package wallet

import (
	"context"
	"strconv"
	"strings"
	"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"
)

// PostingCommand 描述一次具有稳定业务引用的代理主钱包正向入账。
type PostingCommand struct {
	ShopID          uint
	WalletID        uint
	Amount          int64
	ReferenceType   string
	ReferenceID     uint
	TransactionType string
	UserID          uint
	Creator         uint
	Remark          string
	Metadata        *string
	RequestID       string
	CorrelationID   string
}

// PostingResult 返回统一入账后的资金快照。
type PostingResult struct {
	WalletID       uint
	BalanceBefore  int64
	BalanceAfter   int64
	Version        int
	AlreadyApplied bool
}

// CreditedEvent 是代理主钱包正向入账成功后的可靠领域事实。
type CreditedEvent struct {
	EventID         string    `json:"event_id"`
	WalletID        uint      `json:"wallet_id"`
	ShopID          uint      `json:"shop_id"`
	Amount          int64     `json:"amount"`
	BalanceBefore   int64     `json:"balance_before"`
	BalanceAfter    int64     `json:"balance_after"`
	Version         int       `json:"version"`
	ReferenceType   string    `json:"reference_type"`
	ReferenceID     uint      `json:"reference_id"`
	TransactionType string    `json:"transaction_type"`
	OccurredAt      time.Time `json:"occurred_at"`
	RequestID       string    `json:"request_id,omitempty"`
	CorrelationID   string    `json:"correlation_id,omitempty"`
}

// CreditEventWriter 在调用方事务内追加正向入账事件。
type CreditEventWriter interface {
	Append(ctx context.Context, tx *gorm.DB, event CreditedEvent) error
}

// PostingService 统一代理主钱包充值与人工调整入账。
type PostingService struct {
	eventWriter CreditEventWriter
	now         func() time.Time
}

// NewPostingService 创建统一代理主钱包入账服务。
func NewPostingService(eventWriter CreditEventWriter, now func() time.Time) *PostingService {
	if now == nil {
		now = time.Now
	}
	return &PostingService{eventWriter: eventWriter, now: now}
}

// PostInTx 在调用方事务内完成锁定、入账、唯一流水和 Outbox 事件。
func (s *PostingService) PostInTx(ctx context.Context, tx *gorm.DB, command PostingCommand) (PostingResult, error) {
	if s == nil || s.eventWriter == nil || tx == nil {
		return PostingResult{}, errors.New(errors.CodeInternalError, "代理主钱包入账能力未完整配置")
	}
	if err := validatePostingCommand(command); err != nil {
		return PostingResult{}, err
	}

	var stored model.AgentWallet
	if err := tx.WithContext(ctx).Clauses(clause.Locking{Strength: "UPDATE"}).
		Where("shop_id = ? AND wallet_type = ?", command.ShopID, constants.AgentWalletTypeMain).
		First(&stored).Error; err != nil {
		if err == gorm.ErrRecordNotFound {
			return PostingResult{}, errors.New(errors.CodeWalletNotFound, "代理主钱包不存在")
		}
		return PostingResult{}, errors.Wrap(errors.CodeDatabaseError, err, "锁定代理主钱包失败")
	}
	if command.WalletID > 0 && command.WalletID != stored.ID {
		return PostingResult{}, errors.New(errors.CodeConflict, "入账业务单与代理主钱包归属不一致")
	}

	existing, err := findExistingPosting(ctx, tx, command.ReferenceType, command.ReferenceID)
	if err != nil {
		return PostingResult{}, err
	}
	if existing != nil {
		if existing.AgentWalletID != stored.ID || existing.Amount != command.Amount || existing.TransactionType != command.TransactionType {
			return PostingResult{}, errors.New(errors.CodeConflict, "业务单已存在不一致的钱包入账流水")
		}
		return PostingResult{WalletID: stored.ID, BalanceBefore: existing.BalanceBefore, BalanceAfter: existing.BalanceAfter, Version: stored.Version, AlreadyApplied: true}, nil
	}

	aggregate := domainwallet.AgentWallet{
		ID: stored.ID, ShopID: stored.ShopID, WalletType: stored.WalletType,
		Balance: stored.Balance, FrozenBalance: stored.FrozenBalance,
		CreditEnabled: stored.CreditEnabled, CreditLimit: stored.CreditLimit,
		Status: stored.Status, Version: stored.Version,
	}
	if err := aggregate.Credit(command.Amount); err != nil {
		return PostingResult{}, err
	}
	now := s.now().UTC()
	update := 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, "version": gorm.Expr("version + 1"), "updated_at": now})
	if update.Error != nil {
		return PostingResult{}, errors.Wrap(errors.CodeDatabaseError, update.Error, "增加代理主钱包余额失败")
	}
	if update.RowsAffected != 1 {
		return PostingResult{}, errors.New(errors.CodeConflict, "钱包版本已变化，请重试")
	}

	referenceType := strings.TrimSpace(command.ReferenceType)
	remark := strings.TrimSpace(command.Remark)
	transaction := &model.AgentWalletTransaction{
		AgentWalletID: stored.ID, ShopID: stored.ShopID, UserID: command.UserID,
		TransactionType: command.TransactionType, Amount: command.Amount,
		BalanceBefore: stored.Balance, BalanceAfter: aggregate.Balance, Status: constants.TransactionStatusSuccess,
		ReferenceType: &referenceType, ReferenceID: &command.ReferenceID, Remark: &remark, Metadata: command.Metadata,
		Creator: command.Creator, ShopIDTag: stored.ShopIDTag, EnterpriseIDTag: stored.EnterpriseIDTag,
	}
	if err := tx.WithContext(ctx).Create(transaction).Error; err != nil {
		return PostingResult{}, errors.Wrap(errors.CodeDatabaseError, err, "创建代理主钱包入账流水失败")
	}
	event := CreditedEvent{
		EventID:  "agent-wallet:" + referenceType + ":" + strconv.FormatUint(uint64(command.ReferenceID), 10) + ":credited",
		WalletID: stored.ID, ShopID: stored.ShopID, Amount: command.Amount,
		BalanceBefore: stored.Balance, BalanceAfter: aggregate.Balance, Version: stored.Version + 1,
		ReferenceType: referenceType, ReferenceID: command.ReferenceID, TransactionType: command.TransactionType,
		OccurredAt: now, RequestID: command.RequestID, CorrelationID: command.CorrelationID,
	}
	if err := s.eventWriter.Append(ctx, tx, event); err != nil {
		return PostingResult{}, errors.Wrap(errors.CodeDatabaseError, err, "写入代理主钱包入账事件失败")
	}
	return PostingResult{WalletID: stored.ID, BalanceBefore: stored.Balance, BalanceAfter: aggregate.Balance, Version: stored.Version + 1}, nil
}

func validatePostingCommand(command PostingCommand) error {
	if command.ShopID == 0 || command.Amount <= 0 || command.ReferenceID == 0 {
		return errors.New(errors.CodeInvalidParam, "代理主钱包入账参数无效")
	}
	referenceType := strings.TrimSpace(command.ReferenceType)
	validRecharge := referenceType == constants.ReferenceTypeTopup && command.TransactionType == constants.AgentTransactionTypeRecharge
	validAdjustment := referenceType == constants.ReferenceTypeManualAdjustment && command.TransactionType == constants.AgentTransactionTypeAdjustment
	if !validRecharge && !validAdjustment {
		return errors.New(errors.CodeInvalidParam, "代理主钱包入账业务类型无效")
	}
	return nil
}

func findExistingPosting(ctx context.Context, tx *gorm.DB, referenceType string, referenceID uint) (*model.AgentWalletTransaction, error) {
	var transaction model.AgentWalletTransaction
	err := tx.WithContext(ctx).Unscoped().
		Where("reference_type = ? AND reference_id = ? AND transaction_type IN ? AND status = ?",
			strings.TrimSpace(referenceType), referenceID, []string{constants.AgentTransactionTypeRecharge, constants.AgentTransactionTypeAdjustment}, constants.TransactionStatusSuccess).
		First(&transaction).Error
	if err == nil {
		return &transaction, nil
	}
	if err == gorm.ErrRecordNotFound {
		return nil, nil
	}
	return nil, errors.Wrap(errors.CodeDatabaseError, err, "查询代理主钱包入账流水失败")
}