package blockchain

import (
	"context"
	"strings"
	"testing"
	"time"

	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
	"github.com/prysmaticlabs/go-ssz"
	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
	"github.com/prysmaticlabs/prysm/beacon-chain/db"
	testDB "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
	"github.com/prysmaticlabs/prysm/beacon-chain/forkchoice/protoarray"
	stateTrie "github.com/prysmaticlabs/prysm/beacon-chain/state"
	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateutil"
	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
	"github.com/prysmaticlabs/prysm/shared/attestationutil"
	"github.com/prysmaticlabs/prysm/shared/bytesutil"
	"github.com/prysmaticlabs/prysm/shared/featureconfig"
	"github.com/prysmaticlabs/prysm/shared/params"
	"github.com/prysmaticlabs/prysm/shared/roughtime"
	"github.com/prysmaticlabs/prysm/shared/testutil"
)

func TestStore_OnBlock(t *testing.T) {
	ctx := context.Background()
	db, sc := testDB.SetupDB(t)

	cfg := &Config{
		BeaconDB: db,
		StateGen: stategen.New(db, sc),
	}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}
	genesisStateRoot := [32]byte{}
	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
	if err := db.SaveBlock(ctx, genesis); err != nil {
		t.Error(err)
	}
	validGenesisRoot, err := stateutil.BlockRoot(genesis.Block)
	if err != nil {
		t.Error(err)
	}
	st := testutil.NewBeaconState()
	if err := service.beaconDB.SaveState(ctx, st.Copy(), validGenesisRoot); err != nil {
		t.Fatal(err)
	}
	roots, err := blockTree1(db, validGenesisRoot[:])
	if err != nil {
		t.Fatal(err)
	}
	random := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{Slot: 1, ParentRoot: validGenesisRoot[:]}}
	if err := db.SaveBlock(ctx, random); err != nil {
		t.Error(err)
	}
	randomParentRoot, err := stateutil.BlockRoot(random.Block)
	if err != nil {
		t.Error(err)
	}
	if err := service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: st.Slot(), Root: randomParentRoot[:]}); err != nil {
		t.Fatal(err)
	}
	if err := service.beaconDB.SaveState(ctx, st.Copy(), randomParentRoot); err != nil {
		t.Fatal(err)
	}
	randomParentRoot2 := roots[1]
	if err := service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: st.Slot(), Root: randomParentRoot2[:]}); err != nil {
		t.Fatal(err)
	}
	if err := service.beaconDB.SaveState(ctx, st.Copy(), bytesutil.ToBytes32(randomParentRoot2)); err != nil {
		t.Fatal(err)
	}

	tests := []struct {
		name          string
		blk           *ethpb.BeaconBlock
		s             *stateTrie.BeaconState
		time          uint64
		wantErrString string
	}{
		{
			name:          "parent block root does not have a state",
			blk:           &ethpb.BeaconBlock{},
			s:             st.Copy(),
			wantErrString: "could not reconstruct parent state",
		},
		{
			name:          "block is from the future",
			blk:           &ethpb.BeaconBlock{ParentRoot: randomParentRoot[:], Slot: params.BeaconConfig().FarFutureEpoch},
			s:             st.Copy(),
			wantErrString: "far distant future",
		},
		{
			name:          "could not get finalized block",
			blk:           &ethpb.BeaconBlock{ParentRoot: randomParentRoot[:]},
			s:             st.Copy(),
			wantErrString: "block from slot 0 is not a descendent of the current finalized block",
		},
		{
			name:          "same slot as finalized block",
			blk:           &ethpb.BeaconBlock{Slot: 0, ParentRoot: randomParentRoot2},
			s:             st.Copy(),
			wantErrString: "block is equal or earlier than finalized block, slot 0 < slot 0",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			service.justifiedCheckpt = &ethpb.Checkpoint{Root: validGenesisRoot[:]}
			service.bestJustifiedCheckpt = &ethpb.Checkpoint{Root: validGenesisRoot[:]}
			service.finalizedCheckpt = &ethpb.Checkpoint{Root: validGenesisRoot[:]}
			service.prevFinalizedCheckpt = &ethpb.Checkpoint{Root: validGenesisRoot[:]}
			service.finalizedCheckpt.Root = roots[0]

			root, err := stateutil.BlockRoot(tt.blk)
			if err != nil {
				t.Error(err)
			}
			err = service.onBlock(ctx, &ethpb.SignedBeaconBlock{Block: tt.blk}, root)
			if err == nil || !strings.Contains(err.Error(), tt.wantErrString) {
				t.Errorf("Store.OnBlock() error = %v, wantErr = %v", err, tt.wantErrString)
			}
		})
	}
}

func TestStore_OnBlockBatch(t *testing.T) {
	ctx := context.Background()
	db, sc := testDB.SetupDB(t)

	cfg := &Config{
		BeaconDB: db,
		StateGen: stategen.New(db, sc),
	}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}

	genesisStateRoot := [32]byte{}
	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
	if err := db.SaveBlock(ctx, genesis); err != nil {
		t.Error(err)
	}

	st, keys := testutil.DeterministicGenesisState(t, 64)

	bState := st.Copy()

	blks := []*ethpb.SignedBeaconBlock{}
	blkRoots := [][32]byte{}
	var firstState *stateTrie.BeaconState
	for i := 1; i < 10; i++ {
		b, err := testutil.GenerateFullBlock(bState, keys, testutil.DefaultBlockGenConfig(), uint64(i))
		if err != nil {
			t.Fatal(err)
		}
		bState, err = state.ExecuteStateTransition(ctx, bState, b)
		if err != nil {
			t.Fatal(err)
		}
		if i == 1 {
			firstState = bState.Copy()
		}
		root, err := stateutil.BlockRoot(b.Block)
		if err != nil {
			t.Fatal(err)
		}
		blks = append(blks, b)
		blkRoots = append(blkRoots, root)
	}
	err = db.SaveBlock(context.Background(), blks[0])
	if err != nil {
		t.Fatal(err)
	}
	err = service.stateGen.SaveState(ctx, blkRoots[0], firstState)
	if err != nil {
		t.Fatal(err)
	}
	_, _, _, err = service.onBlockBatch(ctx, blks[1:], blkRoots[1:])
	if err != nil {
		t.Fatal(err)
	}
}

func TestRemoveStateSinceLastFinalized_EmptyStartSlot(t *testing.T) {
	ctx := context.Background()
	db, _ := testDB.SetupDB(t)
	params.UseMinimalConfig()
	defer params.UseMainnetConfig()

	cfg := &Config{BeaconDB: db}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}
	service.genesisTime = time.Now()

	update, err := service.shouldUpdateCurrentJustified(ctx, &ethpb.Checkpoint{})
	if err != nil {
		t.Fatal(err)
	}
	if !update {
		t.Error("Should be able to update justified, received false")
	}
	lastJustifiedBlk := testutil.NewBeaconBlock()
	lastJustifiedBlk.Block.ParentRoot = bytesutil.PadTo([]byte{'G'}, 32)
	lastJustifiedRoot, err := stateutil.BlockRoot(lastJustifiedBlk.Block)
	if err != nil {
		t.Fatal(err)
	}
	newJustifiedBlk := testutil.NewBeaconBlock()
	newJustifiedBlk.Block.Slot = 1
	newJustifiedBlk.Block.ParentRoot = bytesutil.PadTo(lastJustifiedRoot[:], 32)
	newJustifiedRoot, err := stateutil.BlockRoot(newJustifiedBlk.Block)
	if err != nil {
		t.Fatal(err)
	}
	if err := service.beaconDB.SaveBlock(ctx, newJustifiedBlk); err != nil {
		t.Fatal(err)
	}
	if err := service.beaconDB.SaveBlock(ctx, lastJustifiedBlk); err != nil {
		t.Fatal(err)
	}

	diff := (params.BeaconConfig().SlotsPerEpoch - 1) * params.BeaconConfig().SecondsPerSlot
	service.genesisTime = time.Unix(time.Now().Unix()-int64(diff), 0)
	service.justifiedCheckpt = &ethpb.Checkpoint{Root: lastJustifiedRoot[:]}
	update, err = service.shouldUpdateCurrentJustified(ctx, &ethpb.Checkpoint{Root: newJustifiedRoot[:]})
	if err != nil {
		t.Fatal(err)
	}
	if !update {
		t.Error("Should be able to update justified, received false")
	}
}

func TestShouldUpdateJustified_ReturnFalse(t *testing.T) {
	ctx := context.Background()
	db, _ := testDB.SetupDB(t)
	params.UseMinimalConfig()
	defer params.UseMainnetConfig()

	cfg := &Config{BeaconDB: db}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}
	lastJustifiedBlk := testutil.NewBeaconBlock()
	lastJustifiedBlk.Block.ParentRoot = bytesutil.PadTo([]byte{'G'}, 32)
	lastJustifiedRoot, err := stateutil.BlockRoot(lastJustifiedBlk.Block)
	if err != nil {
		t.Fatal(err)
	}
	newJustifiedBlk := testutil.NewBeaconBlock()
	newJustifiedBlk.Block.ParentRoot = bytesutil.PadTo(lastJustifiedRoot[:], 32)
	newJustifiedRoot, err := stateutil.BlockRoot(newJustifiedBlk.Block)
	if err != nil {
		t.Fatal(err)
	}
	if err := service.beaconDB.SaveBlock(ctx, newJustifiedBlk); err != nil {
		t.Fatal(err)
	}
	if err := service.beaconDB.SaveBlock(ctx, lastJustifiedBlk); err != nil {
		t.Fatal(err)
	}

	diff := (params.BeaconConfig().SlotsPerEpoch - 1) * params.BeaconConfig().SecondsPerSlot
	service.genesisTime = time.Unix(time.Now().Unix()-int64(diff), 0)
	service.justifiedCheckpt = &ethpb.Checkpoint{Root: lastJustifiedRoot[:]}

	update, err := service.shouldUpdateCurrentJustified(ctx, &ethpb.Checkpoint{Root: newJustifiedRoot[:]})
	if err != nil {
		t.Fatal(err)
	}
	if update {
		t.Error("Should not be able to update justified, received true")
	}
}

func TestCachedPreState_CanGetFromStateSummary(t *testing.T) {
	resetCfg := featureconfig.InitWithReset(&featureconfig.Flags{NewStateMgmt: true})
	defer resetCfg()

	ctx := context.Background()
	db, sc := testDB.SetupDB(t)

	cfg := &Config{
		BeaconDB: db,
		StateGen: stategen.New(db, sc),
	}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}

	s, err := stateTrie.InitializeFromProto(&pb.BeaconState{Slot: 1, GenesisValidatorsRoot: params.BeaconConfig().ZeroHash[:]})
	if err != nil {
		t.Fatal(err)
	}
	r := [32]byte{'A'}
	b := &ethpb.BeaconBlock{Slot: 1, ParentRoot: r[:]}
	if err := service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: 1, Root: r[:]}); err != nil {
		t.Fatal(err)
	}
	if err := service.stateGen.SaveState(ctx, r, s); err != nil {
		t.Fatal(err)
	}

	if err := service.verifyBlkPreState(ctx, b); err != nil {
		t.Fatal(err)
	}
}

func TestCachedPreState_CanGetFromDB(t *testing.T) {
	resetCfg := featureconfig.InitWithReset(&featureconfig.Flags{NewStateMgmt: true})
	defer resetCfg()

	ctx := context.Background()
	db, sc := testDB.SetupDB(t)

	cfg := &Config{
		BeaconDB: db,
		StateGen: stategen.New(db, sc),
	}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}

	r := [32]byte{'A'}
	b := &ethpb.BeaconBlock{Slot: 1, ParentRoot: r[:]}

	service.finalizedCheckpt = &ethpb.Checkpoint{Root: r[:]}
	err = service.verifyBlkPreState(ctx, b)
	wanted := "could not reconstruct parent state"
	if err.Error() != wanted {
		t.Error("Did not get wanted error")
	}

	s, err := stateTrie.InitializeFromProto(&pb.BeaconState{Slot: 1})
	if err != nil {
		t.Fatal(err)
	}
	if err := service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Slot: 1, Root: r[:]}); err != nil {
		t.Fatal(err)
	}
	if err := service.stateGen.SaveState(ctx, r, s); err != nil {
		t.Fatal(err)
	}

	if err := service.verifyBlkPreState(ctx, b); err != nil {
		t.Fatal(err)
	}
}

func TestUpdateJustified_CouldUpdateBest(t *testing.T) {
	ctx := context.Background()
	db, _ := testDB.SetupDB(t)

	cfg := &Config{BeaconDB: db, StateGen: stategen.New(db, cache.NewStateSummaryCache())}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}

	signedBlock := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{}}
	if err := db.SaveBlock(ctx, signedBlock); err != nil {
		t.Fatal(err)
	}
	r, err := stateutil.BlockRoot(signedBlock.Block)
	if err != nil {
		t.Fatal(err)
	}
	service.justifiedCheckpt = &ethpb.Checkpoint{Root: []byte{'A'}}
	service.bestJustifiedCheckpt = &ethpb.Checkpoint{Root: []byte{'A'}}
	st := testutil.NewBeaconState()
	service.initSyncState[r] = st.Copy()
	if err := db.SaveState(ctx, st.Copy(), r); err != nil {
		t.Fatal(err)
	}

	// Could update
	s := testutil.NewBeaconState()
	if err := s.SetCurrentJustifiedCheckpoint(&ethpb.Checkpoint{Epoch: 1, Root: r[:]}); err != nil {
		t.Fatal(err)
	}
	if err := service.updateJustified(context.Background(), s); err != nil {
		t.Fatal(err)
	}

	if service.bestJustifiedCheckpt.Epoch != s.CurrentJustifiedCheckpoint().Epoch {
		t.Error("Incorrect justified epoch in service")
	}

	// Could not update
	service.bestJustifiedCheckpt.Epoch = 2
	if err := service.updateJustified(context.Background(), s); err != nil {
		t.Fatal(err)
	}

	if service.bestJustifiedCheckpt.Epoch != 2 {
		t.Error("Incorrect justified epoch in service")
	}
}

func TestFillForkChoiceMissingBlocks_CanSave(t *testing.T) {
	ctx := context.Background()
	db, _ := testDB.SetupDB(t)

	cfg := &Config{BeaconDB: db}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}
	service.forkChoiceStore = protoarray.New(0, 0, [32]byte{'A'})
	service.finalizedCheckpt = &ethpb.Checkpoint{}

	genesisStateRoot := [32]byte{}
	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
	if err := db.SaveBlock(ctx, genesis); err != nil {
		t.Error(err)
	}
	validGenesisRoot, err := stateutil.BlockRoot(genesis.Block)
	if err != nil {
		t.Error(err)
	}
	st := testutil.NewBeaconState()

	if err := service.beaconDB.SaveState(ctx, st.Copy(), validGenesisRoot); err != nil {
		t.Fatal(err)
	}
	roots, err := blockTree1(db, validGenesisRoot[:])
	if err != nil {
		t.Fatal(err)
	}

	beaconState, _ := testutil.DeterministicGenesisState(t, 32)
	block := &ethpb.BeaconBlock{Slot: 9, ParentRoot: roots[8], Body: &ethpb.BeaconBlockBody{Graffiti: []byte{}}}
	if err := service.fillInForkChoiceMissingBlocks(context.Background(), block,
		beaconState.FinalizedCheckpoint(), beaconState.CurrentJustifiedCheckpoint()); err != nil {
		t.Fatal(err)
	}

	// 5 nodes from the block tree 1. B0 - B3 - B4 - B6 - B8
	if len(service.forkChoiceStore.Nodes()) != 5 {
		t.Error("Miss match nodes")
	}

	if !service.forkChoiceStore.HasNode(bytesutil.ToBytes32(roots[4])) {
		t.Error("Didn't save node")
	}
	if !service.forkChoiceStore.HasNode(bytesutil.ToBytes32(roots[6])) {
		t.Error("Didn't save node")
	}
	if !service.forkChoiceStore.HasNode(bytesutil.ToBytes32(roots[8])) {
		t.Error("Didn't save node")
	}
}

func TestFillForkChoiceMissingBlocks_FilterFinalized(t *testing.T) {
	ctx := context.Background()
	db, _ := testDB.SetupDB(t)

	cfg := &Config{BeaconDB: db}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}
	service.forkChoiceStore = protoarray.New(0, 0, [32]byte{'A'})
	// Set finalized epoch to 1.
	service.finalizedCheckpt = &ethpb.Checkpoint{Epoch: 1}

	genesisStateRoot := [32]byte{}
	genesis := blocks.NewGenesisBlock(genesisStateRoot[:])
	if err := db.SaveBlock(ctx, genesis); err != nil {
		t.Error(err)
	}
	validGenesisRoot, err := stateutil.BlockRoot(genesis.Block)
	if err != nil {
		t.Error(err)
	}
	st := testutil.NewBeaconState()

	if err := service.beaconDB.SaveState(ctx, st.Copy(), validGenesisRoot); err != nil {
		t.Fatal(err)
	}

	// Define a tree branch, slot 63 <- 64 <- 65
	b63 := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{Slot: 63, Body: &ethpb.BeaconBlockBody{}}}
	if err := service.beaconDB.SaveBlock(ctx, b63); err != nil {
		t.Fatal(err)
	}
	r63, err := stateutil.BlockRoot(b63.Block)
	if err != nil {
		t.Fatal(err)
	}
	b64 := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{Slot: 64, ParentRoot: r63[:], Body: &ethpb.BeaconBlockBody{}}}
	if err := service.beaconDB.SaveBlock(ctx, b64); err != nil {
		t.Fatal(err)
	}
	r64, err := stateutil.BlockRoot(b64.Block)
	if err != nil {
		t.Fatal(err)
	}
	b65 := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{Slot: 65, ParentRoot: r64[:], Body: &ethpb.BeaconBlockBody{}}}
	if err := service.beaconDB.SaveBlock(ctx, b65); err != nil {
		t.Fatal(err)
	}

	beaconState, _ := testutil.DeterministicGenesisState(t, 32)
	if err := service.fillInForkChoiceMissingBlocks(context.Background(), b65.Block, beaconState.FinalizedCheckpoint(), beaconState.CurrentJustifiedCheckpoint()); err != nil {
		t.Fatal(err)
	}

	// There should be 2 nodes, block 65 and block 64.
	if len(service.forkChoiceStore.Nodes()) != 2 {
		t.Error("Miss match nodes")
	}

	// Block with slot 63 should be in fork choice because it's less than finalized epoch 1.
	if !service.forkChoiceStore.HasNode(r63) {
		t.Error("Didn't save node")
	}
}

// blockTree1 constructs the following tree:
//    /- B1
// B0           /- B5 - B7
//    \- B3 - B4 - B6 - B8
// (B1, and B3 are all from the same slots)
func blockTree1(db db.Database, genesisRoot []byte) ([][]byte, error) {
	b0 := &ethpb.BeaconBlock{Slot: 0, ParentRoot: genesisRoot}
	r0, err := ssz.HashTreeRoot(b0)
	if err != nil {
		return nil, err
	}
	b1 := &ethpb.BeaconBlock{Slot: 1, ParentRoot: r0[:]}
	r1, err := ssz.HashTreeRoot(b1)
	if err != nil {
		return nil, err
	}
	b3 := &ethpb.BeaconBlock{Slot: 3, ParentRoot: r0[:]}
	r3, err := ssz.HashTreeRoot(b3)
	if err != nil {
		return nil, err
	}
	b4 := &ethpb.BeaconBlock{Slot: 4, ParentRoot: r3[:]}
	r4, err := ssz.HashTreeRoot(b4)
	if err != nil {
		return nil, err
	}
	b5 := &ethpb.BeaconBlock{Slot: 5, ParentRoot: r4[:]}
	r5, err := ssz.HashTreeRoot(b5)
	if err != nil {
		return nil, err
	}
	b6 := &ethpb.BeaconBlock{Slot: 6, ParentRoot: r4[:]}
	r6, err := ssz.HashTreeRoot(b6)
	if err != nil {
		return nil, err
	}
	b7 := &ethpb.BeaconBlock{Slot: 7, ParentRoot: r5[:]}
	r7, err := ssz.HashTreeRoot(b7)
	if err != nil {
		return nil, err
	}
	b8 := &ethpb.BeaconBlock{Slot: 8, ParentRoot: r6[:]}
	r8, err := ssz.HashTreeRoot(b8)
	if err != nil {
		return nil, err
	}
	st := testutil.NewBeaconState()

	for _, b := range []*ethpb.BeaconBlock{b0, b1, b3, b4, b5, b6, b7, b8} {
		beaconBlock := testutil.NewBeaconBlock()
		beaconBlock.Block.Slot = b.Slot
		beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.ParentRoot, 32)
		beaconBlock.Block.Body = &ethpb.BeaconBlockBody{}
		if err := db.SaveBlock(context.Background(), beaconBlock); err != nil {
			return nil, err
		}
		if err := db.SaveState(context.Background(), st.Copy(), bytesutil.ToBytes32(beaconBlock.Block.ParentRoot)); err != nil {
			return nil, err
		}
	}
	if err := db.SaveState(context.Background(), st.Copy(), r1); err != nil {
		return nil, err
	}
	if err := db.SaveState(context.Background(), st.Copy(), r7); err != nil {
		return nil, err
	}
	if err := db.SaveState(context.Background(), st.Copy(), r8); err != nil {
		return nil, err
	}
	return [][]byte{r0[:], r1[:], nil, r3[:], r4[:], r5[:], r6[:], r7[:], r8[:]}, nil
}

func TestCurrentSlot_HandlesOverflow(t *testing.T) {
	svc := Service{genesisTime: roughtime.Now().Add(1 * time.Hour)}

	slot := svc.CurrentSlot()

	if slot != 0 {
		t.Fatalf("Expected slot to be 0, got %d", slot)
	}
}

func TestAncestor_HandleSkipSlot(t *testing.T) {
	ctx := context.Background()
	db, _ := testDB.SetupDB(t)

	cfg := &Config{BeaconDB: db}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}

	b1 := &ethpb.BeaconBlock{Slot: 1, ParentRoot: []byte{'a'}}
	r1, err := ssz.HashTreeRoot(b1)
	if err != nil {
		t.Fatal(err)
	}
	b100 := &ethpb.BeaconBlock{Slot: 100, ParentRoot: r1[:]}
	r100, err := ssz.HashTreeRoot(b100)
	if err != nil {
		t.Fatal(err)
	}
	b200 := &ethpb.BeaconBlock{Slot: 200, ParentRoot: r100[:]}
	r200, err := ssz.HashTreeRoot(b200)
	if err != nil {
		t.Fatal(err)
	}
	for _, b := range []*ethpb.BeaconBlock{b1, b100, b200} {
		beaconBlock := testutil.NewBeaconBlock()
		beaconBlock.Block.Slot = b.Slot
		beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.ParentRoot, 32)
		beaconBlock.Block.Body = &ethpb.BeaconBlockBody{}
		if err := db.SaveBlock(context.Background(), beaconBlock); err != nil {
			t.Fatal(err)
		}
	}

	// Slots 100 to 200 are skip slots. Requesting root at 150 will yield root at 100. The last physical block.
	r, err := service.ancestor(context.Background(), r200[:], 150)
	if err != nil {
		t.Fatal(err)
	}
	if bytesutil.ToBytes32(r) != r100 {
		t.Error("Did not get correct root")
	}

	// Slots 1 to 100 are skip slots. Requesting root at 50 will yield root at 1. The last physical block.
	r, err = service.ancestor(context.Background(), r200[:], 50)
	if err != nil {
		t.Fatal(err)
	}
	if bytesutil.ToBytes32(r) != r1 {
		t.Error("Did not get correct root")
	}
}

func TestEnsureRootNotZeroHashes(t *testing.T) {
	ctx := context.Background()
	cfg := &Config{}
	service, err := NewService(ctx, cfg)
	if err != nil {
		t.Fatal(err)
	}
	service.genesisRoot = [32]byte{'a'}

	r := service.ensureRootNotZeros(params.BeaconConfig().ZeroHash)
	if r != service.genesisRoot {
		t.Error("Did not get wanted justified root")
	}
	root := [32]byte{'b'}
	r = service.ensureRootNotZeros(root)
	if r != root {
		t.Error("Did not get wanted justified root")
	}
}

func TestFinalizedImpliesNewJustified(t *testing.T) {
	db, sc := testDB.SetupDB(t)
	ctx := context.Background()
	type args struct {
		cachedCheckPoint        *ethpb.Checkpoint
		stateCheckPoint         *ethpb.Checkpoint
		diffFinalizedCheckPoint bool
	}
	tests := []struct {
		name string
		args args
		want *ethpb.Checkpoint
	}{
		{
			name: "Same justified, do nothing",
			args: args{
				cachedCheckPoint: &ethpb.Checkpoint{Epoch: 1, Root: []byte{'a'}},
				stateCheckPoint:  &ethpb.Checkpoint{Epoch: 1, Root: []byte{'a'}},
			},
			want: &ethpb.Checkpoint{Epoch: 1, Root: []byte{'a'}},
		},
		{
			name: "Different justified, higher epoch, cache new justified",
			args: args{
				cachedCheckPoint: &ethpb.Checkpoint{Epoch: 1, Root: []byte{'a'}},
				stateCheckPoint:  &ethpb.Checkpoint{Epoch: 2, Root: []byte{'b'}},
			},
			want: &ethpb.Checkpoint{Epoch: 2, Root: []byte{'b'}},
		},
		{
			name: "finalized has different justified, cache new justified",
			args: args{
				cachedCheckPoint:        &ethpb.Checkpoint{Epoch: 1, Root: []byte{'a'}},
				stateCheckPoint:         &ethpb.Checkpoint{Epoch: 1, Root: []byte{'b'}},
				diffFinalizedCheckPoint: true,
			},
			want: &ethpb.Checkpoint{Epoch: 1, Root: []byte{'b'}},
		},
	}
	for _, test := range tests {
		beaconState := testutil.NewBeaconState()
		if err := beaconState.SetCurrentJustifiedCheckpoint(test.args.stateCheckPoint); err != nil {
			t.Fatal(err)
		}
		service, err := NewService(ctx, &Config{BeaconDB: db, StateGen: stategen.New(db, sc)})
		if err != nil {
			t.Fatal(err)
		}
		service.justifiedCheckpt = test.args.cachedCheckPoint
		if err := service.beaconDB.SaveStateSummary(ctx, &pb.StateSummary{Root: bytesutil.PadTo(test.want.Root, 32)}); err != nil {
			t.Fatal(err)
		}
		genesisState := testutil.NewBeaconState()
		if err := service.beaconDB.SaveState(ctx, genesisState, bytesutil.ToBytes32(test.want.Root)); err != nil {
			t.Fatal(err)
		}

		if test.args.diffFinalizedCheckPoint {
			b1 := &ethpb.BeaconBlock{Slot: 1, ParentRoot: []byte{'a'}}
			r1, err := ssz.HashTreeRoot(b1)
			if err != nil {
				t.Fatal(err)
			}
			b100 := &ethpb.BeaconBlock{Slot: 100, ParentRoot: r1[:]}
			r100, err := ssz.HashTreeRoot(b100)
			if err != nil {
				t.Fatal(err)
			}
			for _, b := range []*ethpb.BeaconBlock{b1, b100} {
				beaconBlock := testutil.NewBeaconBlock()
				beaconBlock.Block.Slot = b.Slot
				beaconBlock.Block.ParentRoot = bytesutil.PadTo(b.ParentRoot, 32)
				if err := service.beaconDB.SaveBlock(context.Background(), beaconBlock); err != nil {
					t.Fatal(err)
				}
			}
			service.finalizedCheckpt = &ethpb.Checkpoint{Root: []byte{'c'}, Epoch: 1}
			service.justifiedCheckpt.Root = r100[:]
		}

		if err := service.finalizedImpliesNewJustified(ctx, beaconState); err != nil {
			t.Fatal(err)
		}
		if !attestationutil.CheckPointIsEqual(test.want, service.justifiedCheckpt) {
			t.Error("Did not get wanted check point")
		}
	}
}