import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:provider/provider.dart';
import 'package:shared_preferences/shared_preferences.dart';

import 'package:fuel_tax_tracker/screens/data_settings_screen.dart';
import 'package:fuel_tax_tracker/screens/main_shell.dart';
import 'package:fuel_tax_tracker/services/app_state.dart';

/// Confirms the bottom nav actually switches between the four tabs and
/// that each one builds without crashing against a freshly-constructed,
/// not-yet-synced [AppState] — the same "no cloud connected, no vehicles
/// yet" state a real fresh install starts in.
void main() {
  testWidgets('bottom nav switches between all four tabs', (tester) async {
    final appState = AppState()..isLoading = false;

    await tester.pumpWidget(
      ChangeNotifierProvider.value(
        value: appState,
        child: const MaterialApp(home: MainShell()),
      ),
    );

    // Receipts is the default tab.
    expect(find.widgetWithText(AppBar, 'Receipts'), findsOneWidget);

    await tester.tap(find.widgetWithText(NavigationDestination, 'Vehicles'));
    await tester.pumpAndSettle();
    expect(find.widgetWithText(AppBar, 'Vehicles'), findsOneWidget);

    await tester.tap(find.widgetWithText(NavigationDestination, 'Reports'));
    await tester.pumpAndSettle();
    expect(find.widgetWithText(AppBar, 'Fuel Report'), findsOneWidget);

    await tester.tap(find.widgetWithText(NavigationDestination, 'Settings'));
    await tester.pumpAndSettle();
    expect(find.widgetWithText(AppBar, 'Settings'), findsOneWidget);

    await tester.tap(find.widgetWithText(NavigationDestination, 'Receipts'));
    await tester.pumpAndSettle();
    expect(find.widgetWithText(AppBar, 'Receipts'), findsOneWidget);
  });

  testWidgets('Receipts tab shows an empty state with no fuel entries yet', (tester) async {
    final appState = AppState()..isLoading = false;

    await tester.pumpWidget(
      ChangeNotifierProvider.value(
        value: appState,
        child: const MaterialApp(home: MainShell()),
      ),
    );

    expect(find.textContaining('No fuel entries'), findsOneWidget);
  });

  testWidgets('a right-to-left swipe on the body advances to the next tab', (tester) async {
    final appState = AppState()..isLoading = false;

    await tester.pumpWidget(
      ChangeNotifierProvider.value(
        value: appState,
        child: const MaterialApp(home: MainShell()),
      ),
    );

    expect(find.widgetWithText(AppBar, 'Receipts'), findsOneWidget);

    await tester.fling(find.byType(PageView), const Offset(-400, 0), 1000);
    await tester.pumpAndSettle();

    expect(find.widgetWithText(AppBar, 'Vehicles'), findsOneWidget);

    // And a left-to-right swipe goes back.
    await tester.fling(find.byType(PageView), const Offset(400, 0), 1000);
    await tester.pumpAndSettle();

    expect(find.widgetWithText(AppBar, 'Receipts'), findsOneWidget);
  });

  testWidgets(
      "swiping away from Receipts and back preserves its selected date range "
      '(AutomaticKeepAliveClientMixin keeping the tab alive across the PageView, '
      'not just the old IndexedStack)', (tester) async {
    final appState = AppState()..isLoading = false;

    await tester.pumpWidget(
      ChangeNotifierProvider.value(
        value: appState,
        child: const MaterialApp(home: MainShell()),
      ),
    );

    await tester.tap(find.text('Last 3 Months'));
    await tester.pumpAndSettle();

    // Swipe all the way to Settings and back.
    await tester.tap(find.widgetWithText(NavigationDestination, 'Settings'));
    await tester.pumpAndSettle();
    await tester.tap(find.widgetWithText(NavigationDestination, 'Receipts'));
    await tester.pumpAndSettle();

    final selectedLabel = tester.widget<Text>(find.text('Last 3 Months'));
    expect((selectedLabel.style?.fontWeight), FontWeight.w800, reason: 'still the active range');
  });

  group('first-launch onboarding tour', () {
    setUp(() {
      SharedPreferences.setMockInitialValues({});
    });

    Future<AppState> pumpShellWithFreshTour(WidgetTester tester) async {
      // AppState.hasSeenOnboardingTour defaults to true precisely so that
      // ad-hoc AppState() construction elsewhere (every other test in this
      // file included) doesn't trigger the tour — these tests explicitly
      // flip it to false to reproduce a real fresh install's state.
      final appState = AppState()
        ..isLoading = false
        ..hasSeenOnboardingTour = false;

      await tester.pumpWidget(
        ChangeNotifierProvider.value(
          value: appState,
          child: const MaterialApp(home: MainShell()),
        ),
      );
      await tester.pumpAndSettle();
      return appState;
    }

    testWidgets('shows step 1 (Receipts) automatically on first launch', (tester) async {
      await pumpShellWithFreshTour(tester);

      expect(find.text('Add Receipts Here'), findsOneWidget);
      expect(find.text('Step 1 of 4'), findsOneWidget);
      expect(find.widgetWithText(AppBar, 'Receipts'), findsOneWidget);
    });

    testWidgets('does not show the tour once hasSeenOnboardingTour is true', (tester) async {
      final appState = AppState()
        ..isLoading = false
        ..hasSeenOnboardingTour = true;

      await tester.pumpWidget(
        ChangeNotifierProvider.value(
          value: appState,
          child: const MaterialApp(home: MainShell()),
        ),
      );
      await tester.pumpAndSettle();

      expect(find.text('Add Receipts Here'), findsNothing);
    });

    testWidgets('tapping the dimmed barrier does not dismiss the tour or reach the highlighted button',
        (tester) async {
      await pumpShellWithFreshTour(tester);

      // Top-left corner, away from the card and from the highlighted "+"
      // (which sits top-right in the AppBar).
      await tester.tapAt(const Offset(10, 10));
      await tester.pumpAndSettle();

      expect(find.text('Add Receipts Here'), findsOneWidget, reason: 'tour still showing');
      expect(find.widgetWithText(AppBar, 'Add Vehicle'), findsNothing,
          reason: "the receipt '+' — which opens vehicle creation when there are no "
              "vehicles yet — was not actually reached");
    });

    testWidgets('Next advances through all four steps, switching tabs and pushing Settings > Data',
        (tester) async {
      await pumpShellWithFreshTour(tester);

      expect(find.text('Add Receipts Here'), findsOneWidget);
      expect(find.widgetWithText(AppBar, 'Receipts'), findsOneWidget);

      await tester.tap(find.widgetWithText(FilledButton, 'Next'));
      await tester.pumpAndSettle();
      expect(find.text('Add Vehicles Here'), findsOneWidget);
      expect(find.text('Step 2 of 4'), findsOneWidget);
      expect(find.widgetWithText(AppBar, 'Vehicles'), findsOneWidget);

      await tester.tap(find.widgetWithText(FilledButton, 'Next'));
      await tester.pumpAndSettle();
      expect(find.text('Choose a Report Date Range'), findsOneWidget);
      expect(find.widgetWithText(AppBar, 'Fuel Report'), findsOneWidget);

      await tester.tap(find.widgetWithText(FilledButton, 'Next'));
      await tester.pumpAndSettle();
      expect(find.text('Back Up to the Cloud'), findsOneWidget);
      expect(find.text('Step 4 of 4'), findsOneWidget);
      expect(find.byType(DataSettingsScreen), findsOneWidget, reason: 'tour pushed Settings > Data');
      expect(find.text('Cloud Storage'), findsOneWidget);
      expect(find.widgetWithText(FilledButton, 'Got It'), findsOneWidget,
          reason: 'last step reads "Got It", not "Next"');
    });

    testWidgets(
        'finishing on the last step pops the tour-pushed Data screen and marks the tour seen',
        (tester) async {
      final appState = await pumpShellWithFreshTour(tester);

      for (var i = 0; i < 3; i++) {
        await tester.tap(find.widgetWithText(FilledButton, 'Next'));
        await tester.pumpAndSettle();
      }
      expect(find.byType(DataSettingsScreen), findsOneWidget);

      await tester.tap(find.widgetWithText(FilledButton, 'Got It'));
      await tester.pumpAndSettle();

      expect(find.byType(DataSettingsScreen), findsNothing, reason: 'tour-pushed screen popped');
      expect(find.text('Back Up to the Cloud'), findsNothing, reason: 'overlay gone');
      expect(appState.hasSeenOnboardingTour, isTrue);

      final prefs = await SharedPreferences.getInstance();
      expect(prefs.getBool('has_seen_onboarding_tour'), isTrue,
          reason: 'persisted so the tour never shows again on this device');
    });

    testWidgets('Skip Tour on the very first step ends the tour immediately and marks it seen',
        (tester) async {
      final appState = await pumpShellWithFreshTour(tester);

      await tester.tap(find.widgetWithText(TextButton, 'Skip Tour'));
      await tester.pumpAndSettle();

      expect(find.text('Add Receipts Here'), findsNothing);
      expect(appState.hasSeenOnboardingTour, isTrue);
      expect(find.widgetWithText(AppBar, 'Receipts'), findsOneWidget,
          reason: 'stayed on the tab it started on');
    });

    testWidgets('Skip Tour from the last step still pops the tour-pushed Data screen',
        (tester) async {
      await pumpShellWithFreshTour(tester);

      for (var i = 0; i < 3; i++) {
        await tester.tap(find.widgetWithText(FilledButton, 'Next'));
        await tester.pumpAndSettle();
      }
      expect(find.byType(DataSettingsScreen), findsOneWidget);

      await tester.tap(find.widgetWithText(TextButton, 'Skip Tour'));
      await tester.pumpAndSettle();

      expect(find.byType(DataSettingsScreen), findsNothing);
    });
  });
}