package connmgr

import (
	"context"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/benbjohnson/clock"
	"github.com/libp2p/go-libp2p/core/crypto"
	"github.com/libp2p/go-libp2p/core/network"
	"github.com/libp2p/go-libp2p/core/peer"
	tu "github.com/libp2p/go-libp2p/core/test"

	ma "github.com/multiformats/go-multiaddr"
	"github.com/stretchr/testify/require"
)

type tconn struct {
	network.Conn

	peer             peer.ID
	closed           uint32 // to be used atomically. Closed if 1
	disconnectNotify func(net network.Network, conn network.Conn)
}

func (c *tconn) Close() error {
	atomic.StoreUint32(&c.closed, 1)
	if c.disconnectNotify != nil {
		c.disconnectNotify(nil, c)
	}
	return nil
}

func (c *tconn) isClosed() bool {
	return atomic.LoadUint32(&c.closed) == 1
}

func (c *tconn) RemotePeer() peer.ID {
	return c.peer
}

func (c *tconn) Stat() network.ConnStats {
	return network.ConnStats{
		Stats: network.Stats{
			Direction: network.DirOutbound,
		},
		NumStreams: 1,
	}
}

func (c *tconn) RemoteMultiaddr() ma.Multiaddr {
	addr, err := ma.NewMultiaddr("/ip4/127.0.0.1/udp/1234")
	if err != nil {
		panic("cannot create multiaddr")
	}
	return addr
}

func randConn(t testing.TB, discNotify func(network.Network, network.Conn)) network.Conn {
	pid := tu.RandPeerIDFatal(t)
	return &tconn{peer: pid, disconnectNotify: discNotify}
}

// Make sure multiple trim calls block.
func TestTrimBlocks(t *testing.T) {
	cm, err := NewConnManager(200, 300, WithGracePeriod(0))
	require.NoError(t, err)
	defer cm.Close()

	cm.lastTrimMu.RLock()

	doneCh := make(chan struct{}, 2)
	go func() {
		cm.TrimOpenConns(context.Background())
		doneCh <- struct{}{}
	}()
	go func() {
		cm.TrimOpenConns(context.Background())
		doneCh <- struct{}{}
	}()
	time.Sleep(time.Millisecond)
	select {
	case <-doneCh:
		cm.lastTrimMu.RUnlock()
		t.Fatal("expected trim to block")
	default:
		cm.lastTrimMu.RUnlock()
	}
	<-doneCh
	<-doneCh
}

// Make sure trim returns when closed.
func TestTrimClosed(t *testing.T) {
	cm, err := NewConnManager(200, 300, WithGracePeriod(0))
	require.NoError(t, err)
	require.NoError(t, cm.Close())
	cm.TrimOpenConns(context.Background())
}

// Make sure joining an existing trim works.
func TestTrimJoin(t *testing.T) {
	cm, err := NewConnManager(200, 300, WithGracePeriod(0))
	require.NoError(t, err)
	defer cm.Close()

	cm.lastTrimMu.RLock()
	var wg sync.WaitGroup
	wg.Add(3)
	go func() {
		defer wg.Done()
		cm.TrimOpenConns(context.Background())
	}()
	time.Sleep(time.Millisecond)
	go func() {
		defer wg.Done()
		cm.TrimOpenConns(context.Background())
	}()
	go func() {
		defer wg.Done()
		cm.TrimOpenConns(context.Background())
	}()
	time.Sleep(time.Millisecond)
	cm.lastTrimMu.RUnlock()
	wg.Wait()
}

func TestConnTrimming(t *testing.T) {
	cm, err := NewConnManager(200, 300, WithGracePeriod(0))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()

	var conns []network.Conn
	for i := 0; i < 300; i++ {
		rc := randConn(t, nil)
		conns = append(conns, rc)
		not.Connected(nil, rc)
	}

	for _, c := range conns {
		if c.(*tconn).isClosed() {
			t.Fatal("nothing should be closed yet")
		}
	}

	for i := 0; i < 100; i++ {
		cm.TagPeer(conns[i].RemotePeer(), "foo", 10)
	}

	cm.TagPeer(conns[299].RemotePeer(), "badfoo", -5)

	cm.TrimOpenConns(context.Background())

	for i := 0; i < 100; i++ {
		c := conns[i]
		if c.(*tconn).isClosed() {
			t.Fatal("these shouldnt be closed")
		}
	}

	if !conns[299].(*tconn).isClosed() {
		t.Fatal("conn with bad tag should have gotten closed")
	}
}

func TestConnsToClose(t *testing.T) {
	addConns := func(cm *BasicConnMgr, n int) {
		not := cm.Notifee()
		for i := 0; i < n; i++ {
			conn := randConn(t, nil)
			not.Connected(nil, conn)
		}
	}

	t.Run("below hi limit", func(t *testing.T) {
		cm, err := NewConnManager(0, 10, WithGracePeriod(0))
		require.NoError(t, err)
		defer cm.Close()
		addConns(cm, 5)
		require.Empty(t, cm.getConnsToClose())
	})

	t.Run("below low limit", func(t *testing.T) {
		cm, err := NewConnManager(10, 0, WithGracePeriod(0))
		require.NoError(t, err)
		defer cm.Close()
		addConns(cm, 5)
		require.Empty(t, cm.getConnsToClose())
	})

	t.Run("below low and hi limit", func(t *testing.T) {
		cm, err := NewConnManager(1, 1, WithGracePeriod(0))
		require.NoError(t, err)
		defer cm.Close()
		addConns(cm, 1)
		require.Empty(t, cm.getConnsToClose())
	})

	t.Run("within silence period", func(t *testing.T) {
		cm, err := NewConnManager(1, 1, WithGracePeriod(10*time.Minute))
		require.NoError(t, err)
		defer cm.Close()
		addConns(cm, 1)
		require.Empty(t, cm.getConnsToClose())
	})
}

func TestGetTagInfo(t *testing.T) {
	start := time.Now()
	cm, err := NewConnManager(1, 1, WithGracePeriod(10*time.Minute))
	require.NoError(t, err)
	defer cm.Close()

	not := cm.Notifee()
	conn := randConn(t, nil)
	not.Connected(nil, conn)
	end := time.Now()

	other := tu.RandPeerIDFatal(t)
	tag := cm.GetTagInfo(other)
	if tag != nil {
		t.Fatal("expected no tag")
	}

	tag = cm.GetTagInfo(conn.RemotePeer())
	if tag == nil {
		t.Fatal("expected tag")
	}
	if tag.FirstSeen.Before(start) || tag.FirstSeen.After(end) {
		t.Fatal("expected first seen time")
	}
	if tag.Value != 0 {
		t.Fatal("expected zero value")
	}
	if len(tag.Tags) != 0 {
		t.Fatal("expected no tags")
	}
	if len(tag.Conns) != 1 {
		t.Fatal("expected one connection")
	}
	for s, tm := range tag.Conns {
		if s != conn.RemoteMultiaddr().String() {
			t.Fatal("unexpected multiaddr")
		}
		if tm.Before(start) || tm.After(end) {
			t.Fatal("unexpected connection time")
		}
	}

	cm.TagPeer(conn.RemotePeer(), "tag", 5)
	tag = cm.GetTagInfo(conn.RemotePeer())
	if tag == nil {
		t.Fatal("expected tag")
	}
	if tag.FirstSeen.Before(start) || tag.FirstSeen.After(end) {
		t.Fatal("expected first seen time")
	}
	if tag.Value != 5 {
		t.Fatal("expected five value")
	}
	if len(tag.Tags) != 1 {
		t.Fatal("expected no tags")
	}
	for tString, v := range tag.Tags {
		if tString != "tag" || v != 5 {
			t.Fatal("expected tag value")
		}
	}
	if len(tag.Conns) != 1 {
		t.Fatal("expected one connection")
	}
	for s, tm := range tag.Conns {
		if s != conn.RemoteMultiaddr().String() {
			t.Fatal("unexpected multiaddr")
		}
		if tm.Before(start) || tm.After(end) {
			t.Fatal("unexpected connection time")
		}
	}
}

func TestTagPeerNonExistant(t *testing.T) {
	cm, err := NewConnManager(1, 1, WithGracePeriod(10*time.Minute))
	require.NoError(t, err)
	defer cm.Close()

	id := tu.RandPeerIDFatal(t)
	cm.TagPeer(id, "test", 1)

	if !cm.segments.get(id).peers[id].temp {
		t.Fatal("expected 1 temporary entry")
	}
}

func TestUntagPeer(t *testing.T) {
	cm, err := NewConnManager(1, 1, WithGracePeriod(10*time.Minute))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()

	conn := randConn(t, nil)
	not.Connected(nil, conn)
	rp := conn.RemotePeer()
	cm.TagPeer(rp, "tag", 5)
	cm.TagPeer(rp, "tag two", 5)

	id := tu.RandPeerIDFatal(t)
	cm.UntagPeer(id, "test")
	if len(cm.segments.get(rp).peers[rp].tags) != 2 {
		t.Fatal("expected tags to be uneffected")
	}

	cm.UntagPeer(conn.RemotePeer(), "test")
	if len(cm.segments.get(rp).peers[rp].tags) != 2 {
		t.Fatal("expected tags to be uneffected")
	}

	cm.UntagPeer(conn.RemotePeer(), "tag")
	if len(cm.segments.get(rp).peers[rp].tags) != 1 {
		t.Fatal("expected tag to be removed")
	}
	if cm.segments.get(rp).peers[rp].value != 5 {
		t.Fatal("expected aggreagte tag value to be 5")
	}
}

func TestGetInfo(t *testing.T) {
	start := time.Now()
	const gp = 10 * time.Minute
	cm, err := NewConnManager(1, 5, WithGracePeriod(gp))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()
	conn := randConn(t, nil)
	not.Connected(nil, conn)
	cm.TrimOpenConns(context.Background())
	end := time.Now()

	info := cm.GetInfo()
	if info.HighWater != 5 {
		t.Fatal("expected highwater to be 5")
	}
	if info.LowWater != 1 {
		t.Fatal("expected highwater to be 1")
	}
	if info.LastTrim.Before(start) || info.LastTrim.After(end) {
		t.Fatal("unexpected last trim time")
	}
	if info.GracePeriod != gp {
		t.Fatal("unexpected grace period")
	}
	if info.ConnCount != 1 {
		t.Fatal("unexpected number of connections")
	}
}

func TestDoubleConnection(t *testing.T) {
	const gp = 10 * time.Minute
	cm, err := NewConnManager(1, 5, WithGracePeriod(gp))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()
	conn := randConn(t, nil)
	not.Connected(nil, conn)
	cm.TagPeer(conn.RemotePeer(), "foo", 10)
	not.Connected(nil, conn)
	if cm.connCount.Load() != 1 {
		t.Fatal("unexpected number of connections")
	}
	if cm.segments.get(conn.RemotePeer()).peers[conn.RemotePeer()].value != 10 {
		t.Fatal("unexpected peer value")
	}
}

func TestDisconnected(t *testing.T) {
	const gp = 10 * time.Minute
	cm, err := NewConnManager(1, 5, WithGracePeriod(gp))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()
	conn := randConn(t, nil)
	not.Connected(nil, conn)
	cm.TagPeer(conn.RemotePeer(), "foo", 10)

	not.Disconnected(nil, randConn(t, nil))
	if cm.connCount.Load() != 1 {
		t.Fatal("unexpected number of connections")
	}
	if cm.segments.get(conn.RemotePeer()).peers[conn.RemotePeer()].value != 10 {
		t.Fatal("unexpected peer value")
	}

	not.Disconnected(nil, &tconn{peer: conn.RemotePeer()})
	if cm.connCount.Load() != 1 {
		t.Fatal("unexpected number of connections")
	}
	if cm.segments.get(conn.RemotePeer()).peers[conn.RemotePeer()].value != 10 {
		t.Fatal("unexpected peer value")
	}

	not.Disconnected(nil, conn)
	if cm.connCount.Load() != 0 {
		t.Fatal("unexpected number of connections")
	}
	if cm.segments.countPeers() != 0 {
		t.Fatal("unexpected number of peers")
	}
}

func TestGracePeriod(t *testing.T) {
	const gp = 100 * time.Millisecond
	mockClock := clock.NewMock()
	cm, err := NewConnManager(10, 20, WithGracePeriod(gp), WithSilencePeriod(time.Hour), WithClock(mockClock))
	require.NoError(t, err)
	defer cm.Close()

	not := cm.Notifee()

	var conns []network.Conn

	// Add a connection and wait the grace period.
	{
		rc := randConn(t, not.Disconnected)
		conns = append(conns, rc)
		not.Connected(nil, rc)

		mockClock.Add(2 * gp)

		if rc.(*tconn).isClosed() {
			t.Fatal("expected conn to remain open")
		}
	}

	// quickly add 30 connections (sending us above the high watermark)
	for i := 0; i < 30; i++ {
		rc := randConn(t, not.Disconnected)
		conns = append(conns, rc)
		not.Connected(nil, rc)
	}

	cm.TrimOpenConns(context.Background())

	for _, c := range conns {
		if c.(*tconn).isClosed() {
			t.Fatal("expected no conns to be closed")
		}
	}

	mockClock.Add(200 * time.Millisecond)

	cm.TrimOpenConns(context.Background())

	closed := 0
	for _, c := range conns {
		if c.(*tconn).isClosed() {
			closed++
		}
	}

	if closed != 21 {
		t.Fatal("expected to have closed 21 connections")
	}
}

// see https://github.com/libp2p/go-libp2p-connmgr/issues/23
func TestQuickBurstRespectsSilencePeriod(t *testing.T) {
	mockClock := clock.NewMock()
	cm, err := NewConnManager(10, 20, WithGracePeriod(0), WithClock(mockClock))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()

	var conns []network.Conn

	// quickly produce 30 connections (sending us above the high watermark)
	for i := 0; i < 30; i++ {
		rc := randConn(t, not.Disconnected)
		conns = append(conns, rc)
		not.Connected(nil, rc)
	}

	// wait for a few seconds
	mockClock.Add(3 * time.Second)

	// only the first trim is allowed in; make sure we close at most 20 connections, not all of them.
	var closed int
	for _, c := range conns {
		if c.(*tconn).isClosed() {
			closed++
		}
	}
	if closed > 20 {
		t.Fatalf("should have closed at most 20 connections, closed: %d", closed)
	}
	if total := closed + int(cm.connCount.Load()); total != 30 {
		t.Fatalf("expected closed connections + open conn count to equal 30, value: %d", total)
	}
}

func TestPeerProtectionSingleTag(t *testing.T) {
	cm, err := NewConnManager(19, 20, WithGracePeriod(0), WithSilencePeriod(time.Hour))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()

	var conns []network.Conn
	addConn := func(value int) {
		rc := randConn(t, not.Disconnected)
		conns = append(conns, rc)
		not.Connected(nil, rc)
		cm.TagPeer(rc.RemotePeer(), "test", value)
	}

	// produce 20 connections with unique peers.
	for i := 0; i < 20; i++ {
		addConn(20)
	}

	// protect the first 5 peers.
	var protected []network.Conn
	for _, c := range conns[0:5] {
		cm.Protect(c.RemotePeer(), "global")
		protected = append(protected, c)
		// tag them negatively to make them preferred for pruning.
		cm.TagPeer(c.RemotePeer(), "test", -100)
	}

	// add 1 more conn, this shouldn't send us over the limit as protected conns don't count
	addConn(20)

	time.Sleep(100 * time.Millisecond)
	cm.TrimOpenConns(context.Background())

	for _, c := range conns {
		if c.(*tconn).isClosed() {
			t.Error("connection was closed by connection manager")
		}
	}

	// add 5 more connection, sending the connection manager overboard.
	for i := 0; i < 5; i++ {
		addConn(20)
	}

	cm.TrimOpenConns(context.Background())

	for _, c := range protected {
		if c.(*tconn).isClosed() {
			t.Error("protected connection was closed by connection manager")
		}
	}

	closed := 0
	for _, c := range conns {
		if c.(*tconn).isClosed() {
			closed++
		}
	}
	if closed != 2 {
		t.Errorf("expected 2 connection to be closed, found %d", closed)
	}

	// unprotect the first peer.
	cm.Unprotect(protected[0].RemotePeer(), "global")

	// add 2 more connections, sending the connection manager overboard again.
	for i := 0; i < 2; i++ {
		addConn(20)
	}

	cm.TrimOpenConns(context.Background())

	if !protected[0].(*tconn).isClosed() {
		t.Error("unprotected connection was kept open by connection manager")
	}
	for _, c := range protected[1:] {
		if c.(*tconn).isClosed() {
			t.Error("protected connection was closed by connection manager")
		}
	}
}

func TestPeerProtectionMultipleTags(t *testing.T) {
	cm, err := NewConnManager(19, 20, WithGracePeriod(0), WithSilencePeriod(time.Hour))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()

	// produce 20 connections with unique peers.
	var conns []network.Conn
	for i := 0; i < 20; i++ {
		rc := randConn(t, not.Disconnected)
		conns = append(conns, rc)
		not.Connected(nil, rc)
		cm.TagPeer(rc.RemotePeer(), "test", 20)
	}

	// protect the first 5 peers under two tags.
	var protected []network.Conn
	for _, c := range conns[0:5] {
		cm.Protect(c.RemotePeer(), "tag1")
		cm.Protect(c.RemotePeer(), "tag2")
		protected = append(protected, c)
		// tag them negatively to make them preferred for pruning.
		cm.TagPeer(c.RemotePeer(), "test", -100)
	}

	// add one more connection, sending the connection manager overboard.
	not.Connected(nil, randConn(t, not.Disconnected))

	cm.TrimOpenConns(context.Background())

	for _, c := range protected {
		if c.(*tconn).isClosed() {
			t.Error("protected connection was closed by connection manager")
		}
	}

	// remove the protection from one tag.
	for _, c := range protected {
		if !cm.Unprotect(c.RemotePeer(), "tag1") {
			t.Error("peer should still be protected")
		}
	}

	// add 2 more connections, sending the connection manager overboard again.
	for i := 0; i < 2; i++ {
		rc := randConn(t, not.Disconnected)
		not.Connected(nil, rc)
		cm.TagPeer(rc.RemotePeer(), "test", 20)
	}

	cm.TrimOpenConns(context.Background())

	// connections should still remain open, as they were protected.
	for _, c := range protected[0:] {
		if c.(*tconn).isClosed() {
			t.Error("protected connection was closed by connection manager")
		}
	}

	// unprotect the first peer entirely.
	cm.Unprotect(protected[0].RemotePeer(), "tag2")

	// add 2 more connections, sending the connection manager overboard again.
	for i := 0; i < 2; i++ {
		rc := randConn(t, not.Disconnected)
		not.Connected(nil, rc)
		cm.TagPeer(rc.RemotePeer(), "test", 20)
	}

	cm.TrimOpenConns(context.Background())

	if !protected[0].(*tconn).isClosed() {
		t.Error("unprotected connection was kept open by connection manager")
	}
	for _, c := range protected[1:] {
		if c.(*tconn).isClosed() {
			t.Error("protected connection was closed by connection manager")
		}
	}

}

func TestPeerProtectionIdempotent(t *testing.T) {
	cm, err := NewConnManager(10, 20, WithGracePeriod(0), WithSilencePeriod(time.Hour))
	require.NoError(t, err)
	defer cm.Close()

	id, _ := tu.RandPeerID()
	cm.Protect(id, "global")
	cm.Protect(id, "global")
	cm.Protect(id, "global")
	cm.Protect(id, "global")

	if len(cm.protected[id]) > 1 {
		t.Error("expected peer to be protected only once")
	}

	if !cm.Unprotect(id, "unused") {
		t.Error("expected peer to continue to be protected")
	}

	if !cm.Unprotect(id, "unused2") {
		t.Error("expected peer to continue to be protected")
	}

	if cm.Unprotect(id, "global") {
		t.Error("expected peer to be unprotected")
	}

	if len(cm.protected) > 0 {
		t.Error("expected no protections")
	}
}

func TestUpsertTag(t *testing.T) {
	cm, err := NewConnManager(1, 1, WithGracePeriod(10*time.Minute))
	require.NoError(t, err)
	defer cm.Close()
	not := cm.Notifee()
	conn := randConn(t, nil)
	rp := conn.RemotePeer()

	// this is an early tag, before the Connected notification arrived.
	cm.UpsertTag(rp, "tag", func(v int) int { return v + 1 })
	if len(cm.segments.get(rp).peers[rp].tags) != 1 {
		t.Fatal("expected a tag")
	}
	if cm.segments.get(rp).peers[rp].value != 1 {
		t.Fatal("expected a tag value of 1")
	}

	// now let's notify the connection.
	not.Connected(nil, conn)

	cm.UpsertTag(rp, "tag", func(v int) int { return v + 1 })
	if len(cm.segments.get(rp).peers[rp].tags) != 1 {
		t.Fatal("expected a tag")
	}
	if cm.segments.get(rp).peers[rp].value != 2 {
		t.Fatal("expected a tag value of 2")
	}

	cm.UpsertTag(rp, "tag", func(v int) int { return v - 1 })
	if len(cm.segments.get(rp).peers[rp].tags) != 1 {
		t.Fatal("expected a tag")
	}
	if cm.segments.get(rp).peers[rp].value != 1 {
		t.Fatal("expected a tag value of 1")
	}
}

func TestTemporaryEntriesClearedFirst(t *testing.T) {
	cm, err := NewConnManager(1, 1, WithGracePeriod(0))
	require.NoError(t, err)

	id := tu.RandPeerIDFatal(t)
	cm.TagPeer(id, "test", 20)

	if cm.GetTagInfo(id).Value != 20 {
		t.Fatal("expected an early tag with value 20")
	}

	not := cm.Notifee()
	conn1, conn2 := randConn(t, nil), randConn(t, nil)
	not.Connected(nil, conn1)
	not.Connected(nil, conn2)

	cm.TrimOpenConns(context.Background())
	if cm.GetTagInfo(id) != nil {
		t.Fatal("expected no temporary tags after trimming")
	}
}

func TestTemporaryEntryConvertedOnConnection(t *testing.T) {
	cm, err := NewConnManager(1, 1, WithGracePeriod(0))
	require.NoError(t, err)
	defer cm.Close()

	conn := randConn(t, nil)
	cm.TagPeer(conn.RemotePeer(), "test", 20)

	ti := cm.segments.get(conn.RemotePeer()).peers[conn.RemotePeer()]

	if ti.value != 20 || !ti.temp {
		t.Fatal("expected a temporary tag with value 20")
	}

	not := cm.Notifee()
	not.Connected(nil, conn)

	if ti.value != 20 || ti.temp {
		t.Fatal("expected a non-temporary tag with value 20")
	}
}

// see https://github.com/libp2p/go-libp2p-connmgr/issues/82
func TestConcurrentCleanupAndTagging(t *testing.T) {
	cm, err := NewConnManager(1, 1, WithGracePeriod(0), WithSilencePeriod(time.Millisecond))
	require.NoError(t, err)
	defer cm.Close()

	for i := 0; i < 1000; i++ {
		conn := randConn(t, nil)
		cm.TagPeer(conn.RemotePeer(), "test", 20)
	}
}

type mockConn struct {
	stats network.ConnStats
}

func (m mockConn) Close() error                                          { panic("implement me") }
func (m mockConn) LocalPeer() peer.ID                                    { panic("implement me") }
func (m mockConn) RemotePeer() peer.ID                                   { panic("implement me") }
func (m mockConn) RemotePublicKey() crypto.PubKey                        { panic("implement me") }
func (m mockConn) LocalMultiaddr() ma.Multiaddr                          { panic("implement me") }
func (m mockConn) RemoteMultiaddr() ma.Multiaddr                         { panic("implement me") }
func (m mockConn) Stat() network.ConnStats                               { return m.stats }
func (m mockConn) ID() string                                            { panic("implement me") }
func (m mockConn) IsClosed() bool                                        { panic("implement me") }
func (m mockConn) NewStream(ctx context.Context) (network.Stream, error) { panic("implement me") }
func (m mockConn) GetStreams() []network.Stream                          { panic("implement me") }
func (m mockConn) Scope() network.ConnScope                              { panic("implement me") }
func (m mockConn) ConnState() network.ConnectionState                    { return network.ConnectionState{} }

func makeSegmentsWithPeerInfos(peerInfos peerInfos) *segments {
	var s = func() *segments {
		ret := segments{}
		for i := range ret.buckets {
			ret.buckets[i] = &segment{
				peers: make(map[peer.ID]*peerInfo),
			}
		}
		return &ret
	}()

	for _, pi := range peerInfos {
		segment := s.get(pi.id)
		segment.Lock()
		segment.peers[pi.id] = pi
		segment.Unlock()
	}

	return s
}

func TestPeerInfoSorting(t *testing.T) {
	t.Run("starts with temporary connections", func(t *testing.T) {
		p1 := &peerInfo{id: peer.ID("peer1")}
		p2 := &peerInfo{id: peer.ID("peer2"), temp: true}
		pis := peerInfos{p1, p2}
		pis.SortByValueAndStreams(makeSegmentsWithPeerInfos(pis), false)
		require.Equal(t, pis, peerInfos{p2, p1})
	})

	t.Run("starts with low-value connections", func(t *testing.T) {
		p1 := &peerInfo{id: peer.ID("peer1"), value: 40}
		p2 := &peerInfo{id: peer.ID("peer2"), value: 20}
		pis := peerInfos{p1, p2}
		pis.SortByValueAndStreams(makeSegmentsWithPeerInfos(pis), false)
		require.Equal(t, pis, peerInfos{p2, p1})
	})

	t.Run("prefer peers with no streams", func(t *testing.T) {
		p1 := &peerInfo{id: peer.ID("peer1"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: network.ConnStats{NumStreams: 0}}: time.Now(),
			},
		}
		p2 := &peerInfo{id: peer.ID("peer2"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: network.ConnStats{NumStreams: 1}}: time.Now(),
			},
		}
		pis := peerInfos{p2, p1}
		pis.SortByValueAndStreams(makeSegmentsWithPeerInfos(pis), false)
		require.Equal(t, pis, peerInfos{p1, p2})
	})

	t.Run("in a memory emergency, starts with incoming connections and higher streams", func(t *testing.T) {
		incoming := network.ConnStats{}
		incoming.Direction = network.DirInbound
		outgoing := network.ConnStats{}
		outgoing.Direction = network.DirOutbound

		outgoingSomeStreams := network.ConnStats{Stats: network.Stats{Direction: network.DirOutbound}, NumStreams: 1}
		outgoingMoreStreams := network.ConnStats{Stats: network.Stats{Direction: network.DirOutbound}, NumStreams: 2}
		p1 := &peerInfo{
			id: peer.ID("peer1"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: outgoingSomeStreams}: time.Now(),
			},
		}
		p2 := &peerInfo{
			id: peer.ID("peer2"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: outgoingSomeStreams}: time.Now(),
				&mockConn{stats: incoming}:            time.Now(),
			},
		}
		p3 := &peerInfo{
			id: peer.ID("peer3"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: outgoing}: time.Now(),
				&mockConn{stats: incoming}: time.Now(),
			},
		}
		p4 := &peerInfo{
			id: peer.ID("peer4"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: outgoingMoreStreams}: time.Now(),
				&mockConn{stats: incoming}:            time.Now(),
			},
		}
		pis := peerInfos{p1, p2, p3, p4}
		pis.SortByValueAndStreams(makeSegmentsWithPeerInfos(pis), true)
		// p3 is first because it is inactive (no streams).
		// p4 is second because it has the most streams and we priortize killing
		// connections with the higher number of streams.
		require.Equal(t, pis, peerInfos{p3, p4, p2, p1})
	})

	t.Run("in a memory emergency, starts with connections that have many streams", func(t *testing.T) {
		p1 := &peerInfo{
			id: peer.ID("peer1"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: network.ConnStats{NumStreams: 100}}: time.Now(),
			},
		}
		p2 := &peerInfo{
			id: peer.ID("peer2"),
			conns: map[network.Conn]time.Time{
				&mockConn{stats: network.ConnStats{NumStreams: 80}}: time.Now(),
				&mockConn{stats: network.ConnStats{NumStreams: 40}}: time.Now(),
			},
		}
		pis := peerInfos{p1, p2}
		pis.SortByValueAndStreams(makeSegmentsWithPeerInfos(pis), true)
		require.Equal(t, pis, peerInfos{p2, p1})
	})
}

func TestSafeConcurrency(t *testing.T) {
	t.Run("Safe Concurrency", func(t *testing.T) {
		cl := clock.NewMock()

		p1 := &peerInfo{id: peer.ID("peer1"), conns: map[network.Conn]time.Time{}}
		p2 := &peerInfo{id: peer.ID("peer2"), conns: map[network.Conn]time.Time{}}
		pis := peerInfos{p1, p2}

		ss := makeSegmentsWithPeerInfos(pis)

		const runs = 10
		const concurrency = 10
		var wg sync.WaitGroup
		for i := 0; i < concurrency; i++ {
			wg.Add(1)
			go func() {
				// add conns. This mimics new connection events
				pis := peerInfos{p1, p2}
				for i := 0; i < runs; i++ {
					pi := pis[i%len(pis)]
					s := ss.get(pi.id)
					s.Lock()
					s.peers[pi.id].conns[randConn(t, nil)] = cl.Now()
					s.Unlock()
				}
				wg.Done()
			}()

			wg.Add(1)
			go func() {
				pis := peerInfos{p1, p2}
				for i := 0; i < runs; i++ {
					pis.SortByValueAndStreams(ss, false)
				}
				wg.Done()
			}()
		}

		wg.Wait()
	})
}