events/nostr_publisher.py

"""
NIP-52 calendar event publishing for the events extension.

Builds NIP-52 calendar events from the Event model, signs them via the
core `NostrSigner` abstraction (backend-agnostic: LocalSigner,
RemoteBunkerSigner, etc.), and publishes via the NostrClient.

Kind 31922 is used for date-only events; kind 31923 (time-based) is used
when event_start_date / event_end_date include a time component.

Reference: https://github.com/nostr-protocol/nips/blob/master/52.md
"""

import time
from datetime import datetime, timezone

from lnbits.core.signers import NostrSigner
from loguru import logger

from .models import Event
from .nostr.event import NostrEvent


def _has_time(value: str | None) -> bool:
    """ISO 8601 datetime strings contain a 'T' between date and time."""
    return value is not None and "T" in value


def _to_unix(value: str) -> int:
    """Parse ISO 8601 datetime (assume UTC if naive) to unix seconds."""
    dt = datetime.fromisoformat(value)
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=timezone.utc)
    return int(dt.timestamp())


def build_nip52_event(event: Event, pubkey: str) -> NostrEvent:
    """
    Convert an Event model to a NIP-52 calendar event.

    Time-based (kind 31923) if event_start_date carries an HH:MM, otherwise
    date-based (kind 31922). Tags:
      d                  - event.id
      title              - event.name
      start              - unix timestamp (31923) or YYYY-MM-DD (31922)
      end                - same encoding (optional)
      image, location, t (categories) - optional
      tickets_available     - current remaining capacity (omitted when unlimited)
      tickets_sold          - running paid-count (always emitted; clients can
                              derive original_capacity = available + sold)
      tickets_price         - price_per_ticket (always emitted; 0 means free)
      tickets_currency      - the currency string
      tickets_allow_fiat    - "true" when fiat checkout is enabled (omitted otherwise)
      tickets_fiat_currency - the fiat settle currency (only when allow_fiat)
    Content:  event.info

    The four ticket_* tags are AIO custom additions outside the NIP-52
    spec; spec-compliant clients ignore unknown tags so this stays
    backwards-compatible. They let connected clients render the
    "X tickets remaining" badge and the Buy CTA without an extra REST hop,
    and pick up live inventory updates via the same relay subscription.
    """
    time_based = _has_time(event.event_start_date)
    kind = 31923 if time_based else 31922
    start_value = (
        str(_to_unix(event.event_start_date)) if time_based else event.event_start_date
    )

    tags = [
        ["d", event.id],
        ["title", event.name],
        ["start", start_value],
    ]

    end_unix: int | None = None
    if event.event_end_date:
        end_value = (
            str(_to_unix(event.event_end_date)) if time_based else event.event_end_date
        )
        tags.append(["end", end_value])
        if time_based:
            end_unix = _to_unix(event.event_end_date)

    if time_based:
        start_unix = _to_unix(event.event_start_date)
        start_day = start_unix // 86400
        end_day = (end_unix // 86400) if end_unix is not None else start_day
        for day in range(start_day, end_day + 1):
            tags.append(["D", str(day)])

    if event.banner:
        tags.append(["image", event.banner])
    if event.location:
        tags.append(["location", event.location])
    for cat in event.categories or []:
        tags.append(["t", cat])

    # `amount_tickets == 0` means unlimited capacity in this extension's
    # schema. Omitting the tag is how clients distinguish unlimited from
    # "0 left" (sold out).
    if event.amount_tickets > 0:
        tags.append(["tickets_available", str(event.amount_tickets)])
    tags.append(["tickets_sold", str(event.sold)])
    tags.append(["tickets_price", str(event.price_per_ticket)])
    tags.append(["tickets_currency", event.currency])
    # Fiat-checkout config — only emitted when allow_fiat is on so
    # clients can branch the buy UI without re-reading the schema.
    if event.allow_fiat:
        tags.append(["tickets_allow_fiat", "true"])
        if event.fiat_currency:
            tags.append(["tickets_fiat_currency", event.fiat_currency])

    nostr_event = NostrEvent(
        pubkey=pubkey,
        created_at=int(time.time()),
        kind=kind,
        tags=tags,
        content=event.info or "",
    )
    nostr_event.id = nostr_event.event_id
    return nostr_event


def build_nip52_delete_event(event: Event, pubkey: str) -> NostrEvent:
    """
    Build a kind 5 delete event for a published NIP-52 calendar event.

    Uses an 'a' tag to reference the parameterized replaceable event per
    NIP-09. The referenced kind must match what we published — 31923 for
    time-based events, 31922 for date-only.
    """
    referenced_kind = 31923 if _has_time(event.event_start_date) else 31922
    nostr_event = NostrEvent(
        pubkey=pubkey,
        created_at=int(time.time()),
        kind=5,
        tags=[
            ["a", f"{referenced_kind}:{pubkey}:{event.id}"],
        ],
        content="Event canceled",
    )
    nostr_event.id = nostr_event.event_id
    return nostr_event


async def publish_event_to_nostr(
    nostr_client,
    event: Event,
    signer: NostrSigner,
    delete: bool = False,
) -> NostrEvent | None:
    """
    Build, sign, and publish a NIP-52 calendar event (or delete event).

    Signing routes through the core `NostrSigner` abstraction —
    `signer.pubkey` for the event identity, `await signer.sign_event(...)`
    for the Schnorr signature. The signer backend (LocalSigner /
    RemoteBunkerSigner) is transparent to this function.

    Returns the published NostrEvent for metadata storage, or None on failure.
    """
    if not nostr_client:
        logger.debug("[EVENTS] No NostrClient available, skipping publish")
        return None

    try:
        if delete:
            nostr_event = build_nip52_delete_event(event, signer.pubkey)
        else:
            nostr_event = build_nip52_event(event, signer.pubkey)

        # Hand the unsigned event to the signer — it fills in `id`,
        # `pubkey`, and `sig`. The signer's serialization rules match
        # NIP-01 (same as the local `event_id` property uses), so the
        # returned id matches what we'd have computed locally.
        unsigned = {
            "kind": nostr_event.kind,
            "created_at": nostr_event.created_at,
            "tags": nostr_event.tags,
            "content": nostr_event.content,
        }
        signed = await signer.sign_event(unsigned)
        nostr_event.id = signed["id"]
        nostr_event.pubkey = signed["pubkey"]
        nostr_event.sig = signed["sig"]

        await nostr_client.publish_nostr_event(nostr_event)

        logger.info(
            f"[EVENTS] Published NIP-52 {'delete' if delete else 'calendar'} "
            f"event: {nostr_event.id[:16]}... (kind {nostr_event.kind})"
        )
        return nostr_event

    except Exception as e:
        logger.warning(f"[EVENTS] Failed to publish to Nostr: {e}")
        return None