import 'dart:async';

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

/// Official Google TEST ad unit ids. ALWAYS used outside release builds —
/// tapping your own real ad unit during development/testing is invalid
/// traffic and AdMob suspends accounts for it, so this is not optional.
const bannerAdUnitIdPrueba = 'ca-app-pub-3940256099942544/6300978111';
const interstitialAdUnitIdPrueba = 'ca-app-pub-3940256099942544/1033173712';

/// Real banner unit id, provisioned in the AdMob console (iap-freemium-unlock).
const _bannerAdUnitIdReal = 'ca-app-pub-6038935671414339/5658618378';

/// Real interstitial unit id, provisioned in the AdMob console (iap-freemium-unlock).
const _interstitialAdUnitIdReal = 'ca-app-pub-6038935671414339/4189478248';

/// TESTING-PHASE SWITCH. While `true`, release builds serve Google's official
/// TEST ad units instead of the real ones, so none of the closed-testing
/// human testers can generate invalid traffic against the AdMob account
/// (they cannot be registered as AdMob test devices). Flip to `false` for
/// the production release — that is the ONLY change needed to start serving
/// real ads. This does NOT affect the AdMob application id in
/// `AndroidManifest.xml`, which stays real in every build (it only
/// initializes the SDK and carries none of the click risk).
const usarAnunciosDePruebaEnRelease = true;

/// Real id in release builds only, and only once [usarAnunciosDePruebaEnRelease]
/// is flipped to `false`; test id everywhere else (debug/profile, including
/// internal-testing-track builds run via `flutter run --release` on a
/// personal device — see the "never tap your own ads" note above).
const bannerAdUnitId =
    kReleaseMode && !usarAnunciosDePruebaEnRelease
        ? _bannerAdUnitIdReal
        : bannerAdUnitIdPrueba;
const interstitialAdUnitId =
    kReleaseMode && !usarAnunciosDePruebaEnRelease
        ? _interstitialAdUnitIdReal
        : interstitialAdUnitIdPrueba;

/// 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({
    required bool Function() esPremium,
    DateTime Function()? ahora,
    Future<bool> Function()? mostrarInterstitialImpl,
    Duration? timeoutIntentoInterstitial,
  }) : _esPremium = esPremium,
       _ahora = ahora ?? DateTime.now,
       _mostrarInterstitialImpl =
           mostrarInterstitialImpl ?? _mostrarInterstitialAdMob,
       _timeoutIntentoInterstitial =
           timeoutIntentoInterstitial ?? timeoutIntentoInterstitialPorDefecto;

  /// 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);

  /// FIX 2 (code review): bounds `InterstitialAd.load`'s callback wait
  /// inside [_mostrarInterstitialAdMob] so a load callback that never fires
  /// cannot hang a caller — every call site (`pantalla_alarmas.dart`,
  /// `pantalla_favoritos.dart`,
  /// `ajustes/pantalla_ajustes_emisoras_personalizadas.dart`) `await`s
  /// [intentarInterstitial] before opening its form.
  static const timeoutCargaInterstitialPorDefecto = Duration(seconds: 5);

  /// FIX 2 (code review): bounds the wait for the ad to actually PRESENT
  /// (`onAdShowedFullScreenContent`) or fail
  /// (`onAdFailedToShowFullScreenContent`) after `show()`. This method
  /// deliberately never waits for the ad to be DISMISSED — the caller is
  /// not blocked on ad dismissal at all, only on the ad actually rendering.
  static const timeoutPresentacionInterstitialPorDefecto = Duration(seconds: 5);

  /// FIX 2 (code review): the overall bound applied around the INJECTED
  /// [_mostrarInterstitialImpl] itself (production default: the sum of the
  /// two timeouts above, plus headroom) — so ANY implementation, including
  /// a future bug in an injected fake or a different ad SDK, can never hang
  /// a caller indefinitely. Injectable so tests can use a short value.
  static const timeoutIntentoInterstitialPorDefecto = Duration(seconds: 15);

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

  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;
    // FIX 2 (code review): bound the injected implementation itself — no
    // caller may ever await this indefinitely, regardless of what
    // [_mostrarInterstitialImpl] does internally. A timeout is treated
    // exactly like "no ad shown": `false`, cap not consumed.
    final mostrado = await _mostrarInterstitialImpl().timeout(
      _timeoutIntentoInterstitial,
      onTimeout: () => false,
    );
    if (mostrado) {
      _mostrados++;
      _ultimoMostrado = _ahora();
    }
    return mostrado;
  }

  static Future<bool> _mostrarInterstitialAdMob() async {
    try {
      final cargaCompleter = Completer<InterstitialAd?>();
      // FIX 2 (code review): a load callback that never fires used to hang
      // this await forever. `expiradoCarga` guards a LATE callback that
      // still arrives after the timeout — the ad is disposed instead of
      // leaked, and never completes the already-abandoned completer.
      var expiradoCarga = false;
      await InterstitialAd.load(
        adUnitId: interstitialAdUnitId,
        request: const AdRequest(),
        adLoadCallback: InterstitialAdLoadCallback(
          onAdLoaded: (ad) {
            if (expiradoCarga) {
              ad.dispose();
              return;
            }
            if (!cargaCompleter.isCompleted) cargaCompleter.complete(ad);
          },
          onAdFailedToLoad: (error) {
            debugPrint('[PluriWave][anuncios] interstitial load ERROR $error');
            if (!cargaCompleter.isCompleted) cargaCompleter.complete(null);
          },
        ),
      );
      final InterstitialAd? cargado;
      try {
        cargado = await cargaCompleter.future.timeout(
          timeoutCargaInterstitialPorDefecto,
        );
      } on TimeoutException {
        expiradoCarga = true;
        return false;
      }
      if (cargado == null) return false;

      // FIX 6 (code review): only a genuinely PRESENTED ad may consume the
      // session cap. `onAdFailedToShowFullScreenContent` used to complete
      // the same completer as a real dismissal and the method returned
      // `true` unconditionally — a failed-to-show ad silently burned one of
      // only 2 session slots.
      //
      // FIX 2 (code review): this method no longer waits for the ad to be
      // DISMISSED at all — only for it to PRESENT or fail to present — and
      // that wait is itself bounded, so a `fullScreenContentCallback` that
      // never fires cannot hang the caller either. `expiradoPresentacion`
      // guards a late callback the same way `expiradoCarga` does above.
      var expiradoPresentacion = false;
      final presentacionCompleter = Completer<bool>();
      cargado.fullScreenContentCallback = FullScreenContentCallback(
        onAdShowedFullScreenContent: (ad) {
          if (!presentacionCompleter.isCompleted) {
            presentacionCompleter.complete(true);
          }
        },
        onAdDismissedFullScreenContent: (ad) {
          ad.dispose();
        },
        onAdFailedToShowFullScreenContent: (ad, error) {
          if (expiradoPresentacion) {
            ad.dispose();
            return;
          }
          ad.dispose();
          if (!presentacionCompleter.isCompleted) {
            presentacionCompleter.complete(false);
          }
        },
      );
      await cargado.show();
      try {
        return await presentacionCompleter.future.timeout(
          timeoutPresentacionInterstitialPorDefecto,
        );
      } on TimeoutException {
        expiradoPresentacion = true;
        await cargado.dispose();
        return false;
      }
    } catch (e) {
      debugPrint('[PluriWave][anuncios] interstitial ERROR $e');
      return false;
    }
  }
}