import 'package:flutter/material.dart';

/// The full-screen "spotlight" shown by one step of the first-launch
/// guided tour: a dimmed barrier with a cut-out hole around whatever
/// [targetKey] currently points to (or, if that key isn't laid out yet or
/// doesn't resolve, just a plain dimmed barrier with the card centered),
/// plus a card explaining that element with Next/Skip controls.
///
/// This widget is purely presentational — it doesn't know about tabs,
/// routes, or persistence. `MainShell` is responsible for sequencing
/// steps, navigating to the right screen/route before each one, and
/// recording that the tour's been seen once it ends.
class OnboardingTourOverlay extends StatelessWidget {
  final GlobalKey targetKey;
  final String title;
  final String description;
  final int stepNumber;
  final int totalSteps;
  final VoidCallback onNext;
  final VoidCallback onSkip;

  const OnboardingTourOverlay({
    super.key,
    required this.targetKey,
    required this.title,
    required this.description,
    required this.stepNumber,
    required this.totalSteps,
    required this.onNext,
    required this.onSkip,
  });

  Rect? _targetRect() {
    final renderObject = targetKey.currentContext?.findRenderObject();
    if (renderObject is! RenderBox || !renderObject.hasSize) return null;
    return renderObject.localToGlobal(Offset.zero) & renderObject.size;
  }

  @override
  Widget build(BuildContext context) {
    final rect = _targetRect()?.inflate(6);
    final media = MediaQuery.of(context);
    final isLastStep = stepNumber >= totalSteps;
    final colorScheme = Theme.of(context).colorScheme;

    // Prefer placing the card below the highlighted element; only flip
    // above it if there's not enough room below on this screen.
    final cardBelow = rect == null || (rect.bottom + 260) < media.size.height;
    final cardTop = cardBelow ? (rect?.bottom ?? media.size.height * 0.38) + 16 : null;
    final cardBottom = !cardBelow ? media.size.height - rect.top + 16 : null;

    return Stack(
      children: [
        Positioned.fill(
          child: GestureDetector(
            behavior: HitTestBehavior.opaque,
            // Swallows every tap on the barrier (and the spotlight hole
            // itself) so the highlighted element can't be accidentally
            // triggered mid-tour — Next/Skip on the card are the only way
            // to advance.
            onTap: () {},
            child: CustomPaint(
              painter: _SpotlightPainter(
                targetRect: rect,
                color: Colors.black.withValues(alpha: 0.75),
              ),
            ),
          ),
        ),
        if (rect != null)
          Positioned(
            left: rect.left,
            top: rect.top,
            width: rect.width,
            height: rect.height,
            child: IgnorePointer(
              child: DecoratedBox(
                decoration: BoxDecoration(
                  border: Border.all(color: colorScheme.primary, width: 2.5),
                  borderRadius: BorderRadius.circular(12),
                ),
              ),
            ),
          ),
        Positioned(
          left: 20,
          right: 20,
          top: cardTop,
          bottom: cardBottom,
          child: SafeArea(
            child: Card(
              elevation: 8,
              child: Padding(
                padding: const EdgeInsets.all(20),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      'Step $stepNumber of $totalSteps',
                      style: Theme.of(context).textTheme.labelMedium?.copyWith(
                            color: colorScheme.primary,
                            fontWeight: FontWeight.w700,
                          ),
                    ),
                    const SizedBox(height: 6),
                    Text(title, style: Theme.of(context).textTheme.titleLarge),
                    const SizedBox(height: 8),
                    Text(description, style: Theme.of(context).textTheme.bodyMedium),
                    const SizedBox(height: 20),
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceBetween,
                      children: [
                        TextButton(onPressed: onSkip, child: const Text('Skip Tour')),
                        FilledButton(onPressed: onNext, child: Text(isLastStep ? 'Got It' : 'Next')),
                      ],
                    ),
                  ],
                ),
              ),
            ),
          ),
        ),
      ],
    );
  }
}

class _SpotlightPainter extends CustomPainter {
  final Rect? targetRect;
  final Color color;

  const _SpotlightPainter({required this.targetRect, required this.color});

  @override
  void paint(Canvas canvas, Size size) {
    final barrierPaint = Paint()..color = color;
    final fullPath = Path()..addRect(Offset.zero & size);
    final rect = targetRect;
    if (rect == null) {
      canvas.drawPath(fullPath, barrierPaint);
      return;
    }
    final holePath = Path()..addRRect(RRect.fromRectAndRadius(rect, const Radius.circular(12)));
    canvas.drawPath(Path.combine(PathOperation.difference, fullPath, holePath), barrierPaint);
  }

  @override
  bool shouldRepaint(covariant _SpotlightPainter oldDelegate) =>
      oldDelegate.targetRect != targetRect || oldDelegate.color != color;
}