import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_blue_plus/flutter_blue_plus.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:permission_handler/permission_handler.dart';
import '../../core/app_colors.dart';
import '../../providers/auth_provider.dart';
import '../../providers/omron_device_provider.dart';
import '../../services/omron_ble_service.dart';

class DeviceScanPage extends ConsumerStatefulWidget {
  const DeviceScanPage({super.key});
  @override ConsumerState<DeviceScanPage> createState() => _DeviceScanPageState();
}

class _DeviceScanPageState extends ConsumerState<DeviceScanPage> {
  final _results = <ScanResult>[];
  bool _scanning = false;
  String? _connectingId;
  StreamSubscription? _scanSub;

  @override void initState() {
    super.initState();
    // 一次性订阅，持续整个页面生命周期
    _scanSub = FlutterBluePlus.scanResults.listen((list) {
      if (!mounted) return;
      setState(() { _results.clear(); _results.addAll(list); });
    });
    _start();
  }

  @override void dispose() {
    _scanSub?.cancel();
    FlutterBluePlus.stopScan();
    super.dispose();
  }

  Future<void> _start() async {
    setState(() => _scanning = true);

    await [Permission.bluetoothScan, Permission.bluetoothConnect].request();

    try { await FlutterBluePlus.turnOn(); } catch (e) { debugPrint('[BLE Scan] 操作失败: $e'); }

    try { await FlutterBluePlus.stopScan(); } catch (e) { debugPrint('[BLE Scan] 操作失败: $e'); }
    await FlutterBluePlus.startScan(
      timeout: const Duration(seconds: 30),
      androidScanMode: AndroidScanMode.lowLatency,
    );

    Future.delayed(const Duration(seconds: 30), () {
      FlutterBluePlus.stopScan();
      if (mounted) setState(() => _scanning = false);
    });
  }

  Future<void> _connect(ScanResult r) async {
    setState(() => _connectingId = r.device.remoteId.toString());
    FlutterBluePlus.stopScan();

    try {
      final ble = ref.read(omronBleServiceProvider);
      await ble.connect(r.device);
      final name = r.advertisementData.localName.isNotEmpty
          ? r.advertisementData.localName
          : (r.device.platformName.isNotEmpty ? r.device.platformName : '血压计');

      await ref.read(omronDeviceProvider.notifier).bind(r.device.remoteId.toString(), name);

      ble.readings.listen((reading) async {
        try {
          final api = ref.read(apiClientProvider);
          await api.post('/api/health-records', data: reading.toHealthRecord());
          await ref.read(omronDeviceProvider.notifier).onReading(reading);
        } catch (e) { debugPrint('[BLE Scan] 操作失败: $e'); }
      });

      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('已连接 $name'), backgroundColor: AppColors.success),
        );
        Navigator.pop(context);
      }
    } catch (_) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('连接失败，请重试'), backgroundColor: AppColors.error),
        );
        _start();
      }
    } finally {
      if (mounted) setState(() => _connectingId = null);
    }
  }

  // ═══════════════════ UI ═══════════════════

  @override Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: AppColors.background,
      appBar: AppBar(backgroundColor: AppColors.cardBackground, title: const Text('添加血压计')),
      body: Column(children: [
        Container(
          width: double.infinity, padding: const EdgeInsets.all(16),
          color: AppColors.iconBg,
          child: Row(children: [
            if (_scanning) ...[
              const SizedBox(width: 16, height: 16, child: CircularProgressIndicator(strokeWidth: 2, color: Color(0xFF5B8DEF))),
              const SizedBox(width: 12),
            ],
            Text(_scanning ? '正在扫描...' : '发现 ${_results.length} 台设备',
              style: const TextStyle(fontSize: 15, color: Color(0xFF666666))),
          ]),
        ),
        if (!_scanning && _results.isEmpty) _buildEmpty(),
        Expanded(
          child: ListView.builder(
            padding: const EdgeInsets.symmetric(vertical: 8),
            itemCount: _results.length,
            itemBuilder: (_, i) => _buildTile(_results[i]),
          ),
        ),
        if (!_scanning)
          Padding(
            padding: const EdgeInsets.all(16),
            child: SizedBox(width: double.infinity, child: OutlinedButton.icon(
              onPressed: _start,
              icon: const Icon(Icons.refresh),
              label: const Text('重新扫描'),
              style: OutlinedButton.styleFrom(
                foregroundColor: AppColors.primary,
                side: const BorderSide(color: Color(0xFF5B8DEF)),
                shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(14)),
                padding: const EdgeInsets.symmetric(vertical: 14),
              ),
            )),
          ),
      ]),
    );
  }

  Widget _buildTile(ScanResult r) {
    final isBP = OmronBleService.isBpDevice(r);
    final name = r.advertisementData.localName.isNotEmpty
        ? r.advertisementData.localName
        : (r.device.platformName.isNotEmpty ? r.device.platformName : '未知设备');
    final isConnecting = _connectingId == r.device.remoteId.toString();

    return Container(
      margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 4),
      padding: const EdgeInsets.all(14),
      decoration: BoxDecoration(
        color: AppColors.cardBackground, borderRadius: BorderRadius.circular(16),
        boxShadow: AppColors.cardShadow,
        border: isBP ? Border.all(color: AppColors.primary, width: 1.5) : null,
      ),
      child: Row(children: [
        Container(
          width: 44, height: 44,
          decoration: BoxDecoration(color: isBP ? AppColors.iconBg : AppColors.cardInner, borderRadius: BorderRadius.circular(12)),
          child: Icon(Icons.bluetooth, size: 24, color: isBP ? AppColors.primary : AppColors.textHint),
        ),
        const SizedBox(width: 12),
        Expanded(
          child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
            Row(children: [
              Flexible(child: Text(name, style: const TextStyle(fontSize: 17, fontWeight: FontWeight.w600, color: AppColors.textPrimary))),
              if (isBP) ...[
                const SizedBox(width: 6),
                Container(padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 2), decoration: BoxDecoration(color: AppColors.primary, borderRadius: BorderRadius.circular(4)), child: const Text('血压计', style: TextStyle(fontSize: 11, color: Colors.white))),
              ],
            ]),
            const SizedBox(height: 2),
            Text('信号: ${_rssiLabel(r.rssi)}  ·  ${r.device.remoteId}', style: const TextStyle(fontSize: 13, color: AppColors.textHint)),
          ]),
        ),
        if (isConnecting)
          const SizedBox(width: 24, height: 24, child: CircularProgressIndicator(strokeWidth: 2, color: Color(0xFF5B8DEF)))
        else
          GestureDetector(
            onTap: () => _connect(r),
            child: Container(padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8), decoration: BoxDecoration(gradient: AppColors.primaryGradient, borderRadius: BorderRadius.circular(12)), child: const Text('连接', style: TextStyle(fontSize: 15, fontWeight: FontWeight.w600, color: Colors.white))),
          ),
      ]),
    );
  }

  Widget _buildEmpty() => Padding(
    padding: const EdgeInsets.all(32),
    child: Column(children: [
      Icon(Icons.bluetooth_disabled, size: 64, color: AppColors.textHint),
      const SizedBox(height: 16),
      const Text('未发现设备', style: TextStyle(fontSize: 18, fontWeight: FontWeight.w500, color: AppColors.textPrimary)),
      const SizedBox(height: 24),
      _tip('1', '确保血压计已装电池'),
      _tip('2', '长按血压计蓝牙键 3 秒直到图标闪烁'),
      _tip('3', '手机靠近血压计（1米内）'),
      _tip('4', '打开手机蓝牙'),
    ]),
  );

  Widget _tip(String num, String text) => Padding(
    padding: const EdgeInsets.only(bottom: 8),
    child: Row(crossAxisAlignment: CrossAxisAlignment.start, children: [
      Container(width: 20, height: 20, alignment: Alignment.center, decoration: BoxDecoration(color: AppColors.primary, borderRadius: BorderRadius.circular(10)), child: Text(num, style: const TextStyle(color: Colors.white, fontSize: 12, fontWeight: FontWeight.w600))),
      const SizedBox(width: 10),
      Expanded(child: Text(text, style: TextStyle(fontSize: 14, color: AppColors.textSecondary))),
    ]),
  );

  String _rssiLabel(int rssi) {
    if (rssi > -55) return '强';
    if (rssi > -70) return '中';
    return '弱';
  }
}