restaurant/nostr_publisher.py

"""
Nostr publishing for the restaurant extension.

Three event types are published:

  1. Restaurant profile  → kind 0    (NIP-01 metadata)
  2. Menu items          → kind 30402 (NIP-99 classified listing,
                                       parameterized replaceable)
  3. Deletions           → kind 5    (NIP-09 deletion request)

Customer-facing webapps subscribe to a restaurant's pubkey to assemble
its menu in real time. Festivals / collective spaces are external curated
lists (NIP-51) that simply enumerate restaurant pubkeys; the extension
itself has no awareness of festivals.

Signing
-------
Events are signed with the *restaurant's* keypair if `restaurant.nostr_pubkey`
is set, otherwise with the LNbits Account keypair of the wallet's owner.
This lets a single LNbits account host multiple restaurants under
distinct Nostr identities, while keeping a sane default for owners
who don't care about identity separation.
"""

import json
import re
import time
from typing import Optional

import coincurve
from loguru import logger

from .models import MenuItem, Restaurant
from .nostr.event import NostrEvent


_SLUG_NON_ALNUM = re.compile(r"[^a-z0-9]+")


def _slugify(name: str) -> str:
    """
    Convert a node name to a lowercase ASCII slug suitable for the
    Nostr `t` (hashtag) tag. Relays and clients filter on `#t` values
    by exact match, so 'Hot Beverages' must become 'hot-beverages'
    for the filter `{"#t": ["hot-beverages"]}` to find it.

    Best-effort:
      * Lowercase
      * Replace any run of non-alphanumeric characters with '-'
      * Strip leading/trailing dashes
      * Empty / whitespace-only input returns ''
    """
    s = (name or "").strip().lower()
    s = _SLUG_NON_ALNUM.sub("-", s)
    s = s.strip("-")
    return s


# --------------------------------------------------------------------- #
# Builders                                                              #
# --------------------------------------------------------------------- #


def build_restaurant_metadata_event(restaurant: Restaurant, pubkey: str) -> NostrEvent:
    """
    Build a kind 0 (NIP-01 metadata) event for a restaurant profile.

    `content` is a JSON object with the canonical metadata fields
    (`name`, `about`, `picture`, `banner`, `website`, ...).
    """
    content = {
        "name": restaurant.name,
        "display_name": restaurant.name,
        "about": restaurant.description or "",
    }
    if restaurant.logo_url:
        content["picture"] = restaurant.logo_url
    if restaurant.banner_url:
        content["banner"] = restaurant.banner_url
    if restaurant.social_links.website:
        content["website"] = restaurant.social_links.website

    tags: list[list[str]] = [["t", "restaurant"]]
    if restaurant.location:
        tags.append(["location", restaurant.location])
    if restaurant.geohash:
        tags.append(["g", restaurant.geohash])

    nostr_event = NostrEvent(
        pubkey=pubkey,
        created_at=int(time.time()),
        kind=0,
        tags=tags,
        content=json.dumps(content, separators=(",", ":"), ensure_ascii=False),
    )
    nostr_event.id = nostr_event.event_id
    return nostr_event


def build_menu_item_event(
    item: MenuItem,
    restaurant: Restaurant,
    pubkey: str,
    *,
    ancestor_names: tuple[str, ...] = (),
) -> NostrEvent:
    """
    Build a NIP-99 classified listing (kind 30402) for a menu item.

    Tags
    ----
      d         item.id (addressable identifier — replaceable per NIP-33)
      title     item.name
      summary   item.description (truncated, optional)
      price     [price, "<amount>", "<currency>"]
      image     each entry in item.images
      t         "menu", each ancestor node name (slugified, root-first),
                each dietary tag, each allergen (prefixed `allergen:`),
                each ingredient (prefixed `ingr:`)
      l         "restaurant:<restaurant.id>" (link back to the operator)
      location  restaurant.location (if set)
      g         restaurant.geohash (if set)
      status    "active" | "sold" (NIP-99 standard) — sold-out state

    `ancestor_names` is the chain of node names from the root down to
    (and including) the item's own node, e.g.
        ("Drinks", "Hot Beverages", "Coffee-based")
    Each is slugified to lowercase ASCII so `#t=hot-beverages` filters
    work cleanly. Caller (views_api._publish_menu_item) walks the
    materialized path; this builder stays DB-free.

    Content is markdown — currently `item.description`; can be expanded
    later to include rich allergen/ingredient blocks.
    """
    price_currency = (item.currency or "sat").upper()
    tags: list[list[str]] = [
        ["d", item.id],
        ["title", item.name],
        ["price", f"{item.price:g}", price_currency],
        ["l", f"restaurant:{restaurant.id}"],
        ["t", "menu"],
    ]
    if item.description:
        tags.append(["summary", item.description[:140]])
    for img in item.images or []:
        tags.append(["image", img])
    # Ancestor categories — slugified, deduped, root-first.
    seen_slugs: set[str] = set()
    for ancestor in ancestor_names:
        slug = _slugify(ancestor)
        if slug and slug not in seen_slugs:
            seen_slugs.add(slug)
            tags.append(["t", slug])
    for diet in item.dietary or []:
        tags.append(["t", diet])
    for allergen in item.allergens or []:
        tags.append(["t", f"allergen:{allergen}"])
    for ingredient in item.ingredients or []:
        tags.append(["t", f"ingr:{ingredient}"])
    if restaurant.location:
        tags.append(["location", restaurant.location])
    if restaurant.geohash:
        tags.append(["g", restaurant.geohash])

    sold_out = item.stock is not None and item.stock <= 0
    tags.append(["status", "sold" if sold_out or not item.is_available else "active"])

    content = item.description or item.name

    nostr_event = NostrEvent(
        pubkey=pubkey,
        created_at=int(time.time()),
        kind=30402,
        tags=tags,
        content=content,
    )
    nostr_event.id = nostr_event.event_id
    return nostr_event


def build_delete_event(
    addressable_kind: int, identifier: str, pubkey: str, reason: str = ""
) -> NostrEvent:
    """
    Build a NIP-09 deletion request (kind 5) for a parameterized
    replaceable event. `addressable_kind` is the kind of the target
    (e.g. 30402 for a menu item) and `identifier` is the `d`-tag.
    """
    nostr_event = NostrEvent(
        pubkey=pubkey,
        created_at=int(time.time()),
        kind=5,
        tags=[["a", f"{addressable_kind}:{pubkey}:{identifier}"]],
        content=reason,
    )
    nostr_event.id = nostr_event.event_id
    return nostr_event


# --------------------------------------------------------------------- #
# Signing + publishing                                                  #
# --------------------------------------------------------------------- #


def sign_nostr_event(nostr_event: NostrEvent, private_key_hex: str) -> None:
    """Schnorr-sign a NostrEvent in place (BIP-340)."""
    privkey = coincurve.PrivateKey(bytes.fromhex(private_key_hex))
    sig = privkey.sign_schnorr(bytes.fromhex(nostr_event.id))
    nostr_event.sig = sig.hex()


async def publish_event(
    nostr_client,
    nostr_event: NostrEvent,
    private_key_hex: str,
) -> Optional[NostrEvent]:
    """Sign and publish a built NostrEvent. Returns the event on success
    so callers can persist its id + created_at, or None on failure."""
    if not nostr_client:
        logger.debug("[RESTAURANT] No NostrClient; skipping publish")
        return None
    try:
        sign_nostr_event(nostr_event, private_key_hex)
        await nostr_client.publish_nostr_event(nostr_event)
        logger.info(
            f"[RESTAURANT] Published kind {nostr_event.kind} "
            f"event {nostr_event.id[:16]}..."
        )
        return nostr_event
    except Exception as e:
        logger.warning(f"[RESTAURANT] Failed to publish: {e}")
        return None