laic-backend/service/billing_service.go

package service

import (
	"errors"
	"fmt"
	"strconv"
	"strings"
	"time"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"

	"laic-backend/cache"
	"laic-backend/common"
	"laic-backend/logger"
	"laic-backend/model"
	"laic-backend/tool"
	"laic-backend/vo"
)

const (
	gbBytes                 = 1024 * 1024 * 1024 // 1 GB 字节数
	defaultTrafficUnitPrice = 10.0               // 云媒体流量单价（元/GB）
)

// trafficDeductLua 原子扣减：key 不存在时用 MySQL 快照兜底初始化，再判断并扣减。
// 返回 {status, before, after}：status=1 成功，0 余额不足。
const trafficDeductLua = `
local key = KEYS[1]
local delta = tonumber(ARGV[1])
local fallback = tonumber(ARGV[2])
local before = 0
if redis.call('EXISTS', key) == 0 then
  redis.call('SET', key, fallback)
  before = fallback
else
  before = tonumber(redis.call('GET', key))
end
if before < delta then
  return {0, before, before}
end
local after = redis.call('DECRBY', key, delta)
return {1, before, after}
`

type BillingService struct{}

var DefaultBillingService = &BillingService{}

// CarrierAPI 运营商接口抽象（查询用量 / 充值）
type CarrierAPI interface {
	QueryUsage(iccid string) (usedGb float64, carrierStatus string, err error)
	Recharge(iccid string, amountGb int) (orderNo string, err error)
}

// MockCarrierAPI 运营商 Mock（仅供开发注入，不作为默认生产通道）
type MockCarrierAPI struct{}

func (m *MockCarrierAPI) QueryUsage(iccid string) (float64, string, error) {
	return 0.0, "normal", nil
}

func (m *MockCarrierAPI) Recharge(iccid string, amountGb int) (string, error) {
	return fmt.Sprintf("MOCK-%d", time.Now().UnixNano()), nil
}

// carrier 默认禁用，未接入真实运营商前不产生虚假用量或充值成功。
var carrier CarrierAPI

// mysqlBalance 读取用户 MySQL 流量快照
func (b *BillingService) mysqlBalance(userID int64) (int64, error) {
	var u model.User
	if err := common.DB.Select("traffic_balance").First(&u, userID).Error; err != nil {
		return 0, err
	}
	return u.TrafficBalance, nil
}

// GetBalance 查询流量余额（Redis 权威，缺 key 时用 MySQL 快照兜底）
func (b *BillingService) GetBalance(userID int64) (*vo.TrafficBalanceVO, *common.BusiError) {
	balance, err := b.currentBalance(userID)
	if err != nil {
		logger.ERROR("查询流量余额失败", err)
		return nil, common.ErrInternal
	}
	return &vo.TrafficBalanceVO{
		BalanceBytes: balance,
		BalanceGb:    float64(balance) / float64(gbBytes),
	}, nil
}

// currentBalance 返回 Redis 权威余额；缺 key 时先用 MySQL 快照 SetNX 初始化
func (b *BillingService) currentBalance(userID int64) (int64, error) {
	key := cache.TrafficKeyOf(userID)
	bal, err := common.GetInt64(key)
	if err == nil {
		return bal, nil
	}
	fallback, err := b.mysqlBalance(userID)
	if err != nil {
		return 0, err
	}
	if _, err := common.SetNX(key, fallback); err != nil {
		return 0, err
	}
	// SetNX 失败说明并发下已有值，重读一次
	bal, err = common.GetInt64(key)
	if err != nil {
		return fallback, nil
	}
	return bal, nil
}

// Deduct 在一个事务内扣减用户余额和平台共享资源，并写入统一账务流水。
// idempotencyKey 必须由调用方按业务事件稳定生成。
func (b *BillingService) Deduct(userID int64, bytes int64, sourceType string, sourceID int64, idempotencyKey string) (bool, *common.BusiError) {
	if bytes <= 0 {
		return true, nil
	}
	if idempotencyKey == "" {
		return false, common.ErrParam
	}
	now := time.Now()
	var busiErr *common.BusiError
	var alreadyDeducted bool
	err := common.DB.Transaction(func(tx *gorm.DB) error {
		var existing model.TrafficLedger
		if err := tx.Where("idempotency_key = ?", idempotencyKey+":user").First(&existing).Error; err == nil {
			alreadyDeducted = true
			return nil
		} else if !errors.Is(err, gorm.ErrRecordNotFound) {
			return err
		}

		var user model.User
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Select("id", "traffic_balance").First(&user, userID).Error; err != nil {
			return err
		}
		if user.TrafficBalance < bytes {
			busiErr = common.ErrTrafficNotEnough
			return busiErr
		}

		var pool model.PlatformResourcePool
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Order("id ASC").First(&pool).Error; err != nil {
			if errors.Is(err, gorm.ErrRecordNotFound) {
				busiErr = common.ErrPlatformTrafficExhausted
			}
			return err
		}
		if pool.AvailableBytes < bytes || pool.Status != "active" {
			busiErr = common.ErrPlatformTrafficExhausted
			return busiErr
		}

		userAfter := user.TrafficBalance - bytes
		platformAfter := pool.AvailableBytes - bytes
		if err := tx.Model(&model.User{}).Where("id = ?", userID).UpdateColumn("traffic_balance", userAfter).Error; err != nil {
			return err
		}
		if err := tx.Model(&pool).Updates(map[string]any{
			"available_bytes": platformAfter,
			"consumed_bytes":  gorm.Expr("consumed_bytes + ?", bytes),
			"version":         gorm.Expr("version + 1"),
			"updated_at":      now,
		}).Error; err != nil {
			return err
		}
		if err := tx.Create(&model.TrafficLedger{
			ID: mustID(), AccountType: "user", AccountID: userID, Direction: "debit",
			AmountBytes: bytes, BalanceBefore: user.TrafficBalance, BalanceAfter: userAfter,
			SourceType: sourceType, SourceID: strconv.FormatInt(sourceID, 10), IdempotencyKey: idempotencyKey + ":user", CreatedAt: now,
		}).Error; err != nil {
			return err
		}
		if err := tx.Create(&model.TrafficLedger{
			ID: mustID(), AccountType: "platform", AccountID: pool.ID, Direction: "debit",
			AmountBytes: bytes, BalanceBefore: pool.AvailableBytes, BalanceAfter: platformAfter,
			SourceType: sourceType, SourceID: strconv.FormatInt(sourceID, 10), IdempotencyKey: idempotencyKey + ":platform", CreatedAt: now,
		}).Error; err != nil {
			return err
		}
		return tx.Create(&model.TrafficUsageLog{
			ID: mustID(), UserID: userID, SourceType: sourceType, SourceID: sourceID,
			BytesUsed: bytes, BalanceBefore: user.TrafficBalance, BalanceAfter: userAfter,
			IdempotencyKey: idempotencyKey, CreatedAt: now,
		}).Error
	})
	if err != nil {
		if busiErr != nil {
			return false, busiErr
		}
		logger.ERROR("流量扣费事务失败", err)
		return false, common.ErrInternal
	}
	if alreadyDeducted {
		return true, nil
	}
	if err := common.Delete(cache.TrafficKeyOf(userID)); err != nil {
		logger.WARN("删除流量余额缓存失败", err)
	}
	return true, nil
}

// credit 充值入账：Redis 权威自增 + MySQL 快照同步
func (b *BillingService) credit(userID int64, bytes int64) error {
	key := cache.TrafficKeyOf(userID)
	if _, err := b.currentBalance(userID); err != nil {
		return err
	}
	_, err := common.IncrBy(key, bytes)
	return err
}

// GetUsagePage 流量消费流水分页
func (b *BillingService) GetUsagePage(userID int64, req *vo.UsagePageReq) (*common.PageResponse[model.TrafficUsageLog], *common.BusiError) {
	db := common.DB.Model(&model.TrafficUsageLog{}).Where("user_id = ?", userID)
	if req.SourceType != "" {
		db = db.Where("source_type = ?", req.SourceType)
	}
	var total int64
	if err := db.Count(&total).Error; err != nil {
		return nil, common.ErrInternal
	}
	var list []model.TrafficUsageLog
	if err := db.Scopes(req.Paginate).Order("created_at DESC, id DESC").Find(&list).Error; err != nil {
		return nil, common.ErrInternal
	}
	return common.Page(req.Pagination, total, list), nil
}

// GetOrderPage 流量订单分页
func (b *BillingService) GetOrderPage(userID int64, req *vo.OrderPageReq) (*common.PageResponse[model.TrafficOrder], *common.BusiError) {
	db := common.DB.Model(&model.TrafficOrder{}).Where("user_id = ?", userID)
	if req.PayStatus != "" {
		db = db.Where("pay_status = ?", req.PayStatus)
	}
	var total int64
	if err := db.Count(&total).Error; err != nil {
		return nil, common.ErrInternal
	}
	var list []model.TrafficOrder
	if err := db.Scopes(req.Paginate).Order("created_at DESC, id DESC").Find(&list).Error; err != nil {
		return nil, common.ErrInternal
	}
	return common.Page(req.Pagination, total, list), nil
}

func (b *BillingService) CreateOrder(userID int64, amountGb int) (*model.TrafficOrder, *common.BusiError) {
	return b.CreateOrderWithPackage(userID, 0, amountGb)
}

func (b *BillingService) CreateOrderWithPackage(userID, packageID int64, amountGb int) (*model.TrafficOrder, *common.BusiError) {
	order := &model.TrafficOrder{ID: mustID(), UserID: userID, PayStatus: "unpaid", CreditStatus: "pending", CreatedAt: time.Now()}
	if packageID > 0 {
		var pkg model.TrafficPackage
		if err := common.DB.Where("id = ? AND status = ?", packageID, "active").First(&pkg).Error; err != nil {
			if errors.Is(err, gorm.ErrRecordNotFound) {
				return nil, common.ErrNotFound
			}
			return nil, common.ErrInternal
		}
		order.PackageID, order.PackageCode = pkg.ID, pkg.Code
		order.AmountBytes, order.UnitPrice, order.TotalPrice = pkg.AmountBytes, pkg.Price/float64(pkg.AmountBytes)*float64(gbBytes), pkg.Price
		order.AmountGb = int(pkg.AmountBytes / gbBytes)
	} else {
		if amountGb <= 0 {
			return nil, common.ErrParam
		}
		order.AmountGb, order.AmountBytes = amountGb, int64(amountGb)*gbBytes
		order.UnitPrice, order.TotalPrice = defaultTrafficUnitPrice, float64(amountGb)*defaultTrafficUnitPrice
	}
	if err := common.DB.Create(order).Error; err != nil {
		logger.ERROR("创建流量订单失败", err)
		return nil, common.ErrInternal
	}
	return order, nil
}

// PayOrder 订单支付入账（admin 确认支付）。
func (b *BillingService) PayOrder(orderID, operatorID int64, paymentKey string) (*model.TrafficOrder, *common.BusiError) {
	var order model.TrafficOrder
	now := time.Now()
	var busiErr *common.BusiError
	if paymentKey == "" {
		paymentKey = strconv.FormatInt(orderID, 10)
	}
	paymentIdempotencyKey := "order:payment:" + paymentKey
	err := common.DB.Transaction(func(tx *gorm.DB) error {
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).First(&order, orderID).Error; err != nil {
			return err
		}
		if order.PayStatus == "paid" || order.CreditStatus == "credited" {
			busiErr = common.ErrOrderPaid
			return busiErr
		}
		bytes := order.AmountBytes
		if bytes <= 0 {
			bytes = int64(order.AmountGb) * gbBytes
		}
		var user model.User
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Select("id", "traffic_balance").First(&user, order.UserID).Error; err != nil {
			return err
		}
		after := user.TrafficBalance + bytes
		if err := tx.Model(&model.User{}).Where("id = ?", user.ID).UpdateColumn("traffic_balance", after).Error; err != nil {
			return err
		}
		ledgerID := mustID()
		if ledgerID == 0 {
			return errors.New("generate ledger id failed")
		}
		if err := tx.Create(&model.TrafficLedger{
			ID: ledgerID, AccountType: "user", AccountID: order.UserID, Direction: "credit",
			AmountBytes: bytes, BalanceBefore: user.TrafficBalance, BalanceAfter: after,
			SourceType: "traffic_order", SourceID: strconv.FormatInt(order.ID, 10),
			IdempotencyKey: paymentIdempotencyKey, OperatorID: operatorID, CreatedAt: now,
		}).Error; err != nil {
			return err
		}
		if err := tx.Model(&order).Updates(map[string]any{
			"pay_status": "paid", "credit_status": "credited", "amount_bytes": bytes,
			"credit_ledger_id": ledgerID, "paid_at": now, "paid_by": operatorID,
			"payment_idempotency_key": paymentIdempotencyKey}).Error; err != nil {
			return err
		}
		order.AmountBytes = bytes
		order.CreditStatus = "credited"
		order.CreditLedgerID = ledgerID
		order.PayStatus = "paid"
		order.PaidAt = &now
		return nil
	})
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, common.ErrOrderNotFound
		}
		if busiErr != nil {
			return nil, busiErr
		}
		if typed, ok := err.(*common.BusiError); ok {
			return nil, typed
		}
		logger.ERROR("订单支付失败", err)
		return nil, common.ErrInternal
	}
	if err := common.Delete(cache.TrafficKeyOf(order.UserID)); err != nil {
		logger.WARN("删除充值余额缓存失败", err)
	}
	return &order, nil
}

// ListSimCards SIM 卡列表
func (b *BillingService) ListSimCards(userID int64, req *vo.SimCardPageReq) (*common.PageResponse[model.SimCard], *common.BusiError) {
	db := common.DB.Model(&model.SimCard{}).Where("user_id = ?", userID)
	if req.Status != "" {
		db = db.Where("status = ?", req.Status)
	}
	var total int64
	if err := db.Count(&total).Error; err != nil {
		return nil, common.ErrInternal
	}
	var list []model.SimCard
	if err := db.Scopes(req.Paginate).Order("updated_at DESC, id DESC").Find(&list).Error; err != nil {
		return nil, common.ErrInternal
	}
	return common.Page(req.Pagination, total, list), nil
}

// GetSimRechargeLogPage SIM 卡充值记录分页
func (b *BillingService) GetSimRechargeLogPage(userID int64, req *vo.SimRechargeLogPageReq) (*common.PageResponse[model.SimRechargeLog], *common.BusiError) {
	db := common.DB.Model(&model.SimRechargeLog{}).Where("user_id = ?", userID)
	if req.SimCardID > 0 {
		db = db.Where("sim_card_id = ?", req.SimCardID)
	}
	if req.RechargeStatus != "" {
		db = db.Where("recharge_status = ?", req.RechargeStatus)
	}
	var total int64
	if err := db.Count(&total).Error; err != nil {
		return nil, common.ErrInternal
	}
	var list []model.SimRechargeLog
	if err := db.Scopes(req.Paginate).Order("created_at DESC, id DESC").Find(&list).Error; err != nil {
		return nil, common.ErrInternal
	}
	return common.Page(req.Pagination, total, list), nil
}

// RechargeSimCard 当前未接入支付确认流程，不向运营商提交充值订单。
func (b *BillingService) RechargeSimCard(userID, simCardID int64, amountGb int) (*model.SimRechargeLog, *common.BusiError) {
	return nil, common.ErrCarrierUnavailable
}

// mustID 生成雪花 ID（失败返回 0，由 DB 约束兜底）
func mustID() int64 {
	id, err := tool.NextID()
	if err != nil {
		logger.ERROR("生成雪花 ID 失败", err)
		return 0
	}
	return id
}

// chargeLiveSessions 只结算设备与云端均确认在线的 streaming 会话。
func (b *BillingService) chargeLiveSessions() {
	var sessions []model.LiveSession
	if err := common.DB.Where("phase = 'streaming' AND device_streaming = ? AND cloud_online = ? AND started_at IS NOT NULL", true, true).Find(&sessions).Error; err != nil {
		logger.ERROR("扫描直播会话失败", err)
		return
	}
	now := time.Now().Truncate(time.Second)
	for i := range sessions {
		b.chargeLiveSession(&sessions[i], now)
	}
}

// chargeLiveSession 通过会话行锁和唯一直播计费段避免多实例重复结算。
func (b *BillingService) chargeLiveSession(session *model.LiveSession, now time.Time) {
	var userID int64
	var needStop bool
	var charged bool
	err := common.DB.Transaction(func(tx *gorm.DB) error {
		var current model.LiveSession
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).First(&current, "id = ?", session.ID).Error; err != nil {
			return err
		}
		if current.Phase != "streaming" || !current.DeviceStreaming || !current.CloudOnline || current.StartedAt == nil {
			return nil
		}
		var dock model.Dock
		if err := tx.Select("user_id").Where("dock_id = ?", current.DockID).First(&dock).Error; err != nil {
			return err
		}
		userID = dock.UserID

		periodStart := *current.StartedAt
		var last model.LiveBillingSegment
		if err := tx.Where("session_id = ?", current.ID).Order("period_end DESC").First(&last).Error; err == nil {
			periodStart = last.PeriodEnd
		} else if !errors.Is(err, gorm.ErrRecordNotFound) {
			return err
		}
		if !now.After(periodStart) {
			return nil
		}
		amount := int64(now.Sub(periodStart).Seconds() * float64(current.MaxBitrateBps) / 8)
		if amount <= 0 {
			return nil
		}
		idempotencyKey := fmt.Sprintf("live:%s:%d:%d", current.ID, periodStart.Unix(), now.Unix())
		segment := model.LiveBillingSegment{
			ID: mustID(), SessionID: current.ID, UserID: userID, PeriodStart: periodStart, PeriodEnd: now,
			Bytes: amount, Status: "pending", IdempotencyKey: idempotencyKey, CreatedAt: now,
		}
		if err := tx.Create(&segment).Error; err != nil {
			if code, _ := common.ParseError(err); code == 1062 {
				return nil
			}
			return err
		}

		var user model.User
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Select("id", "traffic_balance").First(&user, userID).Error; err != nil {
			return err
		}
		var pool model.PlatformResourcePool
		if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).Order("id ASC").First(&pool).Error; err != nil {
			return err
		}
		if user.TrafficBalance < amount || pool.Status != "active" || pool.AvailableBytes < amount {
			if err := tx.Model(&segment).Update("status", "insufficient").Error; err != nil {
				return err
			}
			result := tx.Model(&model.LiveSession{}).Where("id = ? AND phase = 'streaming'", current.ID).Updates(map[string]any{
				"phase": "stopping", "stop_reason": "no_balance", "error_code": "TRAFFIC_NOT_ENOUGH", "updated_at": now,
			})
			if result.Error != nil {
				return result.Error
			}
			needStop = result.RowsAffected == 1
			return nil
		}

		userAfter, platformAfter := user.TrafficBalance-amount, pool.AvailableBytes-amount
		if err := tx.Model(&model.User{}).Where("id = ?", user.ID).UpdateColumn("traffic_balance", userAfter).Error; err != nil {
			return err
		}
		if err := tx.Model(&pool).Updates(map[string]any{
			"available_bytes": platformAfter,
			"consumed_bytes":  gorm.Expr("consumed_bytes + ?", amount),
			"version":         gorm.Expr("version + 1"),
			"updated_at":      now,
		}).Error; err != nil {
			return err
		}
		if err := tx.Create(&model.TrafficLedger{ID: mustID(), AccountType: "user", AccountID: user.ID, Direction: "debit", AmountBytes: amount, BalanceBefore: user.TrafficBalance, BalanceAfter: userAfter, SourceType: "live", SourceID: current.ID, IdempotencyKey: idempotencyKey + ":user", CreatedAt: now}).Error; err != nil {
			return err
		}
		if err := tx.Create(&model.TrafficLedger{ID: mustID(), AccountType: "platform", AccountID: pool.ID, Direction: "debit", AmountBytes: amount, BalanceBefore: pool.AvailableBytes, BalanceAfter: platformAfter, SourceType: "live", SourceID: current.ID, IdempotencyKey: idempotencyKey + ":platform", CreatedAt: now}).Error; err != nil {
			return err
		}
		if err := tx.Create(&model.TrafficUsageLog{ID: mustID(), UserID: user.ID, SourceType: "live", SourceID: 0, BytesUsed: amount, BalanceBefore: user.TrafficBalance, BalanceAfter: userAfter, IdempotencyKey: idempotencyKey, CreatedAt: now}).Error; err != nil {
			return err
		}
		if err := tx.Model(&segment).Updates(map[string]any{"status": "settled", "settled_at": now}).Error; err != nil {
			return err
		}
		charged = true
		return nil
	})
	if err != nil {
		logger.ERROR("直播计费事务失败", err)
		return
	}
	if needStop {
		if _, busiErr := DefaultLiveService.stopForBilling(session.DockID, session.ID); busiErr != nil {
			logger.ERROR("直播余额不足停止推流失败", busiErr)
		}
		return
	}
	if charged {
		if err := common.Delete(cache.TrafficKeyOf(userID)); err != nil {
			logger.WARN("删除直播余额缓存失败", err)
		}
	}
}

// flushBalanceSnapshot 余额快照刷新（定时任务，每 30min）：Redis 权威余额回写 MySQL
func (b *BillingService) flushBalanceSnapshot() {
	keys, err := common.GetKeysWithPrefix(cache.TrafficKeyPrefix)
	if err != nil {
		logger.ERROR("扫描流量余额 key 失败", err)
		return
	}
	for _, key := range keys {
		idStr := strings.TrimPrefix(key, cache.TrafficKeyPrefix)
		userID, err := strconv.ParseInt(idStr, 10, 64)
		if err != nil {
			continue
		}
		bal, err := common.GetInt64(key)
		if err != nil {
			continue
		}
		if err := common.DB.Model(&model.User{}).Where("id = ?", userID).
			UpdateColumn("traffic_balance", bal).Error; err != nil {
			logger.ERROR("回写余额快照失败", err)
		}
	}
}

// syncSimUsage SIM 卡用量同步（定时任务，每 1h）：运营商查询回填 + 用量快照 + 阈值告警
func (b *BillingService) syncSimUsage() {
	var cards []model.SimCard
	if err := common.DB.Where("status = ?", "active").Find(&cards).Error; err != nil {
		logger.ERROR("扫描 SIM 卡失败", err)
		return
	}
	now := time.Now()
	for i := range cards {
		b.syncSimCard(&cards[i], now)
	}
}

func (b *BillingService) syncSimCard(card *model.SimCard, now time.Time) {
	if carrier == nil {
		logger.INFO("SIM 运营商通道未接入:", card.Iccid)
		return
	}
	usedGb, carrierStatus, err := carrier.QueryUsage(card.Iccid)
	if err != nil {
		logger.WARN("查询 SIM 用量失败:", card.Iccid, err)
		return
	}

	updates := map[string]any{
		"used_gb":        usedGb,
		"carrier_status": carrierStatus,
		"last_sync_at":   now,
	}
	if carrierStatus == "cancelled" {
		updates["status"] = "expired"
	}
	if err := common.DB.Model(&model.SimCard{}).Where("id = ?", card.ID).Updates(updates).Error; err != nil {
		logger.ERROR("回填 SIM 用量失败", err)
	}

	remainGb := float64(card.PlanGb) - usedGb
	record := &model.SimUsageRecord{
		ID:            mustID(),
		SimCardID:     card.ID,
		PlanGb:        card.PlanGb,
		UsedGb:        usedGb,
		RemainGb:      remainGb,
		CarrierStatus: carrierStatus,
		SyncedAt:      now,
	}
	if err := common.DB.Create(record).Error; err != nil {
		logger.ERROR("写入 SIM 用量快照失败", err)
	}

	if remainGb < float64(card.PlanGb)*0.1 {
		logger.WARN("SIM 卡流量即将耗尽:", card.Iccid, "剩余", remainGb, "GB")
	}
	if carrierStatus == "suspended" || carrierStatus == "arrears" {
		logger.WARN("SIM 卡运营商状态异常:", card.Iccid, carrierStatus)
	}
}