import 'package:flutter/material.dart';

import '../models/theme_template.dart';

/// 主题模板网格卡片（封面图 + 名称）。
///
/// 用于门店表单中「主题皮肤」选择；[selectedId] 高亮选中态，
/// [onSelected] 回传选中模板的 [ThemeTemplate.id]。
class StoreThemeGrid extends StatelessWidget {
  const StoreThemeGrid({
    super.key,
    required this.templates,
    required this.onSelected,
    this.selectedId,
  });

  /// 可选主题模板列表。
  final List<ThemeTemplate> templates;

  /// 选中回调，回传模板 id。
  final ValueChanged<String> onSelected;

  /// 当前选中的模板 id（高亮）。
  final String? selectedId;

  @override
  Widget build(BuildContext context) {
    if (templates.isEmpty) {
      return const SizedBox(
        height: 80,
        child: Center(child: Text('暂无可用主题模板')),
      );
    }

    return GridView.count(
      crossAxisCount: 3,
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      mainAxisSpacing: 12,
      crossAxisSpacing: 12,
      childAspectRatio: 0.9,
      children: templates.map((template) {
        final selected = template.id == selectedId;
        return _ThemeCard(
          template: template,
          selected: selected,
          onTap: () => onSelected(template.id),
        );
      }).toList(),
    );
  }
}

class _ThemeCard extends StatelessWidget {
  const _ThemeCard({
    required this.template,
    required this.selected,
    required this.onTap,
  });

  final ThemeTemplate template;
  final bool selected;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final primary = _accentColor(template.name);
    final coverUrl = template.coverUrl;

    return InkWell(
      onTap: onTap,
      borderRadius: BorderRadius.circular(12),
      child: Container(
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(12),
          border: Border.all(
            color: selected
                ? Theme.of(context).colorScheme.primary
                : Colors.transparent,
            width: selected ? 2.5 : 1,
          ),
        ),
        child: Column(
          children: [
            // 封面预览（优先 coverUrl，否则用名称哈希色块）。
            Expanded(
              child: Container(
                decoration: BoxDecoration(
                  color: coverUrl == null || coverUrl.isEmpty ? primary : null,
                  borderRadius:
                      const BorderRadius.vertical(top: Radius.circular(10)),
                  image: coverUrl != null && coverUrl.isNotEmpty
                      ? DecorationImage(
                          image: NetworkImage(coverUrl),
                          fit: BoxFit.cover,
                        )
                      : null,
                ),
                alignment: Alignment.center,
                child: coverUrl == null || coverUrl.isEmpty
                    ? Text(
                        template.name.isEmpty ? '主题' : template.name[0],
                        style: const TextStyle(
                          color: Colors.white,
                          fontSize: 28,
                          fontWeight: FontWeight.bold,
                        ),
                      )
                    : null,
              ),
            ),
            // 名称。
            Container(
              height: 34,
              alignment: Alignment.center,
              padding: const EdgeInsets.symmetric(horizontal: 4),
              child: Text(
                template.name,
                maxLines: 1,
                overflow: TextOverflow.ellipsis,
                style: const TextStyle(fontSize: 13, fontWeight: FontWeight.w600),
              ),
            ),
          ],
        ),
      ),
    );
  }

  static const _palette = [
    Color(0xFF3B82F6),
    Color(0xFF8B5CF6),
    Color(0xFFEC4899),
    Color(0xFFF59E0B),
    Color(0xFF10B981),
    Color(0xFF6366F1),
  ];

  static Color _accentColor(String name) {
    var hash = 0;
    for (var i = 0; i < name.length; i++) {
      hash = (hash + name.codeUnitAt(i) * (i + 1)) % _palette.length;
    }
    return _palette[hash];
  }
}