/// <summary>
/// 撤销一个订阅者已有的订阅（如果没有订阅，不会进行任何操作）
/// </summary>
/// <param name="subscriberId">订阅者 ID</param>
/// <param name="targetId">目标 ID</param>
/// <param name="targetType">目标类型</param>
/// <exception cref="ArgumentNullException">有参数为 null</exception>
public async Task RemoveAsync([NotNull] string subscriberId, [NotNull] string targetId,
SubscriptionTargetType targetType)
{
if (subscriberId == null)
{
throw new ArgumentNullException(nameof(subscriberId));
}
if (targetId == null)
{
throw new ArgumentNullException(nameof(targetId));
}
if (subscriberId == targetId || !await IsSubscribedAsync(subscriberId, targetId, targetType))
{
return;
}
var subscriptions = await _dbContext.Subscriptions.Where(s => s.SubscriberId == subscriberId &&
s.TargetId == targetId &&
s.TargetType == targetType)
.ToListAsync();
_dbContext.Subscriptions.RemoveRange(subscriptions);
await _dbContext.SaveChangesAsync();
var redisDb = _redis.GetDatabase();
var cacheKey = UserSubscribedTargetsCacheKey(subscriberId);
foreach (var subscription in subscriptions)
{
await redisDb.SetRemoveAsync(cacheKey,
UserSubscribedTargetCacheValue(subscription.TargetId, subscription.TargetType));
}
await IncreaseSubscriberCountAsync(targetId, targetType, -subscriptions.Count);
}
public async Task <IHttpActionResult> DeleteOne(string targetId, SubscriptionTargetType targetType)
{
var subscriberId = User.Identity.GetUserId();
await _cachedData.Subscriptions.RemoveAsync(subscriberId, targetId, targetType);
return(Ok());
}
/// <summary>
/// 添加一个新订阅（如果已经订阅，不会进行任何操作）
/// </summary>
/// <param name="subscriberId">订阅者 ID</param>
/// <param name="targetId">目标 ID</param>
/// <param name="targetType">目标类型</param>
/// <returns>订阅成功返回 <c>true</c></returns>
/// <exception cref="ArgumentNullException">有参数为 null</exception>
public async Task <bool> AddAsync([NotNull] string subscriberId, [NotNull] string targetId,
SubscriptionTargetType targetType)
{
if (subscriberId == null)
{
throw new ArgumentNullException(nameof(subscriberId));
}
if (targetId == null)
{
throw new ArgumentNullException(nameof(targetId));
}
if (subscriberId == targetId || await IsSubscribedAsync(subscriberId, targetId, targetType))
{
return(false);
}
_dbContext.Subscriptions.Add(new Subscription
{
SubscriberId = subscriberId,
TargetId = targetId,
TargetType = targetType
});
await _dbContext.SaveChangesAsync();
var redisDb = _redis.GetDatabase();
await redisDb.SetAddAsync(UserSubscribedTargetsCacheKey(subscriberId),
UserSubscribedTargetCacheValue(targetId, targetType));
await IncreaseSubscriberCountAsync(targetId, targetType, 1);
return(true);
}
/// <summary>
/// 判断指定用户是否订阅过指定目标
/// </summary>
/// <param name="userId">用户 ID</param>
/// <param name="targetId">目标 ID</param>
/// <param name="targetType">目标类型</param>
/// <returns>如果用户订阅过，返回 <c>true</c></returns>
public async Task <bool> IsSubscribedAsync(string userId, string targetId, SubscriptionTargetType targetType)
{
if (userId == null || targetId == null)
{
return(false);
}
var cacheKey = await InitUserSubscribedTargetsAsync(userId);
return(await _redis.GetDatabase()
.SetContainsAsync(cacheKey, UserSubscribedTargetCacheValue(targetId, targetType)));
}
private async Task IncreaseSubscriberCountAsync([NotNull] string targetId, SubscriptionTargetType targetType,
long value)
{
var cacheKey = TargetSubscriberCountCacheKey(targetId, targetType);
var redisDb = _redis.GetDatabase();
if (await redisDb.KeyExistsAsync(cacheKey))
{
if (value >= 0)
{
await redisDb.StringIncrementAsync(cacheKey, value);
}
else
{
await redisDb.StringDecrementAsync(cacheKey, -value);
}
}
}
/// <summary>
/// 获取指定目标的订阅者数量
/// </summary>
/// <param name="targetId">目标 ID</param>
/// <param name="targetType">目标类型</param>
/// <exception cref="ArgumentNullException"><paramref name="targetId"/> 为 null</exception>
/// <returns>目标的订阅者数量</returns>
public async Task <long> GetSubscriberCountAsync([NotNull] string targetId, SubscriptionTargetType targetType)
{
if (targetId == null)
{
throw new ArgumentNullException(nameof(targetId));
}
var cacheKey = TargetSubscriberCountCacheKey(targetId, targetType);
var redisDb = _redis.GetDatabase();
var cacheResult = await redisDb.StringGetAsync(cacheKey);
if (cacheResult.HasValue)
{
await redisDb.KeyExpireAsync(cacheKey, CachedDataProvider.DefaultTtl);
return((long)cacheResult);
}
var subscriberCount = await _dbContext.Subscriptions
.LongCountAsync(s => s.TargetId == targetId && s.TargetType == targetType);
await redisDb.StringSetAsync(cacheKey, subscriberCount, CachedDataProvider.DefaultTtl);
return(subscriberCount);
}
public async Task <IHttpActionResult> CreateOne(string targetId, SubscriptionTargetType targetType)
{
var subscriberId = User.Identity.GetUserId();
bool existed;
KeylolUser targetUser = null;
switch (targetType)
{
case SubscriptionTargetType.Point:
existed = await _dbContext.Points.AnyAsync(p => p.Id == targetId);
break;
case SubscriptionTargetType.User:
if (subscriberId.Equals(targetId, StringComparison.OrdinalIgnoreCase))
{
return(this.BadRequest(nameof(targetId), Errors.Invalid));
}
targetUser = await _userManager.FindByIdAsync(targetId);
existed = targetUser != null;
break;
case SubscriptionTargetType.Conference:
existed = await _dbContext.Conferences.AnyAsync(c => c.Id == targetId);
break;
default:
throw new ArgumentOutOfRangeException(nameof(targetType), targetType, null);
}
if (!existed)
{
return(this.BadRequest(nameof(targetId), Errors.NonExistent));
}
var succeed = await _cachedData.Subscriptions.AddAsync(subscriberId, targetId, targetType);
if (targetType == SubscriptionTargetType.User && succeed)
{
Debug.Assert(targetUser != null, "targetUser != null");
var subscriberCount =
(int)await _cachedData.Subscriptions.GetSubscriberCountAsync(targetId, targetType);
if (targetUser.NotifyOnSubscribed)
{
await _cachedData.Messages.AddAsync(new Message
{
Type = MessageType.NewSubscriber,
OperatorId = subscriberId,
ReceiverId = targetId,
Count = subscriberCount
});
}
if (targetUser.SteamNotifyOnSubscribed)
{
var subscriber = await _userManager.FindByIdAsync(subscriberId);
await _userManager.SendSteamChatMessageAsync(targetUser,
await _cachedData.Users.IsFriendAsync(subscriberId, targetId)
?$"用户 {subscriber.UserName} 成为了你的第 {subscriberCount} 位听众，并开始与你互相关注。换句话说，你们已经成为好友啦！"
: $"用户 {subscriber.UserName} 关注了你并成为你的第 {subscriberCount} 位听众，你们之间互相关注后会成为好友。");
}
}
return(Ok());
}
private static string TargetSubscriberCountCacheKey(string targetId, SubscriptionTargetType targetType) =>
$"subscriber-count:{targetType.ToString().ToCase(NameConventionCase.PascalCase, NameConventionCase.DashedCase)}:{targetId}";
private static string UserSubscribedTargetCacheValue(string targetId, SubscriptionTargetType targetType) =>
$"{targetType.ToString().ToCase(NameConventionCase.PascalCase, NameConventionCase.DashedCase)}:{targetId}";
