import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.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/pages/settings_page.dart';

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

  @override
  State<RegistrationPage> createState() => _RegistrationPageState();
}

class _RegistrationPageState extends State<RegistrationPage> {
  final _scannerService = ScannerService();
  final _apiService = ApiService();

  String? _zongpaiNo;
  String? _locationCode;
  CodeType? _locationType;
  bool _isLocked = false;
  bool _isSubmitting = false;

  String? _successMessage;
  String? _snackbarMessage;
  Color? _snackbarColor;

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

  void _onScan(ScanResult result) {
    final parsed = CodeParser.parse(result.barcode);
    switch (parsed.type) {
      case CodeType.zongpaiNo:
        setState(() {
          _zongpaiNo = parsed.value;
          _snackbarMessage = null;
          _successMessage = null;
        });
      case CodeType.locationNormal:
      case CodeType.locationTransit:
        if (!_isLocked) {
          setState(() {
            _locationCode = parsed.value;
            _locationType = parsed.type;
            _snackbarMessage = null;
            _successMessage = null;
          });
        }
      case CodeType.invalid:
        _showFeedback('无效码，请重新扫描', isError: true);
    }
  }

  void _showFeedback(String message, {bool isError = false}) {
    setState(() {
      _snackbarMessage = message;
      _snackbarColor = isError ? Colors.red.shade700 : Colors.green.shade700;
    });
    Future.delayed(const Duration(seconds: 2), () {
      if (mounted) setState(() => _snackbarMessage = null);
    });
  }

  String get _statusText {
    if (_isSubmitting) return '正在提交…';
    if (_successMessage != null) return _successMessage!;
    if (_isLocked && _locationCode != null && _zongpaiNo == null) {
      return '货位已锁定，请扫描下一张执行卡';
    }
    final hasZ = _zongpaiNo != null;
    final hasL = _locationCode != null;
    if (hasZ && hasL) return '请确认信息并提交';
    if (hasZ && !hasL) return '请扫描目标货位号';
    if (!hasZ && hasL) return '请扫描执行卡';
    return '等待扫描总排号或货位号…';
  }

  bool get _canSubmit =>
      _zongpaiNo != null && _locationCode != null && !_isSubmitting;

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

    final prefs = await SharedPreferences.getInstance();
    final baseUrl = prefs.getString('api_url') ?? '';
    if (baseUrl.isEmpty) {
      _showFeedback('未配置 API 地址，请前往设置', isError: true);
      return;
    }

    setState(() => _isSubmitting = true);

    final result = await _apiService.registerLocation(
      baseUrl: baseUrl,
      zongpaiNo: _zongpaiNo!,
      locationCode: _locationCode!,
    );

    if (!mounted) return;

    setState(() => _isSubmitting = false);

    if (result.success) {
      setState(() {
        _zongpaiNo = null;
        if (!_isLocked) {
          _locationCode = null;
          _locationType = null;
        }
        _successMessage =
            _isLocked ? '货位已锁定，请扫描下一张执行卡' : '上架成功';
      });
      _showFeedback('上架成功', isError: false);
      Future.delayed(const Duration(milliseconds: 1500), () {
        if (mounted) setState(() => _successMessage = null);
      });
    } else if (result.isDuplicate) {
      _showDuplicateDialog(result.duplicateInfo);
    } else {
      _showFeedback(result.errorMessage ?? '提交失败', isError: true);
    }
  }

  void _showDuplicateDialog(Map<String, dynamic>? info) {
    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (ctx) => AlertDialog(
        backgroundColor: Colors.red.shade50,
        title: const Row(
          children: [
            Icon(Icons.warning, color: Colors.red),
            SizedBox(width: 8),
            Text('重复上架', style: TextStyle(color: Colors.red)),
          ],
        ),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text('总排号：${_zongpaiNo ?? ""}'),
            const SizedBox(height: 4),
            Text('已登记货位：${info?["location_code"] ?? "未知"}'),
            const SizedBox(height: 4),
            Text('登记时间：${info?["registered_at"] ?? "未知"}'),
            const SizedBox(height: 12),
            const Text('请核查实物，确认是否操作错误。',
                style: TextStyle(fontWeight: FontWeight.bold)),
          ],
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: const Text('关闭'),
          ),
        ],
      ),
    );
  }

  void _toggleLock(bool value) {
    if (value && _locationCode == null) {
      _showFeedback('请先扫描货位号', isError: true);
      return;
    }
    setState(() => _isLocked = value);
  }

  String _locationLabel(CodeType? type) {
    if (type == CodeType.locationTransit) return '转运区域';
    return '普通货架';
  }

  Color _locationLabelColor(CodeType? type) {
    if (type == CodeType.locationTransit) return Colors.orange;
    return Colors.blue;
  }

  @override
  Widget build(BuildContext context) {
    final colorScheme = Theme.of(context).colorScheme;

    return Scaffold(
      appBar: AppBar(
        title: const Text('上架登记'),
        actions: [
          Padding(
            padding: const EdgeInsets.only(right: 4),
            child: Row(
              children: [
                const Text('锁定货位', style: TextStyle(fontSize: 13)),
                Switch(
                  value: _isLocked,
                  onChanged: _toggleLock,
                ),
                IconButton(
                  icon: const Icon(Icons.settings),
                  onPressed: () => Navigator.push(
                    context,
                    MaterialPageRoute(builder: (_) => const SettingsPage()),
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
      body: Column(
        children: [
          // Feedback banner
          if (_snackbarMessage != null)
            Container(
              width: double.infinity,
              padding:
                  const EdgeInsets.symmetric(vertical: 10, horizontal: 16),
              color: _snackbarColor,
              child: Text(
                _snackbarMessage!,
                style: const TextStyle(color: Colors.white, fontSize: 14),
                textAlign: TextAlign.center,
              ),
            ),

          // Main form area
          Expanded(
            child: Padding(
              padding: const EdgeInsets.all(16),
              child: Column(
                children: [
                  // Zongpai number field
                  const Align(
                    alignment: Alignment.centerLeft,
                    child: Text('总排号',
                        style: TextStyle(
                            fontSize: 14, fontWeight: FontWeight.w500)),
                  ),
                  const SizedBox(height: 6),
                  Container(
                    width: double.infinity,
                    padding: const EdgeInsets.symmetric(
                        horizontal: 12, vertical: 14),
                    decoration: BoxDecoration(
                      border: Border.all(
                        color: _zongpaiNo != null
                            ? Colors.green
                            : Colors.grey.shade400,
                        width: _zongpaiNo != null ? 2 : 1,
                      ),
                      borderRadius: BorderRadius.circular(8),
                    ),
                    child: Text(
                      _zongpaiNo ?? '',
                      style: TextStyle(
                        fontSize: 20,
                        fontWeight: FontWeight.bold,
                        color: _zongpaiNo != null
                            ? Colors.black87
                            : Colors.grey,
                      ),
                    ),
                  ),

                  const SizedBox(height: 20),

                  // Location field with type label
                  Row(
                    children: [
                      const Text('目标货位',
                          style: TextStyle(
                              fontSize: 14, fontWeight: FontWeight.w500)),
                      if (_locationCode != null) ...[
                        const SizedBox(width: 8),
                        Container(
                          padding: const EdgeInsets.symmetric(
                              horizontal: 6, vertical: 2),
                          decoration: BoxDecoration(
                            color: _locationLabelColor(_locationType)
                                .withValues(alpha: 0.15),
                            borderRadius: BorderRadius.circular(4),
                          ),
                          child: Text(
                            _locationLabel(_locationType),
                            style: TextStyle(
                              fontSize: 11,
                              color: _locationLabelColor(_locationType),
                              fontWeight: FontWeight.bold,
                            ),
                          ),
                        ),
                      ],
                    ],
                  ),
                  const SizedBox(height: 6),
                  Container(
                    width: double.infinity,
                    padding: const EdgeInsets.symmetric(
                        horizontal: 12, vertical: 14),
                    decoration: BoxDecoration(
                      border: Border.all(
                        color: _locationCode != null
                            ? Colors.green
                            : Colors.grey.shade400,
                        width: _locationCode != null ? 2 : 1,
                      ),
                      borderRadius: BorderRadius.circular(8),
                    ),
                    child: Row(
                      children: [
                        Expanded(
                          child: Text(
                            _locationCode ?? '',
                            style: TextStyle(
                              fontSize: 20,
                              fontWeight: FontWeight.bold,
                              color: _locationCode != null
                                  ? Colors.black87
                                  : Colors.grey,
                            ),
                          ),
                        ),
                        if (_isLocked)
                          const Icon(Icons.lock,
                              color: Colors.orange, size: 20),
                      ],
                    ),
                  ),

                  const SizedBox(height: 28),

                  // Submit button
                  SizedBox(
                    width: double.infinity,
                    height: 48,
                    child: ElevatedButton(
                      onPressed: _canSubmit ? _submit : null,
                      style: ElevatedButton.styleFrom(
                        backgroundColor: _canSubmit
                            ? colorScheme.primary
                            : Colors.grey.shade300,
                        foregroundColor: _canSubmit
                            ? Colors.white
                            : Colors.grey.shade600,
                        shape: RoundedRectangleBorder(
                          borderRadius: BorderRadius.circular(8),
                        ),
                      ),
                      child: _isSubmitting
                          ? const SizedBox(
                              width: 22,
                              height: 22,
                              child: CircularProgressIndicator(
                                strokeWidth: 2,
                                color: Colors.white,
                              ),
                            )
                          : const Text('确 认 上 架',
                              style: TextStyle(fontSize: 18)),
                    ),
                  ),
                ],
              ),
            ),
          ),

          // Status bar at bottom
          Container(
            width: double.infinity,
            padding: const EdgeInsets.symmetric(vertical: 12, horizontal: 16),
            color: colorScheme.surfaceContainerHighest,
            child: Row(
              children: [
                Container(
                  width: 8,
                  height: 8,
                  decoration: BoxDecoration(
                    color: _isSubmitting
                        ? Colors.orange
                        : _successMessage != null
                            ? Colors.green
                            : Colors.blue,
                    shape: BoxShape.circle,
                  ),
                ),
                const SizedBox(width: 8),
                Expanded(
                  child: Text(
                    _statusText,
                    style: const TextStyle(fontSize: 14),
                    overflow: TextOverflow.ellipsis,
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}