import 'dart:async';

import 'package:flutter/foundation.dart' show debugPrint;
import 'package:in_app_purchase/in_app_purchase.dart';

/// Outcome kinds the purchase stream can report (Design ADR-2). Mirrors
/// `in_app_purchase`'s [PurchaseStatus] but stays a PluriWave-owned type so
/// [EstadoEntitlement] never imports the plugin package directly — the SAME
/// port-boundary discipline `PuertoAlarmasAndroid` already applies.
enum TipoEventoCompra {
  /// A fresh purchase completed successfully.
  comprada,

  /// [PuertoCompras.restaurar] found a prior purchase.
  restaurada,

  /// The user cancelled the purchase flow before it completed.
  cancelada,

  /// The purchase/restore flow failed (network, billing error, etc).
  error,

  /// [PuertoCompras.restaurar] completed with nothing to restore — NOT an
  /// error (Spec "Restore finds nothing").
  noEncontrada,

  /// A purchase is in-flight (billing dialog shown, awaiting the user).
  pendiente,
}

/// A single purchase-stream event (Design ADR-2). [mensaje] is populated
/// only for [TipoEventoCompra.error], for diagnostics/logging — never shown
/// to the user verbatim.
class EventoCompra {
  const EventoCompra(this.tipo, {this.mensaje});

  final TipoEventoCompra tipo;
  final String? mensaje;
}

/// Purchase I/O abstraction (Design ADR-2): [EstadoEntitlement] depends on
/// this port, never on `in_app_purchase` directly — matches
/// `EstadoAlarmas(android: PuertoAlarmasAndroid)`'s injection shape, and
/// keeps Strict TDD viable with zero plugin channels in unit tests.
abstract class PuertoCompras {
  /// Broadcasts every purchase-flow outcome (Design ADR-2) — [comprar] and
  /// [restaurar] do not return the outcome directly because
  /// `in_app_purchase`'s own API is stream-based (a purchase can complete
  /// asynchronously well after the call that started it, e.g. after leaving
  /// and returning to the app).
  Stream<EventoCompra> get eventos;

  /// Starts the one-time non-consumable purchase flow.
  Future<void> comprar();

  /// Re-queries Play Billing for a prior purchase on this account.
  Future<void> restaurar();
}

/// The SOLE `in_app_purchase` call site (Design ADR-2) — every other file
/// depends on [PuertoCompras] instead.
class ServicioComprasPlayBilling implements PuertoCompras {
  ServicioComprasPlayBilling({InAppPurchase? inAppPurchase})
    : _iap = inAppPurchase ?? InAppPurchase.instance {
    _sub = _iap.purchaseStream.listen(
      _alRecibirCompras,
      onError: (Object error) {
        debugPrint('[PluriWave][compras] purchaseStream ERROR $error');
        _eventos.add(
          EventoCompra(TipoEventoCompra.error, mensaje: error.toString()),
        );
      },
    );
  }

  /// The single non-consumable product id (Design "Interfaces / Contracts").
  static const idProducto = 'pluriwave_premium';

  final InAppPurchase _iap;
  final _eventos = StreamController<EventoCompra>.broadcast();
  StreamSubscription<List<PurchaseDetails>>? _sub;

  @override
  Stream<EventoCompra> get eventos => _eventos.stream;

  @override
  Future<void> comprar() async {
    try {
      final disponible = await _iap.isAvailable();
      if (!disponible) {
        _eventos.add(
          const EventoCompra(
            TipoEventoCompra.error,
            mensaje: 'Play Billing no disponible',
          ),
        );
        return;
      }
      final respuesta = await _iap.queryProductDetails({idProducto});
      final detalle = respuesta.productDetails.firstOrNull;
      if (detalle == null) {
        _eventos.add(
          const EventoCompra(
            TipoEventoCompra.error,
            mensaje: 'Producto no encontrado en Play Console',
          ),
        );
        return;
      }
      final parametros = PurchaseParam(productDetails: detalle);
      await _iap.buyNonConsumable(purchaseParam: parametros);
    } catch (e) {
      debugPrint('[PluriWave][compras] comprar ERROR $e');
      _eventos.add(EventoCompra(TipoEventoCompra.error, mensaje: e.toString()));
    }
  }

  @override
  Future<void> restaurar() async {
    try {
      await _iap.restorePurchases();
    } catch (e) {
      debugPrint('[PluriWave][compras] restaurar ERROR $e');
      _eventos.add(EventoCompra(TipoEventoCompra.error, mensaje: e.toString()));
    }
  }

  void _alRecibirCompras(List<PurchaseDetails> compras) {
    if (compras.isEmpty) {
      // `restorePurchases()` with nothing to restore pushes an EMPTY batch
      // (`in_app_purchase_android` does `_purchaseUpdatedController.add(
      // pastPurchases)` unconditionally) — there is no per-call correlation
      // in this stream, so this fires on ANY empty batch. In practice
      // `restorePurchases` on an account with nothing to restore is the only
      // source of an empty batch this stream would ever emit.
      //
      // Returning silently here (as this did before) left
      // [TipoEventoCompra.noEncontrada] NEVER emitted, so
      // `EstadoEntitlement._compraEnCurso` stayed `true` forever and
      // `hoja_premium.dart` kept BOTH buttons disabled — restore AND buy.
      // A paywall that cannot be paid.
      _eventos.add(const EventoCompra(TipoEventoCompra.noEncontrada));
      return;
    }
    for (final compra in compras) {
      _eventos.add(
        eventoDesdeEstadoCompra(compra.status, mensaje: compra.error?.message),
      );
      if (compra.pendingCompletePurchase) {
        unawaited(_iap.completePurchase(compra));
      }
    }
  }

  Future<void> dispose() async {
    await _sub?.cancel();
    await _eventos.close();
  }
}

/// Pure mapping from `in_app_purchase`'s [PurchaseStatus] to the
/// PluriWave-owned [EventoCompra] (Design ADR-2's port boundary): pulled out
/// of [ServicioComprasPlayBilling] so it is unit-testable with zero plugin
/// channels, mirroring how `servicio_audio.dart` extracts its pure mapping
/// helpers (e.g. `mapearEstadoProceso`) out of the un-instantiable handler.
EventoCompra eventoDesdeEstadoCompra(PurchaseStatus status, {String? mensaje}) {
  return switch (status) {
    PurchaseStatus.pending => const EventoCompra(TipoEventoCompra.pendiente),
    PurchaseStatus.purchased => const EventoCompra(TipoEventoCompra.comprada),
    PurchaseStatus.restored => const EventoCompra(TipoEventoCompra.restaurada),
    PurchaseStatus.error => EventoCompra(
      TipoEventoCompra.error,
      mensaje: mensaje,
    ),
    PurchaseStatus.canceled => const EventoCompra(TipoEventoCompra.cancelada),
  };
}

extension<T> on List<T> {
  T? get firstOrNull => isEmpty ? null : first;
}