import 'dart:async';

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

/// TODO(ads): official Google TEST ad unit ids — AdMob has not provisioned
/// real ones yet (design.md Open Questions). Swap these for the real banner
/// / interstitial unit ids once available; never ship the test ids to
/// production.
const bannerAdUnitIdPrueba = 'ca-app-pub-3940256099942544/6300978111';
const interstitialAdUnitIdPrueba = 'ca-app-pub-3940256099942544/1033173712';

/// Ads port + AdMob adapter (Design "Interfaces / Contracts", ADR-6): owns
/// the entitlement gate for both surfaces, the interstitial's session
/// frequency cap, and is the ONLY `google_mobile_ads` call site besides
/// `banner_anuncio_superior.dart`'s `BannerAd` widget wrapper. The frequency
/// cap and premium gating are pure/injectable (`ahora`,
/// `mostrarInterstitialImpl`) so they are unit-testable with a fake clock
/// and zero AdMob platform channels (Design Testing Strategy).
class ServicioAnuncios {
  ServicioAnuncios({
    bool Function()? esPremium,
    DateTime Function()? ahora,
    Future<bool> Function()? mostrarInterstitialImpl,
  }) : _esPremium = esPremium ?? (() => false),
       _ahora = ahora ?? DateTime.now,
       _mostrarInterstitialImpl =
           mostrarInterstitialImpl ?? _mostrarInterstitialAdMob;

  /// Session-scoped cap (ad-display spec "Interstitial Frequency Cap"): at
  /// most 2 interstitials per process lifetime.
  static const maxInterstitialsPorSesion = 2;

  /// Minimum spacing between two interstitials (ad-display spec, same
  /// requirement).
  static const separacionMinima = Duration(minutes: 3);

  final bool Function() _esPremium;
  final DateTime Function() _ahora;
  final Future<bool> Function() _mostrarInterstitialImpl;

  int _mostrados = 0;
  DateTime? _ultimoMostrado;

  /// Ad-display spec "Persistent Top Banner": absent entirely for premium.
  bool get debeMostrarBanner => !_esPremium();

  bool _dentroDelCap() {
    if (_esPremium()) return false;
    if (_mostrados >= maxInterstitialsPorSesion) return false;
    final ultimo = _ultimoMostrado;
    if (ultimo != null && _ahora().difference(ultimo) < separacionMinima) {
      return false;
    }
    return true;
  }

  /// Attempts to show an interstitial for one of the two allowed CTAs (add
  /// station manually, add alarm). Callers are responsible for the ADR-6
  /// ordering invariant themselves (cap-check-before-interstitial for
  /// add-alarm, so a refusal is never preceded by an ad) — this method only
  /// owns entitlement + frequency-cap gating, never the caller's own
  /// business-rule ordering.
  ///
  /// Returns whether an interstitial actually rendered. A failed/aborted ad
  /// load (network, no fill) does NOT consume the session cap — only a
  /// genuinely SHOWN ad does (Spec intent: the cap limits driver-facing
  /// interruptions, not load attempts).
  Future<bool> intentarInterstitial() async {
    if (!_dentroDelCap()) return false;
    final mostrado = await _mostrarInterstitialImpl();
    if (mostrado) {
      _mostrados++;
      _ultimoMostrado = _ahora();
    }
    return mostrado;
  }

  static Future<bool> _mostrarInterstitialAdMob() async {
    try {
      final cargaCompleter = Completer<InterstitialAd?>();
      await InterstitialAd.load(
        adUnitId: interstitialAdUnitIdPrueba,
        request: const AdRequest(),
        adLoadCallback: InterstitialAdLoadCallback(
          onAdLoaded: (ad) {
            if (!cargaCompleter.isCompleted) cargaCompleter.complete(ad);
          },
          onAdFailedToLoad: (error) {
            debugPrint('[PluriWave][anuncios] interstitial load ERROR $error');
            if (!cargaCompleter.isCompleted) cargaCompleter.complete(null);
          },
        ),
      );
      final cargado = await cargaCompleter.future;
      if (cargado == null) return false;

      final cierreCompleter = Completer<void>();
      cargado.fullScreenContentCallback = FullScreenContentCallback(
        onAdDismissedFullScreenContent: (ad) {
          ad.dispose();
          if (!cierreCompleter.isCompleted) cierreCompleter.complete();
        },
        onAdFailedToShowFullScreenContent: (ad, error) {
          ad.dispose();
          if (!cierreCompleter.isCompleted) cierreCompleter.complete();
        },
      );
      await cargado.show();
      await cierreCompleter.future;
      return true;
    } catch (e) {
      debugPrint('[PluriWave][anuncios] interstitial ERROR $e');
      return false;
    }
  }
}