105 lines
3.5 KiB
C#
105 lines
3.5 KiB
C#
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using TeamsISO.Engine.Domain;
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namespace TeamsISO.Engine.Discovery;
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/// <summary>
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/// Maintains the operator-facing participant list, applying the rename heuristic
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/// from the v1 spec: if a participant source disappears and another participant
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/// source with the same MachineName appears within <see cref="_renameWindow"/>,
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/// the existing <see cref="Participant.Id"/> transfers to the new source.
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/// </summary>
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public sealed class ParticipantTracker
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{
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private readonly TimeSpan _renameWindow;
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private readonly Func<DateTimeOffset> _now;
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private readonly List<MutableParticipant> _participants = new();
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private readonly List<RecentlyRemoved> _recentlyRemoved = new();
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public ParticipantTracker(TimeSpan renameWindow, Func<DateTimeOffset> now)
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{
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_renameWindow = renameWindow;
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_now = now;
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}
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public IReadOnlyList<Participant> Participants =>
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_participants.Select(m => m.ToRecord()).ToList();
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public void Apply(DiscoveryEvent ev)
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{
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switch (ev)
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{
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case DiscoveryEvent.Added a when a.Source.Kind == NdiSourceKind.Participant:
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HandleAdded(a.Source);
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break;
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case DiscoveryEvent.Removed r when r.Source.Kind == NdiSourceKind.Participant:
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HandleRemoved(r.Source);
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break;
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}
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}
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private void HandleAdded(NdiSource source)
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{
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var now = _now();
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PruneRecentlyRemoved(now);
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var match = _recentlyRemoved.FirstOrDefault(rr => rr.MachineName == source.MachineName);
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if (match is not null)
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{
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var existing = _participants.First(p => p.Id == match.Id);
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existing.DisplayName = source.DisplayName!;
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existing.CurrentSource = source;
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existing.LastSeen = now;
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_recentlyRemoved.Remove(match);
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return;
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}
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_participants.Add(new MutableParticipant(
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Id: Guid.NewGuid(),
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DisplayName: source.DisplayName!,
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CurrentSource: source,
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FirstSeen: now,
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LastSeen: now));
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}
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private void HandleRemoved(NdiSource source)
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{
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var now = _now();
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var existing = _participants.FirstOrDefault(p =>
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p.CurrentSource is not null && p.CurrentSource.FullName == source.FullName);
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if (existing is null)
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return;
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existing.CurrentSource = null;
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_recentlyRemoved.Add(new RecentlyRemoved(existing.Id, source.MachineName, now));
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}
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private void PruneRecentlyRemoved(DateTimeOffset now)
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{
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_recentlyRemoved.RemoveAll(rr => now - rr.RemovedAt > _renameWindow);
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}
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private sealed class MutableParticipant
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{
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public Guid Id { get; init; }
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public string DisplayName { get; set; }
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public NdiSource? CurrentSource { get; set; }
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public DateTimeOffset FirstSeen { get; init; }
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public DateTimeOffset LastSeen { get; set; }
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public MutableParticipant(Guid Id, string DisplayName, NdiSource? CurrentSource,
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DateTimeOffset FirstSeen, DateTimeOffset LastSeen)
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{
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this.Id = Id;
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this.DisplayName = DisplayName;
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this.CurrentSource = CurrentSource;
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this.FirstSeen = FirstSeen;
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this.LastSeen = LastSeen;
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}
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public Participant ToRecord() =>
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new(Id, DisplayName, CurrentSource, FirstSeen, LastSeen);
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}
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private sealed record RecentlyRemoved(Guid Id, string MachineName, DateTimeOffset RemovedAt);
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}
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