import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:intl/intl.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/receipt_detail_screen.dart';
import 'package:fuel_tax_tracker/screens/receipts_screen.dart';
import 'package:fuel_tax_tracker/services/app_state.dart';

void main() {
  final vehicle = Vehicle(
    id: 'v1',
    vin: '1FMPU18L1TLB51349',
    nickname: 'Red Truck',
    updatedAt: DateTime.utc(2026, 1, 1),
  );

  testWidgets('shows an empty state with no fuel entries', (tester) async {
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle];

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

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

  testWidgets('shows the hero total and a receipt row with date/amount/vehicle chip',
      (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'v1',
      date: DateTime(2026, 5, 14),
      gallons: 10.523,
      pricePerGallon: 3.5,
      totalCost: 32.48,
      updatedAt: DateTime.utc(2026, 5, 14),
      receiptDriveFileId: 'remote-1',
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle]
      ..fuelEntries = [entry];

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

    // Hero total sums totalCost across all entries — just the one here.
    expect(find.text('\$32.48'), findsNWidgets(2)); // hero total + row amount
    expect(find.text('Total Fuel Cost'), findsOneWidget, reason: 'no year prefix');
    expect(find.text('Total Gallons'), findsOneWidget);
    expect(find.text('11'), findsOneWidget, reason: 'hero total gallons, rounded to whole gallons');
    expect(find.text('May 14, 2026'), findsOneWidget);
    expect(find.text('10.523 gal'), findsOneWidget, reason: 'row subtitle');
    expect(find.text('Red Truck'), findsOneWidget);
  });

  testWidgets(
      'shows an estimated fuel refund in the hero banner and next to each row\'s gallons '
      'when the setting is on', (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'v1',
      date: DateTime(2026, 5, 14),
      gallons: 10.523,
      pricePerGallon: 3.5,
      totalCost: 32.48,
      updatedAt: DateTime.utc(2026, 5, 14),
      receiptDriveFileId: 'remote-1',
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle]
      ..fuelEntries = [entry]
      ..showEstimatedFuelRefund = true;

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

    expect(find.text('Est. Refund'), findsOneWidget, reason: 'replaces the hero icon');
    // 10.523 gal rounds up to 11, * $0.125/gal = $1.375, floored to $1.37 —
    // the hero's own standalone stat value...
    expect(find.text('\$1.37'), findsOneWidget);
    // ...and the same figure again, folded into the row's combined text.
    expect(find.textContaining('10.523 gal  ·  Est. \$1.37'), findsOneWidget);
  });

  testWidgets("doesn't show an estimated fuel refund anywhere when the setting is off (default)",
      (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'v1',
      date: DateTime(2026, 5, 14),
      gallons: 10.523,
      pricePerGallon: 3.5,
      totalCost: 32.48,
      updatedAt: DateTime.utc(2026, 5, 14),
      receiptDriveFileId: 'remote-1',
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle]
      ..fuelEntries = [entry];

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

    expect(appState.showEstimatedFuelRefund, isFalse, reason: 'off by default');
    expect(find.text('Est. Refund'), findsNothing);
    expect(find.textContaining('Est. \$'), findsNothing);
  });

  testWidgets('tapping a receipted row opens the receipt detail page', (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'v1',
      date: DateTime(2026, 5, 14),
      gallons: 10,
      pricePerGallon: 3.5,
      totalCost: 35,
      updatedAt: DateTime.utc(2026, 5, 14),
      receiptDriveFileId: 'remote-1',
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle]
      ..fuelEntries = [entry];

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

    await tester.tap(find.text('May 14, 2026'));
    await tester.pumpAndSettle();

    expect(find.byType(ReceiptDetailScreen), findsOneWidget);
  });

  testWidgets('tapping a row with no receipt photo still opens the detail page', (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'v1',
      date: DateTime(2026, 5, 14),
      gallons: 10,
      pricePerGallon: 3.5,
      totalCost: 35,
      updatedAt: DateTime.utc(2026, 5, 14),
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle]
      ..fuelEntries = [entry];

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

    await tester.tap(find.text('May 14, 2026'));
    await tester.pumpAndSettle();

    expect(find.byType(ReceiptDetailScreen), findsOneWidget,
        reason: 'the data is still viewable/editable even without a photo');
  });

  testWidgets('formats large gallon totals with thousands separators', (tester) async {
    final entry = FuelEntry(
      id: 'e1',
      vehicleId: 'v1',
      date: DateTime(2026, 8, 5),
      gallons: 1234.5678,
      pricePerGallon: 3.5,
      totalCost: 4320.99,
      updatedAt: DateTime.utc(2026, 8, 5),
      receiptDriveFileId: 'remote-1',
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle]
      ..fuelEntries = [entry];

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

    expect(find.text('1,235'), findsOneWidget, reason: 'hero total gallons, rounded to whole gallons');
    expect(find.text('1,234.568 gal'), findsOneWidget, reason: 'row subtitle keeps full precision');
  });

  testWidgets('date range selector filters totals and the list, and recolors the active label',
      (tester) async {
    // These dates are derived from "now" rather than written out, because
    // the screen filters against DateTime.now() (see _DateRange.startDate).
    // Fixed dates quietly change which bucket they land in as the calendar
    // moves — an earlier version of this test hardcoded August dates and
    // started failing the moment September arrived.
    final now = DateTime.now();
    final format = DateFormat.yMMMd();

    // The 1st of this month: always inside all three ranges.
    final recentDate = DateTime(now.year, now.month, 1);
    // The 1st of last month: always inside Last 3 Months, never inside
    // Current Month. Also inside Year to Date except in January, when
    // "last month" lands in the previous year.
    final midDate = DateTime(now.year, now.month - 1, 1);
    final midInYearToDate = midDate.year == now.year;
    // Jan 1 this year: always inside Year to Date. It only falls *outside*
    // Last 3 Months from April onward — before that, Last 3 Months already
    // reaches back to Jan 1 or earlier, so no date at all can be "Year to
    // Date but not Last 3 Months" and that distinction isn't testable.
    final oldDate = DateTime(now.year, 1, 1);
    final oldOutsideLast3Months = oldDate.isBefore(DateTime(now.year, now.month - 2, 1));
    // In January the 1st of this month *is* Jan 1, so these two would
    // render the same date text and findsOneWidget would double-count.
    final oldIsDistinctFromRecent = oldDate != recentDate;

    final recentEntry = FuelEntry(
      id: 'recent',
      vehicleId: 'v1',
      date: recentDate,
      gallons: 10,
      pricePerGallon: 3,
      totalCost: 30,
      updatedAt: recentDate.toUtc(),
      receiptDriveFileId: 'r1',
    );
    final midEntry = FuelEntry(
      id: 'mid',
      vehicleId: 'v1',
      date: midDate,
      gallons: 20,
      pricePerGallon: 3,
      totalCost: 60,
      updatedAt: midDate.toUtc(),
      receiptDriveFileId: 'r2',
    );
    final oldEntry = FuelEntry(
      id: 'old',
      vehicleId: 'v1',
      date: oldDate,
      gallons: 40,
      pricePerGallon: 3,
      totalCost: 120,
      updatedAt: oldDate.toUtc(),
      receiptDriveFileId: 'r3',
    );
    final appState = AppState()
      ..isLoading = false
      ..vehicles = [vehicle]
      ..fuelEntries = [recentEntry, midEntry, oldEntry];

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

    bool isBold(String label) => tester
        .widgetList<Text>(find.text(label))
        .any((t) => t.style?.fontWeight == FontWeight.w800);

    // Defaults to Year to Date.
    expect(find.text(format.format(recentDate)), findsOneWidget);
    if (midInYearToDate) {
      expect(find.text(format.format(midDate)), findsOneWidget);
    }
    if (oldIsDistinctFromRecent) {
      expect(find.text(format.format(oldDate)), findsOneWidget);
    }
    expect(isBold('Year to Date'), isTrue, reason: 'selected by default');

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

    expect(find.text(format.format(recentDate)), findsOneWidget);
    expect(find.text(format.format(midDate)), findsOneWidget,
        reason: 'last month is always within the last three');
    if (oldOutsideLast3Months) {
      expect(find.text(format.format(oldDate)), findsNothing,
          reason: 'older than three months back');
    }
    expect(isBold('Last 3 Months'), isTrue);
    expect(isBold('Year to Date'), isFalse, reason: 'no longer selected');

    await tester.tap(find.text('Current Month'));
    await tester.pumpAndSettle();

    expect(find.text(format.format(recentDate)), findsOneWidget);
    expect(find.text(format.format(midDate)), findsNothing,
        reason: 'not in the current month');
    if (oldIsDistinctFromRecent) {
      expect(find.text(format.format(oldDate)), findsNothing);
    }
  });

  testWidgets(
      'tapping + with no vehicles opens vehicle creation and prompts to create one for the receipt',
      (tester) async {
    final appState = AppState()..isLoading = false;

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

    await tester.tap(find.byIcon(Icons.add));
    await tester.pumpAndSettle();

    expect(find.widgetWithText(AppBar, 'Add Vehicle'), findsOneWidget);
    expect(find.text('Create a vehicle to attach receipt'), findsOneWidget);

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

    expect(find.text('Create a vehicle to attach receipt'), findsNothing);
    expect(find.widgetWithText(AppBar, 'Add Vehicle'), findsOneWidget, reason: 'still on the form');
  });

  // Not covered here: that saving the new vehicle continues into receipt
  // capture (rather than back to an empty Receipts tab). Exercising that
  // needs AddEditVehicleScreen's real _save() to run, which touches a real
  // database — and combining a real sqflite_common_ffi database with
  // testWidgets (as opposed to a plain test()) reliably deadlocks in this
  // project's test environment (confirmed directly: the identical
  // `DatabaseService().init()` call returns immediately under test(), but
  // times out under testWidgets()). Verified manually on-device instead.
}