observer/flutter_app/lib/home/home_screen.dart

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

import '../auth/session_store.dart';
import 'home_view_model.dart';

/// 主界面：当前账号到期时间 + 搜索按钮（强制服务端校验后进相机）+ 充值入口
class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      context.read<HomeViewModel>().refresh();
    });
  }

  Future<void> _onSearch() async {
    final vm = context.read<HomeViewModel>();
    final allowed = await vm.verifyForCamera();
    if (!mounted) return;
    if (vm.sessionExpired) {
      _toLogin();
      return;
    }
    if (!allowed) {
      if (vm.error != null) {
        // 网络/服务端异常：无法确认授权状态，提示错误
        _showBlocked(vm.error);
        return;
      }
      // 服务端确认无有效授权：直接进充值页
      await _onRecharge();
      return;
    }
    await Navigator.of(context).pushNamed('/camera');
    if (mounted) vm.refresh();
  }

  Future<void> _onRecharge() async {
    await Navigator.of(context).pushNamed('/paywall');
    if (mounted) context.read<HomeViewModel>().refresh();
  }

  Future<void> _toLogin() async {
    final container = context.read<SessionStore>();
    await container.clear();
    if (!mounted) return;
    Navigator.of(context).pushReplacementNamed('/login');
  }

  void _showBlocked(String? error) {
    showDialog<void>(
      context: context,
      builder: (ctx) => AlertDialog(
        title: const Text('授权不可用'),
        content: Text(error ?? '授权已过期，请充值后续费'),
        actions: [
          TextButton(
            onPressed: () => Navigator.of(ctx).pop(),
            child: const Text('取消'),
          ),
          FilledButton(
            onPressed: () {
              Navigator.of(ctx).pop();
              _onRecharge();
            },
            child: const Text('去充值'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final vm = context.watch<HomeViewModel>();
    final license = vm.license;
    final active = license?.isActive ?? false;
    final statusText = vm.loading
        ? '加载中…'
        : (license == null || license.expiresAt == null
            ? '未充值'
            : (active
                ? '有效至 ${_fmt(license.expiresAt!)}'
                : '已过期（${_fmt(license.expiresAt!)}）'));

    return Scaffold(
      appBar: AppBar(
        title: const Text('视野'),
        centerTitle: true,
        actions: [
          IconButton(
            tooltip: '退出登录',
            icon: const Icon(Icons.logout),
            onPressed: _toLogin,
          ),
        ],
      ),
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 24),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              const SizedBox(height: 24),
              _StatusCard(
                licenseText: statusText,
                active: active,
              ),
              const SizedBox(height: 40),
              SizedBox(
                height: 88,
                child: FilledButton.icon(
                  onPressed: vm.verifying ? null : _onSearch,
                  style: FilledButton.styleFrom(
                    backgroundColor: Colors.green,
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(44),
                    ),
                  ),
                  icon: vm.verifying
                      ? const SizedBox(
                          width: 24,
                          height: 24,
                          child: CircularProgressIndicator(
                              strokeWidth: 2, color: Colors.white),
                        )
                      : const Icon(Icons.visibility, size: 32),
                  label: Text(
                    vm.verifying ? '正在校验授权…' : '打开视野',
                    style: const TextStyle(
                        fontSize: 22, fontWeight: FontWeight.w600),
                  ),
                ),
              ),
              const SizedBox(height: 16),
              SizedBox(
                height: 52,
                child: OutlinedButton.icon(
                  onPressed: _onRecharge,
                  icon: const Icon(Icons.payment),
                  label: const Text('充值', style: TextStyle(fontSize: 16)),
                ),
              ),
              if (vm.error != null && vm.license != null) ...[
                const SizedBox(height: 16),
                Text(
                  vm.error!,
                  textAlign: TextAlign.center,
                  style: const TextStyle(color: Colors.red),
                ),
              ],
            ],
          ),
        ),
      ),
    );
  }

  static String _fmt(DateTime t) {
    String p(int n) => n.toString().padLeft(2, '0');
    return '${t.year}-${p(t.month)}-${p(t.day)} ${p(t.hour)}:${p(t.minute)}';
  }
}

class _StatusCard extends StatelessWidget {
  final String licenseText;
  final bool active;

  const _StatusCard({
    required this.licenseText,
    required this.active,
  });

  @override
  Widget build(BuildContext context) {
    return Card(
      child: Padding(
        padding: const EdgeInsets.all(20),
        child: Row(
          children: [
            Icon(
              active ? Icons.verified_user : Icons.error_outline,
              color: active ? Colors.green : Colors.orange,
              size: 36,
            ),
            const SizedBox(width: 16),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text('当前账户',
                      style: TextStyle(
                          color: Colors.grey.shade600, fontSize: 13)),
                  const SizedBox(height: 4),
                  Text(
                    licenseText,
                    style: const TextStyle(
                        fontSize: 18, fontWeight: FontWeight.w600),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}