import 'package:flutter/material.dart';
import 'package:flutter_cache_manager/flutter_cache_manager.dart';
import 'package:flutter_svg/flutter_svg.dart';

import '../../../core/api/api_client.dart';
import '../../../core/theme/halo_tokens.dart';

/// Renders a payment-method brand mark fetched from the backend.
///
/// `iconUrl` comes from `payment_methods.icon_url` on the catalog response.
/// Relative paths (the common case — `/assets/payment-icons/<slug>.svg`) are
/// resolved against [ApiClient.baseUrl]. Absolute URLs (operator override)
/// are used as-is.
///
/// First fetch hits the network; the file is then persisted to disk by
/// [DefaultCacheManager] (30-day idle LRU) and served locally on subsequent
/// renders. While the cache lookup is in flight or when [iconUrl] is null,
/// the bundled placeholder is shown so the picker never displays a spinner.
class PaymentIcon extends StatelessWidget {
  final String? iconUrl;
  final double size;
  final Color color;

  const PaymentIcon({
    super.key,
    required this.iconUrl,
    this.size = 24,
    this.color = HaloTokens.brandDark,
  });

  String? get _resolvedUrl {
    final raw = iconUrl;
    if (raw == null || raw.isEmpty) return null;
    if (raw.startsWith('http://') || raw.startsWith('https://')) return raw;
    return '${ApiClient.baseUrl}$raw';
  }

  @override
  Widget build(BuildContext context) {
    final url = _resolvedUrl;
    if (url == null) return _placeholder();

    return FutureBuilder<FileInfo?>(
      future: DefaultCacheManager().getFileFromCache(url),
      builder: (context, cachedSnap) {
        final cached = cachedSnap.data?.file;
        if (cached != null) {
          return SvgPicture.file(cached, width: size, height: size);
        }
        // Cache miss: render placeholder while the download lands, then swap
        // in. We fire the download in the same FutureBuilder body so the next
        // rebuild picks up the freshly-cached file.
        return FutureBuilder(
          future: DefaultCacheManager().getSingleFile(url),
          builder: (context, snap) {
            if (snap.hasData) {
              return SvgPicture.file(snap.data!, width: size, height: size);
            }
            return _placeholder();
          },
        );
      },
    );
  }

  Widget _placeholder() => SvgPicture.asset(
        'assets/payment_icons/placeholder.svg',
        width: size,
        height: size,
        colorFilter: ColorFilter.mode(color, BlendMode.srcIn),
      );
}