//go:build integration

package multinet

import (
	"net"
	"net/netip"
	"runtime"
	"testing"

	"github.com/stretchr/testify/require"
	"github.com/vishvananda/netlink"
	"github.com/vishvananda/netns"
)

func TestDialer(t *testing.T) {
	runInNewNamespace(t, "2 interfaces with multiple routes in different subnets", func(t *testing.T, ns netns.NsHandle) {
		setup(t, map[string][]string{
			"testdev1": {"1.2.30.10/23", "4.4.4.4/8"},
			"testdev2": {"1.2.30.11/23", "4.4.4.5/8"},
		})

		// Do not use `t.Run` because everything should be executed in a single OS thread.

		{ // Restrict to a single subnet.
			d, err := NewDialer(Config{
				Subnets: []string{"1.2.30.0/23"},
			})
			require.NoError(t, err)
			require.Equal(t, []Subnet{
				{
					Mask: netip.MustParsePrefix("1.2.30.0/23"),
					Interfaces: []Source{
						{Name: "testdev1", LocalAddr: &net.TCPAddr{IP: net.IP{1, 2, 30, 10}}},
						{Name: "testdev2", LocalAddr: &net.TCPAddr{IP: net.IP{1, 2, 30, 11}}},
					},
				},
			}, d.(*dialer).subnets)
		}

		{ // Restrict to two subnets.
			d, err := NewDialer(Config{
				Subnets: []string{"1.2.30.0/23", "4.0.0.0/8"},
			})
			require.NoError(t, err)
			require.Equal(t, []Subnet{
				{
					Mask: netip.MustParsePrefix("1.2.30.0/23"),
					Interfaces: []Source{
						{Name: "testdev1", LocalAddr: &net.TCPAddr{IP: net.IP{1, 2, 30, 10}}},
						{Name: "testdev2", LocalAddr: &net.TCPAddr{IP: net.IP{1, 2, 30, 11}}},
					},
				},
				{
					Mask: netip.MustParsePrefix("4.0.0.0/8"),
					Interfaces: []Source{
						{Name: "testdev1", LocalAddr: &net.TCPAddr{IP: net.IP{4, 4, 4, 4}}},
						{Name: "testdev2", LocalAddr: &net.TCPAddr{IP: net.IP{4, 4, 4, 5}}},
					},
				},
			}, d.(*dialer).subnets)
		}
	})
	runInNewNamespace(t, "4 interfaces, 2 for data, 2 internal", func(t *testing.T, ns netns.NsHandle) {
		setup(t, map[string][]string{
			"internal1": {"192.168.0.1/16"},
			"internal2": {"192.168.0.2/16"},
			"data1":     {"10.11.12.101/24"},
			"data2":     {"10.11.12.102/24"},
		})

		d, err := NewDialer(Config{
			Subnets: []string{"10.11.12.0/24", "192.168.0.0/16"},
		})
		require.NoError(t, err)
		require.Equal(t, []Subnet{
			{
				Mask: netip.MustParsePrefix("10.11.12.0/24"),
				Interfaces: []Source{
					{Name: "data1", LocalAddr: &net.TCPAddr{IP: net.IP{10, 11, 12, 101}}},
					{Name: "data2", LocalAddr: &net.TCPAddr{IP: net.IP{10, 11, 12, 102}}},
				},
			},
			{
				Mask: netip.MustParsePrefix("192.168.0.0/16"),
				Interfaces: []Source{
					{Name: "internal1", LocalAddr: &net.TCPAddr{IP: net.IP{192, 168, 0, 1}}},
					{Name: "internal2", LocalAddr: &net.TCPAddr{IP: net.IP{192, 168, 0, 2}}},
				},
			},
		}, d.(*dialer).subnets)
	})
	runInNewNamespace(t, "with ipv6", func(t *testing.T, ns netns.NsHandle) {
		addr1 := "2001:db8:85a3:8d3:1319:8a2e:370:7348/64"
		addr2 := "2001:db8:85a3:8d3:1319:8a2e:370:8192/64"
		setup(t, map[string][]string{
			"testdev1": {addr1},
			"testdev2": {addr2},
		})

		// Do not use `t.Run` because everything should be executed in a single OS thread.

		{ // Restrict to a single subnet.
			d, err := NewDialer(Config{
				Subnets: []string{"2001:db8:85a3:8d3::/64"},
			})
			require.NoError(t, err)
			require.Equal(t, []Subnet{
				{
					Mask: netip.MustParsePrefix("2001:db8:85a3:8d3::/64"),
					Interfaces: []Source{
						{Name: "testdev1", LocalAddr: mustParseIPv6(t, addr1)},
						{Name: "testdev2", LocalAddr: mustParseIPv6(t, addr2)},
					},
				},
			}, d.(*dialer).subnets)
		}
	})
}

func mustParseIPv6(t *testing.T, s string) *net.TCPAddr {
	ip, _, err := net.ParseCIDR(s)
	require.NoError(t, err)
	return &net.TCPAddr{IP: ip}
}

func setup(t *testing.T, config map[string][]string) {
	for name, ips := range config {
		link := createLink(t, name)
		for i := range ips {
			ip, err := netlink.ParseIPNet(ips[i])
			require.NoError(t, err)
			require.NoError(t, netlink.AddrAdd(link, &netlink.Addr{IPNet: ip}))
		}
	}
}

func createLink(t *testing.T, name string) netlink.Link {
	require.NoError(t, netlink.LinkAdd(&netlink.Dummy{LinkAttrs: netlink.LinkAttrs{Name: name}}))

	link, err := netlink.LinkByName(name)
	require.NoError(t, err)
	require.NoError(t, netlink.LinkSetUp(link))
	return link
}

func runInNewNamespace(t *testing.T, name string, f func(t *testing.T, ns netns.NsHandle)) {
	t.Run(name, func(t *testing.T) {
		// To avoid messing with host network settings,
		// we create a new names space and execute tests in it.
		// Switching thread can move us to a different namespace, thus this line.
		runtime.LockOSThread()
		defer runtime.UnlockOSThread()

		origns, err := netns.Get()
		require.NoError(t, err)
		defer origns.Close()
		defer netns.Set(origns)

		newns, err := netns.New()
		require.NoError(t, err)
		defer newns.Close()

		f(t, newns)
	})
}