架构实践：如何构建内容、权限与资产打通的短剧系统底层链路

// Drama 短剧主表：维护核心生命周期与基础属性
type Drama struct {
    ID           uint       `gorm:"primaryKey"`
    Title        string     `gorm:"type:varchar(255);comment:主标题"`
    CoverURL     string     `gorm:"type:varchar(512);comment:封面图"`
    Status       int        `gorm:"type:tinyint;index;comment:0-草稿 1-连载中 2-已完结 3-下架"`
    IsPremium    bool       `gorm:"comment:是否包含付费剧集"`
    TotalEpisode int        `gorm:"comment:总集数"`
    Episodes     []Episode  `gorm:"foreignKey:DramaID"` // 关联剧集
}

// Episode 剧集表：管理单集视频及权限属性
type Episode struct {
    ID          uint   `gorm:"primaryKey"`
    DramaID     uint   `gorm:"index"`
    EpisodeNum  int    `gorm:"comment:第几集"`
    VideoURL    string `gorm:"type:varchar(512)"`
    UnlockType  int    `gorm:"type:tinyint;comment:0-免费 1-VIP免费 2-代币解锁 3-广告解锁"`
    Price       int    `gorm:"comment:解锁需要消耗的代币数量"`
}

// 记录播放进度接口逻辑
func ReportPlayProgress(ctx context.Context, userID uint, episodeID uint, progress int) error {
    redisKey := fmt.Sprintf("play_progress:user:%d:ep:%d", userID, episodeID)
    
    // 写入 Redis，设置过期时间（如 30 天）
    err := redisClient.Set(ctx, redisKey, progress, 30*24*time.Hour).Err()
    if err != nil {
        return err
    }
    
    // 同时可以利用 Redis HyperLogLog 统计该剧集的真实 UV
    uvKey := fmt.Sprintf("ep_uv:%d", episodeID)
    redisClient.PFAdd(ctx, uvKey, userID)
    
    return nil
}

// UnlockEpisode 使用代币解锁剧集的核心逻辑
func UnlockEpisode(db *gorm.DB, userID, episodeID uint, price int) error {
    return db.Transaction(func(tx *gorm.DB) error {
        // 1. 查询用户余额并加行锁 (悲观锁避免并发扣款超卖)
        var wallet UserWallet
        if err := tx.Clauses(clause.Locking{Strength: "UPDATE"}).
            Where("user_id = ?", userID).First(&wallet).Error; err != nil {
            return err
        }
        
        if wallet.Balance < price {
            return errors.New("insufficient balance")
        }
        
        // 2. 扣减余额
        if err := tx.Model(&wallet).Update("balance", gorm.Expr("balance - ?", price)).Error; err != nil {
            return err
        }
        
        // 3. 记录代币流水明细
        flow := AssetFlow{UserID: userID, Amount: -price, Type: "unlock_episode", TargetID: episodeID}
        if err := tx.Create(&flow).Error; err != nil {
            return err
        }
        
        // 4. 生成剧集解锁记录，赋权
        unlockRecord := UnlockRecord{UserID: userID, EpisodeID: episodeID}
        if err := tx.Create(&unlockRecord).Error; err != nil {
            return err
        }
        
        // 提交事务
        return nil
    })
}