package beacon

import (
	"context"
	"encoding/binary"
	"testing"
	"time"

	"github.com/gogo/protobuf/proto"
	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
	"github.com/prysmaticlabs/go-ssz"
	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
	"github.com/prysmaticlabs/prysm/beacon-chain/cache"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
	"github.com/prysmaticlabs/prysm/beacon-chain/db"
	dbTest "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
	stateTrie "github.com/prysmaticlabs/prysm/beacon-chain/state"
	"github.com/prysmaticlabs/prysm/beacon-chain/state/stategen"
	"github.com/prysmaticlabs/prysm/shared/params"
	"github.com/prysmaticlabs/prysm/shared/roughtime"
	"github.com/prysmaticlabs/prysm/shared/testutil"
)

func TestServer_ListBeaconCommittees_CurrentEpoch(t *testing.T) {
	db := dbTest.SetupDB(t)
	defer dbTest.TeardownDB(t, db)
	helpers.ClearCache()

	numValidators := 128
	ctx := context.Background()
	headState := setupActiveValidators(t, db, numValidators)

	m := &mock.ChainService{
		Genesis: roughtime.Now().Add(time.Duration(-1*int64((headState.Slot()*params.BeaconConfig().SecondsPerSlot))) * time.Second),
	}
	bs := &Server{
		HeadFetcher:        m,
		GenesisTimeFetcher: m,
		StateGen:           stategen.New(db, cache.NewStateSummaryCache()),
	}
	b := &ethpb.SignedBeaconBlock{Block: &ethpb.BeaconBlock{}}
	if err := db.SaveBlock(ctx, b); err != nil {
		t.Fatal(err)
	}
	gRoot, err := ssz.HashTreeRoot(b.Block)
	if err != nil {
		t.Fatal(err)
	}
	if err := db.SaveGenesisBlockRoot(ctx, gRoot); err != nil {
		t.Fatal(err)
	}
	if err := db.SaveState(ctx, headState, gRoot); err != nil {
		t.Fatal(err)
	}

	activeIndices, err := helpers.ActiveValidatorIndices(headState, 0)
	if err != nil {
		t.Fatal(err)
	}
	attesterSeed, err := helpers.Seed(headState, 0, params.BeaconConfig().DomainBeaconAttester)
	if err != nil {
		t.Fatal(err)
	}
	committees, err := computeCommittees(0, activeIndices, attesterSeed)
	if err != nil {
		t.Fatal(err)
	}

	wanted := &ethpb.BeaconCommittees{
		Epoch:                0,
		Committees:           committees,
		ActiveValidatorCount: uint64(numValidators),
	}
	res, err := bs.ListBeaconCommittees(context.Background(), &ethpb.ListCommitteesRequest{
		QueryFilter: &ethpb.ListCommitteesRequest_Genesis{Genesis: true},
	})
	if err != nil {
		t.Fatal(err)
	}
	if !proto.Equal(res, wanted) {
		t.Errorf("Expected %v, received %v", wanted, res)
	}
}

func setupActiveValidators(t *testing.T, db db.Database, count int) *stateTrie.BeaconState {
	balances := make([]uint64, count)
	validators := make([]*ethpb.Validator, 0, count)
	for i := 0; i < count; i++ {
		pubKey := make([]byte, params.BeaconConfig().BLSPubkeyLength)
		binary.LittleEndian.PutUint64(pubKey, uint64(i))
		balances[i] = uint64(i)
		validators = append(validators, &ethpb.Validator{
			PublicKey:             pubKey,
			ActivationEpoch:       0,
			ExitEpoch:             params.BeaconConfig().FarFutureEpoch,
			WithdrawalCredentials: make([]byte, 32),
		})
	}
	s := testutil.NewBeaconState()
	if err := s.SetValidators(validators); err != nil {
		return nil
	}
	if err := s.SetBalances(balances); err != nil {
		return nil
	}
	return s
}