package torrent

import (
	"encoding/binary"
	"errors"
	"fmt"
	"io"
	"net"
	"sync"
	"testing"

	"github.com/frankban/quicktest"
	qt "github.com/frankban/quicktest"
	"github.com/stretchr/testify/require"

	"github.com/anacrolix/torrent/metainfo"
	pp "github.com/anacrolix/torrent/peer_protocol"
	"github.com/anacrolix/torrent/storage"
)

// Ensure that no race exists between sending a bitfield, and a subsequent
// Have that would potentially alter it.
func TestSendBitfieldThenHave(t *testing.T) {
	var cl Client
	cl.init(TestingConfig(t))
	cl.initLogger()
	c := cl.newConnection(nil, false, nil, "io.Pipe", "")
	c.setTorrent(cl.newTorrent(metainfo.Hash{}, nil))
	if err := c.t.setInfo(&metainfo.Info{Pieces: make([]byte, metainfo.HashSize*3)}); err != nil {
		t.Log(err)
	}
	r, w := io.Pipe()
	// c.r = r
	c.w = w
	c.startWriter()
	c.locker().Lock()
	c.t._completedPieces.Add(1)
	c.postBitfield( /*[]bool{false, true, false}*/ )
	c.locker().Unlock()
	c.locker().Lock()
	c.have(2)
	c.locker().Unlock()
	b := make([]byte, 15)
	n, err := io.ReadFull(r, b)
	c.locker().Lock()
	// This will cause connection.writer to terminate.
	c.closed.Set()
	c.locker().Unlock()
	require.NoError(t, err)
	require.EqualValues(t, 15, n)
	// Here we see that the bitfield doesn't have piece 2 set, as that should
	// arrive in the following Have message.
	require.EqualValues(t, "\x00\x00\x00\x02\x05@\x00\x00\x00\x05\x04\x00\x00\x00\x02", string(b))
}

type torrentStorage struct {
	writeSem sync.Mutex
}

func (me *torrentStorage) Close() error { return nil }

func (me *torrentStorage) Piece(mp metainfo.Piece) storage.PieceImpl {
	return me
}

func (me *torrentStorage) Completion() storage.Completion {
	return storage.Completion{}
}

func (me *torrentStorage) MarkComplete() error {
	return nil
}

func (me *torrentStorage) MarkNotComplete() error {
	return nil
}

func (me *torrentStorage) ReadAt([]byte, int64) (int, error) {
	panic("shouldn't be called")
}

func (me *torrentStorage) WriteAt(b []byte, _ int64) (int, error) {
	if len(b) != defaultChunkSize {
		panic(len(b))
	}
	me.writeSem.Unlock()
	return len(b), nil
}

func BenchmarkConnectionMainReadLoop(b *testing.B) {
	c := quicktest.New(b)
	var cl Client
	cl.init(&ClientConfig{
		DownloadRateLimiter: unlimited,
	})
	cl.initLogger()
	ts := &torrentStorage{}
	t := cl.newTorrent(metainfo.Hash{}, nil)
	t.initialPieceCheckDisabled = true
	require.NoError(b, t.setInfo(&metainfo.Info{
		Pieces:      make([]byte, 20),
		Length:      1 << 20,
		PieceLength: 1 << 20,
	}))
	t.storage = &storage.Torrent{TorrentImpl: storage.TorrentImpl{Piece: ts.Piece, Close: ts.Close}}
	t.onSetInfo()
	t._pendingPieces.Add(0)
	r, w := net.Pipe()
	cn := cl.newConnection(r, true, r.RemoteAddr(), r.RemoteAddr().Network(), regularNetConnPeerConnConnString(r))
	cn.setTorrent(t)
	mrlErrChan := make(chan error)
	msg := pp.Message{
		Type:  pp.Piece,
		Piece: make([]byte, defaultChunkSize),
	}
	go func() {
		cl.lock()
		err := cn.mainReadLoop()
		if err != nil {
			mrlErrChan <- err
		}
		close(mrlErrChan)
	}()
	wb := msg.MustMarshalBinary()
	b.SetBytes(int64(len(msg.Piece)))
	go func() {
		ts.writeSem.Lock()
		for i := 0; i < b.N; i += 1 {
			cl.lock()
			// The chunk must be written to storage everytime, to ensure the
			// writeSem is unlocked.
			t.pendAllChunkSpecs(0)
			cn.validReceiveChunks = map[RequestIndex]int{
				t.requestIndexFromRequest(newRequestFromMessage(&msg)): 1,
			}
			cl.unlock()
			n, err := w.Write(wb)
			require.NoError(b, err)
			require.EqualValues(b, len(wb), n)
			ts.writeSem.Lock()
		}
		if err := w.Close(); err != nil {
			panic(err)
		}
	}()
	mrlErr := <-mrlErrChan
	if mrlErr != nil && !errors.Is(mrlErr, io.EOF) {
		c.Fatal(mrlErr)
	}
	c.Assert(cn._stats.ChunksReadUseful.Int64(), quicktest.Equals, int64(b.N))
}

func TestConnPexPeerFlags(t *testing.T) {
	var (
		tcpAddr = &net.TCPAddr{IP: net.IPv6loopback, Port: 4848}
		udpAddr = &net.UDPAddr{IP: net.IPv6loopback, Port: 4848}
	)
	testcases := []struct {
		conn *PeerConn
		f    pp.PexPeerFlags
	}{
		{&PeerConn{Peer: Peer{outgoing: false, PeerPrefersEncryption: false}}, 0},
		{&PeerConn{Peer: Peer{outgoing: false, PeerPrefersEncryption: true}}, pp.PexPrefersEncryption},
		{&PeerConn{Peer: Peer{outgoing: true, PeerPrefersEncryption: false}}, pp.PexOutgoingConn},
		{&PeerConn{Peer: Peer{outgoing: true, PeerPrefersEncryption: true}}, pp.PexOutgoingConn | pp.PexPrefersEncryption},
		{&PeerConn{Peer: Peer{RemoteAddr: udpAddr, Network: udpAddr.Network()}}, pp.PexSupportsUtp},
		{&PeerConn{Peer: Peer{RemoteAddr: udpAddr, Network: udpAddr.Network(), outgoing: true}}, pp.PexOutgoingConn | pp.PexSupportsUtp},
		{&PeerConn{Peer: Peer{RemoteAddr: tcpAddr, Network: tcpAddr.Network(), outgoing: true}}, pp.PexOutgoingConn},
		{&PeerConn{Peer: Peer{RemoteAddr: tcpAddr, Network: tcpAddr.Network()}}, 0},
	}
	for i, tc := range testcases {
		f := tc.conn.pexPeerFlags()
		require.EqualValues(t, tc.f, f, i)
	}
}

func TestConnPexEvent(t *testing.T) {
	var (
		udpAddr     = &net.UDPAddr{IP: net.IPv6loopback, Port: 4848}
		tcpAddr     = &net.TCPAddr{IP: net.IPv6loopback, Port: 4848}
		dialTcpAddr = &net.TCPAddr{IP: net.IPv6loopback, Port: 4747}
		dialUdpAddr = &net.UDPAddr{IP: net.IPv6loopback, Port: 4747}
	)
	testcases := []struct {
		t pexEventType
		c *PeerConn
		e pexEvent
	}{
		{
			pexAdd,
			&PeerConn{Peer: Peer{RemoteAddr: udpAddr, Network: udpAddr.Network()}},
			pexEvent{pexAdd, udpAddr, pp.PexSupportsUtp, nil},
		},
		{
			pexDrop,
			&PeerConn{Peer: Peer{RemoteAddr: tcpAddr, Network: tcpAddr.Network(), outgoing: true, PeerListenPort: dialTcpAddr.Port}},
			pexEvent{pexDrop, tcpAddr, pp.PexOutgoingConn, nil},
		},
		{
			pexAdd,
			&PeerConn{Peer: Peer{RemoteAddr: tcpAddr, Network: tcpAddr.Network(), PeerListenPort: dialTcpAddr.Port}},
			pexEvent{pexAdd, dialTcpAddr, 0, nil},
		},
		{
			pexDrop,
			&PeerConn{Peer: Peer{RemoteAddr: udpAddr, Network: udpAddr.Network(), PeerListenPort: dialUdpAddr.Port}},
			pexEvent{pexDrop, dialUdpAddr, pp.PexSupportsUtp, nil},
		},
	}
	for i, tc := range testcases {
		e := tc.c.pexEvent(tc.t)
		require.EqualValues(t, tc.e, e, i)
	}
}

func TestHaveAllThenBitfield(t *testing.T) {
	c := qt.New(t)
	cl := newTestingClient(t)
	tt := cl.newTorrentForTesting()
	// cl.newConnection()
	pc := PeerConn{
		Peer: Peer{t: tt},
	}
	pc.initRequestState()
	pc.peerImpl = &pc
	tt.conns[&pc] = struct{}{}
	c.Assert(pc.onPeerSentHaveAll(), qt.IsNil)
	c.Check(pc.t.connsWithAllPieces, qt.DeepEquals, map[*Peer]struct{}{&pc.Peer: {}})
	pc.peerSentBitfield([]bool{false, false, true, false, true, true, false, false})
	c.Check(pc.peerMinPieces, qt.Equals, 6)
	c.Check(pc.t.connsWithAllPieces, qt.HasLen, 0)
	c.Assert(pc.t.setInfo(&metainfo.Info{
		PieceLength: 0,
		Pieces:      make([]byte, pieceHash.Size()*7),
	}), qt.IsNil)
	pc.t.onSetInfo()
	c.Check(tt.numPieces(), qt.Equals, 7)
	c.Check(tt.pieceAvailabilityRuns(), qt.DeepEquals, []pieceAvailabilityRun{
		// The last element of the bitfield is irrelevant, as the Torrent actually only has 7
		// pieces.
		{2, 0}, {1, 1}, {1, 0}, {2, 1}, {1, 0},
	})
}

func TestApplyRequestStateWriteBufferConstraints(t *testing.T) {
	c := qt.New(t)
	c.Check(interestedMsgLen, qt.Equals, 5)
	c.Check(requestMsgLen, qt.Equals, 17)
	c.Check(maxLocalToRemoteRequests >= 8, qt.IsTrue)
	c.Logf("max local to remote requests: %v", maxLocalToRemoteRequests)
}

func peerConnForPreferredNetworkDirection(localPeerId, remotePeerId int, outgoing, utp, ipv6 bool) *PeerConn {
	pc := PeerConn{}
	pc.outgoing = outgoing
	if utp {
		pc.Network = "udp"
	}
	if ipv6 {
		pc.RemoteAddr = &net.TCPAddr{IP: net.ParseIP(fmt.Sprintf("::420"))}
	} else {
		pc.RemoteAddr = &net.TCPAddr{IP: net.IPv4(1, 2, 3, 4)}
	}
	binary.BigEndian.PutUint64(pc.PeerID[:], uint64(remotePeerId))
	cl := Client{}
	binary.BigEndian.PutUint64(cl.peerID[:], uint64(localPeerId))
	pc.t = &Torrent{cl: &cl}
	return &pc
}

func TestPreferredNetworkDirection(t *testing.T) {
	pc := peerConnForPreferredNetworkDirection
	c := qt.New(t)
	// Prefer outgoing to higher peer ID
	c.Assert(pc(1, 2, true, false, false).hasPreferredNetworkOver(pc(1, 2, false, false, false)), qt.IsTrue)
	c.Assert(pc(1, 2, false, false, false).hasPreferredNetworkOver(pc(1, 2, true, false, false)), qt.IsFalse)
	c.Assert(pc(2, 1, false, false, false).hasPreferredNetworkOver(pc(2, 1, true, false, false)), qt.IsTrue)
	// Don't prefer uTP
	c.Assert(pc(1, 2, false, true, false).hasPreferredNetworkOver(pc(1, 2, false, false, false)), qt.IsFalse)
	// Prefer IPv6
	c.Assert(pc(1, 2, false, false, false).hasPreferredNetworkOver(pc(1, 2, false, false, true)), qt.IsFalse)
	// No difference
	c.Assert(pc(1, 2, false, false, false).hasPreferredNetworkOver(pc(1, 2, false, false, false)), qt.IsFalse)
}