feat(server): implement sealed share lifecycle

Signed-off-by: JustMe <mr.toing@outlook.com>

server/src/WebDrop.Core/Abstractions.cs

@@ -0,0 +1,128 @@
+namespace WebDrop.Core;
+
+public interface IClock
+{
+    long NowMs { get; }
+}
+
+public sealed class SystemClock : IClock
+{
+    public long NowMs => DateTimeOffset.UtcNow.ToUnixTimeMilliseconds();
+}
+
+/// <summary>大帧的字节存储。键由服务生成,实现不得解析。</summary>
+public interface IBlobStore
+{
+    ValueTask PutAsync(string key, ReadOnlyMemory<byte> data, CancellationToken ct = default);
+    ValueTask<byte[]?> ReadAsync(string key, CancellationToken ct = default);
+    void Delete(string key);
+    void DeletePrefix(string prefix);
+    IEnumerable<(string Key, DateTimeOffset LastWrite)> Enumerate();
+}
+
+/// <summary>
+/// 创建频道前的人机/滥用校验(Cap 的 PoW 验证码)。验证码本身不属于本项目:
+/// 校验失败抛 CaptchaRequired,验证服务不可用抛 CaptchaUnavailable(两者对用户的含义不同)。
+/// </summary>
+public interface ICaptchaVerifier
+{
+    bool Enabled { get; }
+    Task VerifyAsync(string? token, CancellationToken ct);
+}
+
+/// <summary>不启用验证码(开发和小型自托管)。</summary>
+public sealed class NullCaptchaVerifier : ICaptchaVerifier
+{
+    public bool Enabled => false;
+    public Task VerifyAsync(string? token, CancellationToken ct) => Task.CompletedTask;
+}
+
+/// <summary>服务提交后发出的通知,传输层据此唤醒订阅者。</summary>
+public interface IChannelEvents
+{
+    void Advanced(Id16 channelId, long seq);
+    void SettingsChanged(Id16 channelId);
+    void SeatsChanged(Id16 channelId);
+    void ChannelDeleted(Id16 channelId);
+}
+
+public sealed class NullChannelEvents : IChannelEvents
+{
+    public void Advanced(Id16 channelId, long seq) { }
+    public void SettingsChanged(Id16 channelId) { }
+    public void SeatsChanged(Id16 channelId) { }
+    public void ChannelDeleted(Id16 channelId) { }
+}
+
+/// <summary>频道和分享资源共用的读写事务入口。Write 串行执行,抛出异常即回滚。</summary>
+public interface IResourceStore
+{
+    T Read<T>(Func<IResourceTx, T> action);
+    T Write<T>(Func<IResourceTx, T> action);
+}
+
+/// <summary>单个数据库事务内的频道、分享与帧操作。</summary>
+public interface IResourceTx
+{
+    // 便捷分享
+    Share? GetShare(Id16 id);
+    void InsertShare(Share share);
+    void UpdateShare(Share share);
+    IReadOnlyList<Id16> ListExpiredShares(long now, int limit);
+    bool HasResourceId(Id16 id);
+    int CountShareVisitors(Id16 id);
+    bool HasShareVisitor(Id16 id, ReadOnlySpan<byte> endpointHash);
+    void InsertShareVisitor(Id16 id, ReadOnlySpan<byte> endpointHash, long joinedAt);
+    void DeleteShareRows(Id16 id);
+    IReadOnlyList<ShareItem> ListShareItems(Id16 id);
+    int CountShareItems(Id16 id);
+    void AddShareBytes(Id16 id, long delta);
+    IReadOnlyList<ShareItem> ListExpiredShareItems(long now, int limit);
+    ShareItem? GetShareItem(Id16 shareId, Id16 itemId);
+    void InsertShareItem(ShareItem item);
+    void UpdateShareItem(ShareItem item);
+    void DeleteShareItemRows(Id16 shareId, Id16 itemId);
+    ShareFrame? GetShareFrame(Id16 shareId, Id16 itemId, uint index);
+    void InsertShareFrame(ShareFrame frame);
+    IReadOnlyList<ShareFrame> ListShareFrames(Id16 shareId, Id16 itemId, uint fromIndex, int limit);
+
+    // 频道
+    Channel? GetChannel(Id16 id);
+    void InsertChannel(Channel channel);
+    void UpdateChannel(Id16 id, ChannelSettings settings, long expiresAt);
+    void TouchChannel(Id16 id, long expiresAt);
+    void AddChannelBytes(Id16 id, long delta);
+    void SetCompactedThrough(Id16 id, long seq);
+    long NextSeq(Id16 id);
+    void DeleteChannelRows(Id16 id);
+    IReadOnlyList<Id16> ListExpiredChannels(long now, int limit);
+
+    // 席位
+    Seat? GetSeat(Id16 channelId, ReadOnlySpan<byte> endpointHash);
+    int CountSeats(Id16 channelId);
+    void InsertSeat(Id16 channelId, Seat seat);
+    bool DeleteSeat(Id16 channelId, ReadOnlySpan<byte> endpointHash);
+    void SetSeatLabel(Id16 channelId, ReadOnlySpan<byte> endpointHash, byte[] label);
+    IReadOnlyList<Seat> ListSeats(Id16 channelId);
+
+    // 条目
+    Item? GetItem(Id16 channelId, Id16 itemId);
+    void InsertItem(Item item);
+    void UpdateItem(Item item);
+    void DeleteItemRows(Id16 channelId, Id16 itemId);
+    int CountItems(Id16 channelId);
+    IReadOnlyList<Item> ListOldestItems(Id16 channelId, int limit);
+    Item? FindSnapshotItem(Id16 channelId, Id16 excludeItemId);
+    IReadOnlyList<Item> ListExpiredItems(long now, int limit);
+
+    // 帧
+    StoredFrame? GetFrame(Id16 channelId, Id16 itemId, uint index);
+    void InsertFrame(StoredFrame frame);
+    IReadOnlyList<StoredFrame> ListFrames(Id16 channelId, Id16 itemId, uint fromIndex, int limit);
+    bool BlobKeyExists(string blobKey);
+
+    // 日志
+    void InsertLog(Id16 channelId, LogEntry entry);
+    IReadOnlyList<LogEntry> ReadLog(Id16 channelId, long fromSeq, int limit);
+    long PruneTombstones(Id16 channelId, long olderThanMs);
+}