import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../services/odoo_service.dart';
import '../utils/theme.dart';
import 'pos_selling_screen.dart';

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

  @override
  State<PosListScreen> createState() => _PosListScreenState();
}

class _PosListScreenState extends State<PosListScreen> {
  List<dynamic> _posConfigs = [];
  bool _isLoading = true;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _fetchPosConfigs());
  }

  Map<int, dynamic> _sessionDetails = {};

  Future<void> _fetchPosConfigs() async {
    final odoo = Provider.of<OdooService>(context, listen: false);
    try {
      // 1. Fetch Configs
      final List<dynamic> configs = await odoo.callKw(
        model: 'pos.config',
        method: 'search_read',
        args: [],
        kwargs: {
          'fields': [
            'id', 
            'name', 
            'current_session_id', 
            'current_session_state', 
            'pos_session_username'
          ],
        },
      );

      // 2. Extract Session IDs
      List<int> sessionIds = [];
      for (var config in configs) {
        if (config['current_session_id'] != null && config['current_session_id'] is List) {
          sessionIds.add(config['current_session_id'][0]); // [id, name]
        }
      }

      // 3. Fetch Session Details (if any valid sessions)
      Map<int, dynamic> details = {};
      if (sessionIds.isNotEmpty) {
        final List<dynamic> sessions = await odoo.callKw(
          model: 'pos.session',
          method: 'read',
          args: [sessionIds],
          kwargs: {
            'fields': ['start_at', 'cash_register_balance_start'] // Basic info. 'total_payments_amount' often requires computation, keeping it simple for now. 
            // Note: 'total_payments_amount' isn't always stored directly on session in some versions, or is 'cash_register_total_entry_encoding'.
            // Let's rely on valid fields we can definitely verify. 
            // For now, we will show Date and Opening. "Sold" might require order calculation which is heavier.
          },
        );
        for (var session in sessions) {
          details[session['id']] = session;
        }
      }
      
      if (mounted) {
        setState(() {
          _posConfigs = configs;
          _sessionDetails = details;
          _isLoading = false;
        });
      }
    } catch (e, stackTrace) {
      print('Error fetching POS configs: $e');
      print(stackTrace);
      if (mounted) {
        setState(() { _isLoading = false; });
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Error fetching POS data: $e')),
        );
      }
    }
  }

  Future<void> _openSession(int configId) async {
    final odoo = Provider.of<OdooService>(context, listen: false);
    setState(() { _isLoading = true; });
    try {
      // Use 'create' on pos.session directly instead of open_session_cb
      // This is more robust for API calls as open_session_cb returns a web action.
      await odoo.callKw(
        model: 'pos.session',
        method: 'create',
        args: [
          {'config_id': configId}
        ],
        kwargs: {},
      );
      
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Session Opened Successfully!')),
        );
        _fetchPosConfigs();
      }
    } catch (e) {
      if (mounted) {
        setState(() { _isLoading = false; });
        // Clean up error message for display
        String errorMsg = e.toString();
        if (errorMsg.contains('OdooException')) {
           errorMsg = errorMsg.replaceAll('OdooException:', '').trim();
        }
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('Error Opening Session: $errorMsg'),
            backgroundColor: Colors.red,
            duration: const Duration(seconds: 4),
          ),
        );
        _fetchPosConfigs();
      }
    }
  }

  Future<void> _createPos(String name) async {
    final odoo = Provider.of<OdooService>(context, listen: false);
    setState(() { _isLoading = true; });
    try {
      await odoo.callKw(
        model: 'pos.config',
        method: 'create',
        args: [
          {'name': name}
        ],
        kwargs: {},
      );
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('POS Created Successfully')),
        );
        _fetchPosConfigs();
      }
    } catch (e) {
      if (mounted) {
        setState(() { _isLoading = false; });
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Error creating POS: $e')),
        );
      }
    }
  }

  Future<void> _deletePos(int id, String name) async {
    final odoo = Provider.of<OdooService>(context, listen: false);
    
    // Show confirmation dialog before deleting
    final bool? confirm = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(20)),
        title: Row(
          children: [
            Container(
              padding: const EdgeInsets.all(8),
              decoration: BoxDecoration(color: Colors.red[50], borderRadius: BorderRadius.circular(10)),
              child: const Icon(Icons.warning_rounded, color: Colors.red),
            ),
            const SizedBox(width: 12),
            const Text('Delete Shop', style: TextStyle(fontWeight: FontWeight.bold)),
          ],
        ),
        content: Text(
          'Are you sure you want to delete "$name"?\nThis action cannot be undone.',
          style: TextStyle(color: Colors.grey[700], fontSize: 15),
        ),
        actionsPadding: const EdgeInsets.fromLTRB(20, 0, 20, 20),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false), 
            style: TextButton.styleFrom(foregroundColor: Colors.grey[600]), 
            child: const Text('Cancel', style: TextStyle(color: Colors.red, fontWeight: FontWeight.bold)), 
          ),
          ElevatedButton(
             onPressed: () => Navigator.pop(context, true),
             style: ElevatedButton.styleFrom(
               backgroundColor: Colors.red,
               foregroundColor: Colors.white,
               elevation: 2,
               shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
               padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 10),
             ), 
             child: const Text('Delete')
          ),
        ],
      ),
    );

    if (confirm != true) return;

    setState(() { _isLoading = true; });
    try {
      // Try to hard delete first
      await odoo.callKw(
        model: 'pos.config',
        method: 'unlink',
        args: [[id]],
        kwargs: {},
      );
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('POS Deleted Successfully')),
        );
        _fetchPosConfigs();
      }
    } catch (e) {
      // If hard delete fails (likely due to existing data), try to archive
      try {
         await odoo.callKw(
          model: 'pos.config',
          method: 'write',
          args: [[id], {'active': false, 'name': '$name (Archived)'}],
          kwargs: {},
        );
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(content: Text('POS Archived Successfully (Hard delete restricted)')),
          );
          _fetchPosConfigs();
        }
      } catch (e2) {
        if (mounted) {
          setState(() { _isLoading = false; });
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('Cannot Delete or Archive: $e2')),
          );
          _fetchPosConfigs();
        }
      }
    }
  }

  Future<void> _closeSession(int sessionId) async {
    final odoo = Provider.of<OdooService>(context, listen: false);
    setState(() { _isLoading = true; });
    try {
      // 1. Try to validate the closing directly
      await odoo.callKw(
        model: 'pos.session',
        method: 'action_pos_session_validate',
        args: [[sessionId]],
        kwargs: {},
      );
      
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Session Closed Successfully')));
        _fetchPosConfigs();
      }
    } catch (e) {
      // Fallback or Error Display
      if (mounted) {
        setState(() { _isLoading = false; });
        String errorMsg = e.toString();
        if (errorMsg.contains('OdooException')) {
           errorMsg = errorMsg.replaceAll('OdooException:', '').trim();
        }
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('Closing Failed: $errorMsg'), backgroundColor: Colors.red),
        );
        _fetchPosConfigs();
      }
    }
  }

  void _showCreateDialog() {
    final TextEditingController nameController = TextEditingController();
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(24)),
        title: Row(
          children: [
            Container(
              padding: const EdgeInsets.all(10),
              decoration: BoxDecoration(color: Colors.green[50], borderRadius: BorderRadius.circular(12)),
              child: const Icon(Icons.add_business_rounded, color: Colors.green, size: 28),
            ),
            const SizedBox(width: 12),
            const Expanded(child: Text('New Point of Sale', style: TextStyle(fontWeight: FontWeight.bold, fontSize: 18))),
          ],
        ),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text('Enter a unique name for your new shop to identify it easily.', style: TextStyle(color: Colors.grey[600], fontSize: 14)),
            const SizedBox(height: 20),
            TextField(
              controller: nameController,
              decoration: InputDecoration(
                labelText: 'Shop Name', 
                hintText: 'e.g. Main Bar',
                prefixIcon: const Icon(Icons.store, color: Colors.green),
                border: OutlineInputBorder(borderRadius: BorderRadius.circular(12), borderSide: BorderSide(color: Colors.green.shade200)),
                focusedBorder: OutlineInputBorder(borderRadius: BorderRadius.circular(12), borderSide: const BorderSide(color: Colors.green, width: 2)),
                filled: true,
                fillColor: Colors.green.withOpacity(0.05),
              ),
              autofocus: true,
              cursorColor: Colors.green,
            ),
            const SizedBox(height: 10),
          ],
        ),
        actionsPadding: const EdgeInsets.fromLTRB(20, 0, 20, 24),
        actions: [
          OutlinedButton(
            onPressed: () => Navigator.pop(context),
            style: OutlinedButton.styleFrom(
              side: const BorderSide(color: Colors.red),
              padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 12),
              shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
            ),
            child: const Text('Cancel', style: TextStyle(color: Colors.red, fontWeight: FontWeight.bold)),
          ),
          ElevatedButton(
            onPressed: () {
              Navigator.pop(context);
              if (nameController.text.isNotEmpty) {
                _createPos(nameController.text);
              }
            },
            style: ElevatedButton.styleFrom(
              backgroundColor: Colors.green,
              foregroundColor: Colors.white,
              elevation: 4,
              shadowColor: Colors.green.withOpacity(0.4),
              padding: const EdgeInsets.symmetric(horizontal: 24, vertical: 12),
              shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
            ),
            child: const Text('Create Shop', style: TextStyle(fontWeight: FontWeight.bold)),
          ),
        ],
        actionsAlignment: MainAxisAlignment.spaceEvenly,
      ),
    );
  }

  // Update build to use extendBodyBehindAppBar: true
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      extendBodyBehindAppBar: true,
      appBar: AppBar(
        title: const Text('Point of Sale', style: TextStyle(fontWeight: FontWeight.bold, fontSize: 24)),
        backgroundColor: Colors.transparent,
        foregroundColor: Colors.white,
        elevation: 0,
        centerTitle: true,
      ),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: _showCreateDialog,
        backgroundColor: AppTheme.primaryColor,
        icon: const Icon(Icons.add, color: Colors.white),
        label: const Text('New Shop', style: TextStyle(color: Colors.white, fontWeight: FontWeight.bold)),
      ),
      body: Container(
        decoration: const BoxDecoration(
          gradient: LinearGradient(
              begin: Alignment.topLeft,
              end: Alignment.bottomRight,
              colors: [Color(0xFF2bb1a5), Color(0xFF1a4d46)], // Rich Teal Gradient
          ),
        ),
        child: _isLoading
            ? const Center(child: CircularProgressIndicator(color: Colors.white))
            : SafeArea(
                child: RefreshIndicator(
                  color: AppTheme.secondaryColor,
                  backgroundColor: Colors.white,
                  onRefresh: _fetchPosConfigs,
                  child: ListView.builder(
                    padding: const EdgeInsets.fromLTRB(20, 10, 20, 80),
                    itemCount: _posConfigs.length,
                    itemBuilder: (context, index) {
                      return _buildPosCard(_posConfigs[index]);
                    },
                  ),
                ),
              ),
      ),
    );
  }

  Widget _buildPosCard(Map<String, dynamic> config) {
    final int id = config['id'];
    final String name = config['name'] is String ? config['name'] : 'Shop';
    final String status = config['current_session_state'] is String ? config['current_session_state'] : 'closed';
    final dynamic rawUsername = config['pos_session_username'];
    final String? username = rawUsername is String ? rawUsername : null;
    
    // Get Session Details
    Map<String, dynamic>? sessionData;
    if (config['current_session_id'] != null && config['current_session_id'] is List) {
       int sessionId = config['current_session_id'][0];
       sessionData = _sessionDetails[sessionId];
    }
    
    // Format Data
    String dateStr = '---';
    String openingStr = '₹ 0.00';
    // String soldStr = '₹ 0.00'; // Need complex calculation or field, omitting for simplicity/safety

    if (sessionData != null) {
      if (sessionData['start_at'] != null) {
        // Simple date parsing or just display string
        dateStr = sessionData['start_at'].toString().split(' ')[0]; // yyyy-mm-dd
      }
      if (sessionData['cash_register_balance_start'] != null) {
         openingStr = '₹ ${sessionData['cash_register_balance_start']}';
      }
    }

    Color statusColor;
    String statusText;
    IconData statusIcon;
    Color cardAccentColor;
    String mainButtonText;
    VoidCallback mainButtonAction;
    
    switch (status) {
      case 'opened':
        statusColor = const Color(0xFF4CAF50); // Bright Green
        statusText = 'Active Session';
        statusIcon = Icons.check_circle_rounded;
        cardAccentColor = const Color(0xFFE8F5E9);
        mainButtonText = 'Continue Selling';
        mainButtonAction = () {
             int sessionId = (config['current_session_id'] != null && config['current_session_id'] is List) ? config['current_session_id'][0] : 0;
             Navigator.push(context, MaterialPageRoute(builder: (context) => PosSellingScreen(shopName: name, sessionId: sessionId)));
        };
        break;
      case 'opening_control':
        statusColor = const Color(0xFF2196F3); // Blue
        statusText = 'Opening';
        statusIcon = Icons.sync;
        cardAccentColor = const Color(0xFFE3F2FD);
        mainButtonText = 'Continue Selling';
        mainButtonAction = () {
             int sessionId = (config['current_session_id'] != null && config['current_session_id'] is List) ? config['current_session_id'][0] : 0;
             Navigator.push(context, MaterialPageRoute(builder: (context) => PosSellingScreen(shopName: name, sessionId: sessionId)));
        };
        break;
      case 'closing_control':
        statusColor = const Color(0xFFFF9800); // Orange
        statusText = 'Closing Control';
        statusIcon = Icons.history_toggle_off;
        cardAccentColor = const Color(0xFFFFF3E0);
        mainButtonText = 'Close Session';
        mainButtonAction = () {
             int sessionId = (config['current_session_id'] != null && config['current_session_id'] is List) ? config['current_session_id'][0] : 0;
             if (sessionId != 0) {
                 _closeSession(sessionId);
             }
        };
        break;
      case 'closed':
      default:
        statusColor = const Color(0xFF757575); // Grey
        statusText = 'Closed';
        statusIcon = Icons.storefront;
        cardAccentColor = const Color(0xFFF5F5F5);
        mainButtonText = 'Open Register';
        mainButtonAction = () => _openSession(id);
        break;
    }

    return Container(
      margin: const EdgeInsets.only(bottom: 20),
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(24),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.2),
            blurRadius: 15,
            offset: const Offset(0, 8),
          ),
        ],
      ),
      child: ClipRRect(
        borderRadius: BorderRadius.circular(24),
        child: Stack(
          children: [
            // Decorative background circle
            Positioned(
              right: -20,
              top: -20,
              child: Container(
                width: 100,
                height: 100,
                decoration: BoxDecoration(
                  color: cardAccentColor,
                  shape: BoxShape.circle,
                ),
              ),
            ),
            Padding(
              padding: const EdgeInsets.all(24),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  // Header Row
                  Row(
                    children: [
                      Container(
                        padding: const EdgeInsets.all(12),
                        decoration: BoxDecoration(
                          color: cardAccentColor,
                          borderRadius: BorderRadius.circular(16),
                        ),
                        child: Icon(Icons.store_mall_directory_rounded, color: statusColor, size: 28),
                      ),
                      const SizedBox(width: 16),
                      Expanded(
                        child: Column(
                          crossAxisAlignment: CrossAxisAlignment.start,
                          children: [
                            Text(
                              name,
                              style: const TextStyle(
                                fontSize: 18,
                                fontWeight: FontWeight.bold,
                                color: Color(0xFF2D3748),
                                letterSpacing: 0.5,
                              ),
                            ),
                            const SizedBox(height: 4),
                            Row(
                              children: [
                                Icon(statusIcon, size: 14, color: statusColor),
                                const SizedBox(width: 6),
                                Text(
                                  statusText,
                                  style: TextStyle(
                                    color: statusColor,
                                    fontWeight: FontWeight.w700,
                                    fontSize: 13,
                                  ),
                                ),
                              ],
                            ),
                          ],
                        ),
                      ),
                      IconButton(
                        onPressed: () => _deletePos(id, name),
                        icon: Icon(Icons.delete_outline_rounded, color: Colors.grey[400]),
                        tooltip: 'Delete',
                      ),
                    ],
                  ),
                  
                  // Info Stats Row (Only if not closed or has session info)
                  if (status != 'closed' || sessionData != null) ...[
                    const SizedBox(height: 20),
                    Container(
                      padding: const EdgeInsets.all(16),
                      decoration: BoxDecoration(
                        color: Colors.grey[50],
                        borderRadius: BorderRadius.circular(16),
                        border: Border.all(color: Colors.grey[200]!),
                      ),
                      child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        children: [
                          _buildStatItem('Date', dateStr),
                          _buildStatItem('Opening', openingStr),
                          // _buildStatItem('Sold', soldStr), // Placeholder for future
                        ],
                      ),
                    ),
                  ],

                  if (username != null && status != 'closed') ...[
                    const SizedBox(height: 16),
                    Row(
                      children: [
                        CircleAvatar(
                          radius: 10,
                          backgroundColor: Colors.grey[300],
                          child: const Icon(Icons.person, size: 14, color: Colors.white),
                        ),
                        const SizedBox(width: 8),
                         Text(
                          'Session by $username',
                          style: TextStyle(color: Colors.grey[600], fontWeight: FontWeight.w500, fontSize: 13),
                        ),
                      ],
                    ),
                  ],
                  
                  const SizedBox(height: 24),
                  
                  // Action Button
                  SizedBox(
                    width: double.infinity,
                    child: ElevatedButton(
                      onPressed: mainButtonAction,
                      style: ElevatedButton.styleFrom(
                        backgroundColor: status != 'closed' ? statusColor : AppTheme.secondaryColor,
                        foregroundColor: Colors.white,
                        padding: const EdgeInsets.symmetric(vertical: 16),
                        elevation: 4,
                        shadowColor: statusColor.withOpacity(0.4),
                        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(16)),
                      ),
                      child: Text(
                        mainButtonText,
                        style: const TextStyle(
                          fontSize: 15,
                          fontWeight: FontWeight.bold,
                          letterSpacing: 0.5,
                        ),
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildStatItem(String label, String value) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(label, style: TextStyle(color: Colors.grey[500], fontSize: 12, fontWeight: FontWeight.bold)),
        const SizedBox(height: 4),
        Text(value, style: const TextStyle(color: Color(0xFF2D3748), fontSize: 14, fontWeight: FontWeight.bold)),
      ],
    );
  }
}