package swarm

import (
	"net"
	"sort"
	"sync"
	"testing"
	"time"

	addrutil "github.com/ipfs/go-libp2p/p2p/net/swarm/addr"
	peer "github.com/ipfs/go-libp2p/p2p/peer"

	testutil "github.com/ipfs/go-libp2p/testutil"
	ci "github.com/ipfs/go-libp2p/testutil/ci"

	manet "gx/ipfs/QmQB7mNP3QE7b4zP2MQmsyJDqG5hzYE2CL8k1VyLWky2Ed/go-multiaddr-net"
	context "gx/ipfs/QmZy2y8t9zQH2a1b8q2ZSLKp17ATuJoCNxxyMFG5qFExpt/go-net/context"
	ma "gx/ipfs/QmcobAGsCjYt5DXoq9et9L8yR8er7o7Cu3DTvpaq12jYSz/go-multiaddr"
)

func acceptAndHang(l net.Listener) {
	conns := make([]net.Conn, 0, 10)
	for {
		c, err := l.Accept()
		if err != nil {
			break
		}
		if c != nil {
			conns = append(conns, c)
		}
	}
	for _, c := range conns {
		c.Close()
	}
}

func TestSimultDials(t *testing.T) {
	// t.Skip("skipping for another test")
	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)

	// connect everyone
	{
		var wg sync.WaitGroup
		connect := func(s *Swarm, dst peer.ID, addr ma.Multiaddr) {
			// copy for other peer
			log.Debugf("TestSimultOpen: connecting: %s --> %s (%s)", s.local, dst, addr)
			s.peers.AddAddr(dst, addr, peer.TempAddrTTL)
			if _, err := s.Dial(ctx, dst); err != nil {
				t.Fatal("error swarm dialing to peer", err)
			}
			wg.Done()
		}

		ifaceAddrs0, err := swarms[0].InterfaceListenAddresses()
		if err != nil {
			t.Fatal(err)
		}
		ifaceAddrs1, err := swarms[1].InterfaceListenAddresses()
		if err != nil {
			t.Fatal(err)
		}

		log.Info("Connecting swarms simultaneously.")
		for i := 0; i < 10; i++ { // connect 10x for each.
			wg.Add(2)
			go connect(swarms[0], swarms[1].local, ifaceAddrs1[0])
			go connect(swarms[1], swarms[0].local, ifaceAddrs0[0])
		}
		wg.Wait()
	}

	// should still just have 1, at most 2 connections :)
	c01l := len(swarms[0].ConnectionsToPeer(swarms[1].local))
	if c01l > 2 {
		t.Error("0->1 has", c01l)
	}
	c10l := len(swarms[1].ConnectionsToPeer(swarms[0].local))
	if c10l > 2 {
		t.Error("1->0 has", c10l)
	}

	for _, s := range swarms {
		s.Close()
	}
}

func newSilentPeer(t *testing.T) (peer.ID, ma.Multiaddr, net.Listener) {
	dst := testutil.RandPeerIDFatal(t)
	lst, err := net.Listen("tcp", ":0")
	if err != nil {
		t.Fatal(err)
	}
	addr, err := manet.FromNetAddr(lst.Addr())
	if err != nil {
		t.Fatal(err)
	}
	addrs := []ma.Multiaddr{addr}
	addrs, err = addrutil.ResolveUnspecifiedAddresses(addrs, nil)
	if err != nil {
		t.Fatal(err)
	}
	t.Log("new silent peer:", dst, addrs[0])
	return dst, addrs[0], lst
}

func TestDialWait(t *testing.T) {
	// t.Skip("skipping for another test")
	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 1)
	s1 := swarms[0]
	defer s1.Close()

	s1.dialT = time.Millisecond * 300 // lower timeout for tests.
	if ci.IsRunning() {
		s1.dialT = time.Second
	}

	// dial to a non-existent peer.
	s2p, s2addr, s2l := newSilentPeer(t)
	go acceptAndHang(s2l)
	defer s2l.Close()
	s1.peers.AddAddr(s2p, s2addr, peer.PermanentAddrTTL)

	before := time.Now()
	if c, err := s1.Dial(ctx, s2p); err == nil {
		defer c.Close()
		t.Fatal("error swarm dialing to unknown peer worked...", err)
	} else {
		t.Log("correctly got error:", err)
	}
	duration := time.Now().Sub(before)

	dt := s1.dialT
	if duration < dt*dialAttempts {
		t.Error("< DialTimeout * dialAttempts not being respected", duration, dt*dialAttempts)
	}
	if duration > 2*dt*dialAttempts {
		t.Error("> 2*DialTimeout * dialAttempts not being respected", duration, 2*dt*dialAttempts)
	}

	if !s1.backf.Backoff(s2p) {
		t.Error("s2 should now be on backoff")
	}
}

func TestDialBackoff(t *testing.T) {
	// t.Skip("skipping for another test")
	if ci.IsRunning() {
		t.Skip("travis will never have fun with this test")
	}

	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)
	s1 := swarms[0]
	s2 := swarms[1]
	defer s1.Close()
	defer s2.Close()

	s1.dialT = time.Second // lower timeout for tests.
	s2.dialT = time.Second // lower timeout for tests.

	s2addrs, err := s2.InterfaceListenAddresses()
	if err != nil {
		t.Fatal(err)
	}
	s1.peers.AddAddrs(s2.local, s2addrs, peer.PermanentAddrTTL)

	// dial to a non-existent peer.
	s3p, s3addr, s3l := newSilentPeer(t)
	go acceptAndHang(s3l)
	defer s3l.Close()
	s1.peers.AddAddr(s3p, s3addr, peer.PermanentAddrTTL)

	// in this test we will:
	//   1) dial 10x to each node.
	//   2) all dials should hang
	//   3) s1->s2 should succeed.
	//   4) s1->s3 should not (and should place s3 on backoff)
	//   5) disconnect entirely
	//   6) dial 10x to each node again
	//   7) s3 dials should all return immediately (except 1)
	//   8) s2 dials should all hang, and succeed
	//   9) last s3 dial ends, unsuccessful

	dialOnlineNode := func(dst peer.ID, times int) <-chan bool {
		ch := make(chan bool)
		for i := 0; i < times; i++ {
			go func() {
				if _, err := s1.Dial(ctx, dst); err != nil {
					t.Error("error dialing", dst, err)
					ch <- false
				} else {
					ch <- true
				}
			}()
		}
		return ch
	}

	dialOfflineNode := func(dst peer.ID, times int) <-chan bool {
		ch := make(chan bool)
		for i := 0; i < times; i++ {
			go func() {
				if c, err := s1.Dial(ctx, dst); err != nil {
					ch <- false
				} else {
					t.Error("succeeded in dialing", dst)
					ch <- true
					c.Close()
				}
			}()
		}
		return ch
	}

	{
		// 1) dial 10x to each node.
		N := 10
		s2done := dialOnlineNode(s2.local, N)
		s3done := dialOfflineNode(s3p, N)

		// when all dials should be done by:
		dialTimeout1x := time.After(s1.dialT)
		// dialTimeout1Ax := time.After(s1.dialT * 2)       // dialAttempts)
		dialTimeout10Ax := time.After(s1.dialT * 2 * 10) // dialAttempts * 10)

		// 2) all dials should hang
		select {
		case <-s2done:
			t.Error("s2 should not happen immediately")
		case <-s3done:
			t.Error("s3 should not happen yet")
		case <-time.After(time.Millisecond):
			// s2 may finish very quickly, so let's get out.
		}

		// 3) s1->s2 should succeed.
		for i := 0; i < N; i++ {
			select {
			case r := <-s2done:
				if !r {
					t.Error("s2 should not fail")
				}
			case <-s3done:
				t.Error("s3 should not happen yet")
			case <-dialTimeout1x:
				t.Error("s2 took too long")
			}
		}

		select {
		case <-s2done:
			t.Error("s2 should have no more")
		case <-s3done:
			t.Error("s3 should not happen yet")
		case <-dialTimeout1x: // let it pass
		}

		// 4) s1->s3 should not (and should place s3 on backoff)
		// N-1 should finish before dialTimeout1x * 2
		for i := 0; i < N; i++ {
			select {
			case <-s2done:
				t.Error("s2 should have no more")
			case r := <-s3done:
				if r {
					t.Error("s3 should not succeed")
				}
			case <-(dialTimeout1x):
				if i < (N - 1) {
					t.Fatal("s3 took too long")
				}
				t.Log("dialTimeout1x * 1.3 hit for last peer")
			case <-dialTimeout10Ax:
				t.Fatal("s3 took too long")
			}
		}

		// check backoff state
		if s1.backf.Backoff(s2.local) {
			t.Error("s2 should not be on backoff")
		}
		if !s1.backf.Backoff(s3p) {
			t.Error("s3 should be on backoff")
		}

		// 5) disconnect entirely

		for _, c := range s1.Connections() {
			c.Close()
		}
		for i := 0; i < 100 && len(s1.Connections()) > 0; i++ {
			<-time.After(time.Millisecond)
		}
		if len(s1.Connections()) > 0 {
			t.Fatal("s1 conns must exit")
		}
	}

	{
		// 6) dial 10x to each node again
		N := 10
		s2done := dialOnlineNode(s2.local, N)
		s3done := dialOfflineNode(s3p, N)

		// when all dials should be done by:
		dialTimeout1x := time.After(s1.dialT)
		// dialTimeout1Ax := time.After(s1.dialT * 2)       // dialAttempts)
		dialTimeout10Ax := time.After(s1.dialT * 2 * 10) // dialAttempts * 10)

		// 7) s3 dials should all return immediately (except 1)
		for i := 0; i < N-1; i++ {
			select {
			case <-s2done:
				t.Error("s2 should not succeed yet")
			case r := <-s3done:
				if r {
					t.Error("s3 should not succeed")
				}
			case <-dialTimeout1x:
				t.Fatal("s3 took too long")
			}
		}

		// 8) s2 dials should all hang, and succeed
		for i := 0; i < N; i++ {
			select {
			case r := <-s2done:
				if !r {
					t.Error("s2 should succeed")
				}
			// case <-s3done:
			case <-(dialTimeout1x):
				t.Fatal("s3 took too long")
			}
		}

		// 9) the last s3 should return, failed.
		select {
		case <-s2done:
			t.Error("s2 should have no more")
		case r := <-s3done:
			if r {
				t.Error("s3 should not succeed")
			}
		case <-dialTimeout10Ax:
			t.Fatal("s3 took too long")
		}

		// check backoff state (the same)
		if s1.backf.Backoff(s2.local) {
			t.Error("s2 should not be on backoff")
		}
		if !s1.backf.Backoff(s3p) {
			t.Error("s3 should be on backoff")
		}

	}
}

func TestDialBackoffClears(t *testing.T) {
	// t.Skip("skipping for another test")
	t.Parallel()

	ctx := context.Background()
	swarms := makeSwarms(ctx, t, 2)
	s1 := swarms[0]
	s2 := swarms[1]
	defer s1.Close()
	defer s2.Close()
	s1.dialT = time.Millisecond * 300 // lower timeout for tests.
	s2.dialT = time.Millisecond * 300 // lower timeout for tests.
	if ci.IsRunning() {
		s1.dialT = 2 * time.Second
		s2.dialT = 2 * time.Second
	}

	// use another address first, that accept and hang on conns
	_, s2bad, s2l := newSilentPeer(t)
	go acceptAndHang(s2l)
	defer s2l.Close()

	// phase 1 -- dial to non-operational addresses
	s1.peers.AddAddr(s2.local, s2bad, peer.PermanentAddrTTL)

	before := time.Now()
	if c, err := s1.Dial(ctx, s2.local); err == nil {
		t.Fatal("dialing to broken addr worked...", err)
		defer c.Close()
	} else {
		t.Log("correctly got error:", err)
	}
	duration := time.Now().Sub(before)

	dt := s1.dialT
	if duration < dt*dialAttempts {
		t.Error("< DialTimeout * dialAttempts not being respected", duration, dt*dialAttempts)
	}
	if duration > 2*dt*dialAttempts {
		t.Error("> 2*DialTimeout * dialAttempts not being respected", duration, 2*dt*dialAttempts)
	}

	if !s1.backf.Backoff(s2.local) {
		t.Error("s2 should now be on backoff")
	} else {
		t.Log("correctly added to backoff")
	}

	// phase 2 -- add the working address. dial should succeed.
	ifaceAddrs1, err := swarms[1].InterfaceListenAddresses()
	if err != nil {
		t.Fatal(err)
	}
	s1.peers.AddAddrs(s2.local, ifaceAddrs1, peer.PermanentAddrTTL)

	if _, err := s1.Dial(ctx, s2.local); err == nil {
		t.Fatal("should have failed to dial backed off peer")
	}

	time.Sleep(baseBackoffTime)

	if c, err := s1.Dial(ctx, s2.local); err != nil {
		t.Fatal(err)
	} else {
		c.Close()
		t.Log("correctly connected")
	}

	if s1.backf.Backoff(s2.local) {
		t.Error("s2 should no longer be on backoff")
	} else {
		t.Log("correctly cleared backoff")
	}
}

func mkAddr(t *testing.T, s string) ma.Multiaddr {
	a, err := ma.NewMultiaddr(s)
	if err != nil {
		t.Fatal(err)
	}

	return a
}

func TestAddressSorting(t *testing.T) {
	u1 := mkAddr(t, "/ip4/152.12.23.53/udp/1234/utp")
	u2l := mkAddr(t, "/ip4/127.0.0.1/udp/1234/utp")
	local := mkAddr(t, "/ip4/127.0.0.1/tcp/1234")
	norm := mkAddr(t, "/ip4/6.5.4.3/tcp/1234")

	l := AddrList{local, u1, u2l, norm}
	sort.Sort(l)

	if !l[0].Equal(u2l) {
		t.Fatal("expected utp local addr to be sorted first: ", l[0])
	}

	if !l[1].Equal(u1) {
		t.Fatal("expected utp addr to be sorted second")
	}

	if !l[2].Equal(local) {
		t.Fatal("expected tcp localhost addr thid")
	}

	if !l[3].Equal(norm) {
		t.Fatal("expected normal addr last")
	}
}