package controller

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"sync"

	. "github.com/onsi/ginkgo/v2"
	. "github.com/onsi/gomega"
	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/types"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"

	terdutv1alpha1 "git.ryuvia.com/niklas/terdut-operator/api/v1alpha1"
	"git.ryuvia.com/niklas/terdut-operator/internal/tdclient"
)

// fakeTerdutServer reproduces the exact stateful semantics of
// /api/bootstrap, /api/service-accounts and /api/version that the
// bootstrap flow depends on (DESIGN.md §6, §11: "terdut-server's REST API
// is faked with a small httptest.Server per controller test ... matching
// the real handlers' request/response shapes"), including the 403-after-
// first-success and 409-on-name-conflict behavior the adopt-on-conflict
// recovery path exists for.
type fakeTerdutServer struct {
	mu           sync.Mutex
	bootstrapped bool
	bootstrap403 bool // force every /api/bootstrap call to 403, even the first
	nextID       int64
	accounts     map[string]int64 // name -> id
	keyMints     map[int64]int    // id -> number of keys minted so far
}

func newFakeTerdutServer() (*fakeTerdutServer, *httptest.Server) {
	f := &fakeTerdutServer{accounts: map[string]int64{}, keyMints: map[int64]int{}}
	return f, httptest.NewServer(f)
}

func (f *fakeTerdutServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	f.mu.Lock()
	defer f.mu.Unlock()

	switch {
	case r.URL.Path == "/api/version":
		writeJSON(w, http.StatusOK, map[string]string{"version": "test"})

	case r.URL.Path == "/api/bootstrap" && r.Method == http.MethodPost:
		if f.bootstrapped || f.bootstrap403 {
			writeJSON(w, http.StatusForbidden, map[string]string{"error": "bootstrap already completed"})
			return
		}
		f.bootstrapped = true
		writeJSON(w, http.StatusCreated, tdclient.BootstrapResult{
			APIKey: tdclient.APIKey{ID: 1, Name: "bootstrap", Key: "admin-key-raw"},
		})

	case r.URL.Path == "/api/service-accounts" && r.Method == http.MethodPost:
		var req struct {
			Name  string `json:"name"`
			Scope string `json:"scope"`
		}
		_ = json.NewDecoder(r.Body).Decode(&req)
		if _, exists := f.accounts[req.Name]; exists {
			writeJSON(w, http.StatusConflict, map[string]string{"error": "a service account with that name already exists"})
			return
		}
		f.nextID++
		id := f.nextID
		f.accounts[req.Name] = id
		f.keyMints[id] = 1
		writeJSON(w, http.StatusCreated, tdclient.CreateServiceAccountResult{
			ServiceAccount: tdclient.ServiceAccount{ID: id, Name: req.Name, Scope: req.Scope},
			Key:            tdclient.APIKey{ID: 1, Name: "initial", Key: fmt.Sprintf("instance-key-%d-initial", id)},
		})

	case r.URL.Path == "/api/service-accounts" && r.Method == http.MethodGet:
		name := r.URL.Query().Get("name")
		id, exists := f.accounts[name]
		if !exists {
			writeJSON(w, http.StatusOK, []tdclient.ServiceAccount{})
			return
		}
		writeJSON(w, http.StatusOK, []tdclient.ServiceAccount{{ID: id, Name: name, Scope: "instance"}})

	default:
		if id, name, ok := parseKeysPath(r.URL.Path); ok && r.Method == http.MethodPost {
			f.keyMints[id]++
			writeJSON(w, http.StatusCreated, tdclient.APIKey{
				ID: int64(f.keyMints[id]), Name: name,
				Key: fmt.Sprintf("instance-key-%d-mint%d", id, f.keyMints[id]),
			})
			return
		}
		w.WriteHeader(http.StatusNotFound)
	}
}

func parseKeysPath(path string) (id int64, mintName string, ok bool) {
	var parsedID int64
	n, err := fmt.Sscanf(path, "/api/service-accounts/%d/keys", &parsedID)
	if err != nil || n != 1 {
		return 0, "", false
	}
	return parsedID, "minted", true
}

func writeJSON(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(v)
}

var _ = Describe("TerdutServer Controller", func() {
	const operatorNamespace = "default"

	var (
		reconciler *TerdutServerReconciler
		name       string
		objKey     types.NamespacedName
	)

	BeforeEach(func() {
		reconciler = &TerdutServerReconciler{
			Client:            k8sClient,
			Scheme:            k8sClient.Scheme(),
			OperatorNamespace: operatorNamespace,
		}
		name = fmt.Sprintf("test-server-%d-%d", GinkgoRandomSeed(), GinkgoParallelProcess())
		objKey = types.NamespacedName{Name: name, Namespace: operatorNamespace}
	})

	AfterEach(func(ctx SpecContext) {
		srv := &terdutv1alpha1.TerdutServer{}
		if err := k8sClient.Get(ctx, objKey, srv); err == nil {
			srv.Finalizers = nil
			_ = k8sClient.Update(ctx, srv)
			_ = k8sClient.Delete(ctx, srv)
		}
		for _, n := range []string{checkpointSecretNameFor(name), credentialsSecretNameFor(name)} {
			_ = k8sClient.Delete(ctx, &corev1.Secret{ObjectMeta: metav1.ObjectMeta{Name: n, Namespace: operatorNamespace}})
		}
	})

	dsnSpec := func() terdutv1alpha1.TerdutServerSpec {
		return terdutv1alpha1.TerdutServerSpec{
			Image:      terdutv1alpha1.ImageSpec{Repository: "example.invalid/terdut-server", Tag: "test"},
			Networking: terdutv1alpha1.NetworkingSpec{Hostname: "terdut.example.invalid", ServicePort: 8080},
			Database:   terdutv1alpha1.DatabaseSpec{DSN: "postgres://terdut@test-postgres:5432/terdut?sslmode=require"},
		}
	}

	createServer := func(ctx context.Context, spec terdutv1alpha1.TerdutServerSpec) {
		srv := &terdutv1alpha1.TerdutServer{
			ObjectMeta: metav1.ObjectMeta{Name: name, Namespace: operatorNamespace},
			Spec:       spec,
		}
		Expect(k8sClient.Create(ctx, srv)).To(Succeed())
	}

	reconcileOnce := func(ctx context.Context) ctrl.Result {
		res, err := reconciler.Reconcile(ctx, reconcile.Request{NamespacedName: objKey})
		Expect(err).NotTo(HaveOccurred())
		return res
	}

	markDeploymentReady := func(ctx context.Context) {
		var deploy appsv1.Deployment
		Expect(k8sClient.Get(ctx, objKey, &deploy)).To(Succeed())
		deploy.Status.ReadyReplicas = 1
		deploy.Status.Replicas = 1
		Expect(k8sClient.Status().Update(ctx, &deploy)).To(Succeed())
	}

	readyCondition := func(ctx context.Context) metav1.Condition {
		srv := &terdutv1alpha1.TerdutServer{}
		Expect(k8sClient.Get(ctx, objKey, srv)).To(Succeed())
		c := meta.FindStatusCondition(srv.Status.Conditions, terdutv1alpha1.ConditionReady)
		Expect(c).NotTo(BeNil(), "Ready condition should always be set after a reconcile past the finalizer-add pass")
		return *c
	}

	Describe("bring-your-own DSN path", func() {
		It("reaches Ready through the full lifecycle: finalizer, Deployment/Service, wait, bootstrap", func(ctx SpecContext) {
			fake, fakeSrv := newFakeTerdutServer()
			DeferCleanup(fakeSrv.Close)
			reconciler.NewClient = func(string) *tdclient.Client { return tdclient.New(fakeSrv.URL) }

			createServer(ctx, dsnSpec())

			// Pass 1: adds the finalizer and returns early.
			reconcileOnce(ctx)
			srv := &terdutv1alpha1.TerdutServer{}
			Expect(k8sClient.Get(ctx, objKey, srv)).To(Succeed())
			Expect(srv.Finalizers).To(ContainElement(finalizerName))

			// Pass 2: creates Deployment + Service, waits for readiness.
			reconcileOnce(ctx)
			Expect(readyCondition(ctx).Reason).To(Equal(terdutv1alpha1.ReasonWaitingForDeployment))

			var deploy appsv1.Deployment
			Expect(k8sClient.Get(ctx, objKey, &deploy)).To(Succeed())
			Expect(deploy.Spec.Template.Spec.Containers[0].Image).To(Equal("example.invalid/terdut-server:test"))
			envNames := map[string]string{}
			for _, e := range deploy.Spec.Template.Spec.Containers[0].Env {
				envNames[e.Name] = e.Value
			}
			Expect(envNames).To(HaveKeyWithValue("TERDUT_DB_DSN", "postgres://terdut@test-postgres:5432/terdut?sslmode=require"))
			Expect(envNames).To(HaveKeyWithValue("TERDUT_OPERATOR_MODE", "true"))

			var svc corev1.Service
			Expect(k8sClient.Get(ctx, objKey, &svc)).To(Succeed())
			Expect(svc.Spec.Ports[0].Port).To(Equal(int32(8080)))

			// Simulate the Deployment becoming ready (envtest has no
			// kubelet/deployment-controller to do this for real).
			markDeploymentReady(ctx)

			// Pass 3: bootstraps for real against the fake server.
			reconcileOnce(ctx)

			Expect(fake.bootstrapped).To(BeTrue())

			Expect(k8sClient.Get(ctx, objKey, srv)).To(Succeed())
			ready := meta.FindStatusCondition(srv.Status.Conditions, terdutv1alpha1.ConditionReady)
			Expect(ready.Status).To(Equal(metav1.ConditionTrue))
			Expect(ready.Reason).To(Equal(terdutv1alpha1.ReasonAdopted))
			Expect(srv.Status.CredentialsSecretRef).NotTo(BeNil())
			Expect(srv.Status.CredentialsSecretRef.Key).To(Equal(credentialsSecretDataKey))

			var credsSecret corev1.Secret
			Expect(k8sClient.Get(ctx, types.NamespacedName{
				Name: srv.Status.CredentialsSecretRef.Name, Namespace: operatorNamespace,
			}, &credsSecret)).To(Succeed())
			Expect(string(credsSecret.Data[credentialsSecretDataKey])).To(Equal("instance-key-1-initial"))

			// The checkpoint is cleaned up once the lasting credential is
			// written (DESIGN.md §6 point 2).
			var checkpoint corev1.Secret
			err := k8sClient.Get(ctx, types.NamespacedName{Name: checkpointSecretName(srv), Namespace: operatorNamespace}, &checkpoint)
			Expect(err).To(HaveOccurred())
		})
	})

	Describe("the adopt-on-409 recovery path", func() {
		It("mints a fresh key instead of erroring when the service account already exists", func(ctx SpecContext) {
			fake, fakeSrv := newFakeTerdutServer()
			DeferCleanup(fakeSrv.Close)
			fake.bootstrapped = true // an earlier attempt already bootstrapped...
			fake.nextID = 1
			fake.accounts[serviceAccountName] = 1 // ...and already created the service account.
			fake.keyMints[1] = 1
			reconciler.NewClient = func(string) *tdclient.Client { return tdclient.New(fakeSrv.URL) }

			createServer(ctx, dsnSpec())
			reconcileOnce(ctx) // finalizer
			reconcileOnce(ctx) // Deployment/Service, WaitingForDeployment
			markDeploymentReady(ctx)

			// The earlier attempt's checkpoint survived (that's how this
			// reconcile can authenticate at all to recover).
			Expect(reconciler.writeSecret(ctx, checkpointSecretName(&terdutv1alpha1.TerdutServer{
				ObjectMeta: metav1.ObjectMeta{Name: name, Namespace: operatorNamespace},
			}), "admin-key-raw")).To(Succeed())

			reconcileOnce(ctx)

			srv := &terdutv1alpha1.TerdutServer{}
			Expect(k8sClient.Get(ctx, objKey, srv)).To(Succeed())
			Expect(meta.FindStatusCondition(srv.Status.Conditions, terdutv1alpha1.ConditionReady).Status).To(Equal(metav1.ConditionTrue))

			var credsSecret corev1.Secret
			Expect(k8sClient.Get(ctx, types.NamespacedName{
				Name: srv.Status.CredentialsSecretRef.Name, Namespace: operatorNamespace,
			}, &credsSecret)).To(Succeed())
			// Minted fresh, not the (never-seen-by-this-reconcile) "initial"
			// key from the account's original creation.
			Expect(string(credsSecret.Data[credentialsSecretDataKey])).To(Equal("instance-key-1-mint2"))
		})
	})

	Describe("the BootstrapStateLost path", func() {
		It("fails closed when the server reports already-bootstrapped with no checkpoint to recover from", func(ctx SpecContext) {
			fake, fakeSrv := newFakeTerdutServer()
			_ = fake
			DeferCleanup(fakeSrv.Close)
			fake.bootstrap403 = true
			reconciler.NewClient = func(string) *tdclient.Client { return tdclient.New(fakeSrv.URL) }

			createServer(ctx, dsnSpec())
			reconcileOnce(ctx) // finalizer
			reconcileOnce(ctx) // Deployment/Service
			markDeploymentReady(ctx)

			reconcileOnce(ctx)

			cond := readyCondition(ctx)
			Expect(cond.Status).To(Equal(metav1.ConditionFalse))
			Expect(cond.Reason).To(Equal(terdutv1alpha1.ReasonBootstrapStateLost))
		})
	})

	Describe("the Zalando postgresClusterRef path", func() {
		zalandoSpec := func(clusterName string) terdutv1alpha1.TerdutServerSpec {
			s := dsnSpec()
			s.Database = terdutv1alpha1.DatabaseSpec{
				PostgresClusterRef: &terdutv1alpha1.PostgresClusterRef{Name: clusterName},
			}
			return s
		}

		It("waits with reason PostgresClusterNotFound when the postgresql CR doesn't exist yet", func(ctx SpecContext) {
			createServer(ctx, zalandoSpec("missing-cluster"))
			reconcileOnce(ctx) // finalizer
			reconcileOnce(ctx)

			Expect(readyCondition(ctx).Reason).To(Equal(terdutv1alpha1.ReasonPostgresClusterNotFound))
		})

		It("resolves a real DSN and reaches Ready once the CR and its generated Secret both exist", func(ctx SpecContext) {
			clusterName := "pg-" + name
			cluster := &unstructured.Unstructured{}
			cluster.SetGroupVersionKind(postgresqlGVK)
			cluster.SetName(clusterName)
			cluster.SetNamespace(operatorNamespace)
			Expect(unstructured.SetNestedField(cluster.Object, map[string]any{}, "spec")).To(Succeed())
			Expect(k8sClient.Create(ctx, cluster)).To(Succeed())
			DeferCleanup(func() { _ = k8sClient.Delete(ctx, cluster) })

			credsSecretName := fmt.Sprintf("terdut.%s.credentials.postgresql.acid.zalan.do", clusterName)
			zalandoSecret := &corev1.Secret{
				ObjectMeta: metav1.ObjectMeta{Name: credsSecretName, Namespace: operatorNamespace},
				Data:       map[string][]byte{"password": []byte("whatever")},
			}
			Expect(k8sClient.Create(ctx, zalandoSecret)).To(Succeed())
			DeferCleanup(func() { _ = k8sClient.Delete(ctx, zalandoSecret) })

			fake, fakeSrv := newFakeTerdutServer()
			_ = fake
			DeferCleanup(fakeSrv.Close)
			reconciler.NewClient = func(string) *tdclient.Client { return tdclient.New(fakeSrv.URL) }

			createServer(ctx, zalandoSpec(clusterName))
			reconcileOnce(ctx) // finalizer
			reconcileOnce(ctx) // Deployment/Service created with resolved DB env

			var deploy appsv1.Deployment
			Expect(k8sClient.Get(ctx, objKey, &deploy)).To(Succeed())
			var dsn string
			for _, e := range deploy.Spec.Template.Spec.Containers[0].Env {
				if e.Name == "TERDUT_DB_DSN" {
					dsn = e.Value
				}
			}
			Expect(dsn).To(Equal(fmt.Sprintf("postgres://terdut@%s.%s.svc:5432/terdut?sslmode=require", clusterName, operatorNamespace)))

			markDeploymentReady(ctx)
			reconcileOnce(ctx)

			Expect(readyCondition(ctx).Status).To(Equal(metav1.ConditionTrue))
		})
	})

	Describe("deletion", func() {
		It("removes the credentials and checkpoint Secrets and the finalizer", func(ctx SpecContext) {
			fake, fakeSrv := newFakeTerdutServer()
			_ = fake
			DeferCleanup(fakeSrv.Close)
			reconciler.NewClient = func(string) *tdclient.Client { return tdclient.New(fakeSrv.URL) }

			createServer(ctx, dsnSpec())
			reconcileOnce(ctx)
			reconcileOnce(ctx)
			markDeploymentReady(ctx)
			reconcileOnce(ctx)

			srv := &terdutv1alpha1.TerdutServer{}
			Expect(k8sClient.Get(ctx, objKey, srv)).To(Succeed())
			credsName := srv.Status.CredentialsSecretRef.Name

			Expect(k8sClient.Delete(ctx, srv)).To(Succeed())
			reconcileOnce(ctx) // runs the finalizer

			err := k8sClient.Get(ctx, objKey, srv)
			Expect(err).To(HaveOccurred(), "the TerdutServer itself should be gone once the finalizer clears")

			var leftover corev1.Secret
			err = k8sClient.Get(ctx, types.NamespacedName{Name: credsName, Namespace: operatorNamespace}, &leftover)
			Expect(err).To(HaveOccurred(), "the credentials Secret should have been cleaned up by the finalizer")
		})
	})

	When("the TerdutServer object no longer exists", func() {
		It("returns no error (deleted between enqueue and reconcile)", func(ctx SpecContext) {
			_, err := reconciler.Reconcile(ctx, reconcile.Request{
				NamespacedName: types.NamespacedName{Name: "never-created", Namespace: operatorNamespace},
			})
			Expect(err).NotTo(HaveOccurred())
		})
	})
})

// checkpointSecretNameFor/credentialsSecretNameFor let AfterEach clean up
// without needing a live TerdutServer object (it may already be gone by
// then in the deletion test).
func checkpointSecretNameFor(name string) string {
	return fmt.Sprintf("default.%s-bootstrap-admin", name)
}
func credentialsSecretNameFor(name string) string {
	return fmt.Sprintf("default.%s-instance-credentials", name)
}