package kubesource

import (
	"context"
	"strings"
	"testing"
	"time"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	dynfake "k8s.io/client-go/dynamic/fake"

	"git.k8s-git-k6n.net/mats/fancy-dns/internal/config"
	"git.k8s-git-k6n.net/mats/fancy-dns/internal/localzone"
	"git.k8s-git-k6n.net/mats/fancy-dns/internal/zonefile"
)

func obj(kind, name string, spec map[string]any) *unstructured.Unstructured {
	return &unstructured.Unstructured{Object: map[string]any{
		"apiVersion": APIGroup + "/" + Version,
		"kind":       kind,
		"metadata":   map[string]any{"name": name, "namespace": "dns", "generation": int64(3)},
		"spec":       spec,
	}}
}

func cgroup(name string, spec map[string]any) *unstructured.Unstructured {
	return obj("ClientGroup", name, spec)
}

func fakeClient(objs ...runtime.Object) *dynfake.FakeDynamicClient {
	return dynfake.NewSimpleDynamicClientWithCustomListKinds(runtime.NewScheme(),
		map[schemaGVR]string{
			ZoneGVR:  "DNSZoneList",
			GroupGVR: "ClientGroupList",
			ListGVR:  "BlockListList",
		}, objs...)
}

func start(t *testing.T, objs ...runtime.Object) (*Source, *dynfake.FakeDynamicClient, chan *Snapshot) {
	t.Helper()
	c := fakeClient(objs...)
	s, err := New(Options{Client: c, Namespace: "dns", Debounce: 10 * time.Millisecond})
	if err != nil {
		t.Fatal(err)
	}
	ch := make(chan *Snapshot, 16)
	s.OnChange(func(sn *Snapshot) { ch <- sn })
	ctx, cancel := context.WithCancel(context.Background())
	done := make(chan struct{})
	go func() { _ = s.Run(ctx); close(done) }()
	t.Cleanup(func() { cancel(); <-done })
	return s, c, ch
}

func next(t *testing.T, ch chan *Snapshot) *Snapshot {
	t.Helper()
	select {
	case sn := <-ch:
		return sn
	case <-time.After(5 * time.Second):
		t.Fatal("no snapshot published")
		return nil
	}
}

var cidrMatch = map[string]any{"cidrs": []any{"10.0.0.0/8"}}

func TestGroupsAreOrderedByPriorityThenName(t *testing.T) {
	_, _, ch := start(t,
		cgroup("b-kids", map[string]any{"priority": int64(10), "policy": "block_only", "match": cidrMatch}),
		cgroup("a-kids", map[string]any{"priority": int64(10), "policy": "deny", "match": cidrMatch}),
		cgroup("first", map[string]any{"priority": int64(1), "policy": "allow", "match": cidrMatch}),
	)
	sn := next(t, ch)
	var names []string
	for _, g := range sn.Groups {
		names = append(names, g.Name)
	}
	if got := strings.Join(names, ","); got != "first,a-kids,b-kids" {
		t.Fatalf("order = %s", got)
	}
}

func TestRejectedObjectIsReportedAndOthersSurvive(t *testing.T) {
	_, _, ch := start(t,
		cgroup("good", map[string]any{"policy": "allow", "match": cidrMatch}),
		cgroup("badpolicy", map[string]any{"policy": "maybe", "match": cidrMatch}),
		cgroup("badcidr", map[string]any{"policy": "deny", "match": map[string]any{"cidrs": []any{"10.0.0.0/33"}}}),
		cgroup("empty", map[string]any{"policy": "deny", "match": map[string]any{}}),
	)
	sn := next(t, ch)
	if len(sn.Groups) != 1 || sn.Groups[0].Name != "good" {
		t.Fatalf("groups = %+v", sn.Groups)
	}
	if len(sn.Problems) != 3 {
		t.Fatalf("problems = %+v", sn.Problems)
	}
}

func TestBrokenEditKeepsLastGoodVersion(t *testing.T) {
	_, c, ch := start(t, cgroup("kids", map[string]any{"policy": "deny", "match": cidrMatch}))
	if sn := next(t, ch); sn.Groups[0].Policy != "deny" {
		t.Fatalf("first = %+v", sn.Groups)
	}
	// A bad edit changes nothing in force, so it publishes nothing...
	bad := cgroup("kids", map[string]any{"policy": "bogus", "match": cidrMatch})
	if _, err := c.Resource(GroupGVR).Namespace("dns").Update(context.Background(), bad, metav1UpdateOptions); err != nil {
		t.Fatal(err)
	}
	select {
	case sn := <-ch:
		t.Fatalf("a rejected edit published a snapshot: %+v", sn.Groups)
	case <-time.After(300 * time.Millisecond):
	}
	// ...and a good edit goes through.
	good := cgroup("kids", map[string]any{"policy": "block_only", "match": cidrMatch})
	if _, err := c.Resource(GroupGVR).Namespace("dns").Update(context.Background(), good, metav1UpdateOptions); err != nil {
		t.Fatal(err)
	}
	if sn := next(t, ch); sn.Groups[0].Policy != "block_only" {
		t.Fatalf("after good edit = %+v", sn.Groups)
	}
}

func TestDeleteRemovesGroup(t *testing.T) {
	_, c, ch := start(t, cgroup("kids", map[string]any{"policy": "deny", "match": cidrMatch}))
	next(t, ch)
	if err := c.Resource(GroupGVR).Namespace("dns").Delete(context.Background(), "kids", metav1DeleteOptions); err != nil {
		t.Fatal(err)
	}
	if sn := next(t, ch); len(sn.Groups) != 0 {
		t.Fatalf("groups = %+v", sn.Groups)
	}
}

func TestBlockListConversion(t *testing.T) {
	for name, tc := range map[string]struct {
		spec map[string]any
		ok   bool
	}{
		"https":       {map[string]any{"url": "https://example.com/hosts", "format": "hosts", "refresh": "6h"}, true},
		"file url":    {map[string]any{"url": "file:///etc/shadow"}, false},
		"no url":      {map[string]any{"format": "hosts"}, false},
		"bad format":  {map[string]any{"url": "https://e.com/x", "format": "yaml"}, false},
		"bad refresh": {map[string]any{"url": "https://e.com/x", "refresh": "soon"}, false},
		"bad mirror":  {map[string]any{"url": "https://e.com/x", "mirror": []any{"file:///x"}}, false},
	} {
		t.Run(name, func(t *testing.T) {
			l, err := convertList(obj("BlockList", "ads", tc.spec))
			if (err == nil) != tc.ok {
				t.Fatalf("err = %v", err)
			}
			if tc.ok && (!l.Enabled || l.Path != "" || l.Refresh != config.Duration(6*time.Hour)) {
				t.Fatalf("list = %+v", l)
			}
		})
	}
}

func zoneSpec(records ...any) map[string]any {
	return map[string]any{"zone": "Home.Example.com", "records": records}
}

func rec(name, typ, value string) map[string]any {
	return map[string]any{"name": name, "type": typ, "value": value}
}

func TestZoneRendersAndRoundTrips(t *testing.T) {
	z, err := convertZone(obj("DNSZone", "home", zoneSpec(
		rec("@", "NS", "ns1.home.example.com."),
		rec("ns1", "A", "10.0.0.1"),
		rec("nas", "A", "10.0.0.2"),
		rec("*.apps", "A", "10.0.0.3"),
	)))
	if err != nil {
		t.Fatal(err)
	}
	if z.apex != "home.example.com." {
		t.Fatalf("apex = %q", z.apex)
	}
	parsed, err := zonefile.Parse(strings.NewReader(z.text), zonefile.Options{Origin: z.apex, File: "t"})
	if err != nil {
		t.Fatalf("rendered zone does not parse: %v\n%s", err, z.text)
	}
	if parsed.SOA == nil || parsed.SOA.Serial != 3 {
		t.Fatalf("SOA serial should be the object generation: %+v", parsed.SOA)
	}
	// Same input, same bytes: replicas must agree.
	again, _ := convertZone(obj("DNSZone", "home", zoneSpec(
		rec("@", "NS", "ns1.home.example.com."),
		rec("ns1", "A", "10.0.0.1"),
		rec("nas", "A", "10.0.0.2"),
		rec("*.apps", "A", "10.0.0.3"),
	)))
	if again.text != z.text {
		t.Fatal("rendering is not deterministic")
	}
	store, err := localzone.Load(writeTemp(t, z), localzone.Options{})
	if err != nil {
		t.Fatal(err)
	}
	if store.Count() == 0 {
		t.Fatal("store loaded no records")
	}
}

func TestZoneRejections(t *testing.T) {
	for name, spec := range map[string]map[string]any{
		"no apex NS":      zoneSpec(rec("nas", "A", "10.0.0.2")),
		"bad value":       zoneSpec(rec("@", "NS", "ns1.home.example.com."), rec("nas", "A", "not-an-ip")),
		"outside zone":    zoneSpec(rec("@", "NS", "ns1.home.example.com."), rec("x.other.org.", "A", "10.0.0.2")),
		"duplicate":       zoneSpec(rec("@", "NS", "ns1.home.example.com."), rec("a", "A", "10.0.0.2"), rec("a", "A", "10.0.0.2")),
		"under delegated": zoneSpec(rec("@", "NS", "ns1.home.example.com."), rec("sub", "NS", "ns.else.net."), rec("x.sub", "A", "10.0.0.2")),
		"soa as record":   zoneSpec(rec("@", "NS", "ns1.home.example.com."), rec("@", "SOA", "a. b. 1 2 3 4 5")),
		"no zone":         {"records": []any{}},
	} {
		t.Run(name, func(t *testing.T) {
			if _, err := convertZone(obj("DNSZone", "z", spec)); err == nil {
				t.Fatal("expected a rejection")
			}
		})
	}
}

func TestDuplicateApexOldestWins(t *testing.T) {
	a := obj("DNSZone", "a", zoneSpec(rec("@", "NS", "ns1.home.example.com.")))
	b := obj("DNSZone", "b", zoneSpec(rec("@", "NS", "ns2.home.example.com.")))
	a.SetCreationTimestamp(metav1Time(1000))
	b.SetCreationTimestamp(metav1Time(2000))
	_, _, ch := start(t, b, a)
	sn := next(t, ch)
	if len(sn.Zones) != 1 || !strings.Contains(sn.Zones["home.example.com."], "ns1.home.example.com.") {
		t.Fatalf("zones = %v", sn.Zones)
	}
	if len(sn.Problems) != 1 || sn.Problems[0].Name != "b" {
		t.Fatalf("problems = %+v", sn.Problems)
	}
}

func TestMergePrecedenceAndDefaults(t *testing.T) {
	base := config.Default()
	base.ACL.Groups = []config.Group{{Name: "yaml", Policy: "allow", Match: config.Match{CIDRs: []string{"192.168.0.0/16"}}}}
	base.Block.Lists = []config.ListSource{{Name: "ads", URL: "https://a/x", Enabled: true}}
	snap := &Snapshot{
		Groups: []config.Group{{Name: "yaml", Policy: "deny"}, {Name: "crd", Policy: "deny"}},
		Lists:  []config.ListSource{{Name: "ads", URL: "https://b/x"}, {Name: "crd-list", URL: "https://c/x", Enabled: true}},
	}
	merged, dropped := Merge(base, snap)
	if len(merged.ACL.Groups) != 2 || merged.ACL.Groups[0].Policy != "allow" || merged.ACL.Groups[1].Name != "crd" {
		t.Fatalf("groups = %+v", merged.ACL.Groups)
	}
	if len(merged.Block.Lists) != 2 || merged.Block.Lists[0].URL != "https://a/x" {
		t.Fatalf("lists = %+v", merged.Block.Lists)
	}
	if got := merged.Block.Lists[1]; got.Format != "auto" || got.Refresh == 0 || got.MaxBytes == 0 {
		t.Fatalf("defaults not applied: %+v", got)
	}
	if len(dropped) != 2 {
		t.Fatalf("dropped = %v", dropped)
	}
	if len(base.ACL.Groups) != 1 || len(base.Block.Lists) != 1 {
		t.Fatal("Merge modified its input")
	}
}

func TestSyncZoneDir(t *testing.T) {
	dir := t.TempDir()
	if ch, err := SyncZoneDir(dir, map[string]string{"a.example.": "x", "b.example.": "y"}); err != nil || !ch {
		t.Fatalf("first sync: %v %v", ch, err)
	}
	if ch, err := SyncZoneDir(dir, map[string]string{"a.example.": "x", "b.example.": "y"}); err != nil || ch {
		t.Fatalf("idempotent sync: %v %v", ch, err)
	}
	if ch, err := SyncZoneDir(dir, map[string]string{"a.example.": "x"}); err != nil || !ch {
		t.Fatalf("removal sync: %v %v", ch, err)
	}
	if got := fileNames(t, dir); got != "a.example.zone" {
		t.Fatalf("files = %s", got)
	}
}

func TestSnapshotSaveLoad(t *testing.T) {
	path := t.TempDir() + "/sub/snap.json"
	in := &Snapshot{Revision: 4, Groups: []config.Group{{Name: "g", Policy: "allow"}}, Zones: map[string]string{"a.": "z"}}
	if err := Save(path, in); err != nil {
		t.Fatal(err)
	}
	out, err := Load(path)
	if err != nil || out.Revision != 4 || out.Groups[0].Name != "g" || out.Zones["a."] != "z" {
		t.Fatalf("%+v %v", out, err)
	}
	if none, err := Load(path + ".missing"); none != nil || err != nil {
		t.Fatalf("missing file: %v %v", none, err)
	}
}