// Author: fruit.com.cn

import 'package:flutter/material.dart';

import '../theme/app_colors.dart';

const double _regularArtSize = 84;
const double _compactArtSize = 60;
const double _regularInnerSize = 56;
const double _compactInnerSize = 40;
const double _regularIconSize = 27;
const double _compactIconSize = 21;
const double _maxContentWidth = 260;
const double _actionMinHeight = 44;
const double _outerArtOpacity = 0.055;
const double _outerBorderOpacity = 0.11;
const double _innerArtOpacity = 0.11;

/// 统一空列表占位：柔和图标、标题、可选说明与操作。
class EmptyState extends StatelessWidget {
  const EmptyState({
    super.key,
    required this.icon,
    required this.title,
    this.subtitle,
    this.actionLabel,
    this.onAction,
    this.compact = false,
  });

  final IconData icon;
  final String title;
  final String? subtitle;
  final String? actionLabel;
  final VoidCallback? onAction;
  final bool compact;

  @override
  Widget build(BuildContext context) {
    final scheme = Theme.of(context).colorScheme;
    final dark = Theme.of(context).brightness == Brightness.dark;
    final iconColor = dark ? AppColors.blueSoft : AppColors.blue;
    final artSize = compact ? _compactArtSize : _regularArtSize;
    final innerSize = compact ? _compactInnerSize : _regularInnerSize;
    final iconSize = compact ? _compactIconSize : _regularIconSize;
    final hasAction = actionLabel != null && onAction != null;
    return Center(
      child: ConstrainedBox(
        key: const Key('empty-state-content'),
        constraints: const BoxConstraints(maxWidth: _maxContentWidth),
        child: Padding(
          key: const Key('empty-state-padding'),
          padding: EdgeInsets.symmetric(
            horizontal: compact ? 16 : 24,
            vertical: compact ? 16 : 28,
          ),
          child: Semantics(
            container: true,
            label: title,
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                ExcludeSemantics(
                  child: Container(
                    key: const Key('empty-state-art'),
                    width: artSize,
                    height: artSize,
                    alignment: Alignment.center,
                    decoration: BoxDecoration(
                      shape: BoxShape.circle,
                      color: AppColors.blue.withValues(alpha: _outerArtOpacity),
                      border: Border.all(
                        color: AppColors.blue.withValues(
                          alpha: _outerBorderOpacity,
                        ),
                      ),
                    ),
                    child: Container(
                      key: const Key('empty-state-art-inner'),
                      width: innerSize,
                      height: innerSize,
                      alignment: Alignment.center,
                      decoration: BoxDecoration(
                        shape: BoxShape.circle,
                        color: AppColors.blue.withValues(
                          alpha: _innerArtOpacity,
                        ),
                      ),
                      child: Icon(
                        icon,
                        key: const Key('empty-state-icon'),
                        size: iconSize,
                        color: iconColor,
                      ),
                    ),
                  ),
                ),
                SizedBox(height: compact ? 10 : 14),
                ExcludeSemantics(
                  child: Text(
                    title,
                    key: const Key('empty-state-title'),
                    maxLines: 2,
                    overflow: TextOverflow.ellipsis,
                    textAlign: TextAlign.center,
                    style: TextStyle(
                      color: scheme.onSurface,
                      fontSize: 15,
                      fontWeight: FontWeight.w600,
                      height: 1.35,
                    ),
                  ),
                ),
                if (subtitle != null) ...[
                  const SizedBox(height: 6),
                  ExcludeSemantics(
                    child: Text(
                      subtitle!,
                      maxLines: 2,
                      overflow: TextOverflow.ellipsis,
                      textAlign: TextAlign.center,
                      style: const TextStyle(
                        color: AppColors.muted,
                        fontSize: 12.5,
                        height: 1.45,
                      ),
                    ),
                  ),
                ],
                if (hasAction) ...[
                  const SizedBox(height: 8),
                  TextButton(
                    key: const Key('empty-state-action'),
                    onPressed: onAction,
                    style: TextButton.styleFrom(
                      foregroundColor: scheme.primary,
                      minimumSize: const Size(44, _actionMinHeight),
                      padding: const EdgeInsets.symmetric(horizontal: 14),
                    ),
                    child: Text(
                      actionLabel!,
                      style: const TextStyle(fontSize: 13),
                    ),
                  ),
                ],
              ],
            ),
          ),
        ),
      ),
    );
  }
}