Init

NostrStreamer/Services/StreamManager.cs

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+using Microsoft.EntityFrameworkCore;
+using Nostr.Client.Client;
+using Nostr.Client.Keys;
+using Nostr.Client.Messages;
+using Nostr.Client.Requests;
+using NostrStreamer.Database;
+
+namespace NostrStreamer.Services;
+
+public class StreamManager
+{
+    private readonly ILogger<StreamManager> _logger;
+    private readonly StreamerContext _db;
+    private readonly Config _config;
+    private readonly INostrClient _nostr;
+
+    public StreamManager(ILogger<StreamManager> logger, StreamerContext db, Config config, INostrClient nostr)
+    {
+        _logger = logger;
+        _db = db;
+        _config = config;
+        _nostr = nostr;
+    }
+
+    public async Task StreamStarted(string streamKey)
+    {
+        var user = await GetUserFromStreamKey(streamKey);
+        if (user == default) throw new Exception("No stream key found");
+
+        _logger.LogInformation("Stream started for: {pubkey}", user.PubKey);
+
+        if (user.Balance <= 0)
+        {
+            throw new Exception("User balance empty");
+        }
+        var ev = CreateStreamEvent(user, "live");
+        _nostr.Send(new NostrEventRequest(ev));
+    }
+
+    public async Task StreamStopped(string streamKey)
+    {
+        var user = await GetUserFromStreamKey(streamKey);
+        if (user == default) throw new Exception("No stream key found");
+
+        _logger.LogInformation("Stream stopped for: {pubkey}", user.PubKey);
+
+        var ev = CreateStreamEvent(user, "ended");
+        _nostr.Send(new NostrEventRequest(ev));
+    }
+
+    public async Task ConsumeQuota(string streamKey, double duration)
+    {
+        var user = await GetUserFromStreamKey(streamKey);
+        if (user == default) throw new Exception("No stream key found");
+
+        const double rate = 21.0d;
+        var cost = Math.Round(duration / 60d * rate);
+        await _db.Users
+            .Where(a => a.PubKey == user.PubKey)
+            .ExecuteUpdateAsync(o => o.SetProperty(v => v.Balance, v => v.Balance - cost));
+
+        _logger.LogInformation("Stream consumed {n} seconds for {pubkey} costing {cost} sats", duration, user.PubKey, cost);
+        if (user.Balance <= 0)
+        {
+            throw new Exception("User balance empty");
+        }
+    }
+
+    private NostrEvent CreateStreamEvent(User user, string state)
+    {
+        var tags = new List<NostrEventTag>()
+        {
+            new("d", user.PubKey),
+            new("title", user.Title ?? ""),
+            new("summary", user.Summary ?? ""),
+            new("streaming", GetStreamUrl(user)),
+            new("image", user.Image ?? ""),
+            new("status", state),
+            new("p", user.PubKey, "", "host")
+        };
+
+        foreach (var tag in user.Tags?.Split(",") ?? Array.Empty<string>())
+        {
+            tags.Add(new("t", tag.Trim()));
+        }
+
+        var ev = new NostrEvent
+        {
+            Kind = (NostrKind)30_311,
+            Content = "",
+            CreatedAt = DateTime.Now,
+            Tags = new NostrEventTags(tags)
+        };
+
+        return ev.Sign(NostrPrivateKey.FromBech32(_config.PrivateKey));
+    }
+
+    private string GetStreamUrl(User u)
+    {
+        var ub = new UriBuilder(_config.SrsPublicHost)
+        {
+            Path = $"/{_config.App}/${u.StreamKey}.m3u8"
+        };
+
+        return ub.Uri.ToString();
+    }
+    
+    private async Task<User?> GetUserFromStreamKey(string streamKey)
+    {
+        return await _db.Users.SingleOrDefaultAsync(a => a.StreamKey == streamKey);
+    }
+}