import 'package:flutter/material.dart';
import 'package:gravity_sdk/gravity_sdk.dart';
import 'package:visibility_detector/visibility_detector.dart';

import 'gravity_content.dart';

class CheckoutVariantButton extends StatefulWidget {
  const CheckoutVariantButton({super.key, required this.onCheckout});
  final VoidCallback onCheckout;

  @override
  State<CheckoutVariantButton> createState() => _CheckoutVariantButtonState();
}

class _CheckoutVariantButtonState extends State<CheckoutVariantButton> {
  ContentExposure? exposure;
  String label = 'Оформить заказ';
  Key visibilityKey = UniqueKey();

  @override
  void initState() {
    super.initState();
    _load();
  }

  Future<void> _load() async {
    try {
      final selected = await loadSelectedContent(
        selector: 'checkout_button',
        pageContext: const PageContext(
          type: ContextType.cart,
          data: [],
          location: 'app://cart',
        ),
      );
      if (!mounted || selected == null) return;
      final config = selected.content.variables.valueOf<Map<String, dynamic>>(
        'checkout_button',
      );
      if (config == null) return;
      final variant = config['variant'];
      final text = config['label'];
      if ((variant != 'A' && variant != 'B') ||
          text is! String ||
          text.trim().isEmpty) {
        return;
      }
      setState(() {
        label = text;
        exposure = ContentExposure(selected);
        visibilityKey = UniqueKey();
      });
    } catch (_) {
      // Кнопка оформления остаётся доступна с исходным текстом.
    }
  }

  @override
  Widget build(BuildContext context) => VisibilityDetector(
    key: visibilityKey,
    onVisibilityChanged: (info) => exposure?.onVisibility(info.visibleFraction),
    child: FilledButton(
      onPressed: () {
        exposure?.click();
        widget.onCheckout();
      },
      child: Text(label),
    ),
  );
}