package sync

import (
	"context"
	"reflect"
	"sync"
	"testing"
	"time"

	"github.com/libp2p/go-libp2p-core/network"
	"github.com/libp2p/go-libp2p-core/peer"
	"github.com/libp2p/go-libp2p-core/protocol"
	"github.com/prysmaticlabs/go-ssz"
	mock "github.com/prysmaticlabs/prysm/beacon-chain/blockchain/testing"
	"github.com/prysmaticlabs/prysm/beacon-chain/core/state"
	db "github.com/prysmaticlabs/prysm/beacon-chain/db/testing"
	p2ptest "github.com/prysmaticlabs/prysm/beacon-chain/p2p/testing"
	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
	ethpb "github.com/prysmaticlabs/prysm/proto/eth/v1alpha1"
	"github.com/prysmaticlabs/prysm/shared/params"
	"github.com/prysmaticlabs/prysm/shared/testutil"
)

func TestRecentBeaconBlocksRPCHandler_ReturnsBlocks(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)
	p1.Connect(p2)
	if len(p1.Host.Network().Peers()) != 1 {
		t.Error("Expected peers to be connected")
	}
	d := db.SetupDB(t)
	defer db.TeardownDB(t, d)

	var blkRoots [][32]byte
	// Populate the database with blocks that would match the request.
	for i := 1; i < 11; i++ {
		blk := &ethpb.BeaconBlock{
			Slot: uint64(i),
		}
		root, err := ssz.SigningRoot(blk)
		if err != nil {
			t.Fatal(err)
		}
		if err := d.SaveBlock(context.Background(), blk); err != nil {
			t.Fatal(err)
		}
		blkRoots = append(blkRoots, root)
	}

	r := &RegularSync{p2p: p1, db: d}
	pcl := protocol.ID("/testing")

	var wg sync.WaitGroup
	wg.Add(1)
	p2.Host.SetStreamHandler(pcl, func(stream network.Stream) {
		defer wg.Done()
		expectSuccess(t, r, stream)
		res := make([]*ethpb.BeaconBlock, 0)
		if err := r.p2p.Encoding().DecodeWithLength(stream, &res); err != nil {
			t.Error(err)
		}
		if len(res) != len(blkRoots) {
			t.Errorf("Received only %d blocks, expected %d", len(res), len(blkRoots))
		}
		for i, blk := range res {
			if blk.Slot != uint64(i+1) {
				t.Errorf("Received unexpected block slot %d but wanted %d", blk.Slot, i+1)
			}
		}
	})

	stream1, err := p1.Host.NewStream(context.Background(), p2.Host.ID(), pcl)
	if err != nil {
		t.Fatal(err)
	}

	err = r.recentBeaconBlocksRPCHandler(context.Background(), blkRoots, stream1)
	if err != nil {
		t.Errorf("Unexpected error: %v", err)
	}

	if testutil.WaitTimeout(&wg, 1*time.Second) {
		t.Fatal("Did not receive stream within 1 sec")
	}
}

func TestRecentBeaconBlocks_RPCRequestSent(t *testing.T) {
	p1 := p2ptest.NewTestP2P(t)
	p2 := p2ptest.NewTestP2P(t)

	blockA := &ethpb.BeaconBlock{Slot: 111}
	blockB := &ethpb.BeaconBlock{Slot: 40}
	// Set up a head state with data we expect.
	blockARoot, err := ssz.HashTreeRoot(blockA)
	if err != nil {
		t.Fatal(err)
	}
	blockBRoot, err := ssz.HashTreeRoot(blockB)
	if err != nil {
		t.Fatal(err)
	}
	genesisState, err := state.GenesisBeaconState(nil, 0, &ethpb.Eth1Data{})
	if err != nil {
		t.Fatal(err)
	}
	genesisState.Slot = 111
	genesisState.BlockRoots[111%params.BeaconConfig().SlotsPerHistoricalRoot] = blockARoot[:]
	finalizedCheckpt := &ethpb.Checkpoint{
		Epoch: 5,
		Root:  blockBRoot[:],
	}

	expectedRoots := [][32]byte{blockBRoot, blockARoot}

	r := &RegularSync{
		p2p: p1,
		chain: &mock.ChainService{
			State:               genesisState,
			FinalizedCheckPoint: finalizedCheckpt,
			Root:                blockARoot[:],
		},
		helloTracker: make(map[peer.ID]*pb.Hello),
		ctx:          context.Background(),
	}

	// Setup streams
	pcl := protocol.ID("/eth2/beacon_chain/req/recent_beacon_blocks/1/ssz")
	var wg sync.WaitGroup
	wg.Add(1)
	p2.Host.SetStreamHandler(pcl, func(stream network.Stream) {
		defer wg.Done()
		out := [][32]byte{}
		if err := p2.Encoding().DecodeWithLength(stream, &out); err != nil {
			t.Fatal(err)
		}
		if !reflect.DeepEqual(out, expectedRoots) {
			t.Fatalf("Did not receive expected message. Got %+v wanted %+v", out, expectedRoots)
		}
		if _, err := stream.Write([]byte{responseCodeSuccess}); err != nil {
			t.Fatalf("Failed to write to stream: %v", err)
		}
		response := []*ethpb.BeaconBlock{blockB, blockA}
		_, err := p2.Encoding().EncodeWithLength(stream, response)
		if err != nil {
			t.Errorf("Could not send response back: %v ", err)
		}
	})

	p1.Connect(p2)
	if err := r.sendRecentBeaconBlocksRequest(context.Background(), expectedRoots, p2.PeerID()); err != nil {
		t.Fatal(err)
	}

	if testutil.WaitTimeout(&wg, 1*time.Second) {
		t.Fatal("Did not receive stream within 1 sec")
	}
}