/// 相册分享页（UI-03 §4 页面 19 重设计；原 UI-01 分享对话框升级为全屏
/// 分享页，文件名保留 share_qr_dialog.dart 兼容既有引用）。
///
/// 手机全屏页（平板内容居中收窄为卡片，同一布局代码两条宽度分支）：
/// 真实封面（可缺省占位）→ 名称/日期地点 → 现场生成二维码（白底突出，
/// data 为观众链接 `{VIEWER_BASE}/a/{token}?lang=`）→ 扫码说明 → Copy
/// link（主操作，复制同一链接）→ Open in browser（次操作，经 url_launcher
/// 外链打开）。相册未公开时以琥珀提示明确「该链接目前无法公开浏览」，
/// 不写「任何人可查看」；URL 文本可长按选中复制（复制失败的选择文本
/// 回退），但公开 token 不作主视觉编号。
library;

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:qr_flutter/qr_flutter.dart';
import 'package:url_launcher/url_launcher.dart';

import '../core/config.dart';
import '../features/albums/album_format.dart';
import '../features/albums/models.dart';
import '../l10n/app_localizations.dart';
import '../ui/components/photo_thumbnail.dart';
import '../ui/tokens.dart';

/// 外链打开注入点（生产=url_launcher；测试 override）。
typedef UrlLauncher = Future<bool> Function(String url);

/// 观众分享链接语言参数（viewer i18n 仅认 zh-CN/en；App locale 前缀映射）。
String shareLangParam(String localeName) =>
    localeName.toLowerCase().startsWith('zh') ? 'zh-CN' : 'en';

/// 分享链接（二维码与复制同一 URL）：`{VIEWER_BASE}/a/{token}?lang=`。
String shareAlbumUrl(Album album, String localeName) =>
    ApiConfig.viewerAlbumUrl(
      album.publicToken,
      lang: shareLangParam(localeName),
    );

/// Provider：外部浏览器打开 URL（LaunchMode.externalApplication——浏览器
/// 才能承载观众页的全部交互，内置 WebView 不适用）。
final urlLauncherProvider = Provider<UrlLauncher>(
  (ref) => (url) => launchUrl(Uri.parse(url), mode: LaunchMode.externalApplication),
);

/// 观众分享页（[album] 来自相册详情；手机全屏 / 宽屏内容居中卡片）。
class ShareQrPage extends ConsumerWidget {
  const ShareQrPage({required this.album, super.key});

  final Album album;

  Future<void> _copy(BuildContext context, String url) async {
    await Clipboard.setData(ClipboardData(text: url));
    if (!context.mounted) return;
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(AppLocalizations.of(context).copiedToClipboard),
      ),
    );
  }

  Future<void> _openInBrowser(
    BuildContext context,
    WidgetRef ref,
    String url,
  ) async {
    final launched = await ref.read(urlLauncherProvider)(url);
    if (!launched || !context.mounted) return;
    Navigator.of(context).pop();
  }

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final theme = Theme.of(context);
    final localeName = l10n.localeName;
    final url = shareAlbumUrl(album, localeName);
    final venue = albumDisplayVenue(album, localeName);
    final start = formatAlbumDateTime(album.startAt, album.timezone, localeName);
    final end = album.endAt == null
        ? null
        : formatAlbumDateTime(album.endAt!, album.timezone, localeName);
    final dateRange = end == null ? start : '$start ~ $end';
    final meta = venue == null ? dateRange : '$dateRange · $venue';
    return Scaffold(
      appBar: AppBar(title: Text(l10n.shareAlbum)),
      body: SingleChildScrollView(
        child: Center(
          // 宽屏（平板）内容收窄居中成卡片；手机全宽卡片。
          child: ConstrainedBox(
            constraints: const BoxConstraints(maxWidth: 480),
            child: Card(
              margin: const EdgeInsets.all(kSpace16),
              child: Padding(
                padding: const EdgeInsets.all(kSpace16),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    // 真实封面（无封面同尺寸中性占位）。
                    ClipRRect(
                      borderRadius: BorderRadius.circular(kRadiusInput),
                      child: PhotoThumbnail(
                        url: album.cover?.url,
                        aspectRatio: 16 / 9,
                      ),
                    ),
                    const SizedBox(height: kSpace16),
                    Text(
                      albumDisplayTitle(album, localeName),
                      textAlign: TextAlign.center,
                      style: theme.textTheme.titleLarge,
                    ),
                    const SizedBox(height: kSpace4),
                    Text(
                      meta,
                      textAlign: TextAlign.center,
                      style: theme.textTheme.bodySmall?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                    const SizedBox(height: kSpace16),
                    // 二维码（白底突出，暗色主题保持扫码对比度）。
                    Center(
                      child: Container(
                        color: Colors.white,
                        padding: const EdgeInsets.all(kSpace12),
                        child: QrImageView(
                          data: url,
                          version: QrVersions.auto,
                          size: 216,
                          backgroundColor: Colors.white,
                        ),
                      ),
                    ),
                    const SizedBox(height: kSpace12),
                    Text(
                      l10n.shareScanHint,
                      textAlign: TextAlign.center,
                      style: theme.textTheme.bodySmall?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                    const SizedBox(height: kSpace8),
                    // 链接文本（可长按选中复制；弱化呈现，不作主视觉）。
                    SelectableText(
                      url,
                      textAlign: TextAlign.center,
                      style: theme.textTheme.labelSmall?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                    if (!album.publicEnabled) ...[
                      const SizedBox(height: kSpace12),
                      Container(
                        padding: const EdgeInsets.all(kSpace12),
                        decoration: BoxDecoration(
                          color: theme.brightness == Brightness.light
                              ? kColorWaiting.withValues(alpha: 0.12)
                              : kColorWaitingDark.withValues(alpha: 0.12),
                          borderRadius: BorderRadius.circular(kRadiusBadge),
                        ),
                        child: Row(
                          children: [
                            Icon(
                              Icons.warning_amber_rounded,
                              size: 18,
                              color: theme.brightness == Brightness.light
                                  ? kColorWaiting
                                  : kColorWaitingDark,
                            ),
                            const SizedBox(width: kSpace8),
                            Expanded(
                              child: Text(
                                l10n.shareNotPublic,
                                style: theme.textTheme.bodySmall?.copyWith(
                                  color: theme.brightness == Brightness.light
                                      ? kColorWaiting
                                      : kColorWaitingDark,
                                ),
                              ),
                            ),
                          ],
                        ),
                      ),
                    ],
                    const SizedBox(height: kSpace16),
                    // Copy link 主操作；浏览器打开为次级入口。
                    FilledButton.icon(
                      onPressed: () => _copy(context, url),
                      icon: const Icon(Icons.copy_outlined, size: 18),
                      label: Text(l10n.copyLink),
                    ),
                    const SizedBox(height: kSpace8),
                    OutlinedButton.icon(
                      onPressed: () => _openInBrowser(context, ref, url),
                      icon: const Icon(Icons.open_in_new, size: 18),
                      label: Text(l10n.openInBrowser),
                    ),
                  ],
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}