package peer

import (
	"bytes"
	"net"
	"reflect"
	"sync/atomic"
	"testing"
)

// Test that we parse IPv4 packets correctly.
func TestIFReader_parsePacket_ipv4(t *testing.T) {
	r := newIFReader(nil, [256]*atomic.Pointer[RemotePeer]{}, nil, nil)

	pkt := make([]byte, 1234)
	pkt[0] = 4 << 4
	pkt[19] = 128

	if ip, ok := r.parsePacket(pkt); !ok || ip != 128 {
		t.Fatal(ip, ok)
	}
}

// Test that we parse IPv6 packets correctly.
func TestIFReader_parsePacket_ipv6(t *testing.T) {
	r := newIFReader(nil, [256]*atomic.Pointer[RemotePeer]{}, nil, nil)

	pkt := make([]byte, 1234)
	pkt[0] = 6 << 4
	pkt[39] = 42

	if ip, ok := r.parsePacket(pkt); !ok || ip != 42 {
		t.Fatal(ip, ok)
	}
}

// Test that empty packets work as expected.
func TestIFReader_parsePacket_emptyPacket(t *testing.T) {
	r := newIFReader(nil, [256]*atomic.Pointer[RemotePeer]{}, nil, nil)

	pkt := make([]byte, 0)
	if ip, ok := r.parsePacket(pkt); ok {
		t.Fatal(ip, ok)
	}
}

// Test that invalid IP versions fail.
func TestIFReader_parsePacket_invalidIPVersion(t *testing.T) {
	r := newIFReader(nil, [256]*atomic.Pointer[RemotePeer]{}, nil, nil)

	for i := byte(1); i < 16; i++ {
		if i == 4 || i == 6 {
			continue
		}
		pkt := make([]byte, 1234)
		pkt[0] = i << 4

		if ip, ok := r.parsePacket(pkt); ok {
			t.Fatal(i, ip, ok)
		}
	}
}

// Test that short IPv4 packets fail.
func TestIFReader_parsePacket_shortIPv4(t *testing.T) {
	r := newIFReader(nil, [256]*atomic.Pointer[RemotePeer]{}, nil, nil)

	pkt := make([]byte, 19)
	pkt[0] = 4 << 4

	if ip, ok := r.parsePacket(pkt); ok {
		t.Fatal(ip, ok)
	}
}

// Test that short IPv6 packets fail.
func TestIFReader_parsePacket_shortIPv6(t *testing.T) {
	r := newIFReader(nil, [256]*atomic.Pointer[RemotePeer]{}, nil, nil)

	pkt := make([]byte, 39)
	pkt[0] = 6 << 4

	if ip, ok := r.parsePacket(pkt); ok {
		t.Fatal(ip, ok)
	}
}

// Test that we can read a packet.
func TestIFReader_readNextpacket(t *testing.T) {
	in, out := net.Pipe()
	r := newIFReader(out, [256]*atomic.Pointer[RemotePeer]{}, nil, nil)
	defer in.Close()
	defer out.Close()

	go in.Write([]byte("hello world!"))

	pkt := r.readNextPacket(make([]byte, bufferSize))
	if !bytes.Equal(pkt, []byte("hello world!")) {
		t.Fatalf("%s", pkt)
	}
}

// ----------------------------------------------------------------------------

type sentPacket struct {
	Relayed bool
	Packet  []byte
	Route   RemotePeer
	Relay   RemotePeer
}

type sendPacketTestHarness struct {
	Packets []sentPacket
}

func (h *sendPacketTestHarness) SendDataPacket(pkt []byte, route *RemotePeer) {
	h.Packets = append(h.Packets, sentPacket{
		Packet: bytes.Clone(pkt),
		Route:  *route,
	})
}

func (h *sendPacketTestHarness) RelayDataPacket(pkt []byte, route, relay *RemotePeer) {
	h.Packets = append(h.Packets, sentPacket{
		Relayed: true,
		Packet:  bytes.Clone(pkt),
		Route:   *route,
		Relay:   *relay,
	})
}

func newIFReaderForSendPacketTesting() (*ifReader, *sendPacketTestHarness) {
	h := &sendPacketTestHarness{}

	routes := [256]*atomic.Pointer[RemotePeer]{}
	for i := range routes {
		routes[i] = &atomic.Pointer[RemotePeer]{}
		routes[i].Store(&RemotePeer{})
	}
	relay := &atomic.Pointer[RemotePeer]{}
	r := newIFReader(nil, routes, relay, h)
	return r, h
}

// Testing that we can send a packet directly.
func TestIFReader_sendPacket_direct(t *testing.T) {
	r, h := newIFReaderForSendPacketTesting()

	route := r.peers[2].Load()
	route.Up = true
	route.Direct = true

	in := []byte("hello world")

	r.sendPacket(in, 2)
	if len(h.Packets) != 1 {
		t.Fatal(h.Packets)
	}

	expected := sentPacket{
		Relayed: false,
		Packet:  in,
		Route:   *route,
	}

	if !reflect.DeepEqual(h.Packets[0], expected) {
		t.Fatal(h.Packets[0])
	}
}

// Testing that we don't send a packet if route isn't up.
func TestIFReader_sendPacket_directNotUp(t *testing.T) {
	r, h := newIFReaderForSendPacketTesting()

	route := r.peers[2].Load()
	route.Direct = true

	in := []byte("hello world")

	r.sendPacket(in, 2)
	if len(h.Packets) != 0 {
		t.Fatal(h.Packets)
	}
}

// Testing that we can send a packet via a relay.
func TestIFReader_sendPacket_relayed(t *testing.T) {
	r, h := newIFReaderForSendPacketTesting()

	route := r.peers[2].Load()
	route.Up = true
	route.Direct = false

	relay := r.peers[3].Load()
	r.relay.Store(relay)
	relay.Up = true
	relay.Direct = true

	in := []byte("hello world")

	r.sendPacket(in, 2)
	if len(h.Packets) != 1 {
		t.Fatal(h.Packets)
	}

	expected := sentPacket{
		Relayed: true,
		Packet:  in,
		Route:   *route,
		Relay:   *relay,
	}

	if !reflect.DeepEqual(h.Packets[0], expected) {
		t.Fatal(h.Packets[0])
	}
}

// Testing that we don't try to send on a nil relay IP.
func TestIFReader_sendPacket_nilRealy(t *testing.T) {
	r, h := newIFReaderForSendPacketTesting()

	route := r.peers[2].Load()
	route.Up = true
	route.Direct = false

	in := []byte("hello world")

	r.sendPacket(in, 2)
	if len(h.Packets) != 0 {
		t.Fatal(h.Packets)
	}
}