func TestValidAfter(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	pi := testutil.RandIdentityOrFatal(t)
	key := cid.NewCidV0(u.Hash([]byte("mock key")))
	conf := DelayConfig{
		ValueVisibility: delay.Fixed(1 * time.Hour),
		Query:           delay.Fixed(0),
	}

	rs := NewServerWithDelay(conf)

	rs.Client(pi).Provide(ctx, key)

	var providers []pstore.PeerInfo
	providers, err := rs.Client(pi).FindProviders(ctx, key)
	if err != nil {
		t.Fatal(err)
	}
	if len(providers) > 0 {
		t.Fail()
	}

	conf.ValueVisibility.Set(0)
	providers, err = rs.Client(pi).FindProviders(ctx, key)
	if err != nil {
		t.Fatal(err)
	}
	t.Log("providers", providers)
	if len(providers) != 1 {
		t.Fail()
	}
}

func TestValidAfter(t *testing.T) {

	pi := testutil.RandIdentityOrFatal(t)
	var key = key.Key("mock key")
	var ctx = context.Background()
	conf := DelayConfig{
		ValueVisibility: delay.Fixed(1 * time.Hour),
		Query:           delay.Fixed(0),
	}

	rs := NewServerWithDelay(conf)

	rs.Client(pi).Provide(ctx, key)

	var providers []peer.PeerInfo
	providers, err := rs.Client(pi).FindProviders(ctx, key)
	if err != nil {
		t.Fatal(err)
	}
	if len(providers) > 0 {
		t.Fail()
	}

	conf.ValueVisibility.Set(0)
	providers, err = rs.Client(pi).FindProviders(ctx, key)
	if err != nil {
		t.Fatal(err)
	}
	t.Log("providers", providers)
	if len(providers) != 1 {
		t.Fail()
	}
}

func TestBasicBitswap(t *testing.T) {
	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
	sg := NewTestSessionGenerator(net)
	defer sg.Close()
	bg := blocksutil.NewBlockGenerator()

	t.Log("Test a one node trying to get one block from another")

	instances := sg.Instances(2)
	blocks := bg.Blocks(1)
	err := instances[0].Exchange.HasBlock(blocks[0])
	if err != nil {
		t.Fatal(err)
	}

	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
	defer cancel()
	blk, err := instances[1].Exchange.GetBlock(ctx, blocks[0].Key())
	if err != nil {
		t.Fatal(err)
	}

	t.Log(blk)
	for _, inst := range instances {
		err := inst.Exchange.Close()
		if err != nil {
			t.Fatal(err)
		}
	}
}

func TestGetBlockFromPeerAfterPeerAnnounces(t *testing.T) {

	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
	block := blocks.NewBlock([]byte("block"))
	g := NewTestSessionGenerator(net)
	defer g.Close()

	peers := g.Instances(2)
	hasBlock := peers[0]
	defer hasBlock.Exchange.Close()

	if err := hasBlock.Exchange.HasBlock(block); err != nil {
		t.Fatal(err)
	}

	wantsBlock := peers[1]
	defer wantsBlock.Exchange.Close()

	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	received, err := wantsBlock.Exchange.GetBlock(ctx, block.Key())
	if err != nil {
		t.Log(err)
		t.Fatal("Expected to succeed")
	}

	if !bytes.Equal(block.Data, received.Data) {
		t.Fatal("Data doesn't match")
	}
}

// session creates a test bitswap session.
//
// NB: It's easy make mistakes by providing the same peer ID to two different
// sessions. To safeguard, use the SessionGenerator to generate sessions. It's
// just a much better idea.
func Session(ctx context.Context, net tn.Network, p testutil.Identity) Instance {
	bsdelay := delay.Fixed(0)
	const bloomSize = 512
	const writeCacheElems = 100

	adapter := net.Adapter(p)
	dstore := ds_sync.MutexWrap(datastore2.WithDelay(ds.NewMapDatastore(), bsdelay))

	bstore, err := blockstore.CachedBlockstore(blockstore.NewBlockstore(
		ds_sync.MutexWrap(dstore)), ctx, blockstore.DefaultCacheOpts())
	if err != nil {
		panic(err.Error()) // FIXME perhaps change signature and return error.
	}

	const alwaysSendToPeer = true

	bs := New(ctx, p.ID(), adapter, bstore, alwaysSendToPeer).(*Bitswap)

	return Instance{
		Peer:            p.ID(),
		Exchange:        bs,
		blockstore:      bstore,
		blockstoreDelay: bsdelay,
	}
}

func MocknetTestRepo(p peer.ID, h host.Host, conf testutil.LatencyConfig, routing core.RoutingOption) core.ConfigOption {
	return func(ctx context.Context) (*core.IpfsNode, error) {
		const kWriteCacheElems = 100
		const alwaysSendToPeer = true
		dsDelay := delay.Fixed(conf.BlockstoreLatency)
		r := &repo.Mock{
			D: ds2.CloserWrap(syncds.MutexWrap(ds2.WithDelay(datastore.NewMapDatastore(), dsDelay))),
		}
		ds := r.Datastore()

		n := &core.IpfsNode{
			Peerstore: h.Peerstore(),
			Repo:      r,
			PeerHost:  h,
			Identity:  p,
		}
		dhtt, err := routing(ctx, n.PeerHost, n.Repo.Datastore())
		if err != nil {
			return nil, err
		}

		bsn := bsnet.NewFromIpfsHost(h, dhtt)
		bstore, err := blockstore.WriteCached(blockstore.NewBlockstore(ds), kWriteCacheElems)
		if err != nil {
			return nil, err
		}
		exch := bitswap.New(ctx, p, bsn, bstore, alwaysSendToPeer)
		n.Blockstore = bstore
		n.Exchange = exch
		n.Routing = dhtt
		return n, nil
	}
}

//  Converts config field to delay
func convertTimeField(field string) delay.D {
	val, err := strconv.Atoi(config[field])
	if err != nil {
		log.Fatalf("Invalid value for %s.", field)
	}
	return delay.Fixed(time.Duration(val) * time.Millisecond)
}

func TestDoubleGet(t *testing.T) {
	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
	sg := NewTestSessionGenerator(net)
	defer sg.Close()
	bg := blocksutil.NewBlockGenerator()

	t.Log("Test a one node trying to get one block from another")

	instances := sg.Instances(2)
	blocks := bg.Blocks(1)

	ctx1, cancel1 := context.WithCancel(context.Background())
	blkch1, err := instances[1].Exchange.GetBlocks(ctx1, []*cid.Cid{blocks[0].Cid()})
	if err != nil {
		t.Fatal(err)
	}

	ctx2, cancel2 := context.WithCancel(context.Background())
	defer cancel2()

	blkch2, err := instances[1].Exchange.GetBlocks(ctx2, []*cid.Cid{blocks[0].Cid()})
	if err != nil {
		t.Fatal(err)
	}

	// ensure both requests make it into the wantlist at the same time
	time.Sleep(time.Millisecond * 100)
	cancel1()

	_, ok := <-blkch1
	if ok {
		t.Fatal("expected channel to be closed")
	}

	err = instances[0].Exchange.HasBlock(blocks[0])
	if err != nil {
		t.Fatal(err)
	}

	select {
	case blk, ok := <-blkch2:
		if !ok {
			t.Fatal("expected to get the block here")
		}
		t.Log(blk)
	case <-time.After(time.Second * 5):
		t.Fatal("timed out waiting on block")
	}

	for _, inst := range instances {
		err := inst.Exchange.Close()
		if err != nil {
			t.Fatal(err)
		}
	}
}

func TestEmptyKey(t *testing.T) {
	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
	sg := NewTestSessionGenerator(net)
	defer sg.Close()
	bs := sg.Instances(1)[0].Exchange

	_, err := bs.GetBlock(context.Background(), key.Key(""))
	if err != blockstore.ErrNotFound {
		t.Error("empty str key should return ErrNotFound")
	}
}

func TestClose(t *testing.T) {
	vnet := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
	sesgen := NewTestSessionGenerator(vnet)
	defer sesgen.Close()
	bgen := blocksutil.NewBlockGenerator()

	block := bgen.Next()
	bitswap := sesgen.Next()

	bitswap.Exchange.Close()
	bitswap.Exchange.GetBlock(context.Background(), block.Key())
}

// Mocks returns |n| connected mock Blockservices
func Mocks(n int) []BlockService {
	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(0))
	sg := bitswap.NewTestSessionGenerator(net)

	instances := sg.Instances(n)

	var servs []BlockService
	for _, i := range instances {
		servs = append(servs, New(i.Blockstore(), i.Exchange))
	}
	return servs
}

// TODO simplify this test. get to the _essence_!
func TestSendToWantingPeer(t *testing.T) {
	if testing.Short() {
		t.SkipNow()
	}

	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
	sg := NewTestSessionGenerator(net)
	defer sg.Close()
	bg := blocksutil.NewBlockGenerator()

	prev := rebroadcastDelay.Set(time.Second / 2)
	defer func() { rebroadcastDelay.Set(prev) }()

	peers := sg.Instances(2)
	peerA := peers[0]
	peerB := peers[1]

	t.Logf("Session %v\n", peerA.Peer)
	t.Logf("Session %v\n", peerB.Peer)

	timeout := time.Second
	waitTime := time.Second * 5

	alpha := bg.Next()
	// peerA requests and waits for block alpha
	ctx, cancel := context.WithTimeout(context.Background(), waitTime)
	defer cancel()
	alphaPromise, err := peerA.Exchange.GetBlocks(ctx, []key.Key{alpha.Key()})
	if err != nil {
		t.Fatal(err)
	}

	// peerB announces to the network that he has block alpha
	ctx, cancel = context.WithTimeout(context.Background(), timeout)
	defer cancel()
	err = peerB.Exchange.HasBlock(ctx, alpha)
	if err != nil {
		t.Fatal(err)
	}

	// At some point, peerA should get alpha (or timeout)
	blkrecvd, ok := <-alphaPromise
	if !ok {
		t.Fatal("context timed out and broke promise channel!")
	}

	if blkrecvd.Key() != alpha.Key() {
		t.Fatal("Wrong block!")
	}

}

func TestSendMessageAsyncButWaitForResponse(t *testing.T) {
	net := VirtualNetwork(mockrouting.NewServer(), delay.Fixed(0))
	responderPeer := testutil.RandIdentityOrFatal(t)
	waiter := net.Adapter(testutil.RandIdentityOrFatal(t))
	responder := net.Adapter(responderPeer)

	var wg sync.WaitGroup

	wg.Add(1)

	expectedStr := "received async"

	responder.SetDelegate(lambda(func(
		ctx context.Context,
		fromWaiter peer.ID,
		msgFromWaiter bsmsg.BitSwapMessage) {

		msgToWaiter := bsmsg.New(true)
		msgToWaiter.AddBlock(blocks.NewBlock([]byte(expectedStr)))
		waiter.SendMessage(ctx, fromWaiter, msgToWaiter)
	}))

	waiter.SetDelegate(lambda(func(
		ctx context.Context,
		fromResponder peer.ID,
		msgFromResponder bsmsg.BitSwapMessage) {

		// TODO assert that this came from the correct peer and that the message contents are as expected
		ok := false
		for _, b := range msgFromResponder.Blocks() {
			if string(b.Data) == expectedStr {
				wg.Done()
				ok = true
			}
		}

		if !ok {
			t.Fatal("Message not received from the responder")
		}
	}))

	messageSentAsync := bsmsg.New(true)
	messageSentAsync.AddBlock(blocks.NewBlock([]byte("data")))
	errSending := waiter.SendMessage(
		context.Background(), responderPeer.ID(), messageSentAsync)
	if errSending != nil {
		t.Fatal(errSending)
	}

	wg.Wait() // until waiter delegate function is executed
}

func PerformDistributionTest(t *testing.T, numInstances, numBlocks int) {
	ctx := context.Background()
	if testing.Short() {
		t.SkipNow()
	}
	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
	sg := NewTestSessionGenerator(net)
	defer sg.Close()
	bg := blocksutil.NewBlockGenerator()

	instances := sg.Instances(numInstances)
	blocks := bg.Blocks(numBlocks)

	t.Log("Give the blocks to the first instance")

	var blkeys []key.Key
	first := instances[0]
	for _, b := range blocks {
		blkeys = append(blkeys, b.Key())
		first.Exchange.HasBlock(ctx, b)
	}

	t.Log("Distribute!")

	wg := sync.WaitGroup{}
	for _, inst := range instances[1:] {
		wg.Add(1)
		go func(inst Instance) {
			defer wg.Done()
			outch, err := inst.Exchange.GetBlocks(ctx, blkeys)
			if err != nil {
				t.Fatal(err)
			}
			for _ = range outch {
			}
		}(inst)
	}
	wg.Wait()

	t.Log("Verify!")

	for _, inst := range instances {
		for _, b := range blocks {
			if _, err := inst.Blockstore().Get(b.Key()); err != nil {
				t.Fatal(err)
			}
		}
	}
}

// Mocks returns |n| connected mock Blockservices
func Mocks(t fataler, n int) []*BlockService {
	net := tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(0))
	sg := bitswap.NewTestSessionGenerator(net)

	instances := sg.Instances(n)

	var servs []*BlockService
	for _, i := range instances {
		bserv, err := New(i.Blockstore(), i.Exchange)
		if err != nil {
			t.Fatal(err)
		}
		servs = append(servs, bserv)
	}
	return servs
}

func TestProviderForKeyButNetworkCannotFind(t *testing.T) { // TODO revisit this

	rs := mockrouting.NewServer()
	net := tn.VirtualNetwork(rs, delay.Fixed(kNetworkDelay))
	g := NewTestSessionGenerator(net)
	defer g.Close()

	block := blocks.NewBlock([]byte("block"))
	pinfo := p2ptestutil.RandTestBogusIdentityOrFatal(t)
	rs.Client(pinfo).Provide(context.Background(), block.Key()) // but not on network

	solo := g.Next()
	defer solo.Exchange.Close()

	ctx, _ := context.WithTimeout(context.Background(), time.Nanosecond)
	_, err := solo.Exchange.GetBlock(ctx, block.Key())

	if err != context.DeadlineExceeded {
		t.Fatal("Expected DeadlineExceeded error")
	}
}

func BenchmarkWithConfig(c worker.Config) func(b *testing.B) {
	return func(b *testing.B) {

		routingDelay := delay.Fixed(0) // during setup

		dstore := ds_sync.MutexWrap(datastore2.WithDelay(ds.NewMapDatastore(), routingDelay))
		bstore := blockstore.NewBlockstore(dstore)
		var testdata []*blocks.Block
		var i int64
		for i = 0; i < kBlocksPerOp; i++ {
			testdata = append(testdata, blocks.NewBlock([]byte(string(i))))
		}
		b.ResetTimer()
		b.SetBytes(kBlocksPerOp)
		for i := 0; i < b.N; i++ {

			b.StopTimer()
			w := worker.NewWorker(offline.Exchange(bstore), c)
			b.StartTimer()

			prev := routingDelay.Set(kEstRoutingDelay) // during measured section

			for _, block := range testdata {
				if err := w.HasBlock(block); err != nil {
					b.Fatal(err)
				}
			}

			routingDelay.Set(prev) // to hasten the unmeasured close period

			b.StopTimer()
			w.Close()
			b.StartTimer()

		}
	}
}

func getVirtualNetwork() tn.Network {
	return tn.VirtualNetwork(mockrouting.NewServer(), delay.Fixed(kNetworkDelay))
}

var (
	HasBlockBufferSize    = 256
	provideKeysBufferSize = 2048
	provideWorkerMax      = 512
)

func init() {
	if flags.LowMemMode {
		HasBlockBufferSize = 64
		provideKeysBufferSize = 512
		provideWorkerMax = 16
	}
}

var rebroadcastDelay = delay.Fixed(time.Minute)

// New initializes a BitSwap instance that communicates over the provided
// BitSwapNetwork. This function registers the returned instance as the network
// delegate.
// Runs until context is cancelled.
func New(parent context.Context, p peer.ID, network bsnet.BitSwapNetwork,
	bstore blockstore.Blockstore, nice bool) exchange.Interface {

	// important to use provided parent context (since it may include important
	// loggable data). It's probably not a good idea to allow bitswap to be
	// coupled to the concerns of the ipfs daemon in this way.
	//
	// FIXME(btc) Now that bitswap manages itself using a process, it probably
	// shouldn't accept a context anymore. Clients should probably use Close()
	// exclusively. We should probably find another way to share logging data

// NewServer returns a mockrouting Server
func NewServer() Server {
	return NewServerWithDelay(DelayConfig{
		ValueVisibility: delay.Fixed(0),
		Query:           delay.Fixed(0),
	})
}