package jarlsets

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"net/netip"
	"reflect"
	"strings"
	"testing"

	"housecarl/internal/jarl"
	"housecarl/internal/model"
)

// fakeJarl is a Jarl with a few zones.
type fakeJarl struct {
	zones   []jarl.ZoneInfo
	records map[int64][]jarl.Record
	down    bool           // AllZones fails
	broken  map[int64]bool // Records fails
	calls   int
}

func (f *fakeJarl) AllZones(ctx context.Context) ([]jarl.ZoneInfo, error) {
	if f.down {
		return nil, errors.New("can't reach Jarl")
	}
	return f.zones, nil
}

func (f *fakeJarl) Records(ctx context.Context, id int64) ([]jarl.Record, error) {
	f.calls++
	if f.broken[id] {
		return nil, errors.New("Jarl answered 500")
	}
	return f.records[id], nil
}

func rec(name, typ, data string) jarl.Record { return jarl.Record{Name: name, Type: typ, Data: data} }

// newFake: example.com in views internal (1) and external (2), linked
// sub-zone wg.example.com in internal (3), other.org only in internal (4),
// a secondary (5), a disabled zone (6), an in-view zone in vps (7).
func newFake() *fakeJarl {
	return &fakeJarl{
		zones: []jarl.ZoneInfo{
			{ID: 1, Name: "example.com.", View: "internal", Type: "primary"},
			{ID: 2, Name: "example.com.", View: "external", Type: "primary"},
			{ID: 3, Name: "wg.example.com.", View: "internal", Type: "primary"},
			{ID: 4, Name: "other.org.", View: "internal", Type: "primary"},
			{ID: 5, Name: "sec.net.", View: "internal", Type: "secondary"},
			{ID: 6, Name: "off.net.", View: "internal", Type: "primary", Disabled: true},
			{ID: 7, Name: "other.org.", View: "vps", Type: "in-view", InView: "internal"},
			{ID: 8, Name: ".", View: "internal", Type: "hint"},
		},
		records: map[int64][]jarl.Record{
			1: {
				rec("example.com.", "NS", "ns1.example.com."),
				rec("nas.example.com.", "A", "10.10.0.20"),
				rec("nas.example.com.", "A", "10.10.0.21"),
				rec("nas.example.com.", "AAAA", "2001:db8:10::20"),
				rec("files.example.com.", "CNAME", "nas.example.com."),
				rec("vpn.example.com.", "CNAME", "peer1.wg.example.com."),
				rec("ext.example.com.", "CNAME", "host.duckdns.org."),
				rec("loop1.example.com.", "CNAME", "loop2.example.com."),
				rec("loop2.example.com.", "CNAME", "loop1"),
				rec("rel.example.com.", "CNAME", "nas"),
				rec("mail.example.com.", "MX", "10 nas.example.com."),
				rec("lab.example.com.", "NS", "ns.lab.example.com."),
				rec("www.example.com.", "A", "10.10.0.30"),
				rec("bad.example.com.", "A", "127.0.0.1"),
				rec("far.example.com.", "A", "192.0.2.9"),
				rec("dead.example.com.", "CNAME", "nothing.example.com."),
				rec("toother.example.com.", "CNAME", "srv.other.org."),
			},
			2: {
				rec("www.example.com.", "A", "203.0.113.30"),
			},
			3: {
				rec("peer1.wg.example.com.", "A", "10.50.50.2"),
			},
			4: {
				rec("srv.other.org.", "A", "10.10.0.40"),
			},
		},
		broken: map[int64]bool{},
	}
}

func resolveOne(t *testing.T, f *fakeJarl, s string) *Lookup {
	t.Helper()
	l := &lookup{ctx: context.Background(), src: f, zones: f.zones, records: map[int64][]jarl.Record{}, errs: map[int64]error{}}
	return l.resolve(model.ParseJarlName(s))
}

func TestResolve(t *testing.T) {
	f := newFake()
	cases := []struct {
		name    string
		addrs   []string
		chain   []string
		problem string // part of it
		found   string
	}{
		{name: "nas.example.com@internal", addrs: []string{"10.10.0.20", "10.10.0.21", "2001:db8:10::20"}, found: "internal"},
		{name: "NAS.Example.com.@internal", addrs: []string{"10.10.0.20", "10.10.0.21", "2001:db8:10::20"}, found: "internal"},
		{name: "files.example.com@internal", addrs: []string{"10.10.0.20", "10.10.0.21", "2001:db8:10::20"}, chain: []string{"nas.example.com"}},
		{name: "rel.example.com@internal", addrs: []string{"10.10.0.20", "10.10.0.21", "2001:db8:10::20"}, chain: []string{"nas.example.com"}},
		// Into the sub-zone, and into another zone of the same view.
		{name: "vpn.example.com@internal", addrs: []string{"10.50.50.2"}, chain: []string{"peer1.wg.example.com"}},
		{name: "toother.example.com@internal", addrs: []string{"10.10.0.40"}, chain: []string{"srv.other.org"}},
		// Only internal has wg.example.com, but external's example.com
		// answers for the name too (that it doesn't exist): the view must be
		// named.
		{name: "peer1.wg.example.com", problem: "views external, internal"},
		{name: "srv.other.org", problem: "views internal, vps"},
		// Views give different answers.
		{name: "www.example.com@internal", addrs: []string{"10.10.0.30"}},
		{name: "www.example.com@external", addrs: []string{"203.0.113.30"}},
		{name: "www.example.com", problem: "views external, internal: name the view"},
		{name: "www.example.com@vps", problem: "no zone in view vps holds www.example.com"},
		// An in-view zone serves the other view's records.
		{name: "srv.other.org@vps", addrs: []string{"10.10.0.40"}},
		{name: "ext.example.com@internal", chain: []string{"host.duckdns.org"}, problem: "its CNAME leads to host.duckdns.org, which Housecarl can't follow"},
		{name: "loop1.example.com@internal", problem: "loop"},
		{name: "dead.example.com@internal", chain: []string{"nothing.example.com"}, problem: "nothing.example.com, which has no A or AAAA record"},
		{name: "mail.example.com@internal", problem: "has no A, AAAA or CNAME record"},
		{name: "missing.example.com@internal", problem: "has no A, AAAA or CNAME record"},
		{name: "host.lab.example.com@internal", problem: "below a delegation (NS records at lab.example.com)"},
		{name: "a.sec.net", problem: "is a secondary zone"},
		{name: "a.off.net", problem: "is disabled"},
		{name: "nowhere.test", problem: "no zone in Jarl holds nowhere.test"},
	}
	for _, c := range cases {
		lu := resolveOne(t, f, c.name)
		if lu.Error != "" {
			t.Errorf("%s: error %s", c.name, lu.Error)
		}
		if !reflect.DeepEqual(lu.Addresses, c.addrs) {
			t.Errorf("%s: addresses %v, want %v (problem %q)", c.name, lu.Addresses, c.addrs, lu.Problem)
		}
		if c.chain != nil && !reflect.DeepEqual(lu.Chain, c.chain) {
			t.Errorf("%s: chain %v, want %v", c.name, lu.Chain, c.chain)
		}
		if c.problem == "" && lu.Problem != "" || !strings.Contains(lu.Problem, c.problem) {
			t.Errorf("%s: problem %q, want %q", c.name, lu.Problem, c.problem)
		}
		if c.found != "" && lu.Found != c.found {
			t.Errorf("%s: found in %q, want %q", c.name, lu.Found, c.found)
		}
	}
}

func TestResolveNoViews(t *testing.T) {
	f := &fakeJarl{zones: []jarl.ZoneInfo{{ID: 1, Name: "lan.", Type: "primary"}},
		records: map[int64][]jarl.Record{1: {rec("nas.lan.", "A", "192.168.1.5")}}}
	if lu := resolveOne(t, f, "nas.lan"); !reflect.DeepEqual(lu.Addresses, []string{"192.168.1.5"}) || lu.Problem != "" {
		t.Errorf("%+v", lu)
	}
}

// harness is a resolver over the fake Jarl, with lan = 10.10.0.0/24 and
// wg = 10.50.50.0/24 connected.
type harness struct {
	r       *Resolver
	f       *fakeJarl
	st      *model.State
	conn    map[netip.Prefix]string
	applies int
	audits  []string
	saved   string
}

func newHarness(sets ...*model.AddressSet) *harness {
	h := &harness{f: newFake(), conn: map[netip.Prefix]string{
		netip.MustParsePrefix("10.10.0.0/24"):  "lan",
		netip.MustParsePrefix("10.50.50.0/24"): "wg",
	}}
	h.st = &model.State{Zones: []*model.Zone{{Name: "lan"}, {Name: "wg"}, {Name: "wan"}}, Sets: sets}
	h.r = &Resolver{Source: h.f, State: func() *model.State { return h.st }, Log: slog.New(slog.NewTextHandler(io.Discard, nil)),
		Connected: func(*model.State) map[netip.Prefix]string { return h.conn },
		Apply: func(ctx context.Context) error {
			h.applies++
			h.r.Applied(h.r.Entries(h.st))
			return nil
		},
		Audit: func(ctx context.Context, set, detail string) { h.audits = append(h.audits, set+": "+detail) },
		Load:  func(ctx context.Context) (string, error) { return h.saved, nil },
		Save:  func(ctx context.Context, v string) error { h.saved = v; return nil }}
	return h
}

func jset(name string, within []string, names ...string) *model.AddressSet {
	j := &model.JarlSource{Within: within}
	for _, n := range names {
		j.Names = append(j.Names, model.ParseJarlName(n))
	}
	return &model.AddressSet{Name: name, Jarl: j}
}

func TestWithin(t *testing.T) {
	h := newHarness(
		jset("nas", []string{"lan"}, "nas.example.com@internal", "vpn.example.com@internal", "bad.example.com@internal", "far.example.com@internal"),
		jset("wide", []string{"lan", "wg", "192.0.2.0/24", "2001:db8:10::/64"}, "nas.example.com@internal", "vpn.example.com@internal", "far.example.com@internal"),
		jset("none", []string{"lan"}, "missing.example.com@internal"),
	)
	h.r.Refresh(context.Background())
	got := h.r.Entries(h.st)
	want := map[string][]string{
		"nas":  {"10.10.0.20", "10.10.0.21"},
		"wide": {"10.10.0.20", "10.10.0.21", "10.50.50.2", "192.0.2.9", "2001:db8:10::20"},
		"none": {},
	}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("entries %v, want %v", got, want)
	}
	st := h.r.Status(h.st, h.st.Sets[0])
	why := map[string]string{}
	for _, n := range st.Names {
		for _, a := range n.Addresses {
			why[a.Address] = a.Why
		}
	}
	if why["10.10.0.20"] != "" || !strings.Contains(why["10.50.50.2"], "not within lan") || !strings.Contains(why["127.0.0.1"], "loopback") || why["2001:db8:10::20"] == "" {
		t.Errorf("why: %v", why)
	}
	codes := map[string]int{}
	for _, p := range h.r.Problems(h.st) {
		codes[p.Code]++
	}
	// nas: 3 left out (v6, wg, loopback, far = 4); wide: none; none: a name problem.
	if codes["jarl_outside"] != 4 || codes["jarl_name"] != 1 || codes["jarl_unreachable"] != 0 {
		t.Errorf("problems %v: %+v", codes, h.r.Problems(h.st))
	}
	// The lan interface loses its address: its networks as last seen count.
	h.conn = map[netip.Prefix]string{}
	if got := h.r.Entries(h.st)["nas"]; !reflect.DeepEqual(got, []string{"10.10.0.20", "10.10.0.21"}) {
		t.Errorf("without lan's address: %v", got)
	}
}

func TestKeepsWhatItHad(t *testing.T) {
	h := newHarness(jset("nas", []string{"lan", "wg"}, "nas.example.com@internal", "peer1.wg.example.com@internal"))
	ctx := context.Background()
	h.r.Refresh(ctx)
	if h.applies != 1 || len(h.audits) != 1 || !strings.Contains(h.audits[0], "added 10.10.0.20, 10.10.0.21, 10.50.50.2") {
		t.Fatalf("first read: %d applies, audits %v", h.applies, h.audits)
	}
	// Nothing changed: no apply.
	h.r.Refresh(ctx)
	if h.applies != 1 {
		t.Errorf("unchanged: %d applies", h.applies)
	}
	// Jarl down: the addresses stay, a warning says so.
	h.f.down = true
	h.r.Refresh(ctx)
	if got := h.r.Entries(h.st)["nas"]; len(got) != 3 || h.applies != 1 {
		t.Errorf("Jarl down: %v, %d applies", got, h.applies)
	}
	if ps := h.r.Problems(h.st); len(ps) != 2 || ps[0].Code != "jarl_unreachable" || ps[1].Code != "jarl_outside" {
		t.Errorf("Jarl down: %+v", ps)
	}
	// One zone's records fail: only its name keeps the old addresses.
	h.f.down = false
	h.f.broken[3] = true
	h.f.records[1][1] = rec("nas.example.com.", "A", "10.10.0.22")
	h.r.Refresh(ctx)
	if got := h.r.Entries(h.st)["nas"]; !reflect.DeepEqual(got, []string{"10.10.0.21", "10.10.0.22", "10.50.50.2"}) {
		t.Errorf("one zone down: %v", got)
	}
	if h.applies != 2 || !strings.Contains(h.audits[1], "added 10.10.0.22; removed 10.10.0.20") {
		t.Errorf("audits %v", h.audits)
	}
	// After a restart, before Jarl is read: what was saved.
	r2 := &Resolver{Load: h.r.Load, State: h.r.State, Connected: h.r.Connected}
	r2.Restore(ctx)
	if got := r2.Entries(h.st)["nas"]; !reflect.DeepEqual(got, []string{"10.10.0.21", "10.10.0.22", "10.50.50.2"}) {
		t.Errorf("restored: %v", got)
	}
	// Jarl answers that the name is gone: its addresses go.
	h.f.broken[3] = false
	h.f.records[3] = nil
	h.r.Refresh(ctx)
	if got := h.r.Entries(h.st)["nas"]; !reflect.DeepEqual(got, []string{"10.10.0.21", "10.10.0.22"}) {
		t.Errorf("deleted record: %v", got)
	}
	// A name taken out of the set is forgotten.
	h.st.Sets[0].Jarl.Names = h.st.Sets[0].Jarl.Names[:1]
	h.r.Refresh(ctx)
	if len(h.r.data.Lookups) != 1 {
		t.Errorf("lookups %v", h.r.data.Lookups)
	}
}

func TestNotConfigured(t *testing.T) {
	h := newHarness(jset("nas", []string{"lan"}, "nas.example.com@internal"))
	h.r.Source = nil
	h.r.Refresh(context.Background())
	if ps := h.r.Problems(h.st); len(ps) != 1 || ps[0].Code != "jarl_not_configured" {
		t.Errorf("%+v", ps)
	}
	if got := h.r.Entries(h.st); !reflect.DeepEqual(got, map[string][]string{"nas": {}}) {
		t.Errorf("%v", got)
	}
}

// TestNoSetsNoApply: without Jarl sets nothing is applied, not even at the
// first read (an empty configuration must never be applied).
func TestNoSetsNoApply(t *testing.T) {
	h := newHarness()
	h.r.Refresh(context.Background())
	if h.applies != 0 {
		t.Errorf("%d applies", h.applies)
	}
}