import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';

import 'package:aves/model/source/collection_source.dart';
import 'package:aves/remote/remote_settings.dart';
import 'package:aves/remote/remote_sync_bus.dart';
import 'package:aves/remote/remote_repository.dart';
import 'package:aves/services/common/services.dart';
import 'package:aves/remote/remote_client.dart';
import 'package:aves/remote/auth_client.dart';
import 'package:aves/remote/collection_source_remote_ext.dart';

class RemoteController {
  RemoteController._();
  static final RemoteController instance = RemoteController._();

  static const _kBootstrapDone = 'remote_bootstrap_done';
  bool _syncInFlight = false;

  Future<bool> bootstrapDone() async {
    final storage = FlutterSecureStorage();
    return (await storage.read(key: _kBootstrapDone)) == '1';
  }

  Future<void> _setBootstrapDone() async {
    final storage = FlutterSecureStorage();
    await storage.write(key: _kBootstrapDone, value: '1');
  }

  /// Chiamare all’avvio: imposta lo stato icona (grigio/verde) coerente con settings.
  Future<void> initBusFromSettings() async {
    final s = await RemoteSettings.load();
    if (!s.enabled) {
      RemoteSyncBus.instance.setDisabled();
    } else {
      // enabled: stato iniziale "upToDate" (poi la sync può cambiare)
      final opId = RemoteSyncBus.instance.start(total: 0, showOverlay: false);
      RemoteSyncBus.instance.finishUpToDate(opId: opId);
    }
  }

  /// Logica d’avvio app:
  /// - se remote OFF -> nascondi remoti dalla UI (memoria only) e stop
  /// - se remote ON:
  ///   - se bootstrap done -> append DB immediato + sync silenzioso
  ///   - se bootstrap NOT done -> opzionale resume bootstrap
  Future<void> onAppStart({
    required CollectionSource source,
    bool resumeBootstrapIfEnabled = true,
  }) async {
    final s = await RemoteSettings.load();

    if (!s.enabled) {
      RemoteSyncBus.instance.setDisabled();
      final remotesInMemory = source.allEntries.where((e) => e.origin == 1).toSet();
      if (remotesInMemory.isNotEmpty) {
        source.removeEntriesFromMemory(remotesInMemory);
      }
      return;
    }

    final done = await bootstrapDone();
    if (done) {
      await source.appendRemoteEntriesFromDb();
      // sync in background (solo icona)
      unawaited(fullSync(source: source, showOverlay: false));
    } else {
      if (resumeBootstrapIfEnabled) {
        unawaited(fullSync(
          source: source,
          showOverlay: true,
          markBootstrapDoneOnSuccess: true,
        ));
      }
    }
  }

  /// Toggle da icona (tap)
  Future<void> toggleRemote({required CollectionSource source}) async {
    final s = await RemoteSettings.load();

    if (s.enabled) {
      // TURN OFF
      final upd = RemoteSettings(
        enabled: false,
        baseUrl: s.baseUrl,
        indexPath: s.indexPath,
        email: s.email,
        password: s.password,
      );
      await upd.save();

      debugPrint('[remote] toggle -> enabled=false (OFF)');

      // nascondi remoti (memoria only)
      final remotesInMemory = source.allEntries.where((e) => e.origin == 1).toSet();
      if (remotesInMemory.isNotEmpty) {
        source.removeEntriesFromMemory(remotesInMemory);
      }

      // invalida sync in corso e icona grigia
      RemoteSyncBus.instance.setDisabled();
      debugPrint('[remote] toggled OFF -> removed remotes from memory=${remotesInMemory.length}');
      return;
    }

    // TURN ON
    final upd = RemoteSettings(
      enabled: true,
      baseUrl: s.baseUrl,
      indexPath: s.indexPath,
      email: s.email,
      password: s.password,
    );
    await upd.save();

    debugPrint('[remote] toggle -> enabled=true (ON)');

    final first = !(await bootstrapDone());
    if (first) {
      debugPrint('[remote] first enable -> FULL sync with overlay');
      await fullSync(
        source: source,
        showOverlay: true,
        markBootstrapDoneOnSuccess: true,
      );
      return;
    }

    debugPrint('[remote] enable -> append DB then background sync');
    await source.appendRemoteEntriesFromDb();
    unawaited(fullSync(source: source, showOverlay: false));
  }

  /// Full sync remoto:
  /// - showOverlay=true solo bootstrap
  /// - showOverlay=false -> solo icona
  Future<void> fullSync({
    required CollectionSource source,
    required bool showOverlay,
    bool markBootstrapDoneOnSuccess = false,
  }) async {
    if (_syncInFlight) {
      debugPrint('[remote] sync skipped (already in flight)');
      return;
    }
    _syncInFlight = true;

    final s = await RemoteSettings.load();
    if (!s.enabled) {
      RemoteSyncBus.instance.setDisabled();
      _syncInFlight = false;
      return;
    }

    // Start: token opId (protezione anti-race)
    final opId = RemoteSyncBus.instance.start(total: 0, showOverlay: showOverlay);

    try {
      // base URL vuota -> server down
      if (s.baseUrl.trim().isEmpty) {
        debugPrint('[remote] serverDown (empty baseUrl)');
        RemoteSyncBus.instance.failServerDown(opId: opId);
        return;
      }

      RemoteAuth? auth;
      if (s.email.isNotEmpty && s.password.isNotEmpty) {
        auth = RemoteAuth(baseUrl: s.baseUrl, email: s.email, password: s.password);
      }

      final client = RemoteJsonClient(s.baseUrl, s.indexPath, auth: auth);

      // fetch full list
      final items = await client.fetchAll().timeout(const Duration(seconds: 30));
      final total = items.length;

      debugPrint('[remote] sync start overlay=$showOverlay total=$total');

      // aggiorna total corretto
      RemoteSyncBus.instance.update(opId: opId, done: 0, total: total);

      final repo = RemoteRepository(localMediaDb.rawDb);
      await repo.deleteAllRemotes();

      const chunkSize = 200;
      int done = 0;
      final serverIds = items.map((e) => e.id).where((v) => v.isNotEmpty).toSet();

      for (var offset = 0; offset < total; offset += chunkSize) {
        final end = (offset + chunkSize < total) ? offset + chunkSize : total;
        await repo.upsertAll(items.sublist(offset, end), chunkSize: chunkSize);
        done = end;
        RemoteSyncBus.instance.update(opId: opId, done: done, total: total);
      }

      await repo.pruneMissingRemotes(serverIds);

      // mostra remoti in UI (dopo sync)
      await source.appendRemoteEntriesFromDb();

      debugPrint('[remote] sync done');

      if (markBootstrapDoneOnSuccess) {
        await _setBootstrapDone();
      }

      RemoteSyncBus.instance.finishUpToDate(opId: opId);
    } on TimeoutException {
      debugPrint('[remote] serverDown (timeout)');
      RemoteSyncBus.instance.failServerDown(opId: opId);
    } catch (e) {
      debugPrint('[remote] serverDown (error=$e)');
      RemoteSyncBus.instance.failServerDown(opId: opId);
    } finally {
      _syncInFlight = false;
    }
  }
}