import 'dart:async';

import 'package:flutter/foundation.dart';

import 'package:sxchnge_analytics/sxchnge_analytics.dart';

import '../models/wallet.dart';
import '../services/contracts.dart';

class WalletProvider extends ChangeNotifier {
  WalletProvider(this.service, this.analytics);
  final WalletService service;
  final AnalyticsService analytics;
  WalletSnapshot? data;
  bool loading = false,
      failed = false,
      profileLoading = false,
      profileFailed = false,
      saving = false,
      saveFailed = false;
  String? preferredLocale;
  bool _disposed = false;
  int _revision = 0;
  Timer? _poll;
  final _settlements = <String, (JourneyRecorder, JourneyOperation)>{};
  CurrencyAccount? account(String? id) {
    for (final a in data?.accounts ?? <CurrencyAccount>[]) {
      if (a.id == id) return a;
    }
    return null;
  }

  WalletOperation? operation(String id) {
    for (final o in data?.operations ?? <WalletOperation>[]) {
      if (o.id == id) return o;
    }
    return null;
  }

  bool get hasPending =>
      data?.operations.any((o) => o.status == OperationStatus.pending) ?? false;
  Future<void> refresh() async {
    final rev = ++_revision;
    loading = true;
    failed = false;
    notifyListeners();
    try {
      final result = await service.fetch();
      if (_disposed || rev != _revision) return;
      data = result;
      for (final o in result.operations) {
        if (o.status == OperationStatus.pending) continue;
        final pair = _settlements.remove(o.id);
        if (pair != null) {
          pair.$1.finish(
            pair.$2,
            simulated: service.isSimulated,
            failure: o.status == OperationStatus.failed
                ? JourneyFailure.declined
                : null,
            terminal: true,
          );
          pair.$1.dispose();
        }
      }
    } catch (_) {
      if (_disposed || rev != _revision) return;
      failed = true;
    }
    if (_disposed || rev != _revision) return;
    loading = false;
    _poll?.cancel();
    if (hasPending) {
      _poll = Timer(const Duration(seconds: 3), () {
        if (!_disposed) refresh();
      });
    }
    notifyListeners();
  }

  void track(
    WalletOperation operation,
    JourneyRecorder recorder,
    JourneyKind kind,
  ) {
    final step = recorder.begin(
      kind,
      JourneyStep.settlement,
      simulated: service.isSimulated,
    );
    _settlements[operation.id] = (recorder, step);
    final snapshot = data;
    if (snapshot != null) {
      data = WalletSnapshot(
        accounts: snapshot.accounts,
        operations: [
          operation,
          ...snapshot.operations.where((o) => o.id != operation.id),
        ],
      );
    }
    unawaited(refresh());
  }

  Future<void> loadProfile() async {
    if (profileLoading) return;
    profileLoading = true;
    profileFailed = false;
    notifyListeners();
    try {
      final result = await service.profile();
      if (_disposed) return;
      preferredLocale = result.locale;
    } catch (_) {
      if (_disposed) return;
      profileFailed = true;
    }
    profileLoading = false;
    notifyListeners();
  }

  Future<bool> saveLocale(String locale) async {
    if (saving) return false;
    saving = true;
    saveFailed = false;
    notifyListeners();
    try {
      final result = await service.saveLocale(locale);
      if (_disposed) return false;
      preferredLocale = result.locale;
    } catch (_) {
      if (_disposed) return false;
      saveFailed = true;
    }
    saving = false;
    notifyListeners();
    return !saveFailed;
  }

  @override
  void dispose() {
    _disposed = true;
    _poll?.cancel();
    for (final p in _settlements.values) {
      p.$1.dispose(abandonActive: false);
    }
    _settlements.clear();
    super.dispose();
  }
}