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

import 'package:fuel_tax_tracker/models/fuel_entry.dart';
import 'package:fuel_tax_tracker/models/vehicle.dart';
import 'package:fuel_tax_tracker/screens/report_screen.dart';
import 'package:fuel_tax_tracker/services/app_state.dart';

/// Covers the per-vehicle selection cards on the Reports tab: with a date
/// range in place (now defaulted automatically — see
/// defaultReportDateRange/ReportScreen.initState), every vehicle with a
/// receipted entry in range starts selected (colored like the "Share"
/// button), tapping one to deselect it
/// drops it from the total (and, by extension, the generated report) and
/// reverts its coloring to a plain unselected card, and deselecting every
/// vehicle shows a distinct "nothing selected" message rather than "no
/// entries in range". There's deliberately no checkbox — selection state is
/// conveyed by color alone.
void main() {
  final vehicleA = Vehicle(id: 'a', vin: 'VINAAAAAAAAAAAAAA', nickname: 'Truck', updatedAt: DateTime.utc(2026, 1, 1));
  final vehicleB = Vehicle(id: 'b', vin: 'VINBBBBBBBBBBBBBB', nickname: 'Van', updatedAt: DateTime.utc(2026, 1, 1));

  // ReportScreen's date range now defaults to the current fuel-tax-refund
  // period (see defaultReportDateRange) as soon as it opens — dating these
  // entries to "now" means they always fall inside that default range,
  // without these tests needing to drive the date pickers themselves.
  final now = DateTime.now();

  FuelEntry entryFor(String vehicleId, String id, double gallons, double cost) => FuelEntry(
        id: id,
        vehicleId: vehicleId,
        date: now,
        gallons: gallons,
        pricePerGallon: cost / gallons,
        totalCost: cost,
        updatedAt: now.toUtc(),
        receiptDriveFileId: 'remote-$id',
      );

  Future<AppState> pumpReport(WidgetTester tester, {bool showEstimatedFuelRefund = false}) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicleA, vehicleB]
      ..fuelEntries = [
        entryFor('a', 'e1', 10, 35),
        entryFor('b', 'e2', 20, 70),
      ]
      ..showEstimatedFuelRefund = showEstimatedFuelRefund;

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

  Card cardFor(WidgetTester tester, String vehicleLabel) => tester.widget<Card>(
        find.ancestor(of: find.text(vehicleLabel), matching: find.byType(Card)),
      );

  testWidgets('both vehicles start colored as selected once a range with entries for both is picked',
      (tester) async {
    await pumpReport(tester);

    final colorScheme = Theme.of(tester.element(find.text('Truck'))).colorScheme;

    expect(cardFor(tester, 'Truck').color, colorScheme.primary);
    expect(cardFor(tester, 'Van').color, colorScheme.primary);
    expect(find.text('30.000 gal · \$105.00'), findsOneWidget, reason: 'combined total');
  });

  testWidgets(
      'shows an estimated fuel refund below each vehicle\'s total cost and next to the '
      'combined total, when the setting is on', (tester) async {
    await pumpReport(tester, showEstimatedFuelRefund: true);

    // Truck: 10 gal * $0.125/gal = $1.25. Van: 20 gal * $0.125/gal = $2.50.
    expect(find.text('Est. \$1.25'), findsOneWidget);
    expect(find.text('Est. \$2.50'), findsOneWidget);
    // Combined: 30 gal * $0.125/gal = $3.75, folded into the Total row.
    expect(find.text('30.000 gal · \$105.00 · Est. \$3.75'), findsOneWidget);
  });

  testWidgets('shows no estimated fuel refund anywhere when the setting is off (default)',
      (tester) async {
    await pumpReport(tester);

    expect(find.textContaining('Est. \$'), findsNothing);
  });

  testWidgets('tapping a selected vehicle deselects it (reverts its coloring) and drops it from the total',
      (tester) async {
    await pumpReport(tester);

    final colorScheme = Theme.of(tester.element(find.text('Truck'))).colorScheme;

    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();

    expect(find.text('20.000 gal · \$70.00'), findsOneWidget, reason: "only Van's total remains");
    expect(cardFor(tester, 'Truck').color, isNot(colorScheme.primary), reason: 'deselected');
    expect(cardFor(tester, 'Van').color, colorScheme.primary, reason: 'still selected');
  });

  testWidgets('tapping a deselected vehicle again reselects it (restores its coloring)',
      (tester) async {
    await pumpReport(tester);

    final colorScheme = Theme.of(tester.element(find.text('Truck'))).colorScheme;

    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();
    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();

    expect(cardFor(tester, 'Truck').color, colorScheme.primary);
    expect(find.text('30.000 gal · \$105.00'), findsOneWidget, reason: 'both counted again');
  });

  testWidgets('tapping Preview opens the report preview screen', (tester) async {
    await pumpReport(tester);

    await tester.scrollUntilVisible(find.text('Preview'), 300, scrollable: find.byType(Scrollable));
    await tester.tap(find.text('Preview'));
    // Not pumpAndSettle: PdfPreview's own internal rendering isn't under
    // test here (no platform channel mocked for it) — just that Preview
    // actually navigates. A couple of bounded pumps are enough for that
    // navigation (a synchronous PDF build, no plugin calls) to land.
    await tester.pump();
    await tester.pump(const Duration(milliseconds: 300));

    expect(find.text('Report Preview'), findsOneWidget);
  });

  testWidgets('deselecting every vehicle shows a distinct "nothing selected" message',
      (tester) async {
    await pumpReport(tester);

    await tester.tap(find.text('Truck'));
    await tester.pumpAndSettle();
    await tester.tap(find.text('Van'));
    await tester.pumpAndSettle();

    expect(
      find.text('No vehicles selected — tap at least one above to build a report.'),
      findsOneWidget,
    );
    expect(find.text('Preview'), findsNothing);
    expect(find.text('Share'), findsNothing);
    expect(find.text('Print'), findsNothing);
    // The cards themselves stay visible so the user can tap one again.
    expect(find.text('Truck'), findsOneWidget);
    expect(find.text('Van'), findsOneWidget);
  });
}