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

import 'package:mews/presentation/reader/swipe_navigator.dart';

Widget _wrap(SwipeNavigator navigator) => MaterialApp(
      home: Scaffold(
        body: Center(
          child: SizedBox(
            width: 800,
            height: 600,
            child: navigator,
          ),
        ),
      ),
    );

SwipeNavigator _navigator({
  required VoidCallback onBack,
  required VoidCallback onForward,
  bool canGoBack = true,
  bool canGoForward = true,
  double? contentWidth,
}) =>
    SwipeNavigator(
      contentWidth: contentWidth,
      canGoBack: canGoBack,
      canGoForward: canGoForward,
      backTitle: 'Previous page',
      forwardTitle: 'Next page',
      background: const Color(0xfffaf8f3),
      onBack: onBack,
      onForward: onForward,
      child: const ColoredBox(
        color: Color(0xff18191b),
        child: SizedBox.expand(),
      ),
    );

void main() {
  testWidgets('dragging right reveals the previous page and commits',
      (tester) async {
      var back = 0;
      var forward = 0;
      await tester.pumpWidget(_wrap(_navigator(
        onBack: () => back++,
        onForward: () => forward++,
      )));

      // Swipes begin at the screen edge; mid-page drags select text.
      final center = tester.getCenter(find.byType(SwipeNavigator));
      final gesture = await tester.startGesture(Offset(20, center.dy));
      await gesture.moveBy(const Offset(300, 0));
      await tester.pump();

      // The neighbor is peeking in with its title while the page slides away.
      expect(find.text('Previous page'), findsOneWidget);

      await gesture.up();
      await tester.pumpAndSettle();

      expect(back, 1);
      expect(forward, 0);
    });

  testWidgets('dragging left commits forward navigation', (tester) async {
    var back = 0;
    var forward = 0;
    await tester.pumpWidget(_wrap(_navigator(
      onBack: () => back++,
      onForward: () => forward++,
    )));

    final center = tester.getCenter(find.byType(SwipeNavigator));
    final gesture = await tester.startGesture(Offset(780, center.dy));
    await gesture.moveBy(const Offset(-300, 0));
    await tester.pump();
    expect(find.text('Next page'), findsOneWidget);

    await gesture.up();
    await tester.pumpAndSettle();

    expect(forward, 1);
    expect(back, 0);
  });

  testWidgets('a short drag springs back without navigating', (tester) async {
    var back = 0;
    await tester.pumpWidget(_wrap(_navigator(
      onBack: () => back++,
      onForward: () {},
    )));

    final center = tester.getCenter(find.byType(SwipeNavigator));
    final gesture = await tester.startGesture(Offset(20, center.dy));
    await gesture.moveBy(const Offset(80, 0));
    await tester.pump();
    await gesture.up();
    await tester.pumpAndSettle();

    expect(back, 0);
    // The neighbor disappeared again.
    expect(find.text('Previous page'), findsNothing);
  });

  testWidgets('swipes anywhere in the margin beside the column',
      (tester) async {
    var back = 0;
    await tester.pumpWidget(_wrap(_navigator(
      onBack: () => back++,
      onForward: () {},
      // A 40em column leaves 200px margins on an 800px surface.
      contentWidth: 400,
    )));

    final center = tester.getCenter(find.byType(SwipeNavigator));
    // Deep inside the left margin, far past the base edge zone.
    final gesture = await tester.startGesture(Offset(180, center.dy));
    await gesture.moveBy(const Offset(300, 0));
    await tester.pump();
    expect(find.text('Previous page'), findsOneWidget);
    await gesture.up();
    await tester.pumpAndSettle();
    expect(back, 1);
  });

  testWidgets('drags over the content column still belong to selection',
      (tester) async {
    var back = 0;
    await tester.pumpWidget(_wrap(_navigator(
      onBack: () => back++,
      onForward: () {},
      contentWidth: 400,
    )));

    final center = tester.getCenter(find.byType(SwipeNavigator));
    // Inside the column: no swipe, nothing peeks.
    final gesture = await tester.startGesture(Offset(400, center.dy));
    await gesture.moveBy(const Offset(300, 0));
    await tester.pump();
    expect(find.text('Previous page'), findsNothing);
    await gesture.up();
    await tester.pumpAndSettle();
    expect(back, 0);
  });

  testWidgets('directions without pages rubber-band and never commit',
      (tester) async {
    var back = 0;
    var forward = 0;
    await tester.pumpWidget(_wrap(_navigator(
      onBack: () => back++,
      onForward: () => forward++,
      canGoBack: false,
      canGoForward: false,
    )));

    final center = tester.getCenter(find.byType(SwipeNavigator));
    final gesture = await tester.startGesture(Offset(20, center.dy));
    await gesture.moveBy(const Offset(400, 0));
    await tester.pump();
    // No neighbor title shows when there is nothing to go back to.
    expect(find.text('Previous page'), findsNothing);

    await gesture.up();
    await tester.pumpAndSettle();

    expect(back, 0);
    expect(forward, 0);
  });
}