package hostnat

import (
	"slices"
	"testing"
)

func TestParseDefaultUplink(t *testing.T) {
	t.Parallel()

	output := "default via 192.168.1.1 dev enp5s0 proto dhcp src 192.168.1.40 metric 100\n"
	uplink, err := ParseDefaultUplink(output)
	if err != nil {
		t.Fatalf("ParseDefaultUplink returned error: %v", err)
	}
	if uplink != "enp5s0" {
		t.Fatalf("uplink = %q, want enp5s0", uplink)
	}
}

func TestParseDefaultUplinkFailsWithoutRoute(t *testing.T) {
	t.Parallel()

	if _, err := ParseDefaultUplink("10.0.0.0/24 dev br-fc proto kernel scope link src 10.0.0.1\n"); err == nil {
		t.Fatal("expected ParseDefaultUplink to fail without a default route")
	}
}

func TestRulesRequireRuntimeData(t *testing.T) {
	t.Parallel()

	tests := []struct {
		name      string
		guestIP   string
		tapDevice string
		uplink    string
	}{
		{name: "guest ip", tapDevice: "tap-fc-abcd1234", uplink: "eth0"},
		{name: "tap", guestIP: "172.16.0.8", uplink: "eth0"},
		{name: "uplink", guestIP: "172.16.0.8", tapDevice: "tap-fc-abcd1234"},
	}

	for _, tt := range tests {
		tt := tt
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()
			if _, err := Rules(tt.guestIP, tt.tapDevice, tt.uplink); err == nil {
				t.Fatalf("expected Rules to fail for missing %s", tt.name)
			}
		})
	}
}

func TestRulePlans(t *testing.T) {
	t.Parallel()

	rules, err := Rules("172.16.0.8", "tap-fc-abcd1234", "eth0")
	if err != nil {
		t.Fatalf("Rules returned error: %v", err)
	}
	if len(rules) != 3 {
		t.Fatalf("rule count = %d, want 3", len(rules))
	}

	if got, want := RuleArgs("-A", rules[0]), []string{"-t", "nat", "-A", "POSTROUTING", "-s", "172.16.0.8/32", "-o", "eth0", "-j", "MASQUERADE"}; !slices.Equal(got, want) {
		t.Fatalf("postrouting args = %v, want %v", got, want)
	}
	if got, want := RuleArgs("-A", rules[1]), []string{"-A", "FORWARD", "-i", "tap-fc-abcd1234", "-o", "eth0", "-j", "ACCEPT"}; !slices.Equal(got, want) {
		t.Fatalf("forward-out args = %v, want %v", got, want)
	}
	if got, want := RuleArgs("-A", rules[2]), []string{"-A", "FORWARD", "-i", "eth0", "-o", "tap-fc-abcd1234", "-m", "state", "--state", "RELATED,ESTABLISHED", "-j", "ACCEPT"}; !slices.Equal(got, want) {
		t.Fatalf("forward-in args = %v, want %v", got, want)
	}

	addPlan := AddPlan(rules)
	if got, want := addPlan[0], []string{"sysctl", "-w", "net.ipv4.ip_forward=1"}; !slices.Equal(got, want) {
		t.Fatalf("sysctl command = %v, want %v", got, want)
	}
	removePlan := RemovePlan(rules)
	if got, want := removePlan[0], []string{"-t", "nat", "-D", "POSTROUTING", "-s", "172.16.0.8/32", "-o", "eth0", "-j", "MASQUERADE"}; !slices.Equal(got, want) {
		t.Fatalf("remove NAT command = %v, want %v", got, want)
	}
}
