package service

import (
	"context"
	"errors"
	"testing"
	"time"

	edgenode "iop/apps/edge/internal/node"
	"iop/packages/go/config"
)

// longSlotCount reads the group's long in-flight counter for a provider slot.
func longSlotCount(m *modelQueueManager, groupKey, nodeID, providerID string) int {
	m.mu.Lock()
	defer m.mu.Unlock()
	if providerID != "" {
		key := providerResourceKey{nodeID: nodeID, providerID: providerID}
		if res, ok := m.resources[key]; ok {
			return res.longInFlight
		}
		return 0
	}
	g, ok := m.groups[groupKey]
	if !ok {
		return -1
	}
	return g.longInflight[nodeID]
}

func inflightSlotCount(m *modelQueueManager, groupKey, nodeID, providerID string) int {
	m.mu.Lock()
	defer m.mu.Unlock()
	if providerID != "" {
		key := providerResourceKey{nodeID: nodeID, providerID: providerID}
		if res, ok := m.resources[key]; ok {
			return res.inFlight
		}
		return 0
	}
	g, ok := m.groups[groupKey]
	if !ok {
		return -1
	}
	return g.inflight[nodeID]
}

// TestModelQueueLongDispatchReservesBothCounters verifies S04: a long request
// occupies both the normal in-flight counter and the long in-flight counter, and
// every terminal reason (complete/error/cancelled) recovers both.
func TestModelQueueLongDispatchReservesBothCounters(t *testing.T) {
	for _, reason := range []string{"complete", "error", "cancelled"} {
		t.Run(reason, func(t *testing.T) {
			entry := &edgenode.NodeEntry{NodeID: "node-long"}
			cands := []candidateNode{{entry: entry, capacity: 3, providerID: "prov-long", longContextCapacity: 2}}
			m := newModelQueueManager(nil)

			sel, err := m.admit(context.Background(), "g-long", "", "", cands, groupPolicy{}, nil, true, false)
			if err != nil || sel == nil {
				t.Fatalf("long admit: %v", err)
			}
			if got := inflightSlotCount(m, "g-long", "node-long", "prov-long"); got != 1 {
				t.Errorf("normal in-flight after admit = %d, want 1", got)
			}
			if got := longSlotCount(m, "g-long", "node-long", "prov-long"); got != 1 {
				t.Errorf("long in-flight after admit = %d, want 1", got)
			}

			m.trackLease(sel.leaseID, "run-long-1")
			if got := m.longInFlightForProvider("node-long", "prov-long"); got != 1 {
				t.Errorf("longInFlightForProvider after track = %d, want 1", got)
			}

			m.releaseRun("run-long-1", reason)
			if got := inflightSlotCount(m, "g-long", "node-long", "prov-long"); got != 0 {
				t.Errorf("normal in-flight after %s = %d, want 0", reason, got)
			}
			if got := longSlotCount(m, "g-long", "node-long", "prov-long"); got != 0 {
				t.Errorf("long in-flight after %s = %d, want 0", reason, got)
			}
			if got := m.longInFlightForProvider("node-long", "prov-long"); got != 0 {
				t.Errorf("longInFlightForProvider after %s = %d, want 0", reason, got)
			}
		})
	}
}

// TestQueueSkipsLongHeadWhenNormalBehindCanDispatch verifies the queue-skip
// contract (S06 / queue-skip): when the head of the queue is a long request
// whose provider long slots are full, a normal request queued behind it is
// still dispatched on ordinary capacity, and the blocked long head stays queued.
func TestQueueSkipsLongHeadWhenNormalBehindCanDispatch(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-skip"}
	// Provider has normal capacity 2 and a single long slot.
	cands := []candidateNode{{entry: entry, capacity: 2, providerID: "prov-skip", longContextCapacity: 1}}
	m := newModelQueueManager(nil)

	m.mu.Lock()
	g := m.getOrCreateGroupLocked("g-skip", groupPolicy{})
	// One long request already in flight: the single long slot is full while one
	// of the two normal slots remains free.
	g.inflight["node-skip:prov-skip"] = 1
	g.longInflight["node-skip:prov-skip"] = 1

	longItem := &queueItem{
		candidates: cands,
		waitCh:     make(chan admitResult, 1),
		deadline:   time.Now().Add(2 * time.Second),
		long:       true,
	}
	normalItem := &queueItem{
		candidates: cands,
		waitCh:     make(chan admitResult, 1),
		deadline:   time.Now().Add(2 * time.Second),
	}
	// long head first, normal request queued behind it.
	g.queue = []*queueItem{longItem, normalItem}
	m.pumpAllLocked()
	m.mu.Unlock()

	// The normal request behind the blocked long head must be dispatched.
	select {
	case res := <-normalItem.waitCh:
		if res.err != nil {
			t.Fatalf("normal item expected dispatch, got error: %v", res.err)
		}
		if res.candidate == nil || res.candidate.providerID != "prov-skip" {
			t.Fatalf("normal item: unexpected candidate %v", res.candidate)
		}
	default:
		t.Fatal("normal request behind long head was not dispatched (head-of-line blocking)")
	}

	// The long head must remain queued because its long slot is still full.
	select {
	case <-longItem.waitCh:
		t.Fatal("long head should not dispatch while its long slot is full")
	default:
	}

	m.mu.Lock()
	if len(g.queue) != 1 || g.queue[0] != longItem {
		n := len(g.queue)
		m.mu.Unlock()
		t.Fatalf("expected only the long head to remain queued, got %d item(s)", n)
	}
	m.mu.Unlock()
}

// TestQueueSkipPreservesFIFOAmongDispatchableNormalItems verifies that the
// front-scan dispatch keeps FIFO order among equally-dispatchable items: with a
// single normal slot, the earlier queued item is dispatched first and the later
// one only after another slot frees.
func TestQueueSkipPreservesFIFOAmongDispatchableNormalItems(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-fifo2"}
	cands := []candidateNode{{entry: entry, capacity: 1, providerID: "prov-fifo2"}}
	m := newModelQueueManager(nil)

	m.mu.Lock()
	g := m.getOrCreateGroupLocked("g-fifo2", groupPolicy{})
	// Fill the single normal slot so both queued items must wait.
	g.inflight["node-fifo2:prov-fifo2"] = 1
	first := &queueItem{candidates: cands, waitCh: make(chan admitResult, 1), deadline: time.Now().Add(2 * time.Second)}
	second := &queueItem{candidates: cands, waitCh: make(chan admitResult, 1), deadline: time.Now().Add(2 * time.Second)}
	g.queue = []*queueItem{first, second}
	m.mu.Unlock()

	// Release one slot: only the earlier (first) item may dispatch.
	m.mu.Lock()
	m.releaseSlotLocked("g-fifo2", "node-fifo2", "prov-fifo2", false)
	m.mu.Unlock()

	select {
	case res := <-first.waitCh:
		if res.err != nil {
			t.Fatalf("first item dispatch error: %v", res.err)
		}
	default:
		t.Fatal("first (earliest) item was not dispatched first")
	}
	select {
	case <-second.waitCh:
		t.Fatal("second item should still wait (only one slot freed)")
	default:
	}

	// Release again → the second item dispatches.
	m.mu.Lock()
	m.releaseSlotLocked("g-fifo2", "node-fifo2", "prov-fifo2", false)
	m.mu.Unlock()
	select {
	case res := <-second.waitCh:
		if res.err != nil {
			t.Fatalf("second item dispatch error: %v", res.err)
		}
	default:
		t.Fatal("second item not dispatched after second slot release")
	}
}

// TestModelQueueNormalRequestDoesNotReserveLongSlot verifies a normal request
// occupies only the normal in-flight counter, never the long counter, even on a
// provider that declares long capacity.
func TestModelQueueNormalRequestDoesNotReserveLongSlot(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-n"}
	cands := []candidateNode{{entry: entry, capacity: 3, providerID: "prov-n", longContextCapacity: 2}}
	m := newModelQueueManager(nil)

	sel, err := m.admit(context.Background(), "g-n", "", "", cands, groupPolicy{}, nil, false, false) // long omitted → normal
	if err != nil || sel == nil {
		t.Fatalf("normal admit: %v", err)
	}
	if got := inflightSlotCount(m, "g-n", "node-n", "prov-n"); got != 1 {
		t.Errorf("normal in-flight = %d, want 1", got)
	}
	if got := longSlotCount(m, "g-n", "node-n", "prov-n"); got != 0 {
		t.Errorf("long in-flight for normal request = %d, want 0", got)
	}
}

// TestModelQueueLongSlotFullExcludesLongKeepsNormal verifies S05 and D06: a
// provider whose long slots are full is excluded from long candidates (the long
// request moves to another provider or queues), but the same provider remains a
// valid candidate for normal requests while its normal capacity has room.
func TestModelQueueLongSlotFullExcludesLongKeepsNormal(t *testing.T) {
	entryA := &edgenode.NodeEntry{NodeID: "node-a"}
	entryB := &edgenode.NodeEntry{NodeID: "node-b"}
	cands := []candidateNode{
		{entry: entryA, capacity: 3, priority: 0, providerID: "prov-a", longContextCapacity: 1},
		{entry: entryB, capacity: 3, priority: 1, providerID: "prov-b", longContextCapacity: 1},
	}
	m := newModelQueueManager(nil)

	// Long #1 → prov-a (priority 0 preferred), filling prov-a's single long slot.
	sel1, err := m.admit(context.Background(), "g-x", "", "", cands, groupPolicy{}, nil, true, false)
	if err != nil || sel1 == nil {
		t.Fatalf("long1 admit: %v", err)
	}
	if sel1.providerID != "prov-a" {
		t.Fatalf("long1 provider = %q, want prov-a", sel1.providerID)
	}

	// Long #2 must skip the long-full prov-a and land on prov-b.
	sel2, err := m.admit(context.Background(), "g-x", "", "", cands, groupPolicy{}, nil, true, false)
	if err != nil || sel2 == nil {
		t.Fatalf("long2 admit: %v", err)
	}
	if sel2.providerID != "prov-b" {
		t.Fatalf("long2 provider = %q, want prov-b (prov-a long slot full)", sel2.providerID)
	}

	// A normal request restricted to the long-full prov-a is still admitted,
	// because normal admission ignores long slot state (D06).
	normalCands := []candidateNode{cands[0]}
	selN, err := m.admit(context.Background(), "g-x", "", "", normalCands, groupPolicy{}, nil, false, false)
	if err != nil || selN == nil {
		t.Fatalf("normal admit on long-full provider: %v", err)
	}
	if selN.providerID != "prov-a" {
		t.Fatalf("normal provider = %q, want prov-a", selN.providerID)
	}

	// A further long request restricted to the long-full prov-a cannot be
	// admitted immediately; it queues and times out.
	longOnlyA := []candidateNode{cands[0]}
	_, err = m.admit(context.Background(), "g-x", "", "", longOnlyA, groupPolicy{maxQueue: 1, queueTimeout: 20 * time.Millisecond}, nil, true, false)
	if !errors.Is(err, errQueueTimeout) {
		t.Fatalf("long request on long-full provider: expected queue timeout, got %v", err)
	}
}

func TestModelQueueReasonLongContextCapacityFull(t *testing.T) {
	entryA := &edgenode.NodeEntry{NodeID: "node-a"}
	cands := []candidateNode{
		{entry: entryA, capacity: 3, priority: 0, providerID: "prov-a", longContextCapacity: 1},
	}
	m := newModelQueueManager(nil)

	// Long #1 → prov-a, filling prov-a's single long slot.
	_, _, err := m.admitWithReason(context.Background(), "g-x", "", "", cands, groupPolicy{}, nil, true, false)
	if err != nil {
		t.Fatalf("first admit: %v", err)
	}

	// Long #2 → prov-a. It should block because longContextCapacity is full.
	done := make(chan struct{})
	go func() {
		defer close(done)
		// The queue timeout has to outlast the observation window below: the
		// assertion can only read the item's reason while the item is queued.
		_, _, err := m.admitWithReason(context.Background(), "g-x", "", "", cands, groupPolicy{maxQueue: 1, queueTimeout: 500 * time.Millisecond}, nil, true, false)
		if !errors.Is(err, errQueueTimeout) {
			t.Errorf("expected timeout, got %v", err)
		}
	}()

	// Poll rather than sleeping a fixed slice: under load the goroutine can need
	// more than a few milliseconds to reach the queue.
	waitForQueueLen(t, m, "g-x", 1)

	m.mu.Lock()
	g, ok := m.groups["g-x"]
	if !ok || len(g.queue) != 1 {
		m.mu.Unlock()
		t.Fatalf("expected 1 queued item, got group ok=%t, len=%d", ok, len(g.queue))
	}
	reason := g.queue[0].reason
	m.mu.Unlock()

	if reason != "long_context_capacity_full" {
		t.Errorf("expected queue reason 'long_context_capacity_full', got %q", reason)
	}

	<-done
}

func TestModelQueueReasonCapacityFull(t *testing.T) {
	entryA := &edgenode.NodeEntry{NodeID: "node-a"}
	cands := []candidateNode{
		{entry: entryA, capacity: 1, priority: 0, providerID: "prov-a"},
	}
	m := newModelQueueManager(nil)

	// #1 → prov-a, filling capacity.
	_, _, err := m.admitWithReason(context.Background(), "g-y", "", "", cands, groupPolicy{}, nil, false, false)
	if err != nil {
		t.Fatalf("first admit: %v", err)
	}

	// #2 → prov-a. It should block because capacity is full.
	done := make(chan struct{})
	go func() {
		defer close(done)
		// As above: the item must stay queued long enough to be observed.
		_, _, err := m.admitWithReason(context.Background(), "g-y", "", "", cands, groupPolicy{maxQueue: 1, queueTimeout: 500 * time.Millisecond}, nil, false, false)
		if !errors.Is(err, errQueueTimeout) {
			t.Errorf("expected timeout, got %v", err)
		}
	}()

	waitForQueueLen(t, m, "g-y", 1)

	m.mu.Lock()
	g, ok := m.groups["g-y"]
	if !ok || len(g.queue) != 1 {
		m.mu.Unlock()
		t.Fatalf("expected 1 queued item")
	}
	reason := g.queue[0].reason
	m.mu.Unlock()

	if reason != "capacity_full" {
		t.Errorf("expected queue reason 'capacity_full', got %q", reason)
	}

	<-done
}

func TestProviderLongCapacitySharedAcrossOrnithModelAliases(t *testing.T) {
	const (
		nodeID     = "rtx5090-lemonade-node"
		providerID = "rtx5090-lemonade"
	)
	modelAliases := []string{"ornith:35b", "ornith-fast"}
	entry := &edgenode.NodeEntry{NodeID: nodeID}
	cands := []candidateNode{
		{entry: entry, capacity: 5, providerID: providerID, longContextCapacity: 1},
	}
	store := edgenode.NewNodeStore()
	store.Add(&edgenode.NodeRecord{
		ID: nodeID,
		Providers: []config.NodeProviderConf{
			{
				ID:                  providerID,
				Capacity:            5,
				LongContextCapacity: 1,
				Adapter:             "vllm",
			},
		},
	})
	m := newModelQueueManager(store)
	m.setStore(store)

	start := make(chan struct{})
	resCh := make(chan concurrentAdmitResult, 2)

	for i := 0; i < 2; i++ {
		go func(id int) {
			<-start
			ctx, cancel := context.WithTimeout(context.Background(), 50*time.Millisecond)
			defer cancel()
			groupKey := modelAliases[id]
			sel, err := m.admit(ctx, groupKey, "", "", cands, groupPolicy{maxQueue: 1, queueTimeout: 30 * time.Millisecond}, nil, true, false)
			resCh <- concurrentAdmitResult{candidate: sel, err: err}
		}(i)
	}

	close(start)

	var results []concurrentAdmitResult
	for i := 0; i < 2; i++ {
		results = append(results, <-resCh)
	}

	successCount := 0
	failCount := 0
	var successSel *candidateNode
	for _, res := range results {
		if res.err == nil {
			successCount++
			successSel = res.candidate
		} else {
			failCount++
		}
	}

	if successCount != 1 || failCount != 1 {
		t.Fatalf("expected exactly 1 success and 1 failure under concurrent long admission (capacity=1), got success=%d fail=%d", successCount, failCount)
	}

	// Verify long peak was 1
	if got := m.longInFlightForProvider(nodeID, providerID); got != 1 {
		t.Errorf("expected long peak to be 1, got %d", got)
	}

	// Release successful slot
	m.trackLease(successSel.leaseID, "run-shared-1")
	m.releaseRun("run-shared-1", "complete")

	// Verify long counts recovered to 0
	if got := m.longInFlightForProvider(nodeID, providerID); got != 0 {
		t.Errorf("expected long counts to recover to 0 after release, got %d", got)
	}
}

func TestProviderResourceLongReleaseAfterCapacityDisabled(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-ref-1"}
	cands := []candidateNode{{entry: entry, capacity: 1, providerID: "prov-ref-1", longContextCapacity: 1}}
	store := edgenode.NewNodeStore()
	rec := &edgenode.NodeRecord{
		ID: "node-ref-1",
		Providers: []config.NodeProviderConf{
			{ID: "prov-ref-1", Capacity: 1, LongContextCapacity: 1, Adapter: "vllm"},
		},
	}
	store.Add(rec)
	m := newModelQueueManager(store)
	m.setStore(store)

	sel, err := m.admit(context.Background(), "g-ref", "", "", cands, groupPolicy{}, nil, true, false)
	if err != nil || sel == nil {
		t.Fatalf("admit: %v", err)
	}

	if got := m.longInFlightForProvider("node-ref-1", "prov-ref-1"); got != 1 {
		t.Fatalf("expected longInFlight=1, got %d", got)
	}

	rec.Providers[0].Capacity = 0
	rec.Providers[0].LongContextCapacity = 0
	m.setStore(store)

	m.trackLease(sel.leaseID, "run-ref-1")
	m.releaseRun("run-ref-1", "complete")

	if got := m.longInFlightForProvider("node-ref-1", "prov-ref-1"); got != 0 {
		t.Errorf("longInFlight after capacity disabled release = %d, want 0", got)
	}
}

func TestProviderResourceLongReservationUsesEffectiveRefreshState(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-eff"}
	cands := []candidateNode{{entry: entry, capacity: 1, providerID: "prov-eff", longContextCapacity: 1}}
	store := edgenode.NewNodeStore()
	rec := &edgenode.NodeRecord{
		ID: "node-eff",
		Providers: []config.NodeProviderConf{
			{ID: "prov-eff", Capacity: 1, LongContextCapacity: 1, Adapter: "vllm"},
		},
	}
	store.Add(rec)
	m := newModelQueueManager(store)
	m.setStore(store)

	_, err := m.admit(context.Background(), "g-eff", "", "", cands, groupPolicy{}, nil, true, false)
	if err != nil {
		t.Fatalf("first admit: %v", err)
	}

	done := make(chan struct{})
	go func() {
		defer close(done)
		_, err := m.admit(context.Background(), "g-eff", "", "", cands, groupPolicy{maxQueue: 1}, nil, true, false)
		if err != nil {
			t.Errorf("queued admit failed: %v", err)
		}
	}()

	waitForQueueLen(t, m, "g-eff", 1)

	rec.Providers[0].LongContextCapacity = 0
	m.setStore(store)

	m.releaseSlotWithLong("g-eff", "node-eff", "prov-eff", true)

	<-done

	if got := m.longInFlightForProvider("node-eff", "prov-eff"); got != 0 {
		t.Errorf("expected longInFlight=0 for the dispatched queued run under disabled capacity, got %d", got)
	}
}

func TestProviderResourceOrphanRemovedAfterLastRelease(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-orph"}
	cands := []candidateNode{{entry: entry, capacity: 1, providerID: "prov-orph", longContextCapacity: 1}}
	store := edgenode.NewNodeStore()
	rec := &edgenode.NodeRecord{
		ID: "node-orph",
		Providers: []config.NodeProviderConf{
			{ID: "prov-orph", Capacity: 1, LongContextCapacity: 1, Adapter: "vllm"},
		},
	}
	store.Add(rec)
	m := newModelQueueManager(store)
	m.setStore(store)

	_, err := m.admit(context.Background(), "g-orph", "", "", cands, groupPolicy{}, nil, true, false)
	if err != nil {
		t.Fatalf("admit: %v", err)
	}

	key := providerResourceKey{nodeID: "node-orph", providerID: "prov-orph"}
	if res := m.resources[key]; res == nil || res.orphan {
		t.Fatal("expected active non-orphan resource")
	}

	rec.Providers = nil
	m.setStore(store)

	m.mu.Lock()
	res, ok := m.resources[key]
	m.mu.Unlock()
	if !ok || res == nil || !res.orphan {
		t.Fatalf("expected resource to be kept as orphan, ok=%t, res=%v", ok, res)
	}

	m.releaseSlotWithLong("g-orph", "node-orph", "prov-orph", true)

	m.mu.Lock()
	_, ok = m.resources[key]
	m.mu.Unlock()
	if ok {
		t.Fatal("expected orphan resource to be removed from map after last release")
	}
}

// TestGlobalPumpLongHeadDoesNotBlockNormalOtherGroup verifies that head-of-line
// avoidance holds across model groups, not only inside one queue: a long request
// that arrived first and is stuck on a full long slot must not hold up a normal
// request that arrived later in a different group and fits ordinary capacity.
func TestGlobalPumpLongHeadDoesNotBlockNormalOtherGroup(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-xg"}
	// Two normal slots, a single long slot.
	cands := []candidateNode{{entry: entry, capacity: 2, providerID: "prov-xg", longContextCapacity: 1}}
	m := newModelQueueManager(nil)

	// One long request in flight fills the only long slot; one normal slot is free.
	if _, err := m.admit(context.Background(), "g-xg-a", "", "", cands, groupPolicy{}, nil, true, false); err != nil {
		t.Fatalf("long admit: %v", err)
	}

	// Arrival order: the blocked long request first, the normal one behind it in
	// another group.
	longItem := queueItemForTest(cands, true)
	enqueueForTest(m, "g-xg-a", longItem, nil)
	normalItem := queueItemForTest(cands, false)
	enqueueForTest(m, "g-xg-b", normalItem, nil)

	m.mu.Lock()
	m.pumpAllLocked()
	m.mu.Unlock()

	select {
	case res := <-normalItem.waitCh:
		if res.err != nil {
			t.Fatalf("normal item in the other group expected dispatch, got error: %v", res.err)
		}
	default:
		t.Fatal("normal request in another group was blocked behind a long head (cross-group head-of-line blocking)")
	}
	select {
	case <-longItem.waitCh:
		t.Fatal("long head must stay queued while its long slot is full")
	default:
	}

	if got := pendingItemCount(m); got != 1 {
		t.Fatalf("expected only the long head to remain pending, got %d item(s)", got)
	}
}

// TestGlobalPumpNoLeakAfterMixedLongAndNormalDrain verifies that repeated mixed
// long/normal traffic across groups leaves every counter at zero: a scheduler
// that reserves in one place and releases in another is exactly where long-slot
// leaks hide.
func TestGlobalPumpNoLeakAfterMixedLongAndNormalDrain(t *testing.T) {
	entry := &edgenode.NodeEntry{NodeID: "node-drain"}
	cands := []candidateNode{{entry: entry, capacity: 2, providerID: "prov-drain", longContextCapacity: 1}}
	m := newModelQueueManager(nil)

	for round := 0; round < 20; round++ {
		long, err := m.admit(context.Background(), "g-drain-a", "", "", cands, groupPolicy{}, nil, true, false)
		if err != nil || long == nil {
			t.Fatalf("round %d long admit: %v", round, err)
		}
		normal, err := m.admit(context.Background(), "g-drain-b", "", "", cands, groupPolicy{}, nil, false, false)
		if err != nil || normal == nil {
			t.Fatalf("round %d normal admit: %v", round, err)
		}
		m.releaseLease(long.leaseID, "complete")
		m.releaseLease(normal.leaseID, "complete")
	}

	inFlight, longInFlight := providerResourceCounts(m, "node-drain", "prov-drain")
	if inFlight != 0 || longInFlight != 0 {
		t.Fatalf("expected zero counters after drain, got inflight=%d long=%d", inFlight, longInFlight)
	}
	if got := leaseCount(m); got != 0 {
		t.Fatalf("expected zero live leases after drain, got %d", got)
	}
	if got := pendingItemCount(m); got != 0 {
		t.Fatalf("expected zero pending items after drain, got %d", got)
	}
}