// setAppliedIndex persists a new applied index.
func setAppliedIndex(eng engine.Engine, raftID proto.RaftID, appliedIndex uint64) error {
	return engine.MVCCPut(eng, nil, /* stats */
		keys.RaftAppliedIndexKey(raftID),
		proto.ZeroTimestamp,
		proto.Value{Bytes: encoding.EncodeUint64(nil, appliedIndex)},
		nil /* txn */)
}

// setAppliedIndex persists a new applied index.
func setAppliedIndex(eng engine.Engine, rangeID roachpb.RangeID, appliedIndex uint64) error {
	return engine.MVCCPut(eng, nil, /* stats */
		keys.RaftAppliedIndexKey(rangeID),
		roachpb.ZeroTimestamp,
		roachpb.MakeValueFromBytes(encoding.EncodeUint64(nil, appliedIndex)),
		nil /* txn */)
}

func setAppliedIndex(
	ctx context.Context,
	eng engine.ReadWriter,
	ms *enginepb.MVCCStats,
	rangeID roachpb.RangeID,
	appliedIndex,
	leaseAppliedIndex uint64,
) error {
	var value roachpb.Value
	value.SetInt(int64(appliedIndex))

	if err := engine.MVCCPut(ctx, eng, ms,
		keys.RaftAppliedIndexKey(rangeID),
		hlc.ZeroTimestamp,
		value,
		nil /* txn */); err != nil {
		return err
	}
	value.SetInt(int64(leaseAppliedIndex))
	return engine.MVCCPut(ctx, eng, ms,
		keys.LeaseAppliedIndexKey(rangeID),
		hlc.ZeroTimestamp,
		value,
		nil /* txn */)
}

// loadAppliedIndex returns the Raft applied index and the lease applied index.
func loadAppliedIndex(
	ctx context.Context, reader engine.Reader, rangeID roachpb.RangeID,
) (uint64, uint64, error) {
	var appliedIndex uint64
	v, _, err := engine.MVCCGet(ctx, reader, keys.RaftAppliedIndexKey(rangeID),
		hlc.ZeroTimestamp, true, nil)
	if err != nil {
		return 0, 0, err
	}
	if v != nil {
		int64AppliedIndex, err := v.GetInt()
		if err != nil {
			return 0, 0, err
		}
		appliedIndex = uint64(int64AppliedIndex)
	}
	// TODO(tschottdorf): code duplication.
	var leaseAppliedIndex uint64
	v, _, err = engine.MVCCGet(ctx, reader, keys.LeaseAppliedIndexKey(rangeID),
		hlc.ZeroTimestamp, true, nil)
	if err != nil {
		return 0, 0, err
	}
	if v != nil {
		int64LeaseAppliedIndex, err := v.GetInt()
		if err != nil {
			return 0, 0, err
		}
		leaseAppliedIndex = uint64(int64LeaseAppliedIndex)
	}

	return appliedIndex, leaseAppliedIndex, nil
}

// setAppliedIndex persists a new applied index.
func setAppliedIndex(eng engine.Engine, ms *engine.MVCCStats, rangeID roachpb.RangeID, appliedIndex uint64) error {
	var value roachpb.Value
	value.SetInt(int64(appliedIndex))

	return engine.MVCCPut(eng, ms,
		keys.RaftAppliedIndexKey(rangeID),
		roachpb.ZeroTimestamp,
		value,
		nil /* txn */)
}

// loadAppliedIndex retrieves the applied index from the supplied engine.
func (r *Range) loadAppliedIndex(eng engine.Engine) (uint64, error) {
	var appliedIndex uint64
	if r.isInitialized() {
		appliedIndex = raftInitialLogIndex
	} else {
		appliedIndex = 0
	}
	v, _, err := engine.MVCCGet(eng, keys.RaftAppliedIndexKey(r.Desc().RaftID),
		proto.ZeroTimestamp, true, nil)
	if err != nil {
		return 0, err
	}
	if v != nil {
		_, appliedIndex = encoding.DecodeUint64(v.Bytes)
	}
	return appliedIndex, nil
}

// createRangeData creates sample range data in all possible areas of
// the key space. Returns a slice of the encoded keys of all created
// data.
func createRangeData(t *testing.T, r *Replica) []engine.MVCCKey {
	ts0 := hlc.ZeroTimestamp
	ts := hlc.Timestamp{WallTime: 1}
	desc := r.Desc()
	keyTSs := []struct {
		key roachpb.Key
		ts  hlc.Timestamp
	}{
		{keys.AbortCacheKey(r.RangeID, testTxnID), ts0},
		{keys.AbortCacheKey(r.RangeID, testTxnID2), ts0},
		{keys.RangeFrozenStatusKey(r.RangeID), ts0},
		{keys.RangeLastGCKey(r.RangeID), ts0},
		{keys.RaftAppliedIndexKey(r.RangeID), ts0},
		{keys.RaftTruncatedStateKey(r.RangeID), ts0},
		{keys.LeaseAppliedIndexKey(r.RangeID), ts0},
		{keys.RangeStatsKey(r.RangeID), ts0},
		{keys.RaftHardStateKey(r.RangeID), ts0},
		{keys.RaftLastIndexKey(r.RangeID), ts0},
		{keys.RaftLogKey(r.RangeID, 1), ts0},
		{keys.RaftLogKey(r.RangeID, 2), ts0},
		{keys.RangeLastReplicaGCTimestampKey(r.RangeID), ts0},
		{keys.RangeLastVerificationTimestampKey(r.RangeID), ts0},
		{keys.RangeDescriptorKey(desc.StartKey), ts},
		{keys.TransactionKey(roachpb.Key(desc.StartKey), uuid.NewV4()), ts0},
		{keys.TransactionKey(roachpb.Key(desc.StartKey.Next()), uuid.NewV4()), ts0},
		{keys.TransactionKey(fakePrevKey(desc.EndKey), uuid.NewV4()), ts0},
		// TODO(bdarnell): KeyMin.Next() results in a key in the reserved system-local space.
		// Once we have resolved https://github.com/cockroachdb/cockroach/issues/437,
		// replace this with something that reliably generates the first valid key in the range.
		//{r.Desc().StartKey.Next(), ts},
		// The following line is similar to StartKey.Next() but adds more to the key to
		// avoid falling into the system-local space.
		{append(append([]byte{}, desc.StartKey...), '\x02'), ts},
		{fakePrevKey(r.Desc().EndKey), ts},
	}

	keys := []engine.MVCCKey{}
	for _, keyTS := range keyTSs {
		if err := engine.MVCCPut(context.Background(), r.store.Engine(), nil, keyTS.key, keyTS.ts, roachpb.MakeValueFromString("value"), nil); err != nil {
			t.Fatal(err)
		}
		keys = append(keys, engine.MVCCKey{Key: keyTS.key, Timestamp: keyTS.ts})
	}
	return keys
}

// loadAppliedIndexLocked retrieves the applied index from the supplied engine.
// loadAppliedIndexLocked requires that the replica lock is held.
func (r *Replica) loadAppliedIndexLocked(eng engine.Engine) (uint64, error) {
	var appliedIndex uint64
	if r.isInitializedLocked() {
		appliedIndex = raftInitialLogIndex
	} else {
		appliedIndex = 0
	}
	v, _, err := engine.MVCCGet(eng, keys.RaftAppliedIndexKey(r.RangeID),
		roachpb.ZeroTimestamp, true, nil)
	if err != nil {
		return 0, err
	}
	if v != nil {
		int64AppliedIndex, err := v.GetInt()
		if err != nil {
			return 0, err
		}
		appliedIndex = uint64(int64AppliedIndex)
	}
	return appliedIndex, nil
}

// loadAppliedIndex retrieves the applied index from the supplied engine.
func (r *Replica) loadAppliedIndex(eng engine.Engine) (uint64, error) {
	var appliedIndex uint64
	if r.isInitialized() {
		appliedIndex = raftInitialLogIndex
	} else {
		appliedIndex = 0
	}
	v, _, err := engine.MVCCGet(eng, keys.RaftAppliedIndexKey(r.Desc().RangeID),
		roachpb.ZeroTimestamp, true, nil)
	if err != nil {
		return 0, err
	}
	if v != nil {
		var err error
		_, appliedIndex, err = encoding.DecodeUint64(v.GetRawBytes())
		if err != nil {
			return 0, err
		}
	}
	return appliedIndex, nil
}

// loadAppliedIndex retrieves the applied index from the supplied engine.
func loadAppliedIndex(eng engine.Reader, rangeID roachpb.RangeID, isInitialized bool) (uint64, error) {
	var appliedIndex uint64
	if isInitialized {
		appliedIndex = raftInitialLogIndex
	} else {
		appliedIndex = 0
	}
	v, _, err := engine.MVCCGet(context.Background(), eng, keys.RaftAppliedIndexKey(rangeID),
		roachpb.ZeroTimestamp, true, nil)
	if err != nil {
		return 0, err
	}
	if v != nil {
		int64AppliedIndex, err := v.GetInt()
		if err != nil {
			return 0, err
		}
		appliedIndex = uint64(int64AppliedIndex)
	}
	return appliedIndex, nil
}