package sync

import (
	"context"

	"github.com/gogo/protobuf/proto"
	ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
	"github.com/prysmaticlabs/go-ssz"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/state/interop"
	"github.com/prysmaticlabs/prysm/shared/bytesutil"
)

func (r *Service) beaconBlockSubscriber(ctx context.Context, msg proto.Message) error {
	block := msg.(*ethpb.BeaconBlock)

	headState, err := r.chain.HeadState(ctx)
	if err != nil {
		log.Errorf("Head state is not available: %v", err)
		return nil
	}
	// Ignore block older than last finalized checkpoint.
	if block.Slot < helpers.StartSlot(headState.FinalizedCheckpoint.Epoch) {
		log.Debugf("Received a block older than finalized checkpoint, %d < %d",
			block.Slot, helpers.StartSlot(headState.FinalizedCheckpoint.Epoch))
		return nil
	}

	blockRoot, err := ssz.SigningRoot(block)
	if err != nil {
		log.Errorf("Could not sign root block: %v", err)
		return nil
	}

	// Handle block when the parent is unknown
	if !r.db.HasBlock(ctx, bytesutil.ToBytes32(block.ParentRoot)) {
		r.pendingQueueLock.Lock()
		r.slotToPendingBlocks[block.Slot] = block
		r.seenPendingBlocks[blockRoot] = true
		r.pendingQueueLock.Unlock()
		return nil
	}

	err = r.chain.ReceiveBlockNoPubsub(ctx, block)
	if err != nil {
		interop.WriteBlockToDisk(block, true /*failed*/)
	}
	return err
}