package controller

import (
	"context"
	"testing"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/client/fake"

	v1alpha1 "git.unkin.net/unkin/kea-operator/api/v1alpha1"
)

func testScheme(t *testing.T) *runtime.Scheme {
	t.Helper()
	s := runtime.NewScheme()
	if err := clientgoscheme.AddToScheme(s); err != nil {
		t.Fatal(err)
	}
	if err := v1alpha1.AddToScheme(s); err != nil {
		t.Fatal(err)
	}
	return s
}

func newClusterFixture() *v1alpha1.KeaCluster {
	return &v1alpha1.KeaCluster{
		ObjectMeta: metav1.ObjectMeta{Name: "pxe", Namespace: "dhcp-system"},
		Spec: v1alpha1.KeaClusterSpec{
			Replicas:   int32ptr(2),
			DomainName: "main.unkin.net",
			HA:         v1alpha1.HASpec{Mode: v1alpha1.HAHotStandby},
		},
	}
}

func TestKeaClusterReconcileCreatesWorkload(t *testing.T) {
	scheme := testScheme(t)
	cluster := newClusterFixture()
	subnet := &v1alpha1.KeaSubnet{
		ObjectMeta: metav1.ObjectMeta{Name: "s13", Namespace: "dhcp-system"},
		Spec:       v1alpha1.KeaSubnetSpec{Subnet: "198.18.13.0/24", Pools: []string{"198.18.13.200 - 198.18.13.220"}},
	}
	cl := fake.NewClientBuilder().
		WithScheme(scheme).
		WithStatusSubresource(&v1alpha1.KeaCluster{}).
		WithObjects(cluster, subnet).
		Build()

	r := &KeaClusterReconciler{Client: cl, Scheme: scheme}
	if _, err := r.Reconcile(context.Background(), ctrl.Request{NamespacedName: types.NamespacedName{Namespace: "dhcp-system", Name: "pxe"}}); err != nil {
		t.Fatalf("reconcile: %v", err)
	}

	// ConfigMap rendered with the subnet.
	var cm corev1.ConfigMap
	if err := cl.Get(context.Background(), types.NamespacedName{Namespace: "dhcp-system", Name: "pxe-config"}, &cm); err != nil {
		t.Fatalf("configmap not created: %v", err)
	}
	if got := cm.Data["kea-dhcp4.conf"]; got == "" || !contains(got, "198.18.13.0/24") {
		t.Errorf("configmap missing subnet render")
	}

	// StatefulSet with 2 containers and a config-hash annotation.
	var sts appsv1.StatefulSet
	if err := cl.Get(context.Background(), types.NamespacedName{Namespace: "dhcp-system", Name: "pxe"}, &sts); err != nil {
		t.Fatalf("statefulset not created: %v", err)
	}
	if *sts.Spec.Replicas != 2 {
		t.Errorf("expected 2 replicas, got %d", *sts.Spec.Replicas)
	}
	if len(sts.Spec.Template.Spec.Containers) != 2 {
		t.Errorf("expected kea-dhcp4 + kea-ctrl-agent containers, got %d", len(sts.Spec.Template.Spec.Containers))
	}
	if sts.Spec.Template.Annotations["kea.unkin.net/config-hash"] == "" {
		t.Errorf("missing config-hash annotation")
	}

	// Anycast + headless services.
	for _, name := range []string{"pxe", "pxe-headless"} {
		var svc corev1.Service
		if err := cl.Get(context.Background(), types.NamespacedName{Namespace: "dhcp-system", Name: name}, &svc); err != nil {
			t.Errorf("service %s not created: %v", name, err)
		}
	}
}

// TestReconcileWiresInitContainer asserts the entrypoint refactor's pod shape:
// a kea-init initContainer prepares config + waits for HA peer DNS, and the two
// main containers exec kea directly with no wrapper shell. The init script comes
// from the ConfigMap (so its hash rolls the STS), and the old per-container
// entrypoint scripts are gone.
func TestReconcileWiresInitContainer(t *testing.T) {
	scheme := testScheme(t)
	cluster := newClusterFixture()
	cl := fake.NewClientBuilder().
		WithScheme(scheme).
		WithStatusSubresource(&v1alpha1.KeaCluster{}).
		WithObjects(cluster).
		Build()
	r := &KeaClusterReconciler{Client: cl, Scheme: scheme}
	if _, err := r.Reconcile(context.Background(), ctrl.Request{NamespacedName: types.NamespacedName{Namespace: "dhcp-system", Name: "pxe"}}); err != nil {
		t.Fatalf("reconcile: %v", err)
	}

	// ConfigMap carries init.sh and no longer the per-container entrypoints.
	var cm corev1.ConfigMap
	if err := cl.Get(context.Background(), types.NamespacedName{Namespace: "dhcp-system", Name: "pxe-config"}, &cm); err != nil {
		t.Fatalf("configmap not created: %v", err)
	}
	if cm.Data["init.sh"] == "" {
		t.Errorf("configmap missing init.sh")
	}
	for _, gone := range []string{"entrypoint-dhcp4.sh", "entrypoint-ctrlagent.sh"} {
		if _, ok := cm.Data[gone]; ok {
			t.Errorf("configmap must not still carry %q", gone)
		}
	}

	var sts appsv1.StatefulSet
	if err := cl.Get(context.Background(), types.NamespacedName{Namespace: "dhcp-system", Name: "pxe"}, &sts); err != nil {
		t.Fatalf("statefulset not created: %v", err)
	}
	spec := sts.Spec.Template.Spec

	// Exactly one initContainer, named kea-init, running init.sh with POD_NAME
	// sourced from the downward API.
	if len(spec.InitContainers) != 1 || spec.InitContainers[0].Name != "kea-init" {
		t.Fatalf("expected one kea-init initContainer, got %#v", spec.InitContainers)
	}
	initC := spec.InitContainers[0]
	if got := initC.Command; len(got) != 2 || got[0] != "/bin/sh" || got[1] != "/etc/kea-operator/init.sh" {
		t.Errorf("init command = %v, want [/bin/sh /etc/kea-operator/init.sh]", got)
	}
	var podNameFromDownward bool
	for _, e := range initC.Env {
		if e.Name == "POD_NAME" && e.ValueFrom != nil && e.ValueFrom.FieldRef != nil && e.ValueFrom.FieldRef.FieldPath == "metadata.name" {
			podNameFromDownward = true
		}
	}
	if !podNameFromDownward {
		t.Errorf("init container must source POD_NAME from downward API metadata.name, env=%#v", initC.Env)
	}

	// Main containers exec kea directly (no /bin/sh wrapper).
	wantCmd := map[string][]string{
		"kea-dhcp4":      {"/usr/sbin/kea-dhcp4", "-c", "/var/run/kea/kea-dhcp4.conf"},
		"kea-ctrl-agent": {"/usr/sbin/kea-ctrl-agent", "-c", "/var/run/kea/kea-ctrl-agent.conf"},
	}
	for _, ctr := range spec.Containers {
		want, ok := wantCmd[ctr.Name]
		if !ok {
			t.Errorf("unexpected container %q", ctr.Name)
			continue
		}
		if len(ctr.Command) == 0 || ctr.Command[0] == "/bin/sh" {
			t.Errorf("container %q must exec kea directly, got %v", ctr.Name, ctr.Command)
		}
		if !equalStrings(ctr.Command, want) {
			t.Errorf("container %q command = %v, want %v", ctr.Name, ctr.Command, want)
		}
	}
}

func equalStrings(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}

// TestConfigHashChangesWithSubnets guards the roll trigger: adding a subnet
// must change the pod-template config hash (so the STS rolls).
func TestConfigHashChangesWithSubnets(t *testing.T) {
	scheme := testScheme(t)

	hashFor := func(objs ...client.Object) string {
		base := []client.Object{newClusterFixture()}
		cl := fake.NewClientBuilder().
			WithScheme(scheme).
			WithStatusSubresource(&v1alpha1.KeaCluster{}).
			WithObjects(append(base, objs...)...).
			Build()
		r := &KeaClusterReconciler{Client: cl, Scheme: scheme}
		if _, err := r.Reconcile(context.Background(), ctrl.Request{NamespacedName: types.NamespacedName{Namespace: "dhcp-system", Name: "pxe"}}); err != nil {
			t.Fatal(err)
		}
		var sts appsv1.StatefulSet
		if err := cl.Get(context.Background(), types.NamespacedName{Namespace: "dhcp-system", Name: "pxe"}, &sts); err != nil {
			t.Fatal(err)
		}
		return sts.Spec.Template.Annotations["kea.unkin.net/config-hash"]
	}

	empty := hashFor()
	withSubnet := hashFor(&v1alpha1.KeaSubnet{
		ObjectMeta: metav1.ObjectMeta{Name: "s13", Namespace: "dhcp-system"},
		Spec:       v1alpha1.KeaSubnetSpec{Subnet: "198.18.13.0/24"},
	})
	if empty == withSubnet {
		t.Errorf("config hash did not change when a subnet was added")
	}
}

func TestClusterRefFiltersSubnets(t *testing.T) {
	scheme := testScheme(t)
	cluster := newClusterFixture()
	mine := &v1alpha1.KeaSubnet{
		ObjectMeta: metav1.ObjectMeta{Name: "mine", Namespace: "dhcp-system"},
		Spec:       v1alpha1.KeaSubnetSpec{Subnet: "198.18.13.0/24", ClusterRef: "pxe"},
	}
	other := &v1alpha1.KeaSubnet{
		ObjectMeta: metav1.ObjectMeta{Name: "other", Namespace: "dhcp-system"},
		Spec:       v1alpha1.KeaSubnetSpec{Subnet: "10.9.9.0/24", ClusterRef: "someone-else"},
	}
	cl := fake.NewClientBuilder().WithScheme(scheme).
		WithStatusSubresource(&v1alpha1.KeaCluster{}).
		WithObjects(cluster, mine, other).Build()
	r := &KeaClusterReconciler{Client: cl, Scheme: scheme}
	if _, err := r.Reconcile(context.Background(), ctrl.Request{NamespacedName: types.NamespacedName{Namespace: "dhcp-system", Name: "pxe"}}); err != nil {
		t.Fatal(err)
	}
	var cm corev1.ConfigMap
	_ = cl.Get(context.Background(), types.NamespacedName{Namespace: "dhcp-system", Name: "pxe-config"}, &cm)
	conf := cm.Data["kea-dhcp4.conf"]
	if !contains(conf, "198.18.13.0/24") {
		t.Errorf("cluster-matched subnet missing from config")
	}
	if contains(conf, "10.9.9.0/24") {
		t.Errorf("subnet bound to another cluster leaked into config")
	}
}

func contains(hay, needle string) bool {
	return len(hay) >= len(needle) && (indexOf(hay, needle) >= 0)
}

func indexOf(hay, needle string) int {
	for i := 0; i+len(needle) <= len(hay); i++ {
		if hay[i:i+len(needle)] == needle {
			return i
		}
	}
	return -1
}