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)
		}
	}
}

// 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
}