import 'dart:io';

import 'package:device_plugin_interface/device_plugin_interface.dart';
import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:get/get.dart';

import '../../../core/theme/app_palette.dart';
import '../../../data/services/background_launch_consent.dart';
import '../../../devices/device_hub.dart';
import '../../../devices/device_vendors.dart';
import '../../../routes/app_routes.dart';
import '../../main_tab/controllers/main_tab_controller.dart';

/// AI 耳机（恒玄 Echo-one）的连接页——走 [DeviceHub] 里的耳机插件。
///
/// 两端的用户前提不同（插件按平台各写一套）：
/// - Android：经典蓝牙 RFCOMM/SPP，`bondedDevices` 给的是系统**已配对**列表；
/// - iOS：CoreBluetooth GATT 桥接，给的是系统里**当前已连接**且带该 service 的耳机，
///   id 是 CBPeripheral 的 UUID 而不是 MAC。
///
/// 所以 Android 只要配过对就能连；iOS 必须先在系统蓝牙里把耳机连上。页面文案按平台分开。
class BesScanView extends StatefulWidget {
  const BesScanView({super.key});

  @override
  State<BesScanView> createState() => _BesScanViewState();
}

class _BesScanViewState extends State<BesScanView> {
  /// 展示用的设备名。当前固件的广播名。
  static const String _targetName = 'Echo-one';

  /// 认哪些广播名：设备端 2026-08-31 把广播名从 `DEEPVOICE` 改成 `Echo-one`，
  /// 但 Android 的配对列表给的是系统缓存的配对名，改名前配过对的手机在重新配对
  /// 之前仍然报旧名。旧名可在存量设备全部换代后删除。
  static const List<String> _acceptedNames = ['Echo-one', 'DEEPVOICE'];

  DevicePlugin get _plugin => DeviceHub.to.plugin(DeviceVendors.bes)!;
  final RxList<DiscoveredDevice> _devices = <DiscoveredDevice>[].obs;
  final RxBool _loading = true.obs;
  bool _connecting = false;
  Worker? _sessionsWorker;
  bool _finished = false;

  @override
  void initState() {
    super.initState();
    // 主动连接失败后耳机才连上手机的场景：原生靠 ACL 广播自动补 RFCOMM，
    // 一旦上线，这页也要把绑定存下来并跳回设备页。
    // `_connecting` 期间不开火：候选循环自己会收尾。
    _sessionsWorker = ever<List<DeviceSession>>(DeviceHub.to.sessions, (_) {
      if (_liveSession != null && mounted && !_finished && !_connecting) {
        _finish();
      }
    });
    WidgetsBinding.instance.addPostFrameCallback((_) => _load());
  }

  DeviceSession? get _liveSession => DeviceHub.to.sessionOf(DeviceVendors.bes);

  @override
  void dispose() {
    _sessionsWorker?.dispose();
    super.dispose();
  }

  Future<void> _finish() async {
    _finished = true;
    final s = _liveSession;
    if (s != null && s.deviceId.isNotEmpty) {
      await _plugin.rememberDevice(
          DiscoveredDevice(id: s.deviceId, name: s.info.name));
    }
    final name = s?.info.name ?? '';
    Get.snackbar('连接成功', '${name.isEmpty ? _targetName : name} 已连接',
        snackPosition: SnackPosition.TOP,
        duration: const Duration(seconds: 2));
    Get.offAllNamed(Routes.home);
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (Get.isRegistered<MainTabController>()) {
        MainTabController.to.showDeviceAfterConnect();
      }
    });
  }

  Future<void> _load() async {
    _loading.value = true;
    try {
      await _plugin.ensureReady();
      // 进页面时已经连上**不再直接跳回主页**：这页要展示已配对的耳机并把
      // 「当前连着的那台」高亮出来。想回主页点那一行即可（走 _finish）。
      final target = await _findTargets();
      _devices.assignAll(target);
      // 只有一台目标耳机时直接连；但用户拒绝过后台自动连接就不再自动发起。
      if (target.length == 1 &&
          _liveSession == null &&
          !BackgroundLaunchConsent.declined) {
        await _connect(target.first, userInitiated: false);
      }
    } catch (e) {
      Get.snackbar('besReadFailed'.tr, '无法获取已配对设备：$e',
          snackPosition: SnackPosition.TOP);
    } finally {
      _loading.value = false;
    }
  }

  /// 取目标耳机列表。iOS 上 CBCentralManager 变成 .poweredOn 要等系统回调，
  /// 在那之前列表是空的，所以要轮询几次再判定「没找到」。
  Future<List<DiscoveredDevice>> _findTargets() async {
    final int attempts = Platform.isIOS ? 10 : 1;
    for (var i = 0; i < attempts; i++) {
      final list = await _plugin.bondedDevices();
      final target = list.where((d) {
        final n = d.name.toUpperCase();
        return _acceptedNames.any((t) => n.contains(t.toUpperCase()));
      }).toList();
      if (target.isNotEmpty || i == attempts - 1) return target;
      await Future.delayed(const Duration(milliseconds: 300));
      if (!mounted) return const [];
    }
    return const [];
  }

  Future<void> _connect(DiscoveredDevice d, {bool userInitiated = true}) async {
    if (_connecting) return;
    if (d.id.isEmpty) return;
    // 绑定后耳机开机会自动回连，属于后台自动连接，先取得用户明示同意。
    if (!await BackgroundLaunchConsent.ensure(userInitiated: userInitiated)) {
      if (userInitiated) {
        Get.snackbar(
            'autoConnectRequired'.tr,
            BackgroundLaunchConsent.declined
                ? 'autoConnectReenableHint'.tr
                : 'autoConnectRequiredDesc'.tr,
            snackPosition: SnackPosition.TOP);
      }
      return;
    }
    setState(() => _connecting = true);
    try {
      // 候选 = 用户点的那台（永远第一）+ 列表里的同名设备。
      // 身份由连上之后的 MAC 校验来定，连接阶段只要「拨通一条链路」即可——
      // 同名的另一行既可能是同一只耳机的另一个 BR/EDR 地址（Android TWS 双地址），
      // 也可能是另一台同款耳机，两种都值得试。
      final tappedName = d.name.trim().toUpperCase();
      final candidates = <String>[d.id];
      for (final row in _devices) {
        final n = row.name.trim().toUpperCase();
        if (row.id.isEmpty || n != tappedName) continue;
        if (candidates.any((c) => c.toUpperCase() == row.id.toUpperCase())) {
          continue;
        }
        candidates.add(row.id);
      }

      bool ok = false;
      for (final addr in candidates) {
        try {
          await _plugin.connect(addr,
              options: DeviceConnectOptions(extra: {'name': d.name}));
          ok = true;
        } on DeviceException catch (e) {
          debugPrint('bes connect $addr failed: ${e.code}');
          ok = false;
        }
        if (ok || !mounted) break;
      }
      if (!mounted) return;
      if (ok) {
        if (!_finished) await _finish();
      } else {
        Get.snackbar(
          '连接失败',
          Platform.isIOS
              ? '请确认 $_targetName 在系统蓝牙里显示"已连接"，再回到这里重试'
              : '请确认 $_targetName 已开机、在手机附近，且没有被其它手机/电脑占用；'
                  '耳机与手机连上后会自动重连',
          snackPosition: SnackPosition.TOP,
          duration: const Duration(seconds: 4),
        );
      }
    } finally {
      if (mounted) setState(() => _connecting = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final bool isDark = Theme.of(context).brightness == Brightness.dark;
    return Scaffold(
      backgroundColor: AppPalette.background(isDark),
      appBar: AppBar(
        backgroundColor: AppPalette.background(isDark),
        elevation: 0,
        title: const Text('添加 AI 耳机（$_targetName）'),
        actions: [
          IconButton(icon: const Icon(Icons.refresh), onPressed: _load),
        ],
      ),
      body: _connecting
          ? Center(
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  const CircularProgressIndicator(),
                  const SizedBox(height: 16),
                  Text('besConnecting'.tr),
                ],
              ),
            )
          : Obx(() {
              if (_loading.value) {
                return const Center(child: CircularProgressIndicator());
              }
              if (_devices.isEmpty) return _empty(isDark);
              // 连接态必须在**这里**读出来再传下去：ListView 的 itemBuilder 是
              // 延迟调用的，在 _tile 里读 Rx 不会被这个 Obx 收集到。
              DeviceHub.to.sessions.length;
              final live = _liveSession;
              return ListView.separated(
                padding: EdgeInsets.fromLTRB(16.w, 16.h, 16.w, 24.h),
                itemCount: _devices.length,
                separatorBuilder: (_, __) => SizedBox(height: 12.h),
                itemBuilder: (context, i) => _tile(
                  _devices[i],
                  isDark,
                  connected: live != null && _isLiveDevice(_devices[i], live),
                ),
              );
            }),
    );
  }

  Widget _empty(bool isDark) {
    return Center(
      child: Padding(
        padding: EdgeInsets.symmetric(horizontal: 32.w),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(Icons.headset_off, size: 56.sp, color: AppPalette.brand300),
            SizedBox(height: 12.h),
            Text('没有找到 $_targetName 耳机',
                style: TextStyle(
                    fontSize: 15.sp,
                    color: AppPalette.textSecondary(isDark))),
            SizedBox(height: 6.h),
            Text(
              Platform.isIOS
                  ? '请先在系统「设置 → 蓝牙」里连接 $_targetName（显示"已连接"），再回到这里'
                  : '$_targetName 走经典蓝牙，请先在系统「设置 → 蓝牙」里完成配对，再回到这里连接',
              textAlign: TextAlign.center,
              style: TextStyle(
                  fontSize: 12.sp, color: AppPalette.textHint(isDark)),
            ),
          ],
        ),
      ),
    );
  }

  /// 这一行是不是当前正连着的那台。不能只比地址：Android 上耳机是 TWS 双地址，
  /// 系统配对列表给的地址不一定是真正跑 SPP 的那个。地址对不上时退回比设备名。
  bool _isLiveDevice(DiscoveredDevice d, DeviceSession live) {
    final addr = d.id.toUpperCase();
    final localId = (live.info.metadata['localId'] as String?) ?? live.deviceId;
    if (addr.isNotEmpty && addr == localId.toUpperCase()) return true;
    final n = d.name.trim().toUpperCase();
    final cn = live.info.name.trim().toUpperCase();
    return n.isNotEmpty && n == cn;
  }

  Widget _tile(DiscoveredDevice d, bool isDark, {bool connected = false}) {
    final name = d.name.isEmpty ? 'bleUnknownDevice'.tr : d.name;
    const Color accent = AppPalette.accent;
    final Color idle = AppPalette.textHint(isDark);

    return GestureDetector(
      behavior: HitTestBehavior.opaque,
      onTap: () => connected ? _finish() : _connect(d),
      child: Container(
        padding: EdgeInsets.all(14.w),
        decoration: BoxDecoration(
          color: connected
              ? accent.withValues(alpha: isDark ? 0.16 : 0.08)
              : AppPalette.surface(isDark),
          borderRadius: BorderRadius.circular(14.r),
          border: Border.all(
            color: connected ? accent : AppPalette.border(isDark),
            width: connected ? 1.5 : 1,
          ),
        ),
        child: Row(
          children: [
            Icon(Icons.headphones,
                size: 26.sp, color: connected ? accent : idle),
            SizedBox(width: 12.w),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(name,
                      style: TextStyle(
                          fontSize: 15.sp,
                          fontWeight:
                              connected ? FontWeight.w700 : FontWeight.w500,
                          color: connected
                              ? AppPalette.textPrimary(isDark)
                              : AppPalette.textSecondary(isDark))),
                  SizedBox(height: 2.h),
                  Text(d.id, style: TextStyle(fontSize: 11.sp, color: idle)),
                ],
              ),
            ),
            if (connected) ...[
              Icon(Icons.check_circle, size: 16.sp, color: accent),
              SizedBox(width: 4.w),
            ],
            Text(connected ? 'connected'.tr : 'connect'.tr,
                style: TextStyle(
                    fontSize: 13.sp,
                    fontWeight: FontWeight.w600,
                    color: connected ? accent : idle)),
          ],
        ),
      ),
    );
  }
}