package iface

import (
	"context"
	"fmt"
	"net"
	"net/netip"
	"strings"
	"testing"
	"time"

	"github.com/google/uuid"
	log "github.com/sirupsen/logrus"
	"github.com/stretchr/testify/assert"
	"golang.zx2c4.com/wireguard/wgctrl"
	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"

	"github.com/netbirdio/netbird/client/iface/device"
	"github.com/netbirdio/netbird/client/internal/stdnet"
)

// keep darwin compatibility
const (
	WgIntNumber = 2000
)

var (
	key        string
	peerPubKey string
)

func init() {
	log.SetLevel(log.DebugLevel)
	privateKey, _ := wgtypes.GeneratePrivateKey()
	key = privateKey.String()
	peerPrivateKey, _ := wgtypes.GeneratePrivateKey()
	peerPubKey = peerPrivateKey.PublicKey().String()
}

func TestWGIface_UpdateAddr(t *testing.T) {
	ifaceName := fmt.Sprintf("utun%d", WgIntNumber+4)
	addr := "100.64.0.1/8"
	wgPort := 33100
	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}

	opts := WGIFaceOpts{
		IFaceName:    ifaceName,
		Address:      addr,
		WGPort:       wgPort,
		WGPrivKey:    key,
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}

	iface, err := NewWGIFace(opts)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.Create()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = iface.Close()
		if err != nil {
			t.Error(err)
		}

	}()

	_, err = iface.Up()
	if err != nil {
		t.Fatal(err)
	}

	addrs, err := getIfaceAddrs(ifaceName)
	if err != nil {
		t.Error(err)
	}
	assert.Equal(t, addr, addrs[0].String())

	//update WireGuard address
	addr = "100.64.0.2/8"
	err = iface.UpdateAddr(addr)
	if err != nil {
		t.Fatal(err)
	}

	addrs, err = getIfaceAddrs(ifaceName)
	if err != nil {
		t.Error(err)
	}

	var found bool
	for _, a := range addrs {
		prefix, err := netip.ParsePrefix(a.String())
		assert.NoError(t, err)
		if prefix.Addr().Is4() {
			found = true
			assert.Equal(t, addr, prefix.String())
		}
	}

	if !found {
		t.Fatal("v4 address not found")
	}
}

func getIfaceAddrs(ifaceName string) ([]net.Addr, error) {
	ief, err := net.InterfaceByName(ifaceName)
	if err != nil {
		return nil, err
	}
	addrs, err := ief.Addrs()
	if err != nil {
		return nil, err
	}
	return addrs, nil
}

func Test_CreateInterface(t *testing.T) {
	ifaceName := fmt.Sprintf("utun%d", WgIntNumber+1)
	wgIP := "10.99.99.1/32"
	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}
	opts := WGIFaceOpts{
		IFaceName:    ifaceName,
		Address:      wgIP,
		WGPort:       33100,
		WGPrivKey:    key,
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}

	iface, err := NewWGIFace(opts)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.Create()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = iface.Close()
		if err != nil {
			t.Error(err)
		}
	}()
	wg, err := wgctrl.New()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = wg.Close()
		if err != nil {
			t.Error(err)
		}
	}()
}

func Test_Close(t *testing.T) {
	ifaceName := fmt.Sprintf("utun%d", WgIntNumber+2)
	wgIP := "10.99.99.2/32"
	wgPort := 33100
	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}

	opts := WGIFaceOpts{
		IFaceName:    ifaceName,
		Address:      wgIP,
		WGPort:       wgPort,
		WGPrivKey:    key,
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}

	iface, err := NewWGIFace(opts)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.Create()
	if err != nil {
		t.Fatal(err)
	}
	wg, err := wgctrl.New()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = wg.Close()
		if err != nil {
			t.Error(err)
		}
	}()

	err = iface.Close()
	if err != nil {
		t.Fatal(err)
	}
}

func TestRecreation(t *testing.T) {
	for i := 0; i < 100; i++ {
		t.Run(fmt.Sprintf("down-%d", i), func(t *testing.T) {
			ifaceName := fmt.Sprintf("utun%d", WgIntNumber+2)
			wgIP := "10.99.99.2/32"
			wgPort := 33100
			newNet, err := stdnet.NewNet(context.Background(), nil)
			if err != nil {
				t.Fatal(err)
			}

			opts := WGIFaceOpts{
				IFaceName:    ifaceName,
				Address:      wgIP,
				WGPort:       wgPort,
				WGPrivKey:    key,
				MTU:          DefaultMTU,
				TransportNet: newNet,
			}

			iface, err := NewWGIFace(opts)
			if err != nil {
				t.Fatal(err)
			}

			for {
				_, err = net.InterfaceByName(ifaceName)
				if err != nil {
					t.Logf("interface %s not found: err: %s", ifaceName, err)
					break
				}
				t.Logf("interface %s found", ifaceName)
			}

			err = iface.Create()
			if err != nil {
				t.Fatal(err)
			}
			wg, err := wgctrl.New()
			if err != nil {
				t.Fatal(err)
			}
			defer func() {
				err = wg.Close()
				if err != nil {
					t.Error(err)
				}
			}()

			_, err = iface.Up()
			if err != nil {
				t.Fatal(err)
			}

			for {
				_, err = net.InterfaceByName(ifaceName)
				if err == nil {
					t.Logf("interface %s found", ifaceName)

					break
				}
				t.Logf("interface %s not found: err: %s", ifaceName, err)

			}

			start := time.Now()
			err = iface.Close()
			t.Logf("down time: %s", time.Since(start))
			if err != nil {
				t.Fatal(err)
			}
		})
	}
}

func Test_ConfigureInterface(t *testing.T) {
	ifaceName := fmt.Sprintf("utun%d", WgIntNumber+3)
	wgIP := "10.99.99.5/30"
	wgPort := 33100
	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}
	opts := WGIFaceOpts{
		IFaceName:    ifaceName,
		Address:      wgIP,
		WGPort:       wgPort,
		WGPrivKey:    key,
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}
	iface, err := NewWGIFace(opts)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.Create()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = iface.Close()
		if err != nil {
			t.Error(err)
		}
	}()

	_, err = iface.Up()
	if err != nil {
		t.Fatal(err)
	}

	wg, err := wgctrl.New()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = wg.Close()
		if err != nil {
			t.Error(err)
		}
	}()

	wgDevice, err := wg.Device(ifaceName)
	if err != nil {
		t.Fatal(err)
	}
	if wgDevice.PrivateKey.String() != key {
		t.Fatalf("Private keys don't match after configure: %s != %s", key, wgDevice.PrivateKey.String())
	}
}

func Test_UpdatePeer(t *testing.T) {
	ifaceName := fmt.Sprintf("utun%d", WgIntNumber+4)
	wgIP := "10.99.99.9/30"
	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}

	opts := WGIFaceOpts{
		IFaceName:    ifaceName,
		Address:      wgIP,
		WGPort:       33100,
		WGPrivKey:    key,
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}

	iface, err := NewWGIFace(opts)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.Create()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = iface.Close()
		if err != nil {
			t.Error(err)
		}
	}()

	_, err = iface.Up()
	if err != nil {
		t.Fatal(err)
	}
	keepAlive := 15 * time.Second
	allowedIP := netip.MustParsePrefix("10.99.99.10/32")
	endpoint, err := net.ResolveUDPAddr("udp", "127.0.0.1:9900")
	if err != nil {
		t.Fatal(err)
	}
	err = iface.UpdatePeer(peerPubKey, []netip.Prefix{allowedIP}, keepAlive, endpoint, nil)
	if err != nil {
		t.Fatal(err)
	}
	peer, err := getPeer(ifaceName, peerPubKey)
	if err != nil {
		t.Fatal(err)
	}
	if peer.PersistentKeepaliveInterval != keepAlive {
		t.Fatal("configured peer with mismatched keepalive interval value")
	}

	if peer.Endpoint.String() != endpoint.String() {
		t.Fatal("configured peer with mismatched endpoint")
	}

	var foundAllowedIP bool
	for _, aip := range peer.AllowedIPs {
		if aip.String() == allowedIP.String() {
			foundAllowedIP = true
			break
		}
	}
	if !foundAllowedIP {
		t.Fatal("configured peer with mismatched Allowed IPs")
	}
}

func Test_RemovePeer(t *testing.T) {
	ifaceName := fmt.Sprintf("utun%d", WgIntNumber+4)
	wgIP := "10.99.99.13/30"
	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}

	opts := WGIFaceOpts{
		IFaceName:    ifaceName,
		Address:      wgIP,
		WGPort:       33100,
		WGPrivKey:    key,
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}

	iface, err := NewWGIFace(opts)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.Create()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = iface.Close()
		if err != nil {
			t.Error(err)
		}
	}()

	_, err = iface.Up()
	if err != nil {
		t.Fatal(err)
	}
	keepAlive := 15 * time.Second
	allowedIP := netip.MustParsePrefix("10.99.99.14/32")
	err = iface.UpdatePeer(peerPubKey, []netip.Prefix{allowedIP}, keepAlive, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.RemovePeer(peerPubKey)
	if err != nil {
		t.Fatal(err)
	}

	_, err = getPeer(ifaceName, peerPubKey)
	if err.Error() != "peer not found" {
		t.Fatal(err)
	}
}

func Test_ConnectPeers(t *testing.T) {
	peer1ifaceName := fmt.Sprintf("utun%d", WgIntNumber+400)
	peer1wgIP := netip.MustParsePrefix("10.99.99.17/30")
	peer1Key, _ := wgtypes.GeneratePrivateKey()
	peer1wgPort := 33100

	peer2ifaceName := "utun500"
	peer2wgIP := netip.MustParsePrefix("10.99.99.18/30")
	peer2Key, _ := wgtypes.GeneratePrivateKey()
	peer2wgPort := 33200

	keepAlive := 1 * time.Second
	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}

	guid := fmt.Sprintf("{%s}", uuid.New().String())
	device.CustomWindowsGUIDString = strings.ToLower(guid)

	optsPeer1 := WGIFaceOpts{
		IFaceName:    peer1ifaceName,
		Address:      peer1wgIP.String(),
		WGPort:       peer1wgPort,
		WGPrivKey:    peer1Key.String(),
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}
	iface1, err := NewWGIFace(optsPeer1)
	if err != nil {
		t.Fatal(err)
	}
	err = iface1.Create()
	if err != nil {
		t.Fatal(err)
	}

	_, err = iface1.Up()
	if err != nil {
		t.Fatal(err)
	}

	localIP, err := getLocalIP()
	if err != nil {
		t.Fatal(err)
	}

	peer1endpoint, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", localIP, peer1wgPort))
	if err != nil {
		t.Fatal(err)
	}

	guid = fmt.Sprintf("{%s}", uuid.New().String())
	device.CustomWindowsGUIDString = strings.ToLower(guid)

	newNet, err = stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}

	optsPeer2 := WGIFaceOpts{
		IFaceName:    peer2ifaceName,
		Address:      peer2wgIP.String(),
		WGPort:       peer2wgPort,
		WGPrivKey:    peer2Key.String(),
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}

	iface2, err := NewWGIFace(optsPeer2)
	if err != nil {
		t.Fatal(err)
	}
	err = iface2.Create()
	if err != nil {
		t.Fatal(err)
	}

	_, err = iface2.Up()
	if err != nil {
		t.Fatal(err)
	}

	peer2endpoint, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", localIP, peer2wgPort))
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		err = iface1.Close()
		if err != nil {
			t.Error(err)
		}
		err = iface2.Close()
		if err != nil {
			t.Error(err)
		}
	}()

	err = iface1.UpdatePeer(peer2Key.PublicKey().String(), []netip.Prefix{peer2wgIP}, keepAlive, peer2endpoint, nil)
	if err != nil {
		t.Fatal(err)
	}
	err = iface2.UpdatePeer(peer1Key.PublicKey().String(), []netip.Prefix{peer1wgIP}, keepAlive, peer1endpoint, nil)
	if err != nil {
		t.Fatal(err)
	}
	// todo: investigate why in some tests execution we need 30s
	timeout := 30 * time.Second
	timeoutChannel := time.After(timeout)

	for {
		select {
		case <-timeoutChannel:
			t.Fatalf("waiting for peer handshake timeout after %s", timeout.String())
		default:
		}

		peer, gpErr := getPeer(peer1ifaceName, peer2Key.PublicKey().String())
		if gpErr != nil {
			t.Fatal(gpErr)
		}
		if !peer.LastHandshakeTime.IsZero() {
			t.Log("peers successfully handshake")
			break
		}
	}

}

func Test_UserSpaceAddAllowedIPs(t *testing.T) {
	ifaceName := fmt.Sprintf("utun%d", WgIntNumber+5)
	wgIP := "10.99.99.21/30"
	wgPort := 33105

	newNet, err := stdnet.NewNet(context.Background(), nil)
	if err != nil {
		t.Fatal(err)
	}

	opts := WGIFaceOpts{
		IFaceName:    ifaceName,
		Address:      wgIP,
		WGPort:       wgPort,
		WGPrivKey:    key,
		MTU:          DefaultMTU,
		TransportNet: newNet,
	}

	iface, err := NewWGIFace(opts)
	if err != nil {
		t.Fatal(err)
	}
	err = iface.Create()
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := iface.Close(); err != nil {
			t.Error(err)
		}
	}()

	_, err = iface.Up()
	if err != nil {
		t.Fatal(err)
	}

	keepAlive := 15 * time.Second
	initialAllowedIP := netip.MustParsePrefix("10.99.99.22/32")
	endpoint, err := net.ResolveUDPAddr("udp", "127.0.0.1:9905")
	if err != nil {
		t.Fatal(err)
	}

	// Add peer with initial endpoint and first allowed IP
	err = iface.UpdatePeer(peerPubKey, []netip.Prefix{initialAllowedIP}, keepAlive, endpoint, nil)
	if err != nil {
		t.Fatal(err)
	}

	// Phase 1: generate 500 allowed IPs into a list
	const extraIPs = 500
	addedPrefixes := make([]netip.Prefix, 0, extraIPs)
	for i := 0; i < extraIPs; i++ {
		// Use 172.16.x.y/32 range: i encoded as two octets
		prefix := netip.MustParsePrefix(fmt.Sprintf("172.16.%d.%d/32", i/256, i%256))
		addedPrefixes = append(addedPrefixes, prefix)
	}

	// Phase 2: iterate over the list and add each allowed IP to the peer
	phase2Start := time.Now()
	for _, prefix := range addedPrefixes {
		if addErr := iface.AddAllowedIP(peerPubKey, prefix); addErr != nil {
			t.Fatalf("failed to add allowed IP %s: %v", prefix, addErr)
		}
	}
	t.Logf("Phase 2 (add %d IPs to peer): %s", extraIPs, time.Since(phase2Start))

	// Verify the peer has all 101 allowed IPs (1 initial + 100 added)
	peer, err := getPeer(ifaceName, peerPubKey)
	if err != nil {
		t.Fatal(err)
	}

	if peer.Endpoint.String() != endpoint.String() {
		t.Fatalf("expected endpoint %s, got %s", endpoint, peer.Endpoint)
	}

	allExpected := append([]netip.Prefix{initialAllowedIP}, addedPrefixes...)
	if len(peer.AllowedIPs) != len(allExpected) {
		t.Fatalf("expected %d allowed IPs, got %d", len(allExpected), len(peer.AllowedIPs))
	}

	allowedIPSet := make(map[string]struct{}, len(peer.AllowedIPs))
	for _, aip := range peer.AllowedIPs {
		allowedIPSet[aip.String()] = struct{}{}
	}
	for _, expected := range allExpected {
		if _, found := allowedIPSet[expected.String()]; !found {
			t.Errorf("expected allowed IP %s not found in peer config", expected)
		}
	}
}

func getPeer(ifaceName, peerPubKey string) (wgtypes.Peer, error) {
	wg, err := wgctrl.New()
	if err != nil {
		return wgtypes.Peer{}, err
	}
	defer func() {
		err = wg.Close()
		if err != nil {
			log.Errorf("got error while closing wgctl: %v", err)
		}
	}()

	wgDevice, err := wg.Device(ifaceName)
	if err != nil {
		return wgtypes.Peer{}, err
	}
	for _, peer := range wgDevice.Peers {
		if peer.PublicKey.String() == peerPubKey {
			return peer, nil
		}
	}
	return wgtypes.Peer{}, fmt.Errorf("peer not found")
}

func getLocalIP() (string, error) {
	// Get all interfaces
	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return "", err
	}

	for _, addr := range addrs {
		ipNet, ok := addr.(*net.IPNet)
		if !ok {
			continue
		}
		if ipNet.IP.IsLoopback() {
			continue
		}

		if ipNet.IP.To4() == nil {
			continue
		}
		return ipNet.IP.String(), nil
	}

	return "", fmt.Errorf("no local IP found")
}