package services

import (
	"context"
	"fmt"

	"github.com/shopspring/decimal"
	"go.uber.org/zap"
	"gorm.io/gorm"

	"tyapi-server/internal/config"
	"tyapi-server/internal/domains/finance/entities"
	"tyapi-server/internal/domains/finance/repositories"
)

// WalletAggregateService 钱包聚合服务接口
type WalletAggregateService interface {
	CreateWallet(ctx context.Context, userID string) (*entities.Wallet, error)
	Recharge(ctx context.Context, userID string, amount decimal.Decimal) error
	Deduct(ctx context.Context, userID string, amount decimal.Decimal, apiCallID, transactionID, productID string) error
	GetBalance(ctx context.Context, userID string) (decimal.Decimal, error)
	LoadWalletByUserId(ctx context.Context, userID string) (*entities.Wallet, error)
}

// WalletAggregateServiceImpl 实现

// WalletAggregateServiceImpl 钱包聚合服务实现
type WalletAggregateServiceImpl struct {
	db              *gorm.DB
	walletRepo      repositories.WalletRepository
	transactionRepo repositories.WalletTransactionRepository
	balanceAlertSvc BalanceAlertService
	logger          *zap.Logger
	cfg             *config.Config
}

func NewWalletAggregateService(
	db *gorm.DB,
	walletRepo repositories.WalletRepository,
	transactionRepo repositories.WalletTransactionRepository,
	balanceAlertSvc BalanceAlertService,
	logger *zap.Logger,
	cfg *config.Config,
) WalletAggregateService {
	return &WalletAggregateServiceImpl{
		db:              db,
		walletRepo:      walletRepo,
		transactionRepo: transactionRepo,
		balanceAlertSvc: balanceAlertSvc,
		logger:          logger,
		cfg:             cfg,
	}
}

// CreateWallet 创建钱包
func (s *WalletAggregateServiceImpl) CreateWallet(ctx context.Context, userID string) (*entities.Wallet, error) {
	// 检查是否已存在
	w, _ := s.walletRepo.GetByUserID(ctx, userID)
	if w != nil {
		return nil, fmt.Errorf("用户已存在钱包")
	}
	wallet := entities.NewWallet(userID, decimal.NewFromFloat(s.cfg.Wallet.DefaultCreditLimit))
	created, err := s.walletRepo.Create(ctx, *wallet)
	if err != nil {
		s.logger.Error("创建钱包失败", zap.Error(err))
		return nil, err
	}
	s.logger.Info("钱包创建成功", zap.String("user_id", userID), zap.String("wallet_id", created.ID))
	return &created, nil
}

// Recharge 充值 - 使用事务确保一致性
func (s *WalletAggregateServiceImpl) Recharge(ctx context.Context, userID string, amount decimal.Decimal) error {
	// 使用数据库事务确保一致性
	return s.db.Transaction(func(tx *gorm.DB) error {
		ok, err := s.walletRepo.UpdateBalanceByUserID(ctx, userID, amount, "add")
		if err != nil {
			return fmt.Errorf("更新钱包余额失败: %w", err)
		}
		if !ok {
			return fmt.Errorf("高并发下充值失败，请重试")
		}

		s.logger.Info("钱包充值成功",
			zap.String("user_id", userID),
			zap.String("amount", amount.String()))

		return nil
	})
}

// Deduct 扣款，含欠费规则 - 使用事务确保一致性
func (s *WalletAggregateServiceImpl) Deduct(ctx context.Context, userID string, amount decimal.Decimal, apiCallID, transactionID, productID string) error {
	// 使用数据库事务确保一致性
	return s.db.Transaction(func(tx *gorm.DB) error {
		// 1. 使用乐观锁更新余额（通过用户ID直接更新，避免重复查询）
		ok, err := s.walletRepo.UpdateBalanceByUserID(ctx, userID, amount, "subtract")
		if err != nil {
			return fmt.Errorf("更新钱包余额失败: %w", err)
		}
		if !ok {
			return fmt.Errorf("高并发下扣款失败，请重试")
		}

		// 2. 创建扣款记录（检查是否已存在）
		transaction := entities.NewWalletTransaction(userID, apiCallID, transactionID, productID, amount)

		if err := tx.Create(transaction).Error; err != nil {
			return fmt.Errorf("创建扣款记录失败: %w", err)
		}

		s.logger.Info("钱包扣款成功",
			zap.String("user_id", userID),
			zap.String("amount", amount.String()),
			zap.String("api_call_id", apiCallID),
			zap.String("transaction_id", transactionID))

		// 3. 扣费成功后异步检查余额预警
		go s.checkBalanceAlertAsync(context.Background(), userID)

		return nil
	})
}

// GetBalance 查询余额
func (s *WalletAggregateServiceImpl) GetBalance(ctx context.Context, userID string) (decimal.Decimal, error) {
	w, err := s.walletRepo.GetByUserID(ctx, userID)
	if err != nil {
		return decimal.Zero, fmt.Errorf("钱包不存在")
	}
	return w.Balance, nil
}

func (s *WalletAggregateServiceImpl) LoadWalletByUserId(ctx context.Context, userID string) (*entities.Wallet, error) {
	return s.walletRepo.GetByUserID(ctx, userID)
}

// checkBalanceAlertAsync 异步检查余额预警
func (s *WalletAggregateServiceImpl) checkBalanceAlertAsync(ctx context.Context, userID string) {
	// 获取最新余额
	wallet, err := s.walletRepo.GetByUserID(ctx, userID)
	if err != nil {
		s.logger.Error("获取钱包余额失败", 
			zap.String("user_id", userID), 
			zap.Error(err))
		return
	}

	// 检查并发送预警
	if err := s.balanceAlertSvc.CheckAndSendAlert(ctx, userID, wallet.Balance); err != nil {
		s.logger.Error("余额预警检查失败", 
			zap.String("user_id", userID), 
			zap.Error(err))
	}
}