namespace AcDream.Core.Net.Transport;

/// <summary>
/// Unconditional reliable-transport counters. Increment sites are NOT
/// probe-gated — the counters are plain field writes and always current, so
/// a later probe (N5's <c>[net-tick]</c> extension) or a connected gate can
/// read them without having been armed in advance. Printing stays
/// probe-gated at the call sites that choose to surface them.
/// </summary>
internal sealed class TransportStats
{
    /// <summary>Datagrams re-emitted in response to a server NAK.</summary>
    public long ResendsSent;

    /// <summary>Inbound packets carrying <c>RequestRetransmit</c>.</summary>
    public long NakRequestsReceived;

    /// <summary>
    /// NAKed ids no longer (or never) in the sent-packet cache, dropped
    /// silently instead of answering retail's <c>RejectRetransmit</c>
    /// (divergence register TS-57 — ACE no-ops the reject, and the
    /// standalone unsequenced form would trip ACE's watermark hole).
    /// </summary>
    public long UncachedNakIds;

    /// <summary>Inbound <c>AckSequence</c> values folded into the watermark
    /// (explicit acks plus the NAK <c>ids[0]</c> implicit ack).</summary>
    public long AcksConsumed;

    /// <summary>N2: inbound duplicates of already-decoded packets, dropped
    /// at zero keystream cost (encrypted, at/below the watermark, no parked
    /// key — <c>ProcessNewSeqNum @ 0x00544690</c>).</summary>
    public long InboundDupsDropped;

    /// <summary>N2: inbound packets past the wrap-safe
    /// <c>watermark + 0x7FFF</c> horizon
    /// (<c>SeqIDSanityCheck @ 0x00543A20</c>).</summary>
    public long InboundSanityDrops;

    /// <summary>N2: inbound packets whose checksum failed verification
    /// after admission (a sequenced encrypted failure also re-parks its
    /// consumed key for the retransmission).</summary>
    public long ChecksumFailures;

    /// <summary>N2: inbound keystream words parked in the NAK set — one per
    /// gap-walked missing id (<c>ReceiverData::AddNakked @ 0x00549240</c>
    /// pre-draw) plus one per checksum-failure re-park.</summary>
    public long KeysParked;

    /// <summary>N3: cumulative <c>AckSequence</c> packets emitted by the
    /// 2.0 s sweep (<c>SharedNet::EnqueuePak @ 0x00543B10</c> — retail's
    /// only ack construction site; there is no per-packet ack).</summary>
    public long AcksSent;

    /// <summary>N4: <c>RequestRetransmit</c> packets emitted by the 0.6 s
    /// NAK branch (<c>SharedNet::EnqueueNaks @ 0x00543BD0</c> →
    /// <c>ReceiverData::GetNaks @ 0x005490C0</c>, ≤114 ids each).</summary>
    public long NaksSent;

    /// <summary>N4: mis-parked keystream words reclaimed from validated
    /// cleartext <c>RejectRetransmit</c> sequences (the AD-51 ACE
    /// adaptation; always zero against a retail server).</summary>
    public long RejectWordsReclaimed;

    /// <summary>Live sent-packet cache depth — the N5 watchdog value
    /// (<c>cache=N</c> in <c>[net-tick]</c>; the cache is unbounded like
    /// retail's, so depth is the health signal, not a cap).</summary>
    public int CacheDepth => CacheDepthSource?.Invoke() ?? 0;

    /// <summary>Wired by <see cref="ReliableTransport"/> to the store's
    /// <c>Count</c>.</summary>
    internal Func<int>? CacheDepthSource { get; set; }
}