package app

import (
	"context"
	"testing"
	"time"

	"github.com/miekg/dns"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/schema"
	dynfake "k8s.io/client-go/dynamic/fake"

	"git.k8s-git-k6n.net/mats/fancy-dns/internal/kubesource"
)

func kubeObj(kind, name string, spec map[string]any) *unstructured.Unstructured {
	return &unstructured.Unstructured{Object: map[string]any{
		"apiVersion": kubesource.APIGroup + "/" + kubesource.Version,
		"kind":       kind,
		"metadata":   map[string]any{"name": name, "namespace": "dns", "generation": int64(1)},
		"spec":       spec,
	}}
}

func kubeClient() *dynfake.FakeDynamicClient {
	return dynfake.NewSimpleDynamicClientWithCustomListKinds(runtime.NewScheme(),
		map[schema.GroupVersionResource]string{
			kubesource.ZoneGVR:  "DNSZoneList",
			kubesource.GroupGVR: "ClientGroupList",
			kubesource.ListGVR:  "BlockListList",
		})
}

func eventually(t *testing.T, what string, ok func() bool) {
	t.Helper()
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		if ok() {
			return
		}
		time.Sleep(25 * time.Millisecond)
	}
	t.Fatalf("timed out waiting for %s", what)
}

// TestKubeObjectsReachTheResolver is the point of the Kubernetes source: an
// object applied to the cluster changes what this resolver answers, with no
// reload, and deleting it takes the change back.
func TestKubeObjectsReachTheResolver(t *testing.T) {
	client := kubeClient()
	h := newHarness(t, nil, func(o *Options) {
		o.Kube = KubeOptions{Enabled: true, Namespace: "dns", Client: client, SyncTimeout: 5 * time.Second}
	})
	ctx := context.Background()
	zones := client.Resource(kubesource.ZoneGVR).Namespace("dns")
	groups := client.Resource(kubesource.GroupGVR).Namespace("dns")

	answer := func() string {
		m := h.query("www.kube.test", dns.TypeA)
		if len(m.Answer) == 1 {
			if a, ok := m.Answer[0].(*dns.A); ok && m.Authoritative {
				return a.A.String()
			}
		}
		return ""
	}

	if _, err := zones.Create(ctx, kubeObj("DNSZone", "kube", map[string]any{
		"zone": "kube.test",
		"records": []any{
			map[string]any{"name": "@", "type": "NS", "value": "ns1.kube.test."},
			map[string]any{"name": "ns1", "type": "A", "value": "10.1.2.1"},
			map[string]any{"name": "www", "type": "A", "value": "10.1.2.3"},
		},
	}), metav1.CreateOptions{}); err != nil {
		t.Fatal(err)
	}
	eventually(t, "the DNSZone to be served", func() bool { return answer() == "10.1.2.3" })

	// The cluster's data never lands in the YAML the console writes back.
	if got := len(h.app.cfg.Base().ACL.Groups); got != 0 {
		t.Fatalf("base has %d groups", got)
	}

	if _, err := groups.Create(ctx, kubeObj("ClientGroup", "no-loopback", map[string]any{
		"policy": "deny", "match": map[string]any{"cidrs": []any{"127.0.0.0/8"}},
	}), metav1.CreateOptions{}); err != nil {
		t.Fatal(err)
	}
	eventually(t, "the ClientGroup to refuse the client", func() bool {
		return h.query("www.example.test", dns.TypeA).Rcode == dns.RcodeRefused
	})
	if len(h.app.cfg.Base().ACL.Groups) != 0 || len(h.app.cfg.Get().ACL.Groups) != 1 {
		t.Fatalf("base=%d effective=%d groups", len(h.app.cfg.Base().ACL.Groups), len(h.app.cfg.Get().ACL.Groups))
	}

	// The console cannot overwrite a cluster-owned group.
	if _, err := h.app.putACL(ctx, nil, ""); err != nil {
		t.Fatalf("saving the console's own (empty) list: %v", err)
	}
	if len(h.app.cfg.Get().ACL.Groups) != 1 {
		t.Fatal("saving the file's groups removed the cluster's")
	}

	if err := groups.Delete(ctx, "no-loopback", metav1.DeleteOptions{}); err != nil {
		t.Fatal(err)
	}
	eventually(t, "the deleted ClientGroup to stop applying", func() bool {
		return h.query("www.example.test", dns.TypeA).Rcode == dns.RcodeSuccess
	})

	if err := zones.Delete(ctx, "kube", metav1.DeleteOptions{}); err != nil {
		t.Fatal(err)
	}
	eventually(t, "the deleted DNSZone to stop being authoritative", func() bool { return answer() == "" })
}