package main

import (
	"bytes"
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"

	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"
	"k8s.io/client-go/dynamic"
	dynfake "k8s.io/client-go/dynamic/fake"

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

const rpz = "$TTL 60\ntornberg.me A 10.10.3.10\nk6n.net A 10.10.3.10\n"

const zone = `$TTL 300
@ IN SOA ns1.home.example.com. hostmaster.home.example.com. 1 3600 600 604800 300
@ IN NS ns1.home.example.com.
ns1 IN A 10.0.0.53
nas IN A 10.0.0.20
`

func configMap(ns, name string, data map[string]any) *unstructured.Unstructured {
	return &unstructured.Unstructured{Object: map[string]any{
		"apiVersion": "v1", "kind": "ConfigMap",
		"metadata": map[string]any{"name": name, "namespace": ns},
		"data":     data,
	}}
}

func fakeCluster(objs ...runtime.Object) *dynfake.FakeDynamicClient {
	return dynfake.NewSimpleDynamicClientWithCustomListKinds(runtime.NewScheme(),
		map[schema.GroupVersionResource]string{
			configMaps:             "ConfigMapList",
			kubesource.ZoneGVR:     "DNSZoneList",
			kubesource.GroupGVR:    "ClientGroupList",
			kubesource.ListGVR:     "BlockListList",
			kubesource.OverrideGVR: "AddressOverrideList",
			kubesource.RuleGVR:     "DomainRuleList",
		}, objs...)
}

func useClient(t *testing.T, c dynamic.Interface) {
	t.Helper()
	old := newClient
	newClient = func(kubesource.ClientOptions) (dynamic.Interface, error) { return c, nil }
	t.Cleanup(func() { newClient = old })
}

// TestMigrateFromTheClusterThenApply reads the two ConfigMaps the old console
// wrote, prints manifests without touching anything, and then applies them.
func TestMigrateFromTheClusterThenApply(t *testing.T) {
	c := fakeCluster(
		configMap("dns", "fancy-dns-zones", map[string]any{"zone--home.example.com.zone": zone, "unrelated": "x"}),
		configMap("dns", "fancy-dns-rpz", map[string]any{"address-overrides.rpz": rpz}),
	)
	useClient(t, c)

	var out, errb bytes.Buffer
	if err := migrateMain([]string{"-kube-namespace", "dns"}, &out, &errb); err != nil {
		t.Fatalf("dry run: %v\n%s", err, errb.String())
	}
	for _, want := range []string{"kind: DNSZone", "kind: AddressOverride", "domain: tornberg.me", "zone: home.example.com"} {
		if !strings.Contains(out.String(), want) {
			t.Errorf("manifest lacks %q:\n%s", want, out.String())
		}
	}
	if l, _ := c.Resource(kubesource.OverrideGVR).Namespace("dns").List(context.Background(), metav1.ListOptions{}); len(l.Items) != 0 {
		t.Fatal("the dry run wrote objects")
	}

	out.Reset()
	errb.Reset()
	if err := migrateMain([]string{"-kube-namespace", "dns", "-apply"}, &out, &errb); err != nil {
		t.Fatalf("apply: %v\n%s", err, errb.String())
	}
	if l, _ := c.Resource(kubesource.OverrideGVR).Namespace("dns").List(context.Background(), metav1.ListOptions{}); len(l.Items) != 2 {
		t.Fatalf("%d overrides applied, want 2", len(l.Items))
	}
	if l, _ := c.Resource(kubesource.ZoneGVR).Namespace("dns").List(context.Background(), metav1.ListOptions{}); len(l.Items) != 1 {
		t.Fatalf("%d zones applied, want 1", len(l.Items))
	}
	if !strings.Contains(errb.String(), "old ConfigMaps were not touched") {
		t.Errorf("no reassurance in the report:\n%s", errb.String())
	}
	// The ConfigMaps are exactly as they were.
	cm, err := c.Resource(configMaps).Namespace("dns").Get(context.Background(), "fancy-dns-rpz", metav1.GetOptions{})
	if err != nil || cm.Object["data"].(map[string]any)["address-overrides.rpz"] != rpz {
		t.Fatalf("the source ConfigMap changed: %v %v", cm, err)
	}
	// Running it again changes nothing (create-or-update).
	if err := migrateMain([]string{"-kube-namespace", "dns", "-apply"}, &out, &errb); err != nil {
		t.Fatalf("second apply: %v", err)
	}
}

func TestMigrateOfflineFromFiles(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "home.example.com.zone"), []byte(zone), 0o600); err != nil {
		t.Fatal(err)
	}
	rpzPath := filepath.Join(t.TempDir(), "a.rpz")
	if err := os.WriteFile(rpzPath, []byte(rpz), 0o600); err != nil {
		t.Fatal(err)
	}
	// No cluster client is built when nothing is read from one.
	old := newClient
	newClient = func(kubesource.ClientOptions) (dynamic.Interface, error) {
		t.Fatal("a cluster client was built for an offline run")
		return nil, nil
	}
	defer func() { newClient = old }()

	var out, errb bytes.Buffer
	err := migrateMain([]string{"-kube-namespace", "dns", "-zones-dir", dir, "-rpz-file", rpzPath, "-zones-configmap", "", "-rpz-configmap", ""}, &out, &errb)
	if err != nil {
		t.Fatalf("%v\n%s", err, errb.String())
	}
	if !strings.Contains(out.String(), "kind: DNSZone") || !strings.Contains(out.String(), "kind: AddressOverride") {
		t.Fatalf("manifest:\n%s", out.String())
	}
}

func TestMigrateMissingConfigMapsIsNotAnError(t *testing.T) {
	useClient(t, fakeCluster())
	var out, errb bytes.Buffer
	if err := migrateMain([]string{"-kube-namespace", "dns"}, &out, &errb); err != nil {
		t.Fatalf("%v", err)
	}
	if !strings.Contains(errb.String(), "does not exist") || !strings.Contains(errb.String(), "nothing to migrate") {
		t.Fatalf("report:\n%s", errb.String())
	}
}