package storage

import (
	"sync"
	"testing"

	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
	"github.com/seaweedfs/seaweedfs/weed/storage/super_block"
)

func reportingStore(t *testing.T, vids ...needle.VolumeId) *Store {
	t.Helper()
	store := newTestStore(t, 1)
	for _, vid := range vids {
		mountTestVolume(t, store.Locations[0], vid, "")
	}
	return store
}

// Until the master says it compares digests it may be one that reads a partial
// list as the whole truth, so it keeps getting the whole list.
func TestHeartbeatSendsFullListUntilTheMasterAccepts(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()

	for i := 0; i < 3; i++ {
		heartbeat := store.CollectHeartbeat()
		if len(heartbeat.Volumes) != 2 {
			t.Fatalf("heartbeat %d carried %d volumes, want the full list of 2", i, len(heartbeat.Volumes))
		}
		if len(heartbeat.ChangedVolumes) != 0 {
			t.Fatalf("heartbeat %d sent changes to a master that never accepted them", i)
		}
	}
}

// The one that would be catastrophic: a heartbeat with nothing to report must
// not look like a server that has lost every volume.
func TestQuietHeartbeatDoesNotLookLikeAnEmptyServer(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.Volumes) != 0 || len(heartbeat.ChangedVolumes) != 0 {
		t.Fatalf("expected nothing to report, got %d volumes and %d changes",
			len(heartbeat.Volumes), len(heartbeat.ChangedVolumes))
	}
	if heartbeat.HasNoVolumes {
		t.Error("a heartbeat with nothing to report claimed the server holds no volumes")
	}
}

// The digest covers everything held, not just what was sent, or a master that
// applied the changes could never confirm it is current.
func TestQuietHeartbeatStillDigestsEverythingHeld(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	full := store.CollectHeartbeat()
	store.AcceptVolumeChanges()

	quiet := store.CollectHeartbeat()
	if quiet.GetVolumeDigest() != full.GetVolumeDigest() {
		t.Errorf("digest changed with nothing to report: %d then %d",
			full.GetVolumeDigest(), quiet.GetVolumeDigest())
	}
}

func TestHeartbeatReportsOnlyWhatChanged(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	mountTestVolume(t, store.Locations[0], 3, "")
	heartbeat := store.CollectHeartbeat()

	if len(heartbeat.Volumes) != 0 {
		t.Errorf("a changed-only heartbeat carried a full list of %d", len(heartbeat.Volumes))
	}
	if len(heartbeat.ChangedVolumes) != 1 || heartbeat.ChangedVolumes[0].Id != 3 {
		t.Errorf("expected only the new volume, got %v", heartbeat.ChangedVolumes)
	}
}

func TestHeartbeatReturnsToTheFullListOnRequest(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	store.RequestFullVolumeList()
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.Volumes) != 2 {
		t.Errorf("after a resend request the heartbeat carried %d volumes, want 2", len(heartbeat.Volumes))
	}
	if len(heartbeat.ChangedVolumes) != 0 {
		t.Error("a resend should carry the list, not changes")
	}

	if next := store.CollectHeartbeat(); len(next.Volumes) != 0 {
		t.Errorf("the resend repeated instead of returning to changes: %d volumes", len(next.Volumes))
	}
}

// A reconnect may reach a master that knows nothing about this server.
func TestReconnectingSendsTheFullListAgain(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	store.ResetVolumeReporting()
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.Volumes) != 2 {
		t.Errorf("after reconnecting the heartbeat carried %d volumes, want the full list of 2", len(heartbeat.Volumes))
	}
}

// A volume that goes and comes back has to be reported again, so forgetting it
// while it is away is what makes that work.
func TestRemountedVolumeIsReportedAgain(t *testing.T) {
	store := reportingStore(t, 1)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	store.Locations[0].UnloadVolume(needle.VolumeId(1))
	store.CollectHeartbeat()

	mountTestVolume(t, store.Locations[0], 1, "")
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.ChangedVolumes) != 1 {
		t.Errorf("a remounted volume was not reported: %v", heartbeat.ChangedVolumes)
	}
}

// A request that lands while a heartbeat is being built asked about a later
// state than that heartbeat carries, so it must survive being committed over.
func TestFullListRequestDuringCollectionSurvives(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	full, generation, pass := store.volumeReport.begin()
	if full {
		t.Fatal("expected to be past the first full list")
	}
	store.RequestFullVolumeList()
	store.volumeReport.commit(pass, generation, full)

	if heartbeat := store.CollectHeartbeat(); len(heartbeat.Volumes) != 2 {
		t.Errorf("a resend request made during collection was lost: %d volumes sent", len(heartbeat.Volumes))
	}
}

// A delta says nothing through silence, so a volume that disappears must be
// named or the master keeps counting it until a digest mismatch buys a full
// list. This is what keeps a collection delete from leaving phantom volumes
// in the master's free-slot accounting.
func TestDepartedVolumeIsNamedInTheDelta(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	store.Locations[0].UnloadVolume(needle.VolumeId(2))
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.DeletedVolumes) != 1 || heartbeat.DeletedVolumes[0].Id != 2 {
		t.Fatalf("expected volume 2 to be named as departed, got %v", heartbeat.DeletedVolumes)
	}

	// Named once: the next quiet heartbeat has nothing left to say about it.
	if next := store.CollectHeartbeat(); len(next.DeletedVolumes) != 0 {
		t.Errorf("a departure was reported twice: %v", next.DeletedVolumes)
	}
}

// A full list is already the whole truth; naming departures beside it would
// tell the master to remove what the list already excludes.
func TestFullListCarriesNoDepartures(t *testing.T) {
	store := reportingStore(t, 1, 2)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	store.Locations[0].UnloadVolume(needle.VolumeId(2))
	store.RequestFullVolumeList()
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.Volumes) != 1 {
		t.Fatalf("full list carried %d volumes, want 1", len(heartbeat.Volumes))
	}
	if len(heartbeat.DeletedVolumes) != 0 {
		t.Errorf("a full list named departures: %v", heartbeat.DeletedVolumes)
	}
}

// A volume that moved disks is still held; naming it as departed would have
// the master unregister a volume the same heartbeat re-adds.
func TestMovedVolumeIsNotADeparture(t *testing.T) {
	store := newTestStore(t, 2)
	mountTestVolume(t, store.Locations[0], 1, "")
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	store.Locations[0].UnloadVolume(needle.VolumeId(1))
	// mountTestVolume leaves diskId at zero; the real mount path stamps the
	// destination disk, which is what makes the copy a different report key.
	moved, err := NewVolume(store.Locations[1].Directory, store.Locations[1].IdxDirectory, "", 1,
		NeedleMapInMemory, &super_block.ReplicaPlacement{}, &needle.TTL{}, 0, needle.GetCurrentVersion(), 0, 0)
	if err != nil {
		t.Fatal(err)
	}
	moved.diskId = 1
	store.Locations[1].SetVolume(needle.VolumeId(1), moved)
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.DeletedVolumes) != 0 {
		t.Errorf("a moved volume was named as departed: %v", heartbeat.DeletedVolumes)
	}
	if len(heartbeat.ChangedVolumes) != 1 || heartbeat.ChangedVolumes[0].Id != 1 {
		t.Errorf("the moved volume was not reported as changed: %v", heartbeat.ChangedVolumes)
	}
}

// The entry held for a volume is updated in place rather than rebuilt, so a
// change to what would name it as departed has to reach the entry too.
func TestDepartureNamesTheVolumeAsItIsNow(t *testing.T) {
	store := reportingStore(t, 1)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	v, _ := store.Locations[0].FindVolume(needle.VolumeId(1))
	v.SuperBlock.ReplicaPlacement = &super_block.ReplicaPlacement{SameRackCount: 1}
	store.CollectHeartbeat()

	store.Locations[0].UnloadVolume(needle.VolumeId(1))
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.DeletedVolumes) != 1 {
		t.Fatalf("expected volume 1 to be named as departed, got %v", heartbeat.DeletedVolumes)
	}
	if got := heartbeat.DeletedVolumes[0].ReplicaPlacement; got != uint32(v.ReplicaPlacement.Byte()) {
		t.Errorf("departure named replica placement %d, want %d", got, v.ReplicaPlacement.Byte())
	}
}

// The ticker sends one heartbeat while the response goroutine sends another, so
// two scans can overlap. Each marks the report state in place, so an
// unserialized pair would forget what the other marked and tell the master
// every volume it holds had departed.
func TestOverlappingHeartbeatsNameNoDepartures(t *testing.T) {
	store := reportingStore(t, 1, 2, 3, 4)
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	store.CollectHeartbeat()

	var wg sync.WaitGroup
	departed := make([]int, 8)
	for i := range departed {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			departed[i] = len(store.CollectHeartbeat().DeletedVolumes)
		}(i)
	}
	wg.Wait()

	for i, count := range departed {
		if count != 0 {
			t.Fatalf("overlapping heartbeat %d named %d volumes as departed while all were held", i, count)
		}
	}
}

// The departure message is built from what the entry held, not kept ready as a
// message per volume, so everything the master matches on has to survive the
// round trip through the entry.
func TestDepartureCarriesTheVolumeIdentity(t *testing.T) {
	store := newTestStore(t, 1)
	v := mountTestVolume(t, store.Locations[0], 7, "pictures")
	v.SuperBlock.ReplicaPlacement = &super_block.ReplicaPlacement{SameRackCount: 1}
	v.SuperBlock.Ttl, _ = needle.ReadTTL("5m")
	v.diskId = 3
	store.ResetVolumeReporting()
	store.AcceptVolumeChanges()
	reported := store.CollectHeartbeat().Volumes[0]

	store.Locations[0].UnloadVolume(needle.VolumeId(7))
	heartbeat := store.CollectHeartbeat()
	if len(heartbeat.DeletedVolumes) != 1 {
		t.Fatalf("expected volume 7 to be named as departed, got %v", heartbeat.DeletedVolumes)
	}
	departed := heartbeat.DeletedVolumes[0]
	if departed.Id != reported.Id || departed.DiskId != reported.DiskId ||
		departed.Collection != reported.Collection || departed.DiskType != reported.DiskType ||
		departed.ReplicaPlacement != reported.ReplicaPlacement ||
		departed.Version != reported.Version || departed.Ttl != reported.Ttl {
		t.Errorf("departure named %v, want it to match the volume as reported %v", departed, reported)
	}
}