/// The four (well, five) reciprocity modes from sharing-model.md §3, plus the
/// generic `lend` the core reserves for the future "library of things".
enum OfferType { gift, exchange, sale, wanted, lend }

enum OfferStatus { active, reserved, closed }

/// A publishable offer — the "shop window", deliberately DECOUPLED from Lot /
/// inventory (sharing-model.md §2, core-domain-boundary.md §4.3).
///
/// It carries only a chosen, denormalised *summary* of what's offered — never a
/// foreign key into the seed tables, never the full inventory, never an exact
/// address. This is the privacy seam: the core can publish and sync offers
/// WITHOUT understanding seeds. Everything here is what the person elected to
/// reveal.
class Offer {
  const Offer({
    required this.id,
    required this.authorPubkeyHex,
    required this.summary,
    required this.type,
    required this.approxGeohash,
    this.status = OfferStatus.active,
    this.category,
    this.priceAmount,
    this.priceCurrency,
    this.exchangeTerms,
    this.radiusKm,
    this.imageUrl,
    this.expiresAt,
  });

  /// Stable per-offer identifier (NIP-99 `d` tag → addressable event).
  final String id;

  /// The publishing identity (BIP340 x-only pubkey hex). Derived, per Q1.
  final String authorPubkeyHex;

  /// Human summary the author chose to publish (e.g. "Tomate rosa de Barbastro").
  final String summary;

  final OfferType type;
  final OfferStatus status;

  /// Free-text category, prefilled in-app from Species.family but opaque here.
  final String? category;

  /// LOW-PRECISION geohash only (sharing-model.md §2: "10 km near you", never
  /// exact coordinates). The spike enforces a max length in the transport.
  final String approxGeohash;
  final int? radiusKm;

  final num? priceAmount; // only for sale
  final String? priceCurrency; // ISO 4217 or a community currency (e.g. "G1")
  final String? exchangeTerms; // only for exchange

  final String? imageUrl;
  final DateTime? expiresAt;
}

/// Result of publishing to a transport.
class PublishResult {
  const PublishResult({
    required this.accepted,
    required this.transportRef,
    this.message = '',
  });

  /// Whether the relay/instance accepted the event.
  final bool accepted;

  /// The transport-side id (Nostr event id / ActivityPub object id).
  final String transportRef;
  final String message;
}

/// A discovery query: coarse location + optional facets. Note there is NO way to
/// ask for "everything from person X's inventory" — you can only browse the
/// public shop window by area and kind.
class DiscoveryQuery {
  const DiscoveryQuery({
    required this.geohashPrefix,
    this.types = const {},
    this.limit = 100,
  });

  /// Coarse geohash prefix to search near (e.g. "u09" ≈ tens of km).
  final String geohashPrefix;
  final Set<OfferType> types;
  final int limit;
}