import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:pad_scanner/services/app_config_service.dart';
import 'package:pad_scanner/services/scanner_service.dart';
import 'package:pad_scanner/services/code_parser.dart';
import 'package:pad_scanner/services/api_service.dart';
import 'package:pad_scanner/services/feedback_service.dart';
import 'package:pad_scanner/pages/boxing_detail_page.dart';
import 'package:pad_scanner/widgets/status_bar.dart';

// === 装箱模式 ===

enum BoxingMode {
  one2one, // 一码一箱
  one2many, // 一码多箱
  many2one, // 多码一箱
}

// === 页面阶段 ===

enum _Phase {
  waiting, // 等待扫码
  scanned, // 已扫码，显示信息
  submitted, // 已提交成功
}

// === 主页面 ===

class BoxingPage extends StatefulWidget {
  const BoxingPage({super.key});

  @override
  State<BoxingPage> createState() => _BoxingPageState();
}

class _BoxingPageState extends State<BoxingPage> {
  final _scannerService = ScannerService();
  final _apiService = ApiService();
  final _feedbackService = FeedbackService();

  // 模式
  BoxingMode _mode = BoxingMode.one2one;

  // 阶段
  _Phase _phase = _Phase.waiting;

  // 当前总排号
  String? _zongpaiNo;

  // 排产号信息（来自后端查询）
  String? _paichanNo;
  int? _erpQuantity;
  List<BoxDetailData> _existingBoxes = [];
  int _maxBoxNo = 0;

  // 输入
  final _boxNoController = TextEditingController();
  final _quantityController = TextEditingController();
  final _boxNoFocusNode = FocusNode();
  final _quantityFocusNode = FocusNode();

  // 多码一箱：已扫描过的总排号列表（用于显示）
  final _scannedZongpais = <String>[];

  // 箱号锁定（多码一箱模式）
  bool _boxNoLocked = false;

  // 提交中
  bool _isSubmitting = false;

  // 一码多箱：上次提交的值（用于继续添加预填）
  int? _lastBoxNo;
  int? _lastQuantity;

  // 重复箱号
  bool _isDuplicateBoxNo = false;

  // Status bar state
  StatusDotColor _statusDot = StatusDotColor.blue;
  String _statusText = '等待扫码';
  String? _statusOverrideText;
  StatusDotColor? _statusOverrideDot;

  @override
  void initState() {
    super.initState();
    _scannerService.scanResults.listen(_onScan);
  }

  @override
  void dispose() {
    _boxNoController.dispose();
    _quantityController.dispose();
    _boxNoFocusNode.dispose();
    _quantityFocusNode.dispose();
    _feedbackService.dispose();
    super.dispose();
  }

  // === 模式切换 ===

  String get _modeLabel {
    switch (_mode) {
      case BoxingMode.one2one:
        return '一码一箱';
      case BoxingMode.one2many:
        return '一码多箱';
      case BoxingMode.many2one:
        return '多码一箱';
    }
  }

  void _cycleMode() {
    _feedbackService.trigger(FeedbackEvent.modeSwitch);
    setState(() {
      switch (_mode) {
        case BoxingMode.one2one:
          _mode = BoxingMode.one2many;
        case BoxingMode.one2many:
          _mode = BoxingMode.many2one;
        case BoxingMode.many2one:
          _mode = BoxingMode.one2one;
      }
      _resetState();
    });
  }

  void _resetState() {
    _phase = _Phase.waiting;
    _zongpaiNo = null;
    _paichanNo = null;
    _erpQuantity = null;
    _existingBoxes = [];
    _maxBoxNo = 0;
    _boxNoController.clear();
    _quantityController.clear();
    _scannedZongpais.clear();
    _boxNoLocked = false;
    _isSubmitting = false;
    _lastBoxNo = null;
    _lastQuantity = null;
    _isDuplicateBoxNo = false;
    _statusOverrideText = null;
    _statusOverrideDot = null;
  }

  // === 扫码处理 ===

  void _onScan(ScanResult result) {
    final parsed = CodeParser.parse(result.barcode);

    if (parsed.type != CodeType.zongpaiNo) {
      _feedbackService.trigger(FeedbackEvent.scanInvalid);
      _showStatusOverride(
        '无效码，请重新扫描',
        StatusDotColor.red,
        const Duration(seconds: 2),
      );
      return;
    }

    final zongpai = parsed.value;

    // 多码一箱已提交后：等待下一个扫码
    if (_mode == BoxingMode.many2one && _phase == _Phase.submitted) {
      _handleNextScanMany2One(zongpai);
      return;
    }

    // 一码一箱：允许覆盖，直接查询新二维码（不提前清空状态，避免闪烁）
    if (_mode != BoxingMode.one2one && _phase != _Phase.waiting) {
      return;
    }

    _queryBoxInfo(zongpai);
  }

  void _handleNextScanMany2One(String zongpai) {
    setState(() {
      _phase = _Phase.waiting;
      _zongpaiNo = null;
      _statusOverrideText = null;
    });
    _queryBoxInfo(zongpai);
  }

  Future<void> _queryBoxInfo(String zongpai) async {
    final configService = AppConfigService();
    final baseUrl = await configService.getString('api_url') ?? '';
    if (baseUrl.isEmpty) {
      _feedbackService.trigger(FeedbackEvent.submitFailure);
      _showStatusOverride(
        '未配置 API 地址，请前往设置',
        StatusDotColor.red,
        const Duration(seconds: 2),
      );
      return;
    }

    final result = await _apiService.fetchBoxInfo(
      baseUrl: baseUrl,
      zongpaiNo: zongpai,
    );

    if (!mounted) return;

    if (!result.success) {
      final isNetwork = result.errorMessage == '网络异常，请检查网络连接';
      _feedbackService.trigger(
        isNetwork ? FeedbackEvent.networkError : FeedbackEvent.scanInvalid,
      );
      _showStatusOverride(
        result.errorMessage ?? '查询失败',
        isNetwork ? StatusDotColor.yellow : StatusDotColor.red,
        const Duration(seconds: 2),
      );
      return;
    }

    _feedbackService.trigger(FeedbackEvent.scanValid);

    setState(() {
      _zongpaiNo = zongpai;
      _paichanNo = result.paichanNo;
      _erpQuantity = result.quantity;
      _existingBoxes = result.existingBoxes;
      _maxBoxNo = result.maxBoxNo;
      _phase = _Phase.scanned;
      _isDuplicateBoxNo = false;
      _statusOverrideText = null;

      // 多码一箱：记录已扫描列表
      if (_mode == BoxingMode.many2one && !_scannedZongpais.contains(zongpai)) {
        _scannedZongpais.add(zongpai);
      }

      // 根据模式自动填充
      _applyAutoFill();
    });
  }

  void _applyAutoFill() {
    switch (_mode) {
      case BoxingMode.one2one:
        _boxNoController.text = (_maxBoxNo + 1).toString();
        _quantityController.text = (_erpQuantity ?? 0).toString();
      case BoxingMode.one2many:
        if (_lastBoxNo != null) {
          _boxNoController.text = (_lastBoxNo! + 1).toString();
          _quantityController.text = _lastQuantity?.toString() ?? '';
        } else {
          _boxNoController.text = (_maxBoxNo + 1).toString();
          _quantityController.clear();
        }
      case BoxingMode.many2one:
        if (!_boxNoLocked) {
          _boxNoController.text = (_maxBoxNo + 1).toString();
          _boxNoLocked = true;
        }
        _quantityController.text = (_erpQuantity ?? 0).toString();
    }
    _checkDuplicateBoxNo();
  }

  // === 重复箱号检测 ===

  void _checkDuplicateBoxNo() {
    final boxNo = int.tryParse(_boxNoController.text);
    if (boxNo == null) {
      setState(() => _isDuplicateBoxNo = false);
      return;
    }
    final exists = _existingBoxes.any((b) => b.boxNo == boxNo);
    setState(() => _isDuplicateBoxNo = exists);
  }

  // === 提交 ===

  bool get _canSubmit {
    if (_isSubmitting || _phase != _Phase.scanned) return false;
    if (_zongpaiNo == null) return false;
    final boxNo = int.tryParse(_boxNoController.text);
    final qty = int.tryParse(_quantityController.text);
    if (boxNo == null || qty == null || qty <= 0) return false;
    if (_isDuplicateBoxNo) return false;
    return true;
  }

  Future<void> _submit() async {
    if (!_canSubmit) return;

    final configService = AppConfigService();
    final baseUrl = await configService.getString('api_url') ?? '';
    if (baseUrl.isEmpty) {
      _feedbackService.trigger(FeedbackEvent.submitFailure);
      _showStatusOverride(
        '未配置 API 地址，请前往设置',
        StatusDotColor.red,
        const Duration(seconds: 2),
      );
      return;
    }

    final boxNo = int.parse(_boxNoController.text);
    final quantity = int.parse(_quantityController.text);

    setState(() => _isSubmitting = true);

    final modeStr = switch (_mode) {
      BoxingMode.one2one => 'one-to-one',
      BoxingMode.one2many => 'one-to-many',
      BoxingMode.many2one => 'many-to-one',
    };
    final result = await _apiService.saveBoxRecord(
      baseUrl: baseUrl,
      zongpaiNo: _zongpaiNo!,
      boxNo: boxNo,
      quantity: quantity,
      boxMode: modeStr,
    );

    if (!mounted) return;

    setState(() => _isSubmitting = false);

    if (result.success) {
      _onSubmitSuccess(boxNo, quantity);
    } else if (result.isDuplicate) {
      _feedbackService.trigger(FeedbackEvent.duplicateBoxNo);
      if (_mode == BoxingMode.one2one) {
        _showStatusOverride(
          '该总排号已绑定箱号 ${result.boxNo ?? "?"}，请勿重复装箱',
          StatusDotColor.red,
          const Duration(seconds: 2),
        );
      } else {
        _showStatusOverride(
          '排产号 ${result.paichanNo ?? ""} 下箱号 ${result.boxNo ?? ""} 已存在',
          StatusDotColor.amber,
          const Duration(seconds: 2),
        );
      }
    } else {
      final isNetwork = result.errorMessage == '网络异常，请检查网络连接';
      _feedbackService.trigger(
        isNetwork ? FeedbackEvent.networkError : FeedbackEvent.submitFailure,
      );
      _showStatusOverride(
        result.errorMessage ?? '提交失败',
        isNetwork ? StatusDotColor.yellow : StatusDotColor.red,
        const Duration(seconds: 2),
      );
    }
  }

  void _onSubmitSuccess(int boxNo, int quantity) {
    _feedbackService.trigger(FeedbackEvent.submitSuccess);

    setState(() {
      _lastBoxNo = boxNo;
      _lastQuantity = quantity;
      _existingBoxes = List.from(_existingBoxes)
        ..add(
          BoxDetailData(
            boxNo: boxNo,
            items: [BoxItemData(zongpaiNo: _zongpaiNo!, quantity: quantity)],
          ),
        );
      _maxBoxNo = _maxBoxNo > boxNo ? _maxBoxNo : boxNo;
    });

    switch (_mode) {
      case BoxingMode.one2one:
        _showStatusOverride('装箱成功', StatusDotColor.green, const Duration(milliseconds: 1500));
        Future.delayed(const Duration(milliseconds: 1500), () {
          if (mounted) setState(() => _resetState());
        });

      case BoxingMode.one2many:
        setState(() {
          _phase = _Phase.submitted;
          _zongpaiNo = null;
        });
        _showStatusOverride('装箱成功，可继续添加或返回', StatusDotColor.green, const Duration(milliseconds: 1500));

      case BoxingMode.many2one:
        setState(() {
          _phase = _Phase.submitted;
          _zongpaiNo = null;
        });
        _showStatusOverride('装箱成功，请扫描下一个总排号', StatusDotColor.green, const Duration(milliseconds: 1500));
    }
  }

  // === 操作按钮 ===

  void _onContinueAdding() {
    setState(() {
      _phase = _Phase.waiting;
      _statusOverrideText = null;
    });
  }

  void _onGoBack() {
    setState(() => _resetState());
  }

  // === Status bar management ===

  void _showStatusOverride(String text, StatusDotColor dot, Duration duration) {
    setState(() {
      _statusOverrideText = text;
      _statusOverrideDot = dot;
    });
    Future.delayed(duration, () {
      if (mounted) {
        setState(() {
          _statusOverrideText = null;
          _statusOverrideDot = null;
        });
      }
    });
  }

  // === 导航到详情页 ===

  void _openDetail() {
    Navigator.push(
      context,
      MaterialPageRoute(
        builder: (_) => BoxingDetailPage(
          paichanNo: _paichanNo ?? '',
          existingBoxes: _existingBoxes,
        ),
      ),
    );
  }

  // === 状态文字 ===

  void _updateBaseStatus() {
    if (_isSubmitting) {
      _statusDot = StatusDotColor.orange;
      _statusText = '正在提交…';
      return;
    }
    if (_isDuplicateBoxNo && _phase == _Phase.scanned) {
      _statusDot = StatusDotColor.amber;
      _statusText = '箱号 ${_boxNoController.text} 已存在，请重新输入';
      return;
    }
    switch (_phase) {
      case _Phase.waiting:
        _statusDot = StatusDotColor.blue;
        if (_mode == BoxingMode.many2one && _boxNoLocked) {
          _statusText = '请扫描下一个总排号';
        } else {
          _statusText = '等待扫码';
        }
      case _Phase.scanned:
        _statusDot = StatusDotColor.blue;
        _statusText = '请确认信息并提交';
      case _Phase.submitted:
        _statusDot = StatusDotColor.green;
        switch (_mode) {
          case BoxingMode.one2many:
            _statusText = '装箱成功，可继续添加或返回';
          case BoxingMode.many2one:
            _statusText = '请扫描下一个总排号';
          case BoxingMode.one2one:
            _statusText = '';
        }
    }
  }

  // === Build ===

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;
    final isWaiting = _phase == _Phase.waiting && _zongpaiNo == null;
    final showActionButtons =
        _phase == _Phase.submitted && _mode != BoxingMode.one2one;

    _updateBaseStatus();
    final effectiveDot = _statusOverrideDot ?? _statusDot;
    final effectiveText = _statusOverrideText ?? _statusText;

    return Scaffold(
      appBar: AppBar(
        title: const Text('装箱编号'),
        actions: [
          Padding(
            padding: const EdgeInsets.only(right: 4),
            child: TextButton.icon(
              onPressed: _cycleMode,
              icon: const Icon(Icons.swap_horiz, size: 18),
              label: Text(_modeLabel, style: const TextStyle(fontSize: 13)),
              style: TextButton.styleFrom(
                foregroundColor: _mode == BoxingMode.many2one
                    ? Colors.orange
                    : colorScheme.primary,
              ),
            ),
          ),
        ],
      ),
      body: Column(
        children: [
          // 重复箱号警告条（保留，因为这是输入区关联的即时反馈）
          if (_isDuplicateBoxNo && _phase == _Phase.scanned)
            Container(
              width: double.infinity,
              padding: const EdgeInsets.symmetric(vertical: 8, horizontal: 16),
              color: Colors.amber.shade100,
              child: Text(
                '箱号 ${_boxNoController.text} 已存在，请重新输入',
                style: TextStyle(color: Colors.amber.shade900, fontSize: 13),
              ),
            ),

          // 主内容区
          Expanded(
            child: SingleChildScrollView(
              padding: const EdgeInsets.all(12),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  // === 扫码区 ===
                  _buildScanArea(isWaiting),

                  const SizedBox(height: 12),

                  // === 信息区 ===
                  _buildInfoArea(isWaiting, colorScheme),

                  const Divider(height: 24),

                  // === 输入区 ===
                  _buildInputArea(isWaiting),
                ],
              ),
            ),
          ),

          // 操作按钮（一码多箱 / 多码一箱）
          if (showActionButtons)
            Padding(
              padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 4),
              child: Row(
                children: [
                  Expanded(
                    child: OutlinedButton(
                      onPressed: _onGoBack,
                      style: OutlinedButton.styleFrom(
                        minimumSize: const Size.fromHeight(40),
                      ),
                      child: const Text('返回'),
                    ),
                  ),
                  if (_mode == BoxingMode.one2many) ...[
                    const SizedBox(width: 12),
                    Expanded(
                      child: ElevatedButton(
                        onPressed: _onContinueAdding,
                        style: ElevatedButton.styleFrom(
                          minimumSize: const Size.fromHeight(40),
                        ),
                        child: const Text('继续添加'),
                      ),
                    ),
                  ],
                ],
              ),
            ),

          // 底部状态栏
          StatusBar(dotColor: effectiveDot, text: effectiveText),
        ],
      ),
    );
  }

  // === 扫码区 Widget ===

  Widget _buildScanArea(bool isWaiting) {
    if (isWaiting) {
      return Container(
        width: double.infinity,
        padding: const EdgeInsets.all(16),
        decoration: BoxDecoration(
          color: Colors.grey.shade100,
          borderRadius: BorderRadius.circular(8),
        ),
        child: const Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(Icons.qr_code_scanner, color: Colors.grey, size: 20),
            SizedBox(width: 8),
            Text(
              '请扫描执行卡二维码',
              style: TextStyle(color: Colors.grey, fontSize: 14),
            ),
          ],
        ),
      );
    }

    if (_mode == BoxingMode.many2one && _scannedZongpais.isNotEmpty) {
      return Wrap(
        spacing: 6,
        runSpacing: 4,
        children: _scannedZongpais.map((zp) {
          final isCurrent = zp == _zongpaiNo;
          return Chip(
            avatar: Icon(
              Icons.check_circle,
              size: 16,
              color: isCurrent ? Colors.green : Colors.grey,
            ),
            label: Text(zp, style: const TextStyle(fontSize: 13)),
            visualDensity: VisualDensity.compact,
          );
        }).toList(),
      );
    }

    return Container(
      width: double.infinity,
      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 12),
      decoration: BoxDecoration(
        border: Border.all(color: Colors.green, width: 2),
        borderRadius: BorderRadius.circular(8),
      ),
      child: Row(
        children: [
          const Icon(Icons.check_circle, color: Colors.green, size: 18),
          const SizedBox(width: 8),
          Text(
            _zongpaiNo ?? '',
            style: const TextStyle(
              fontSize: 18,
              fontWeight: FontWeight.bold,
              color: Colors.black87,
            ),
          ),
          const Spacer(),
          const Text(
            '已识别',
            style: TextStyle(fontSize: 12, color: Colors.green),
          ),
        ],
      ),
    );
  }

  // === 信息区 Widget ===

  Widget _buildInfoArea(bool isWaiting, ColorScheme colorScheme) {
    final grey = isWaiting;

    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(
          '排产号：',
          style: TextStyle(
            fontSize: 13,
            color: grey ? Colors.grey : Colors.black54,
          ),
        ),
        const SizedBox(height: 2),
        Text(
          _paichanNo ?? '--',
          style: TextStyle(
            fontSize: 16,
            fontWeight: FontWeight.w600,
            color: grey ? Colors.grey : Colors.black87,
          ),
        ),
        const SizedBox(height: 8),

        Row(
          children: [
            Expanded(
              child: Row(
                children: [
                  Text(
                    '已有箱数：',
                    style: TextStyle(
                      fontSize: 13,
                      color: grey ? Colors.grey : Colors.black54,
                    ),
                  ),
                  Text(
                    grey ? '--' : '${_existingBoxes.length}箱',
                    style: TextStyle(
                      fontSize: 13,
                      fontWeight: FontWeight.w600,
                      color: grey ? Colors.grey : Colors.black87,
                    ),
                  ),
                  const SizedBox(width: 16),
                  Text(
                    '最大箱号：',
                    style: TextStyle(
                      fontSize: 13,
                      color: grey ? Colors.grey : Colors.black54,
                    ),
                  ),
                  Text(
                    grey ? '--' : '$_maxBoxNo',
                    style: TextStyle(
                      fontSize: 13,
                      fontWeight: FontWeight.w600,
                      color: _maxBoxNo > 0
                          ? Colors.amber.shade800
                          : Colors.grey,
                    ),
                  ),
                ],
              ),
            ),
            TextButton(
              onPressed: grey || _existingBoxes.isEmpty ? null : _openDetail,
              style: TextButton.styleFrom(
                padding: const EdgeInsets.symmetric(horizontal: 8),
                minimumSize: Size.zero,
                tapTargetSize: MaterialTapTargetSize.shrinkWrap,
              ),
              child: Text(
                '详情 →',
                style: TextStyle(
                  fontSize: 13,
                  color: grey || _existingBoxes.isEmpty
                      ? Colors.grey.shade400
                      : colorScheme.primary,
                ),
              ),
            ),
          ],
        ),
      ],
    );
  }

  // === 输入区 Widget ===

  Widget _buildInputArea(bool isWaiting) {
    final enabled = !isWaiting && _phase == _Phase.scanned;

    return Row(
      crossAxisAlignment: CrossAxisAlignment.end,
      children: [
        // 箱号输入
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                '箱号',
                style: TextStyle(
                  fontSize: 13,
                  color: enabled ? Colors.black54 : Colors.grey,
                ),
              ),
              const SizedBox(height: 4),
              SizedBox(
                height: 40,
                child: TextField(
                  controller: _boxNoController,
                  focusNode: _boxNoFocusNode,
                  enabled: enabled && !_boxNoLocked,
                  keyboardType: TextInputType.number,
                  inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                  onChanged: (_) => _checkDuplicateBoxNo(),
                  decoration: InputDecoration(
                    contentPadding: const EdgeInsets.symmetric(horizontal: 10),
                    border: const OutlineInputBorder(),
                    enabledBorder: OutlineInputBorder(
                      borderSide: BorderSide(
                        color: _isDuplicateBoxNo
                            ? Colors.amber
                            : Colors.grey.shade400,
                      ),
                    ),
                    suffixIcon: _boxNoLocked
                        ? const Icon(Icons.lock, size: 18, color: Colors.orange)
                        : null,
                  ),
                  style: const TextStyle(fontSize: 16),
                ),
              ),
            ],
          ),
        ),
        const SizedBox(width: 8),

        // 数量输入
        Expanded(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                '数量',
                style: TextStyle(
                  fontSize: 13,
                  color: enabled ? Colors.black54 : Colors.grey,
                ),
              ),
              const SizedBox(height: 4),
              SizedBox(
                height: 40,
                child: TextField(
                  controller: _quantityController,
                  focusNode: _quantityFocusNode,
                  enabled: enabled,
                  keyboardType: TextInputType.number,
                  inputFormatters: [FilteringTextInputFormatter.digitsOnly],
                  decoration: const InputDecoration(
                    contentPadding: EdgeInsets.symmetric(horizontal: 10),
                    border: OutlineInputBorder(),
                  ),
                  style: const TextStyle(fontSize: 16),
                ),
              ),
            ],
          ),
        ),
        const SizedBox(width: 8),

        // 确认按钮
        SizedBox(
          height: 40,
          child: ElevatedButton(
            onPressed: _canSubmit ? _submit : null,
            style: ElevatedButton.styleFrom(
              backgroundColor: _canSubmit
                  ? Theme.of(context).colorScheme.primary
                  : Colors.grey.shade300,
              foregroundColor: _canSubmit ? Colors.white : Colors.grey.shade600,
            ),
            child: _isSubmitting
                ? const SizedBox(
                    width: 18,
                    height: 18,
                    child: CircularProgressIndicator(
                      strokeWidth: 2,
                      color: Colors.white,
                    ),
                  )
                : const Text('确认', style: TextStyle(fontSize: 15)),
          ),
        ),
      ],
    );
  }
}