// lib/pages/product_page.dart

import 'package:flutter/material.dart';
import 'package:garments_billing_software_offline/database/db_helper.dart';

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

  @override
  State<ProductPage> createState() => _ProductPageState();
}

class _ProductPageState extends State<ProductPage> {
  List<Map<String, dynamic>> _products = [];

  // Dropdown data
  List<Map<String, dynamic>> _categories = [];
  List<Map<String, dynamic>> _brands = [];
  List<Map<String, dynamic>> _units = [];
  List<Map<String, dynamic>> _gstRates = [];

  // Controllers
  final _nameController = TextEditingController();
  final _hsnController = TextEditingController();
  final _purchaseController = TextEditingController();
  final _sellingController = TextEditingController();
  final _discountPercentageController = TextEditingController();
  final _quantityController = TextEditingController(); // NEW: Quantity

  // Dropdown selections
  int? _selectedCategoryId;
  int? _selectedBrandId;
  int? _selectedUnitId;
  int? _selectedGstRateId;

  @override
  void initState() {
    super.initState();
    _loadInitialData();
  }

  @override
  void dispose() {
    _nameController.dispose();
    _hsnController.dispose();
    _purchaseController.dispose();
    _sellingController.dispose();
    _discountPercentageController.dispose();
    _quantityController.dispose();
    super.dispose();
  }

  // Load data
  Future<void> _loadInitialData() async {
    await Future.wait([
      _refreshProducts(),
      _loadDropdowns(),
    ]);
  }

  Future<void> _loadDropdowns() async {
    _categories = await DatabaseHelper.instance.readAllCategories();
    _brands = await DatabaseHelper.instance.readAllBrands();
    _units = await DatabaseHelper.instance.readAllUnits();
    _gstRates = await DatabaseHelper.instance.readAllGstRates();
    setState(() {});
  }

  Future<void> _refreshProducts() async {
    _products = await DatabaseHelper.instance.readAllProducts();
    setState(() {});
  }

  // Reset form
  void _resetForm() {
    _nameController.clear();
    _hsnController.clear();
    _purchaseController.clear();
    _sellingController.clear();
    _discountPercentageController.clear();
    _quantityController.clear();
    _selectedCategoryId = null;
    _selectedBrandId = null;
    _selectedUnitId = null;
    _selectedGstRateId = null;
    setState(() {});
  }

  // Save or Update Product
  Future<void> _saveProduct([int? id]) async {
    if (_nameController.text.isEmpty ||
        _hsnController.text.isEmpty ||
        _purchaseController.text.isEmpty ||
        _sellingController.text.isEmpty ||
        _quantityController.text.isEmpty ||
        _selectedCategoryId == null ||
        _selectedBrandId == null ||
        _selectedUnitId == null ||
        _selectedGstRateId == null) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Please fill all required fields.'), backgroundColor: Colors.orange),
        );
      }
      return;
    }

    final purchasePrice = double.tryParse(_purchaseController.text) ?? 0.0;
    final sellingPrice = double.tryParse(_sellingController.text) ?? 0.0;
    final discountPercentage = double.tryParse(_discountPercentageController.text) ?? 0.0;
    final quantity = double.tryParse(_quantityController.text) ?? 0.0;

    final productData = {
      'name': _nameController.text.trim(),
      'hsn_code': _hsnController.text.trim(),
      'category_id': _selectedCategoryId,
      'brand_id': _selectedBrandId,
      'unit_id': _selectedUnitId,
      'gst_rate_id': _selectedGstRateId,
      'purchase_price': purchasePrice,
      'selling_price': sellingPrice,
      'discount_percentage': discountPercentage > 0 ? discountPercentage : null,
      'stock': quantity, // FIXED: Must be 'stock' to match the database column name
    };

    try {
      if (id == null) {
        await DatabaseHelper.instance.insertProduct(productData);
      } else {
        productData['id'] = id;
        await DatabaseHelper.instance.updateProduct(productData);
      }

      _resetForm();
      _refreshProducts();
      if (mounted) Navigator.of(context).pop();
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(content: Text('${productData['name']} saved successfully!')),
        );
      }
    } catch (e) {
      // Print the full error for debugging in the console
      print('Database Error during Product Save/Update: $e');
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Failed to save product. Name might already exist.'), backgroundColor: Colors.red),
        );
      }
    }
  }

  Future<void> _deleteProduct(int id, String name) async {
    await DatabaseHelper.instance.deleteProduct(id);
    _refreshProducts();
    if (mounted) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(content: Text('$name deleted successfully!')),
      );
    }
  }

  // Show View Dialog
  void _showViewDialog(Map<String, dynamic> product) {
    final sellingPrice = product['selling_price'] as double;
    final discountPercentage = product['discount_percentage'] as double? ?? 0.0;
    final discountAmount = sellingPrice * (discountPercentage / 100);
    final quantity = product['stock'] ?? 0.0;

    showDialog(
      context: context,
      builder: (context) {
        return AlertDialog(
          title: Text('Product Details: ${product['name']}'),
          content: SingleChildScrollView(
            child: SizedBox(
              width: 400,
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  _buildDetailRow('Name', product['name']),
                  _buildDetailRow('HSN Code', product['hsn_code']),
                  const Divider(),
                  _buildDetailRow('Category', product['category_name']),
                  _buildDetailRow('Brand', product['brand_name']),
                  _buildDetailRow('Unit', product['unit_name']),
                  _buildDetailRow('GST Rate', '${product['gst_rate']}%'),
                  const Divider(),
                  _buildDetailRow('Purchase Price', '₹ ${product['purchase_price'].toStringAsFixed(2)}'),
                  _buildDetailRow('Selling Price', '₹ ${sellingPrice.toStringAsFixed(2)}'),
                  _buildDetailRow('Discount %', '$discountPercentage%'),
                  _buildDetailRow('Discount Amount', '₹ ${discountAmount.toStringAsFixed(2)}'),
                  _buildDetailRow('quantity', quantity.toString()),
                ],
              ),
            ),
          ),
          actions: [
            TextButton(onPressed: () => Navigator.of(context).pop(), child: const Text('Close')),
          ],
        );
      },
    );
  }

  Widget _buildDetailRow(String label, String value) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 4),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          Text('$label:', style: const TextStyle(fontWeight: FontWeight.w500, color: Colors.grey)),
          Text(value, style: const TextStyle(fontWeight: FontWeight.w600)),
        ],
      ),
    );
  }

  // Show Add/Edit Dialog
  void _showEditDialog([Map<String, dynamic>? product]) {
    final isEditing = product != null;

    // We call _resetForm() at the start to ensure controllers are cleared
    // for a fresh 'Add' or before setting values for 'Edit'.
    _resetForm();

    if (isEditing) {
      // Update controllers with product data
      _nameController.text = product!['name'];
      _hsnController.text = product['hsn_code'];
      _purchaseController.text = product['purchase_price'].toString();
      _sellingController.text = product['selling_price'].toString();
      _discountPercentageController.text = (product['discount_percentage'] ?? 0.0).toString();
      _quantityController.text = (product['stock'] ?? 0.0).toString();

      // Update selected IDs for dropdowns
      _selectedCategoryId = product['category_id'];
      _selectedBrandId = product['brand_id'];
      _selectedUnitId = product['unit_id'];
      _selectedGstRateId = product['gst_rate_id'];
    }

    showDialog(
      context: context,
      builder: (context) {
        // StatefulBuilder is used here to allow the dropdowns to update the dialog state immediately
        return AlertDialog(
          title: Text(isEditing ? 'Edit Product' : 'Add New Product'),
          content: StatefulBuilder(
            builder: (context, setStateDialog) {
              return SingleChildScrollView(
                child: SizedBox(
                  width: 600,
                  child: Column(
                    mainAxisSize: MainAxisSize.min, // Use min size for content
                    children: [
                      TextField(controller: _nameController, decoration: const InputDecoration(labelText: 'Product Name')),
                      TextField(controller: _hsnController, decoration: const InputDecoration(labelText: 'HSN Code')),
                      const SizedBox(height: 16),
                      // Dropdowns
                      _buildDropdown('Category', _categories, _selectedCategoryId, (v) => setStateDialog(() => _selectedCategoryId = v)),
                      _buildDropdown('Brand', _brands, _selectedBrandId, (v) => setStateDialog(() => _selectedBrandId = v)),
                      _buildDropdown('Unit', _units, _selectedUnitId, (v) => setStateDialog(() => _selectedUnitId = v)),
                      _buildDropdown('GST Rate', _gstRates, _selectedGstRateId, (v) => setStateDialog(() => _selectedGstRateId = v), isGst: true),
                      const SizedBox(height: 16),
                      // Numeric Inputs
                      TextField(controller: _purchaseController, keyboardType: const TextInputType.numberWithOptions(decimal: true), decoration: const InputDecoration(labelText: 'Purchase Price')),
                      TextField(controller: _sellingController, keyboardType: const TextInputType.numberWithOptions(decimal: true), decoration: const InputDecoration(labelText: 'Selling Price')),
                      TextField(controller: _discountPercentageController, keyboardType: const TextInputType.numberWithOptions(decimal: true), decoration: const InputDecoration(labelText: 'Discount (%)')),
                      TextField(controller: _quantityController, keyboardType: const TextInputType.numberWithOptions(decimal: true), decoration: const InputDecoration(labelText: 'stock')),
                    ],
                  ),
                ),
              );
            },
          ),
          actions: [
            TextButton(onPressed: () => Navigator.of(context).pop(), child: const Text('Cancel')),
            ElevatedButton(
              onPressed: () => _saveProduct(isEditing ? product!['id'] : null),
              child: Text(isEditing ? 'Update' : 'Add'),
            ),
          ],
        );
      },
    ).then((_) => _refreshProducts()); // Refresh list when dialog closes (regardless of save/cancel)
  }

  // Helper method for building Dropdowns
  Widget _buildDropdown(String label, List<Map<String, dynamic>> items, int? selectedId, Function(int?) onChanged, {bool isGst = false}) {
    // Determine the list of IDs from the items list to check if selectedId is valid
    final validIds = items.map((e) => e['id']).toSet();
    // Reset selectedId if the current value is not in the list (e.g., if it was deleted)
    if (selectedId != null && !validIds.contains(selectedId)) {
      selectedId = null;
    }

    return DropdownButtonFormField<int>(
      decoration: InputDecoration(labelText: label),
      value: selectedId,
      items: items.map((item) {
        // Ensure the value is an int, as the generic type requires it.
        final itemId = item['id'] as int;
        return DropdownMenuItem<int>(
          value: itemId,
          child: Text(isGst ? '${item['rate']}%' : item['name']),
        );
      }).toList(),
      onChanged: onChanged,
    );
  }

  // --- UI Build ---
  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Text('Manage Products', style: TextStyle(fontSize: 28, fontWeight: FontWeight.w600, color: Color(0xFF1E3A8A))),
        const SizedBox(height: 20),
        Card(
          elevation: 4,
          child: Padding(
            padding: const EdgeInsets.all(20),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                const Expanded(child: Text('Add or manage your products and inventory details.', style: TextStyle(color: Colors.grey))),
                ElevatedButton.icon(
                  onPressed: () {
                    if (_categories.isEmpty || _brands.isEmpty || _units.isEmpty || _gstRates.isEmpty) {
                      ScaffoldMessenger.of(context).showSnackBar(const SnackBar(content: Text('Add at least one Category, Brand, Unit & GST first.'), backgroundColor: Colors.orange));
                    } else {
                      _showEditDialog();
                    }
                  },
                  icon: const Icon(Icons.add), label: const Text('Add Product'),
                  style: ElevatedButton.styleFrom(backgroundColor: Colors.indigo.shade600, foregroundColor: Colors.white),
                ),
              ],
            ),
          ),
        ),
        const SizedBox(height: 20),
        const Text('Current Products List', style: TextStyle(fontSize: 20, fontWeight: FontWeight.w600)),
        const SizedBox(height: 10),

        // 👇 NEW: HEADER ROW FOR THE LIST VIEW
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
          child: Row(
            children: [
              // Corresponds to the leading CircleAvatar
              const SizedBox(width: 40),

              Expanded(
                child: Row(
                  children: const [
                    Expanded(flex: 3, child: Text('Product Name', style: TextStyle(fontWeight: FontWeight.bold, color: Colors.blueGrey))),
                    Expanded(flex: 2, child: Text('HSN / Category', style: TextStyle(fontWeight: FontWeight.bold, color: Colors.blueGrey))),
                    Expanded(flex: 1, child: Text('GST %', style: TextStyle(fontWeight: FontWeight.bold, color: Colors.blueGrey))),
                    Expanded(flex: 1, child: Text('Price (₹)', style: TextStyle(fontWeight: FontWeight.bold, color: Colors.blueGrey))),
                    Expanded(flex: 1, child: Text('Stock', style: TextStyle(fontWeight: FontWeight.bold, color: Colors.blueGrey))),
                  ],
                ),
              ),

              // Corresponds to the trailing action icons
              const SizedBox(width: 150),
            ],
          ),
        ),
        Expanded(
          child: Card(
            elevation: 2,
            child: ListView.builder(
              itemCount: _products.length,
              itemBuilder: (context, index) {
                final p = _products[index];
                return Column(
                  children: [
                    ListTile(
                      leading: CircleAvatar(child: Text('${index + 1}', style: const TextStyle(fontSize: 12))),
                      title: Row(
                        children: [
                          Expanded(flex: 3, child: Text(p['name'])),
                          Expanded(flex: 2, child: Text('${p['hsn_code']} / ${p['category_name']}', style: const TextStyle(fontSize: 13))),
                          Expanded(flex: 1, child: Text('${p['gst_rate']}%', style: const TextStyle(fontWeight: FontWeight.bold))),
                          Expanded(flex: 1, child: Text('₹ ${p['selling_price'].toStringAsFixed(2)}', style: const TextStyle(fontWeight: FontWeight.bold))),
                          Expanded(flex: 1, child: Text('Qty: ${p['stock']}', style: const TextStyle(color: Colors.green))),
                        ],
                      ),
                      trailing: SizedBox(
                        width: 150,
                        child: Row(
                          mainAxisAlignment: MainAxisAlignment.end,
                          children: [
                            IconButton(icon: const Icon(Icons.visibility, size: 20, color: Colors.indigo), onPressed: () => _showViewDialog(p)),
                            IconButton(icon: const Icon(Icons.edit, size: 20, color: Colors.blue), onPressed: () => _showEditDialog(p)),
                            IconButton(icon: const Icon(Icons.delete, size: 20, color: Colors.red), onPressed: () => _deleteProduct(p['id'], p['name'])),
                          ],
                        ),
                      ),
                    ),
                    const Divider(height: 1),
                  ],
                );
              },
            ),
          ),
        ),
      ],
    );
  }
}