package wallet

import (
	"context"
	"strconv"
	"time"

	domainwallet "github.com/break/junhong_cmp_fiber/internal/domain/wallet"
	"github.com/break/junhong_cmp_fiber/internal/model"
	"github.com/break/junhong_cmp_fiber/pkg/constants"
	"github.com/break/junhong_cmp_fiber/pkg/errors"
	"gorm.io/gorm"
	"gorm.io/gorm/clause"
)

// ReservationCommand 描述一次具有稳定业务引用的代理主钱包预占操作。
type ReservationCommand struct {
	ShopID          uint
	Amount          int64
	ReferenceType   string
	ReferenceID     uint
	UserID          uint
	Creator         uint
	Subtype         string
	RelatedShopID   *uint
	AssetType       string
	AssetID         uint
	AssetIdentifier string
	Remark          string
	RequestID       string
	CorrelationID   string
}

// ReservationEvent 是代理主钱包预占状态变化事件。
type ReservationEvent struct {
	EventID       string    `json:"event_id"`
	ReservationID uint      `json:"reservation_id"`
	WalletID      uint      `json:"wallet_id"`
	ShopID        uint      `json:"shop_id"`
	Amount        int64     `json:"amount"`
	Status        int       `json:"status"`
	ReferenceType string    `json:"reference_type"`
	ReferenceID   uint      `json:"reference_id"`
	OccurredAt    time.Time `json:"occurred_at"`
	RequestID     string    `json:"request_id,omitempty"`
	CorrelationID string    `json:"correlation_id,omitempty"`
}

// ReservationEventWriter 在业务事务内追加预占状态事件。
type ReservationEventWriter interface {
	Append(ctx context.Context, tx *gorm.DB, event ReservationEvent) error
}

// ReservationService 统一代理主钱包冻结、释放与完成扣除。
type ReservationService struct {
	reservationEvents ReservationEventWriter
	debitEvents       DebitEventWriter
	now               func() time.Time
}

// NewReservationService 创建代理主钱包预占服务。
func NewReservationService(reservationEvents ReservationEventWriter, debitEvents DebitEventWriter, now func() time.Time) *ReservationService {
	if now == nil {
		now = time.Now
	}
	return &ReservationService{reservationEvents: reservationEvents, debitEvents: debitEvents, now: now}
}

// FreezeInTx 在调用方事务内冻结资金并创建唯一预占事实。
func (s *ReservationService) FreezeInTx(ctx context.Context, tx *gorm.DB, command ReservationCommand) error {
	if err := s.validateFreeze(tx, command); err != nil {
		return err
	}
	wallet, aggregate, err := lockMainWallet(ctx, tx, command.ShopID)
	if err != nil {
		return err
	}
	existing, err := findReservation(ctx, tx, command.ReferenceType, command.ReferenceID, false)
	if err != nil {
		return err
	}
	if existing != nil {
		if existing.AgentWalletID == wallet.ID && existing.Amount == command.Amount && existing.Status == constants.AgentWalletReservationStatusFrozen {
			return nil
		}
		return errors.New(errors.CodeConflict, "业务引用已存在不一致的钱包预占")
	}
	if err := aggregate.Freeze(command.Amount); err != nil {
		return err
	}
	now := s.now().UTC()
	if err := updateWalletFunds(ctx, tx, wallet, aggregate, now); err != nil {
		return err
	}
	reservation := &model.AgentWalletReservation{
		AgentWalletID: wallet.ID, ShopID: wallet.ShopID, Amount: command.Amount,
		Status:        constants.AgentWalletReservationStatusFrozen,
		ReferenceType: command.ReferenceType, ReferenceID: command.ReferenceID, Creator: command.Creator,
		ShopIDTag: wallet.ShopIDTag, EnterpriseIDTag: wallet.EnterpriseIDTag,
	}
	if err := tx.WithContext(ctx).Create(reservation).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "创建代理主钱包预占事实失败")
	}
	return s.appendReservationEvent(ctx, tx, reservation, now, command)
}

// ReleaseInTx 幂等释放处于冻结状态的资金预占。
func (s *ReservationService) ReleaseInTx(ctx context.Context, tx *gorm.DB, command ReservationCommand) error {
	return s.finish(ctx, tx, command, constants.AgentWalletReservationStatusReleased)
}

// CompleteInTx 完成冻结资金扣除并创建真实扣款流水与扣款事件。
func (s *ReservationService) CompleteInTx(ctx context.Context, tx *gorm.DB, command ReservationCommand) error {
	return s.finish(ctx, tx, command, constants.AgentWalletReservationStatusCompleted)
}

func (s *ReservationService) finish(ctx context.Context, tx *gorm.DB, command ReservationCommand, targetStatus int) error {
	if err := s.validateFinish(tx, command); err != nil {
		return err
	}
	reservation, err := findReservation(ctx, tx, command.ReferenceType, command.ReferenceID, true)
	if err != nil {
		return err
	}
	if reservation == nil {
		return errors.New(errors.CodeNotFound, "代理主钱包预占事实不存在")
	}
	if (command.ShopID > 0 && reservation.ShopID != command.ShopID) || (command.Amount > 0 && reservation.Amount != command.Amount) {
		return errors.New(errors.CodeConflict, "钱包预占事实与请求不一致")
	}
	command.ShopID = reservation.ShopID
	command.Amount = reservation.Amount
	if reservation.Status == targetStatus {
		return nil
	}
	if reservation.Status != constants.AgentWalletReservationStatusFrozen {
		return errors.New(errors.CodeInvalidStatus, "钱包预占已经进入其他终态")
	}
	wallet, aggregate, err := lockMainWallet(ctx, tx, command.ShopID)
	if err != nil {
		return err
	}
	if wallet.ID != reservation.AgentWalletID {
		return errors.New(errors.CodeConflict, "钱包预占归属不一致")
	}
	if targetStatus == constants.AgentWalletReservationStatusReleased {
		err = aggregate.Release(command.Amount)
	} else {
		err = aggregate.CompleteReserved(command.Amount)
	}
	if err != nil {
		return err
	}
	now := s.now().UTC()
	if err := updateWalletFunds(ctx, tx, wallet, aggregate, now); err != nil {
		return err
	}
	result := tx.WithContext(ctx).Model(&model.AgentWalletReservation{}).
		Where("id = ? AND status = ?", reservation.ID, constants.AgentWalletReservationStatusFrozen).
		Updates(map[string]any{"status": targetStatus, "completed_at": now, "updated_at": now})
	if result.Error != nil {
		return errors.Wrap(errors.CodeDatabaseError, result.Error, "更新代理主钱包预占状态失败")
	}
	if result.RowsAffected != 1 {
		return errors.New(errors.CodeConflict, "钱包预占状态已变化")
	}
	reservation.Status = targetStatus
	reservation.CompletedAt = &now
	if targetStatus == constants.AgentWalletReservationStatusCompleted {
		if err := s.createCompletedDebit(ctx, tx, wallet, aggregate, command, now); err != nil {
			return err
		}
	}
	return s.appendReservationEvent(ctx, tx, reservation, now, command)
}

func (s *ReservationService) validateConfigured(tx *gorm.DB) error {
	if s == nil || s.reservationEvents == nil || s.debitEvents == nil || tx == nil {
		return errors.New(errors.CodeInternalError, "代理主钱包预占能力未完整配置")
	}
	return nil
}

func (s *ReservationService) validateFreeze(tx *gorm.DB, command ReservationCommand) error {
	if err := s.validateConfigured(tx); err != nil {
		return err
	}
	if command.ShopID == 0 || command.ReferenceType != constants.ReferenceTypeOrder || command.ReferenceID == 0 || command.Amount <= 0 {
		return errors.New(errors.CodeInvalidParam, "代理主钱包预占参数无效")
	}
	return nil
}

func (s *ReservationService) validateFinish(tx *gorm.DB, command ReservationCommand) error {
	if err := s.validateConfigured(tx); err != nil {
		return err
	}
	if command.ReferenceType != constants.ReferenceTypeOrder || command.ReferenceID == 0 || command.Amount < 0 {
		return errors.New(errors.CodeInvalidParam, "代理主钱包预占参数无效")
	}
	return nil
}

func lockMainWallet(ctx context.Context, tx *gorm.DB, shopID uint) (model.AgentWallet, *domainwallet.AgentWallet, error) {
	var wallet model.AgentWallet
	if err := tx.WithContext(ctx).Clauses(clause.Locking{Strength: "UPDATE"}).
		Where("shop_id = ? AND wallet_type = ?", shopID, constants.AgentWalletTypeMain).First(&wallet).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return wallet, nil, errors.New(errors.CodeWalletNotFound, "代理主钱包不存在")
		}
		return wallet, nil, errors.Wrap(errors.CodeDatabaseError, err, "锁定代理主钱包失败")
	}
	aggregate := &domainwallet.AgentWallet{
		ID: wallet.ID, ShopID: wallet.ShopID, WalletType: wallet.WalletType,
		Balance: wallet.Balance, FrozenBalance: wallet.FrozenBalance,
		CreditEnabled: wallet.CreditEnabled, CreditLimit: wallet.CreditLimit,
		Status: wallet.Status, Version: wallet.Version,
	}
	return wallet, aggregate, nil
}

func findReservation(ctx context.Context, tx *gorm.DB, referenceType string, referenceID uint, lock bool) (*model.AgentWalletReservation, error) {
	var reservation model.AgentWalletReservation
	query := tx.WithContext(ctx)
	if lock {
		query = query.Clauses(clause.Locking{Strength: "UPDATE"})
	}
	err := query.Where("reference_type = ? AND reference_id = ?", referenceType, referenceID).First(&reservation).Error
	if err == nil {
		return &reservation, nil
	}
	if err == gorm.ErrRecordNotFound {
		return nil, nil
	}
	return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询代理主钱包预占事实失败")
}

func updateWalletFunds(ctx context.Context, tx *gorm.DB, stored model.AgentWallet, aggregate *domainwallet.AgentWallet, now time.Time) error {
	result := tx.WithContext(ctx).Model(&model.AgentWallet{}).
		Where("id = ? AND wallet_type = ? AND status = ? AND version = ?", stored.ID, constants.AgentWalletTypeMain, constants.AgentWalletStatusNormal, stored.Version).
		Updates(map[string]any{
			"balance": aggregate.Balance, "frozen_balance": aggregate.FrozenBalance,
			"version": gorm.Expr("version + 1"), "updated_at": now,
		})
	if result.Error != nil {
		return errors.Wrap(errors.CodeDatabaseError, result.Error, "更新代理主钱包预占资金失败")
	}
	if result.RowsAffected != 1 {
		return errors.New(errors.CodeConflict, "钱包版本已变化，请重试")
	}
	return nil
}

func (s *ReservationService) createCompletedDebit(ctx context.Context, tx *gorm.DB, stored model.AgentWallet, aggregate *domainwallet.AgentWallet, command ReservationCommand, now time.Time) error {
	referenceType := command.ReferenceType
	transaction := &model.AgentWalletTransaction{
		AgentWalletID: stored.ID, ShopID: stored.ShopID, UserID: command.UserID,
		TransactionType: constants.AgentTransactionTypeDeduct, Amount: -command.Amount,
		BalanceBefore: stored.Balance, BalanceAfter: aggregate.Balance,
		Status: constants.TransactionStatusSuccess, ReferenceType: &referenceType, ReferenceID: &command.ReferenceID,
		RelatedShopID: command.RelatedShopID, AssetType: command.AssetType, AssetID: command.AssetID,
		AssetIdentifier: command.AssetIdentifier, Remark: &command.Remark, Creator: command.Creator,
		ShopIDTag: stored.ShopIDTag, EnterpriseIDTag: stored.EnterpriseIDTag,
	}
	if command.Subtype != "" {
		transaction.TransactionSubtype = &command.Subtype
	}
	if err := tx.WithContext(ctx).Create(transaction).Error; err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "创建冻结资金扣款流水失败")
	}
	event := DebitedEvent{
		EventID:  "agent-wallet:order:" + strconv.FormatUint(uint64(command.ReferenceID), 10) + ":debited",
		WalletID: stored.ID, ShopID: stored.ShopID, Amount: command.Amount,
		BalanceBefore: stored.Balance, BalanceAfter: aggregate.Balance, Version: stored.Version + 1,
		ReferenceType: command.ReferenceType, ReferenceID: command.ReferenceID,
		TransactionType: constants.AgentTransactionTypeDeduct, OccurredAt: now,
		RequestID: command.RequestID, CorrelationID: command.CorrelationID,
	}
	if err := s.debitEvents.Append(ctx, tx, event); err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "写入冻结资金扣款事件失败")
	}
	return nil
}

func (s *ReservationService) appendReservationEvent(ctx context.Context, tx *gorm.DB, reservation *model.AgentWalletReservation, now time.Time, command ReservationCommand) error {
	event := ReservationEvent{
		EventID:       "agent-wallet-reservation:" + strconv.FormatUint(uint64(reservation.ID), 10) + ":" + strconv.Itoa(reservation.Status),
		ReservationID: reservation.ID, WalletID: reservation.AgentWalletID, ShopID: reservation.ShopID,
		Amount: reservation.Amount, Status: reservation.Status,
		ReferenceType: reservation.ReferenceType, ReferenceID: reservation.ReferenceID,
		OccurredAt: now, RequestID: command.RequestID, CorrelationID: command.CorrelationID,
	}
	if err := s.reservationEvents.Append(ctx, tx, event); err != nil {
		return errors.Wrap(errors.CodeDatabaseError, err, "写入代理主钱包预占事件失败")
	}
	return nil
}