
        )
        return None
    nostr_client.relay_manager.publish_message(json.dumps(["EVENT", signed]))
    logger.debug(
        f"chatelet: published kind={signed['kind']} id={signed.get('id', '')[:12]}"
    )
    return signed.get("id")


async def send_checkin_dm(booking, room, settings) -> str | None:
    """On confirmation, send the guest a NIP-17 gift-wrapped DM with the
    private check-in details. Encrypted end-to-end to the guest; soft-fails
    (returns None) if the operator signer can't encrypt (LocalSigner pre-
    bunker) or nostrclient isn't installed."""
    account, signer = await _operator_signer()
    if not signer:
        return None
    wrap = await giftwrap.build_dm(
        signer=signer,
        sender_pubkey=account.pubkey,
        recipient_pubkey=booking.guest_pubkey,
        content=_checkin_message(booking, room, settings),
    )
    if not wrap:
        return None
    return _publish_signed(wrap)


def _checkin_message(booking, room, settings) -> str:
    lines = [
        f"Your booking at {room.title} is confirmed! 🏰",
        "",
        f"Check-in:  {booking.check_in} from {settings.checkin_time}",
        f"Check-out: {booking.check_out} by {settings.checkout_time}",
        f"Guests:    {booking.num_guests}",
    ]
    if room.checkin_instructions:
        lines += ["", room.checkin_instructions]
    if settings.cancellation_policy:
        lines += ["", f"Cancellation policy: {settings.cancellation_policy}"]
    return "\n".join(lines)


async def publish_listing(room: Room) -> str | None:
    """Publish/refresh a room's NIP-99 kind:30402 listing (public)."""
    return await _sign_and_publish(events.build_listing_event(room))


async def publish_reservation(booking: Booking) -> str | None:
    """Publish the guest's kind:30078 reservation object, NIP-44 encrypted to
    them. Soft-fails on a LocalSigner (no server-side encrypt) until bunker."""
    unsigned = events.build_reservation_event(booking, booking.guest_pubkey)
    return await _sign_and_publish(unsigned, encrypt_to=booking.guest_pubkey)


async def publish_block_calendar(
    room: Room, start: str, end: str, block_id: str
) -> str | None:
    """Publish a kind:31923 unavailable-range event (public, no PII)."""
    settings = await crud.get_or_create_settings()
    if not settings.publish_availability:
        return None
    return await _sign_and_publish(
        events.build_block_calendar_event(room, start, end, block_id)
    )


async def respond_availability(result, requester_pubkey: str) -> str | None:
    """Publish a kind:22001 availability response (plaintext, public info)."""
    return await _sign_and_publish(
        events.build_availability_response(result, requester_pubkey)
    )


# --- inbound: availability queries (kind:22000) -----------------------------


async def subscribe_inbound() -> None:
    """Permanent task: subscribe to kind:22000 availability queries over
    nostrclient and answer each with a kind:22001 response. This is the
    client-agnostic availability path (any Nostr client can ask), parallel
    to the chatelet_availability RPC. Booking itself stays on the RPC/HTTP
    doors for now (see issue #2 / event-flow.md)."""
    registered = False
    while True:
        try:
            registered = await _availability_tick(registered)
            await asyncio.sleep(_POLL_INTERVAL_S)
        except _NostrclientUnavailable:
            logger.warning(
                "chatelet: nostrclient not installed; availability subscription "
                f"sleeping {_BACKOFF_S}s before retry."
            )
            registered = False
            await asyncio.sleep(_BACKOFF_S)
        except Exception as exc:  # a listener must never die
            logger.error(f"chatelet: availability consumer error (continuing): {exc}")
            await asyncio.sleep(_POLL_INTERVAL_S)


async def _availability_tick(registered: bool) -> bool:
    NostrRouter, nostr_client = _nostrclient()
    if not registered:
        nostr_client.relay_manager.add_subscription(
            _AVAILABILITY_SUB_ID,
            [{"kinds": [KIND_AVAILABILITY_QUERY]}],  # type: ignore[list-item]
        )
        logger.info(
            f"chatelet: subscribed to kind:{KIND_AVAILABILITY_QUERY} "
            "availability queries"
        )

    inbound = NostrRouter.received_subscription_events.get(_AVAILABILITY_SUB_ID)
    while inbound:
        event_message = inbound.pop(0)
        try:
            await _handle_availability_query(event_message)
        except Exception as exc:
            logger.warning(f"chatelet: availability query handler failed (skip): {exc}")
    return True


async def _handle_availability_query(event_message) -> None:
    """Parse a kind:22000 query, compute availability, publish a 22001 reply
    p-tagged to the asker. The event author is the requester (unspoofable —
    it's the signed pubkey)."""
    event = json.loads(event_message.event)
    requester = event.get("pubkey")
    body = json.loads(event.get("content") or "{}")
    room_id, check_in, check_out = (
        body.get("room_id"),
        body.get("check_in"),
        body.get("check_out"),
    )
    if not (requester and room_id and check_in and check_out):
        return  # malformed query — ignore

    try:
        result = await services.get_availability(room_id, check_in, check_out)
    except ValueError:
        return  # unknown room / bad dates — no reply
    await respond_availability(result, requester)