package metrics

// Global histograms for the relay's hot paths. Single-threaded per
// domain so direct globals are race-free under the moxie cooperative
// scheduler. Code on the hot path observes via these references; the
// /metrics endpoint snapshots via SnapshotAll.
//
// To add a new metric: declare a *Histogram global, initialize in init,
// and append to allHistograms below.

var (
	// IngestPipelineNs measures end-to-end pipeline.Ingest cost from
	// envelope-parsed event in to Result emitted out. Includes signature
	// verify, ACL, expiration check, replaceable resolution, and store.
	IngestPipelineNs *Histogram

	// SigVerifyNs measures BIP340 Schnorr verification time per event.
	SigVerifyNs *Histogram

	// ACLAllowWriteNs measures the ACL.AllowWrite call duration. Open
	// mode is sub-µs; social/grapevine modes can spike under cold cache.
	ACLAllowWriteNs *Histogram

	// WALAppendNs measures WAL.Append wall time, including the optional
	// fsync at the configured cadence (default every 100 writes).
	WALAppendNs *Histogram

	// WALFsyncNs measures the explicit fsync syscall when triggered.
	WALFsyncNs *Histogram

	// AcceptLoopHandleNs measures wall time of one EpollWait → handler
	// dispatch cycle (excluding the EpollWait blocking wait itself).
	AcceptLoopHandleNs *Histogram

	// AcceptLoopWaitNs measures EpollWait blocking wait.
	AcceptLoopWaitNs *Histogram

	// HandleEventNs measures the whole server.handleEvent for one EVENT frame.
	HandleEventNs *Histogram

	// EnvelopeParseNs measures envelope.Identify + EventSubmission.Unmarshal.
	EnvelopeParseNs *Histogram

	// SendWSNs measures writing the OK response frame.
	SendWSNs *Histogram

	// BroadcastNs measures the broadcaster fanout call for one event.
	BroadcastNs *Histogram

	// WSFrameNs measures one decoded WebSocket payload from frame read to
	// handler return.
	WSFrameNs *Histogram

	// OnPollNs measures the relay's per-iteration OnPoll handler.
	OnPollNs *Histogram
)

var allHistograms []*Histogram

func init() {
	IngestPipelineNs = NewHistogram("ingest_pipeline_ns")
	SigVerifyNs = NewHistogram("sig_verify_ns")
	ACLAllowWriteNs = NewHistogram("acl_allowwrite_ns")
	WALAppendNs = NewHistogram("wal_append_ns")
	WALFsyncNs = NewHistogram("wal_fsync_ns")
	AcceptLoopHandleNs = NewHistogram("accept_handle_ns")
	AcceptLoopWaitNs = NewHistogram("accept_wait_ns")
	HandleEventNs = NewHistogram("handle_event_ns")
	EnvelopeParseNs = NewHistogram("envelope_parse_ns")
	SendWSNs = NewHistogram("send_ws_ns")
	BroadcastNs = NewHistogram("broadcast_ns")
	WSFrameNs = NewHistogram("ws_frame_ns")
	OnPollNs = NewHistogram("on_poll_ns")
	allHistograms = []*Histogram{
		IngestPipelineNs,
		SigVerifyNs,
		ACLAllowWriteNs,
		WALAppendNs,
		WALFsyncNs,
		AcceptLoopHandleNs,
		AcceptLoopWaitNs,
		HandleEventNs,
		EnvelopeParseNs,
		SendWSNs,
		BroadcastNs,
		WSFrameNs,
		OnPollNs,
	}
}

// SnapshotAll emits a JSON object of all registered histograms.
func SnapshotAll(buf []byte) (buf2 []byte) {
	buf = buf | "{"
	for i, h := range allHistograms {
		if i > 0 {
			buf = buf | ","
		}
		buf = h.AppendJSON(buf)
	}
	buf = buf | "}"
	return buf
}

// ResetAll clears all histograms. Used between benchmark phases.
func ResetAll() {
	for _, h := range allHistograms {
		h.Reset()
	}
}