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

/// 用户头像，支持网络图片 + 首字母 fallback。
class AvatarWidget extends StatelessWidget {
  const AvatarWidget({
    super.key,
    this.url,
    this.name,
    this.size = 40,
  });

  final String? url;
  final String? name;
  final double size;

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final radius = size / 2;

    if (url != null && url!.isNotEmpty) {
      return CachedNetworkImage(
        imageUrl: url!,
        imageBuilder: (_, img) => CircleAvatar(
          radius: radius,
          backgroundImage: img,
        ),
        placeholder: (_, __) => _placeholder(context),
        errorWidget: (_, __, ___) => _placeholder(context),
      );
    }
    return _placeholder(context);
  }

  Widget _placeholder(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final initial =
        (name?.isNotEmpty == true) ? name![0].toUpperCase() : '?';
    return CircleAvatar(
      radius: size / 2,
      backgroundColor: colorScheme.primaryContainer,
      child: Text(
        initial,
        style: TextStyle(
          fontSize: size * 0.4,
          color: colorScheme.onPrimaryContainer,
          fontWeight: FontWeight.w600,
        ),
      ),
    );
  }
}