// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause

package appc

import (
	"encoding/json"
	"net/netip"
	"reflect"
	"testing"

	"tailscale.com/tailcfg"
	"tailscale.com/types/appctype"
	"tailscale.com/types/opt"
)

// TestHandleConnectorTransitIPRequestZeroLength tests that if sent a
// ConnectorTransitIPRequest with 0 TransitIPRequests, we respond with a
// ConnectorTransitIPResponse with 0 TransitIPResponses.
func TestHandleConnectorTransitIPRequestZeroLength(t *testing.T) {
	c := &Conn25{}
	req := ConnectorTransitIPRequest{}
	nid := tailcfg.NodeID(1)

	resp := c.HandleConnectorTransitIPRequest(nid, req)
	if len(resp.TransitIPs) != 0 {
		t.Fatalf("n TransitIPs in response: %d, want 0", len(resp.TransitIPs))
	}
}

// TestHandleConnectorTransitIPRequestStoresAddr tests that if sent a
// request with a transit addr and a destination addr we store that mapping
// and can retrieve it. If sent another req with a different dst for that transit addr
// we store that instead.
func TestHandleConnectorTransitIPRequestStoresAddr(t *testing.T) {
	c := &Conn25{}
	nid := tailcfg.NodeID(1)
	tip := netip.MustParseAddr("0.0.0.1")
	dip := netip.MustParseAddr("1.2.3.4")
	dip2 := netip.MustParseAddr("1.2.3.5")
	mr := func(t, d netip.Addr) ConnectorTransitIPRequest {
		return ConnectorTransitIPRequest{
			TransitIPs: []TransitIPRequest{
				{TransitIP: t, DestinationIP: d},
			},
		}
	}

	resp := c.HandleConnectorTransitIPRequest(nid, mr(tip, dip))
	if len(resp.TransitIPs) != 1 {
		t.Fatalf("n TransitIPs in response: %d, want 1", len(resp.TransitIPs))
	}
	got := resp.TransitIPs[0].Code
	if got != TransitIPResponseCode(0) {
		t.Fatalf("TransitIP Code: %d, want 0", got)
	}
	gotAddr := c.transitIPTarget(nid, tip)
	if gotAddr != dip {
		t.Fatalf("Connector stored destination for tip: %v, want %v", gotAddr, dip)
	}

	// mapping can be overwritten
	resp2 := c.HandleConnectorTransitIPRequest(nid, mr(tip, dip2))
	if len(resp2.TransitIPs) != 1 {
		t.Fatalf("n TransitIPs in response: %d, want 1", len(resp2.TransitIPs))
	}
	got2 := resp.TransitIPs[0].Code
	if got2 != TransitIPResponseCode(0) {
		t.Fatalf("TransitIP Code: %d, want 0", got2)
	}
	gotAddr2 := c.transitIPTarget(nid, tip)
	if gotAddr2 != dip2 {
		t.Fatalf("Connector stored destination for tip: %v, want %v", gotAddr, dip2)
	}
}

// TestHandleConnectorTransitIPRequestMultipleTIP tests that we can
// get a req with multiple mappings and we store them all. Including
// multiple transit addrs for the same destination.
func TestHandleConnectorTransitIPRequestMultipleTIP(t *testing.T) {
	c := &Conn25{}
	nid := tailcfg.NodeID(1)
	tip := netip.MustParseAddr("0.0.0.1")
	tip2 := netip.MustParseAddr("0.0.0.2")
	tip3 := netip.MustParseAddr("0.0.0.3")
	dip := netip.MustParseAddr("1.2.3.4")
	dip2 := netip.MustParseAddr("1.2.3.5")
	req := ConnectorTransitIPRequest{
		TransitIPs: []TransitIPRequest{
			{TransitIP: tip, DestinationIP: dip},
			{TransitIP: tip2, DestinationIP: dip2},
			// can store same dst addr for multiple transit addrs
			{TransitIP: tip3, DestinationIP: dip},
		},
	}
	resp := c.HandleConnectorTransitIPRequest(nid, req)
	if len(resp.TransitIPs) != 3 {
		t.Fatalf("n TransitIPs in response: %d, want 3", len(resp.TransitIPs))
	}

	for i := 0; i < 3; i++ {
		got := resp.TransitIPs[i].Code
		if got != TransitIPResponseCode(0) {
			t.Fatalf("i=%d TransitIP Code: %d, want 0", i, got)
		}
	}
	gotAddr1 := c.transitIPTarget(nid, tip)
	if gotAddr1 != dip {
		t.Fatalf("Connector stored destination for tip(%v): %v, want %v", tip, gotAddr1, dip)
	}
	gotAddr2 := c.transitIPTarget(nid, tip2)
	if gotAddr2 != dip2 {
		t.Fatalf("Connector stored destination for tip(%v): %v, want %v", tip2, gotAddr2, dip2)
	}
	gotAddr3 := c.transitIPTarget(nid, tip3)
	if gotAddr3 != dip {
		t.Fatalf("Connector stored destination for tip(%v): %v, want %v", tip3, gotAddr3, dip)
	}
}

// TestHandleConnectorTransitIPRequestSameTIP tests that if we get
// a req that has more than one TransitIPRequest for the same transit addr
// only the first is stored, and the subsequent ones get an error code and
// message in the response.
func TestHandleConnectorTransitIPRequestSameTIP(t *testing.T) {
	c := &Conn25{}
	nid := tailcfg.NodeID(1)
	tip := netip.MustParseAddr("0.0.0.1")
	tip2 := netip.MustParseAddr("0.0.0.2")
	dip := netip.MustParseAddr("1.2.3.4")
	dip2 := netip.MustParseAddr("1.2.3.5")
	dip3 := netip.MustParseAddr("1.2.3.6")
	req := ConnectorTransitIPRequest{
		TransitIPs: []TransitIPRequest{
			{TransitIP: tip, DestinationIP: dip},
			// cannot have dupe TransitIPs in one ConnectorTransitIPRequest
			{TransitIP: tip, DestinationIP: dip2},
			{TransitIP: tip2, DestinationIP: dip3},
		},
	}

	resp := c.HandleConnectorTransitIPRequest(nid, req)
	if len(resp.TransitIPs) != 3 {
		t.Fatalf("n TransitIPs in response: %d, want 3", len(resp.TransitIPs))
	}

	got := resp.TransitIPs[0].Code
	if got != TransitIPResponseCode(0) {
		t.Fatalf("i=0 TransitIP Code: %d, want 0", got)
	}
	msg := resp.TransitIPs[0].Message
	if msg != "" {
		t.Fatalf("i=0 TransitIP Message: \"%s\", want \"%s\"", msg, "")
	}
	got1 := resp.TransitIPs[1].Code
	if got1 != TransitIPResponseCode(1) {
		t.Fatalf("i=1 TransitIP Code: %d, want 1", got1)
	}
	msg1 := resp.TransitIPs[1].Message
	if msg1 != dupeTransitIPMessage {
		t.Fatalf("i=1 TransitIP Message: \"%s\", want \"%s\"", msg1, dupeTransitIPMessage)
	}
	got2 := resp.TransitIPs[2].Code
	if got2 != TransitIPResponseCode(0) {
		t.Fatalf("i=2 TransitIP Code: %d, want 0", got2)
	}
	msg2 := resp.TransitIPs[2].Message
	if msg2 != "" {
		t.Fatalf("i=2 TransitIP Message: \"%s\", want \"%s\"", msg, "")
	}

	gotAddr1 := c.transitIPTarget(nid, tip)
	if gotAddr1 != dip {
		t.Fatalf("Connector stored destination for tip(%v): %v, want %v", tip, gotAddr1, dip)
	}
	gotAddr2 := c.transitIPTarget(nid, tip2)
	if gotAddr2 != dip3 {
		t.Fatalf("Connector stored destination for tip(%v): %v, want %v", tip2, gotAddr2, dip3)
	}
}

// TestGetDstIPUnknownTIP tests that unknown transit addresses can be looked up without problem.
func TestTransitIPTargetUnknownTIP(t *testing.T) {
	c := &Conn25{}
	nid := tailcfg.NodeID(1)
	tip := netip.MustParseAddr("0.0.0.1")
	got := c.transitIPTarget(nid, tip)
	want := netip.Addr{}
	if got != want {
		t.Fatalf("Unknown transit addr, want: %v, got %v", want, got)
	}
}

func TestPickSplitDNSPeers(t *testing.T) {
	getBytesForAttr := func(name string, domains []string, tags []string) []byte {
		attr := appctype.AppConnectorAttr{
			Name:       name,
			Domains:    domains,
			Connectors: tags,
		}
		bs, err := json.Marshal(attr)
		if err != nil {
			t.Fatalf("test setup: %v", err)
		}
		return bs
	}
	appOneBytes := getBytesForAttr("app1", []string{"example.com"}, []string{"tag:one"})
	appTwoBytes := getBytesForAttr("app2", []string{"a.example.com"}, []string{"tag:two"})
	appThreeBytes := getBytesForAttr("app3", []string{"woo.b.example.com", "hoo.b.example.com"}, []string{"tag:three1", "tag:three2"})
	appFourBytes := getBytesForAttr("app4", []string{"woo.b.example.com", "c.example.com"}, []string{"tag:four1", "tag:four2"})

	makeNodeView := func(id tailcfg.NodeID, name string, tags []string) tailcfg.NodeView {
		return (&tailcfg.Node{
			ID:       id,
			Name:     name,
			Tags:     tags,
			Hostinfo: (&tailcfg.Hostinfo{AppConnector: opt.NewBool(true)}).View(),
		}).View()
	}
	nvp1 := makeNodeView(1, "p1", []string{"tag:one"})
	nvp2 := makeNodeView(2, "p2", []string{"tag:four1", "tag:four2"})
	nvp3 := makeNodeView(3, "p3", []string{"tag:two", "tag:three1"})
	nvp4 := makeNodeView(4, "p4", []string{"tag:two", "tag:three2", "tag:four2"})

	for _, tt := range []struct {
		name   string
		want   map[string][]tailcfg.NodeView
		peers  []tailcfg.NodeView
		config []tailcfg.RawMessage
	}{
		{
			name: "empty",
		},
		{
			name:   "bad-config", // bad config should return a nil map rather than error.
			config: []tailcfg.RawMessage{tailcfg.RawMessage(`hey`)},
		},
		{
			name:   "no-peers",
			config: []tailcfg.RawMessage{tailcfg.RawMessage(appOneBytes)},
		},
		{
			name:   "peers-that-are-not-connectors",
			config: []tailcfg.RawMessage{tailcfg.RawMessage(appOneBytes)},
			peers: []tailcfg.NodeView{
				(&tailcfg.Node{
					ID:   5,
					Name: "p5",
					Tags: []string{"tag:one"},
				}).View(),
				(&tailcfg.Node{
					ID:   6,
					Name: "p6",
					Tags: []string{"tag:one"},
				}).View(),
			},
		},
		{
			name:   "peers-that-dont-match-tags",
			config: []tailcfg.RawMessage{tailcfg.RawMessage(appOneBytes)},
			peers: []tailcfg.NodeView{
				makeNodeView(5, "p5", []string{"tag:seven"}),
				makeNodeView(6, "p6", nil),
			},
		},
		{
			name: "matching-tagged-connector-peers",
			config: []tailcfg.RawMessage{
				tailcfg.RawMessage(appOneBytes),
				tailcfg.RawMessage(appTwoBytes),
				tailcfg.RawMessage(appThreeBytes),
				tailcfg.RawMessage(appFourBytes),
			},
			peers: []tailcfg.NodeView{
				nvp1,
				nvp2,
				nvp3,
				nvp4,
				makeNodeView(5, "p5", nil),
			},
			want: map[string][]tailcfg.NodeView{
				// p5 has no matching tags and so doesn't appear
				"example.com":       {nvp1},
				"a.example.com":     {nvp3, nvp4},
				"woo.b.example.com": {nvp2, nvp3, nvp4},
				"hoo.b.example.com": {nvp3, nvp4},
				"c.example.com":     {nvp2, nvp4},
			},
		},
	} {
		t.Run(tt.name, func(t *testing.T) {
			selfNode := &tailcfg.Node{}
			if tt.config != nil {
				selfNode.CapMap = tailcfg.NodeCapMap{
					tailcfg.NodeCapability(AppConnectorsExperimentalAttrName): tt.config,
				}
			}
			selfView := selfNode.View()
			peers := map[tailcfg.NodeID]tailcfg.NodeView{}
			for _, p := range tt.peers {
				peers[p.ID()] = p
			}
			got := PickSplitDNSPeers(func(_ tailcfg.NodeCapability) bool {
				return true
			}, selfView, peers)
			if !reflect.DeepEqual(got, tt.want) {
				t.Fatalf("got %v, want %v", got, tt.want)
			}
		})
	}
}