package service

import (
	"errors"
	"fmt"

	"affiliate_dash/internal/model"

	"github.com/google/uuid"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

type WalletAdjustInput struct {
	MerchantID     uint
	ActorUserID    uint
	Amount         int64
	IdempotencyKey string
	Note           string
}

func (s *FulfillmentService) AdjustWallet(in WalletAdjustInput) (*model.WalletAccount, error) {
	if in.Amount == 0 {
		return nil, errors.New("调整金额不能为零")
	}
	if in.IdempotencyKey == "" {
		return nil, errors.New("账务调整必须提供幂等键")
	}
	var out model.WalletAccount
	err := s.db.Transaction(func(tx *gorm.DB) error {
		var existing model.WalletLedgerEntry
		if err := tx.Where("merchant_id = ? AND idempotency_key = ?", in.MerchantID, in.IdempotencyKey).First(&existing).Error; err == nil {
			if err := tx.First(&out, existing.WalletAccountID).Error; err != nil {
				return err
			}
			return nil
		} else if !errors.Is(err, gorm.ErrRecordNotFound) {
			return err
		}

		var wallet model.WalletAccount
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Where("merchant_id = ?", in.MerchantID).First(&wallet).Error; err != nil {
			return err
		}
		newBalance := wallet.AvailableBalance + in.Amount
		if newBalance < 0 {
			return errors.New("调整后余额不能小于零")
		}
		if err := tx.Model(&wallet).Update("available_balance", newBalance).Error; err != nil {
			return err
		}
		entryType := model.WalletLedgerAdjust
		if in.Amount > 0 {
			entryType = model.WalletLedgerCredit
		} else {
			entryType = model.WalletLedgerDebit
		}
		idempotencyKey := in.IdempotencyKey
		if err := tx.Create(&model.WalletLedgerEntry{
			MerchantID:      in.MerchantID,
			WalletAccountID: wallet.ID,
			EntryNo:         "WL" + uuid.NewString(),
			Type:            entryType,
			Amount:          in.Amount,
			BalanceAfter:    newBalance,
			ReferenceType:   "manual_adjustment",
			ReferenceNo:     in.IdempotencyKey,
			IdempotencyKey:  &idempotencyKey,
			Note:            in.Note,
		}).Error; err != nil {
			return err
		}
		out = wallet
		out.AvailableBalance = newBalance
		return writeAudit(tx, &in.MerchantID, &in.ActorUserID, nil, "wallet.adjust", "wallet_account", fmt.Sprint(wallet.ID), map[string]int64{"amount": in.Amount})
	})
	if err != nil {
		return nil, err
	}
	return &out, nil
}

func (s *FulfillmentService) GetWallet(merchantID uint) (*model.WalletAccount, error) {
	var wallet model.WalletAccount
	if err := s.db.Where("merchant_id = ?", merchantID).First(&wallet).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, errors.New("商户钱包不存在")
		}
		return nil, err
	}
	return &wallet, nil
}

func (s *FulfillmentService) ListWalletLedger(merchantID uint, page, size int, referenceNo, entryType string) ([]model.WalletLedgerEntry, int64, error) {
	page, size = normalizePage(page, size)
	tx := s.db.Model(&model.WalletLedgerEntry{}).Where("merchant_id = ?", merchantID)
	if referenceNo != "" {
		tx = tx.Where("reference_no LIKE ?", "%"+referenceNo+"%")
	}
	if entryType != "" {
		tx = tx.Where("type = ?", entryType)
	}
	var total int64
	if err := tx.Count(&total).Error; err != nil {
		return nil, 0, err
	}
	var entries []model.WalletLedgerEntry
	err := tx.Order("id DESC").Offset((page - 1) * size).Limit(size).Find(&entries).Error
	return entries, total, err
}