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