/// Cart Page
///
/// Shopping cart screen with items, warehouse selection, discount code,
/// and order summary matching the HTML design.
library;

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import 'package:intl/intl.dart';
import 'package:worker/core/constants/ui_constants.dart';
import 'package:worker/core/router/app_router.dart';
import 'package:worker/core/theme/colors.dart';
import 'package:worker/core/theme/typography.dart';
import 'package:worker/features/cart/presentation/providers/cart_provider.dart';
import 'package:worker/features/cart/presentation/providers/cart_state.dart';
import 'package:worker/features/cart/presentation/widgets/cart_item_widget.dart';

/// Cart Page
///
/// Features:
/// - AppBar with back, title (with count), and clear cart button
/// - Warehouse selection dropdown
/// - Cart items list
/// - Discount code input with apply button
/// - Order summary with breakdown
/// - Checkout button
class CartPage extends ConsumerStatefulWidget {
  const CartPage({super.key});

  @override
  ConsumerState<CartPage> createState() => _CartPageState();
}

class _CartPageState extends ConsumerState<CartPage> {
  final TextEditingController _discountController = TextEditingController();

  @override
  void dispose() {
    _discountController.dispose();
    super.dispose();
  }

  void _clearCart() {
    showDialog<void>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Xóa giỏ hàng'),
        content: const Text('Bạn có chắc chắn muốn xóa toàn bộ giỏ hàng?'),
        actions: [
          TextButton(
            onPressed: () => context.pop(),
            child: const Text('Hủy'),
          ),
          ElevatedButton(
            onPressed: () {
              ref.read(cartProvider.notifier).clearCart();
              context.pop();
              context.pop(); // Also go back from cart page
            },
            style: ElevatedButton.styleFrom(
              backgroundColor: AppColors.danger,
            ),
            child: const Text('Xóa'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final cartState = ref.watch(cartProvider);
    final itemCount = cartState.itemCount;

    final currencyFormatter = NumberFormat.currency(
      locale: 'vi_VN',
      symbol: 'đ',
      decimalDigits: 0,
    );

    return Scaffold(
      backgroundColor: const Color(0xFFF4F6F8),
      appBar: AppBar(
        leading: IconButton(
          icon: const Icon(Icons.arrow_back, color: Colors.black),
          onPressed: () => context.pop(),
        ),
        title: Text('Giỏ hàng ($itemCount)', style: const TextStyle(color: Colors.black)),
        elevation: AppBarSpecs.elevation,
        backgroundColor: AppColors.white,
        foregroundColor: AppColors.grey900,
        centerTitle: false,
        actions: [
          if (cartState.isNotEmpty)
            IconButton(
              icon: const Icon(Icons.delete_outline, color: Colors.black),
              onPressed: _clearCart,
              tooltip: 'Xóa giỏ hàng',
            ),
          const SizedBox(width: AppSpacing.sm),
        ],
      ),
      body: cartState.isEmpty
          ? _buildEmptyCart()
          : SingleChildScrollView(
              child: Column(
                children: [
                  const SizedBox(height: 8),

                  // Warehouse Selection
                  _buildWarehouseSelection(cartState.selectedWarehouse),

                  // Cart Items
                  ...cartState.items.map((item) => CartItemWidget(item: item)),

                  const SizedBox(height: 8),

                  // Discount Code
                  _buildDiscountCodeSection(cartState),

                  // Order Summary
                  _buildOrderSummary(cartState, currencyFormatter),

                  const SizedBox(height: 16),

                  // Checkout Button
                  _buildCheckoutButton(cartState),

                  const SizedBox(height: 24),
                ],
              ),
            ),
    );
  }

  /// Build empty cart state
  Widget _buildEmptyCart() {
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Icon(
            Icons.shopping_cart_outlined,
            size: 80,
            color: AppColors.grey500.withValues(alpha: 0.5),
          ),
          const SizedBox(height: 16),
          Text(
            'Giỏ hàng trống',
            style: AppTypography.headlineMedium.copyWith(
              color: AppColors.grey500,
            ),
          ),
          const SizedBox(height: 8),
          Text(
            'Hãy thêm sản phẩm vào giỏ hàng',
            style: AppTypography.bodyMedium.copyWith(
              color: AppColors.grey500,
            ),
          ),
          const SizedBox(height: 24),
          ElevatedButton.icon(
            onPressed: () => context.go(RouteNames.products),
            icon: const Icon(Icons.shopping_bag_outlined),
            label: const Text('Xem sản phẩm'),
          ),
        ],
      ),
    );
  }

  /// Build warehouse selection card
  Widget _buildWarehouseSelection(String selectedWarehouse) {
    return Container(
      margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: AppColors.white,
        borderRadius: BorderRadius.circular(12),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.05),
            blurRadius: 4,
            offset: const Offset(0, 2),
          ),
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Kho xuất hàng',
            style: AppTypography.labelLarge.copyWith(
              fontWeight: FontWeight.w600,
              color: AppColors.grey900,
            ),
          ),
          const SizedBox(height: 8),
          DropdownButtonFormField<String>(
            initialValue: selectedWarehouse,
            decoration: InputDecoration(
              contentPadding: const EdgeInsets.symmetric(
                horizontal: 12,
                vertical: 8,
              ),
              border: OutlineInputBorder(
                borderRadius: BorderRadius.circular(8),
                borderSide: const BorderSide(color: AppColors.grey100),
              ),
            ),
            items: const [
              DropdownMenuItem(
                value: 'Kho Hà Nội - Nguyễn Trãi',
                child: Text('Kho Hà Nội - Nguyễn Trãi'),
              ),
              DropdownMenuItem(
                value: 'Kho TP.HCM - Quận 7',
                child: Text('Kho TP.HCM - Quận 7'),
              ),
              DropdownMenuItem(
                value: 'Kho Đà Nẵng - Sơn Trà',
                child: Text('Kho Đà Nẵng - Sơn Trà'),
              ),
            ],
            onChanged: (value) {
              if (value != null) {
                ref.read(cartProvider.notifier).selectWarehouse(value);
              }
            },
          ),
        ],
      ),
    );
  }

  /// Build discount code section
  Widget _buildDiscountCodeSection(CartState cartState) {
    return Container(
      margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: AppColors.white,
        borderRadius: BorderRadius.circular(12),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.05),
            blurRadius: 4,
            offset: const Offset(0, 2),
          ),
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Mã giảm giá',
            style: AppTypography.labelLarge.copyWith(
              fontWeight: FontWeight.w600,
              color: AppColors.grey900,
            ),
          ),
          const SizedBox(height: 8),
          Row(
            children: [
              Expanded(
                child: TextField(
                  controller: _discountController,
                  decoration: InputDecoration(
                    hintText: 'Nhập mã giảm giá',
                    contentPadding: const EdgeInsets.symmetric(
                      horizontal: 12,
                      vertical: 12,
                    ),
                    border: OutlineInputBorder(
                      borderRadius: BorderRadius.circular(8),
                      borderSide: const BorderSide(color: AppColors.grey100),
                    ),
                  ),
                ),
              ),
              const SizedBox(width: 8),
              ElevatedButton(
                onPressed: () {
                  if (_discountController.text.isNotEmpty) {
                    ref.read(cartProvider.notifier).applyDiscountCode(
                          _discountController.text,
                        );
                  }
                },
                style: ElevatedButton.styleFrom(
                  padding: const EdgeInsets.symmetric(
                    horizontal: 24,
                    vertical: 12,
                  ),
                ),
                child: const Text('Áp dụng'),
              ),
            ],
          ),

          // Success message for member discount
          if (cartState.memberTier.isNotEmpty)
            Padding(
              padding: const EdgeInsets.only(top: 8),
              child: Row(
                children: [
                  const Icon(
                    Icons.check_circle,
                    color: AppColors.success,
                    size: 16,
                  ),
                  const SizedBox(width: 4),
                  Text(
                    'Bạn được giảm ${cartState.memberDiscountPercent.toStringAsFixed(0)}% (hạng ${cartState.memberTier})',
                    style: AppTypography.bodySmall.copyWith(
                      color: AppColors.success,
                    ),
                  ),
                ],
              ),
            ),
        ],
      ),
    );
  }

  /// Build order summary section
  Widget _buildOrderSummary(CartState cartState, NumberFormat currencyFormatter) {
    return Container(
      margin: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: AppColors.white,
        borderRadius: BorderRadius.circular(12),
        boxShadow: [
          BoxShadow(
            color: Colors.black.withValues(alpha: 0.05),
            blurRadius: 4,
            offset: const Offset(0, 2),
          ),
        ],
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            'Thông tin đơn hàng',
            style: AppTypography.titleMedium.copyWith(
              fontWeight: FontWeight.bold,
            ),
          ),
          const SizedBox(height: 16),

          // Subtotal
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              Text(
                'Tạm tính (${cartState.totalQuantity.toStringAsFixed(0)} ${cartState.items.firstOrNull?.product.unit ?? 'm²'})',
                style: AppTypography.bodyMedium,
              ),
              Text(
                currencyFormatter.format(cartState.subtotal),
                style: AppTypography.bodyMedium,
              ),
            ],
          ),

          const SizedBox(height: 12),

          // Member Discount
          if (cartState.memberDiscount > 0)
            Padding(
              padding: const EdgeInsets.only(bottom: 12),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  Text(
                    'Giảm giá ${cartState.memberTier} (-${cartState.memberDiscountPercent.toStringAsFixed(0)}%)',
                    style: AppTypography.bodyMedium,
                  ),
                  Text(
                    '-${currencyFormatter.format(cartState.memberDiscount)}',
                    style: AppTypography.bodyMedium.copyWith(
                      color: AppColors.success,
                    ),
                  ),
                ],
              ),
            ),

          // Shipping Fee
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              Text(
                'Phí vận chuyển',
                style: AppTypography.bodyMedium,
              ),
              Text(
                cartState.shippingFee > 0
                    ? currencyFormatter.format(cartState.shippingFee)
                    : 'Miễn phí',
                style: AppTypography.bodyMedium,
              ),
            ],
          ),

          const Divider(height: 24),

          // Total
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              Text(
                'Tổng cộng',
                style: AppTypography.titleMedium.copyWith(
                  fontWeight: FontWeight.bold,
                ),
              ),
              Text(
                currencyFormatter.format(cartState.total),
                style: AppTypography.headlineSmall.copyWith(
                  color: AppColors.primaryBlue,
                  fontWeight: FontWeight.bold,
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }

  /// Build checkout button
  Widget _buildCheckoutButton(CartState cartState) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 16),
      child: SizedBox(
        width: double.infinity,
        height: 48,
        child: ElevatedButton(
          onPressed: cartState.isNotEmpty
              ? () {
                  // TODO: Navigate to checkout page when implemented
                  ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(
                      content: Text('Checkout page chưa được triển khai'),
                    ),
                  );
                }
              : null,
          child: const Text(
            'Tiến hành đặt hàng',
            style: TextStyle(
              fontSize: 16,
              fontWeight: FontWeight.w600,
            ),
          ),
        ),
      ),
    );
  }
}