import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import '../../../core/constants/app_colors.dart';
import '../../../data/models/coin.dart';
import '../../../providers/market_provider.dart';
import '../../../providers/asset_provider.dart';

/// 交易页面
class TradePage extends StatefulWidget {
  const TradePage({super.key});

  @override
  State<TradePage> createState() => _TradePageState();
}

class _TradePageState extends State<TradePage> with AutomaticKeepAliveClientMixin {
  @override
  bool get wantKeepAlive => true;

  int _tradeType = 0; // 0=买入, 1=卖出
  Coin? _selectedCoin;
  final _priceController = TextEditingController();
  final _quantityController = TextEditingController();

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      _loadData();
    });
  }

  void _loadData() {
    context.read<MarketProvider>().loadCoins();
    context.read<AssetProvider>().loadOverview();
  }

  @override
  void dispose() {
    _priceController.dispose();
    _quantityController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    super.build(context);
    return Scaffold(
      backgroundColor: AppColors.background,
      body: Consumer2<MarketProvider, AssetProvider>(
        builder: (context, market, asset, _) {
          return SingleChildScrollView(
            padding: const EdgeInsets.all(16),
            child: Column(
              children: [
                _buildCoinSelector(market),
                const SizedBox(height: 16),
                _buildPriceCard(),
                const SizedBox(height: 16),
                _buildTradeForm(asset),
                const SizedBox(height: 16),
                _buildTradeButton(),
              ],
            ),
          );
        },
      ),
    );
  }

  Widget _buildCoinSelector(MarketProvider market) {
    final coins = market.allCoins;
    if (_selectedCoin == null && coins.isNotEmpty) {
      _selectedCoin = coins.first;
      _priceController.text = _selectedCoin!.formattedPrice;
    }

    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: AppColors.cardBackground,
        borderRadius: BorderRadius.circular(16),
      ),
      child: Row(
        children: [
          Container(
            width: 44,
            height: 44,
            decoration: BoxDecoration(
              color: AppColors.primary.withOpacity(0.1),
              borderRadius: BorderRadius.circular(22),
            ),
            child: Center(
              child: Text(
                _selectedCoin?.displayIcon ?? '?',
                style: const TextStyle(fontSize: 20, color: AppColors.primary),
              ),
            ),
          ),
          const SizedBox(width: 12),
          Expanded(
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  _selectedCoin != null ? '${_selectedCoin!.code}/USDT' : '选择币种',
                  style: const TextStyle(
                    fontSize: 18,
                    fontWeight: FontWeight.bold,
                    color: AppColors.textPrimary,
                  ),
                ),
                const SizedBox(height: 4),
                Text(
                  _selectedCoin != null ? _selectedCoin!.name : '点击选择交易对',
                  style: const TextStyle(fontSize: 12, color: AppColors.textSecondary),
                ),
              ],
            ),
          ),
          const Icon(Icons.chevron_right, color: AppColors.textSecondary),
        ],
      ),
    );
  }

  Widget _buildPriceCard() {
    if (_selectedCoin == null) {
      return const SizedBox.shrink();
    }

    final coin = _selectedCoin!;
    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: AppColors.cardBackground,
        borderRadius: BorderRadius.circular(16),
      ),
      child: Column(
        children: [
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  const Text('最新价', style: TextStyle(fontSize: 12, color: AppColors.textSecondary)),
                  const SizedBox(height: 4),
                  Text(
                    '\$${coin.formattedPrice}',
                    style: const TextStyle(
                      fontSize: 24,
                      fontWeight: FontWeight.bold,
                      color: AppColors.textPrimary,
                    ),
                  ),
                ],
              ),
              Container(
                padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
                decoration: BoxDecoration(
                  color: coin.isUp ? AppColors.up.withOpacity(0.2) : AppColors.down.withOpacity(0.2),
                  borderRadius: BorderRadius.circular(8),
                ),
                child: Text(
                  coin.formattedChange,
                  style: TextStyle(
                    fontSize: 16,
                    color: coin.isUp ? AppColors.up : AppColors.down,
                    fontWeight: FontWeight.w600,
                  ),
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }

  Widget _buildTradeForm(AssetProvider asset) {
    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: AppColors.cardBackground,
        borderRadius: BorderRadius.circular(16),
      ),
      child: Column(
        children: [
          // 买入/卖出切换
          Row(
            children: [
              Expanded(
                child: GestureDetector(
                  onTap: () => setState(() => _tradeType = 0),
                  child: Container(
                    padding: const EdgeInsets.symmetric(vertical: 12),
                    decoration: BoxDecoration(
                      color: _tradeType == 0 ? AppColors.up : Colors.transparent,
                      borderRadius: BorderRadius.circular(8),
                    ),
                    child: Center(
                      child: Text(
                        '买入',
                        style: TextStyle(
                          color: _tradeType == 0 ? Colors.white : AppColors.up,
                          fontWeight: FontWeight.w600,
                        ),
                      ),
                    ),
                  ),
                ),
              ),
              const SizedBox(width: 16),
              Expanded(
                child: GestureDetector(
                  onTap: () => setState(() => _tradeType = 1),
                  child: Container(
                    padding: const EdgeInsets.symmetric(vertical: 12),
                    decoration: BoxDecoration(
                      color: _tradeType == 1 ? AppColors.down : Colors.transparent,
                      borderRadius: BorderRadius.circular(8),
                    ),
                    child: Center(
                      child: Text(
                        '卖出',
                        style: TextStyle(
                          color: _tradeType == 1 ? Colors.white : AppColors.down,
                          fontWeight: FontWeight.w600,
                        ),
                      ),
                    ),
                  ),
                ),
              ),
            ],
          ),
          const SizedBox(height: 20),
          // 价格输入
          TextField(
            controller: _priceController,
            keyboardType: const TextInputType.numberWithOptions(decimal: true),
            style: const TextStyle(color: AppColors.textPrimary),
            decoration: const InputDecoration(
              labelText: '价格(USDT)',
              suffixText: 'USDT',
            ),
          ),
          const SizedBox(height: 12),
          // 数量输入
          TextField(
            controller: _quantityController,
            keyboardType: const TextInputType.numberWithOptions(decimal: true),
            style: const TextStyle(color: AppColors.textPrimary),
            decoration: const InputDecoration(
              labelText: '数量',
              suffixText: _selectedCoin?.code ?? '',
            ),
          ),
          const SizedBox(height: 12),
          // 交易金额
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              const Text('交易金额', style: TextStyle(color: AppColors.textSecondary)),
              Text(
                '${_calculateAmount()} USDT',
                style: const TextStyle(color: AppColors.textPrimary, fontWeight: FontWeight.w600),
              ),
            ],
          ),
          const SizedBox(height: 8),
          // 可用余额
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: [
              const Text('可用', style: TextStyle(color: AppColors.textSecondary)),
              Text(
                '${asset.overview?.tradeBalance ?? '0.00'} USDT',
                style: const TextStyle(color: AppColors.textSecondary),
              ),
            ],
          ),
        ],
      ),
    );
  }

  String _calculateAmount() {
    final price = double.tryParse(_priceController.text) ?? 0;
    final quantity = double.tryParse(_quantityController.text) ?? 0;
    return (price * quantity).toStringAsFixed(2);
  }

  Widget _buildTradeButton() {
    final isBuy = _tradeType == 0;
    return Container(
      width: double.infinity,
      height: 48,
      decoration: BoxDecoration(
        gradient: isBuy ? AppColors.buyGradient : AppColors.sellGradient,
        borderRadius: BorderRadius.circular(12),
      ),
      child: Center(
        child: Text(
          isBuy ? '买入 ${_selectedCoin?.code ?? ''}' : '卖出 ${_selectedCoin?.code ?? ''}',
          style: const TextStyle(
            color: Colors.white,
            fontSize: 16,
            fontWeight: FontWeight.w600,
          ),
        ),
      ),
    );
  }
}