package tsigapi

import (
	"context"
	"fmt"
	"time"

	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/client"

	bindv1alpha1 "git.unkin.net/unkin/bind-operator/api/v1alpha1"
)

// createKey creates a BindTSIGKey and waits for the operator to materialise it.
func (s *Server) createKey(ctx context.Context, req createRequest) (*keyResponse, error) {
	algorithm := req.Algorithm
	if algorithm == "" {
		algorithm = string(bindv1alpha1.TSIGHMACSHA256)
	}
	key := &bindv1alpha1.BindTSIGKey{
		ObjectMeta: metav1.ObjectMeta{
			Name:      req.Name,
			Namespace: s.Namespace,
			Labels:    map[string]string{"app.kubernetes.io/managed-by": "bind-tsig-api"},
		},
		Spec: bindv1alpha1.BindTSIGKeySpec{
			Algorithm:  bindv1alpha1.TSIGAlgorithm(algorithm),
			ClusterRef: req.ClusterRef,
			KeyName:    req.Name,
		},
	}
	if err := s.Client.Create(ctx, key); err != nil && !apierrors.IsAlreadyExists(err) {
		return nil, fmt.Errorf("create bindtsigkey: %w", err)
	}
	return s.waitForMaterial(ctx, req.Name)
}

// readKey returns the current material for a key.
func (s *Server) readKey(ctx context.Context, name string) (*keyResponse, error) {
	var key bindv1alpha1.BindTSIGKey
	if err := s.Client.Get(ctx, s.key(name), &key); err != nil {
		return nil, err
	}
	return s.material(ctx, &key)
}

// rotateKey replaces the key material: it deletes the key Secret (the operator
// regenerates it) and bumps a rotation annotation so the cluster controller
// re-renders keys.conf and reloads BIND.
func (s *Server) rotateKey(ctx context.Context, name string) (*keyResponse, error) {
	var key bindv1alpha1.BindTSIGKey
	if err := s.Client.Get(ctx, s.key(name), &key); err != nil {
		return nil, err
	}

	secretName := secretNameFor(&key)
	var secret corev1.Secret
	if err := s.Client.Get(ctx, client.ObjectKey{Namespace: s.Namespace, Name: secretName}, &secret); err == nil {
		if derr := s.Client.Delete(ctx, &secret); derr != nil && !apierrors.IsNotFound(derr) {
			return nil, fmt.Errorf("delete key secret: %w", derr)
		}
	} else if !apierrors.IsNotFound(err) {
		return nil, err
	}

	// Trigger re-generation + re-render by bumping the CR.
	if key.Annotations == nil {
		key.Annotations = map[string]string{}
	}
	key.Annotations[rotationAnnotation] = s.Now().UTC().Format(time.RFC3339Nano)
	if err := s.Client.Update(ctx, &key); err != nil {
		return nil, fmt.Errorf("bump rotation annotation: %w", err)
	}

	return s.waitForNewMaterial(ctx, name, secret.UID)
}

// deleteKey removes the BindTSIGKey (its Secret is garbage-collected).
func (s *Server) deleteKey(ctx context.Context, name string) error {
	key := &bindv1alpha1.BindTSIGKey{ObjectMeta: metav1.ObjectMeta{Name: name, Namespace: s.Namespace}}
	if err := s.Client.Delete(ctx, key); err != nil && !apierrors.IsNotFound(err) {
		return err
	}
	return nil
}

// material reads the key material from the Secret referenced by a BindTSIGKey.
func (s *Server) material(ctx context.Context, key *bindv1alpha1.BindTSIGKey) (*keyResponse, error) {
	var secret corev1.Secret
	if err := s.Client.Get(ctx, client.ObjectKey{Namespace: s.Namespace, Name: secretNameFor(key)}, &secret); err != nil {
		return nil, err
	}
	algorithm := string(secret.Data["algorithm"])
	if algorithm == "" {
		algorithm = string(key.Spec.Algorithm)
	}
	keyName := string(secret.Data["keyName"])
	if keyName == "" {
		keyName = key.Name
	}
	return &keyResponse{
		Name:       key.Name,
		Algorithm:  algorithm,
		Secret:     string(secret.Data["secret"]),
		KeyName:    keyName,
		ClusterRef: key.Spec.ClusterRef,
	}, nil
}

// waitForMaterial polls until the key's Secret exists (operator reconciled).
func (s *Server) waitForMaterial(ctx context.Context, name string) (*keyResponse, error) {
	deadline := s.Now().Add(s.WaitTimeout)
	for {
		var key bindv1alpha1.BindTSIGKey
		if err := s.Client.Get(ctx, s.key(name), &key); err != nil {
			return nil, err
		}
		if resp, err := s.material(ctx, &key); err == nil && resp.Secret != "" {
			return resp, nil
		}
		if s.Now().After(deadline) {
			return nil, fmt.Errorf("timed out waiting for key %q material", name)
		}
		select {
		case <-ctx.Done():
			return nil, ctx.Err()
		case <-time.After(250 * time.Millisecond):
		}
	}
}

// waitForNewMaterial polls until the Secret has been recreated (different UID).
func (s *Server) waitForNewMaterial(ctx context.Context, name string, oldUID types.UID) (*keyResponse, error) {
	deadline := s.Now().Add(s.WaitTimeout)
	for {
		var key bindv1alpha1.BindTSIGKey
		if err := s.Client.Get(ctx, s.key(name), &key); err != nil {
			return nil, err
		}
		var secret corev1.Secret
		err := s.Client.Get(ctx, client.ObjectKey{Namespace: s.Namespace, Name: secretNameFor(&key)}, &secret)
		if err == nil && secret.UID != oldUID && len(secret.Data["secret"]) > 0 {
			return s.material(ctx, &key)
		}
		if s.Now().After(deadline) {
			return nil, fmt.Errorf("timed out waiting for key %q to rotate", name)
		}
		select {
		case <-ctx.Done():
			return nil, ctx.Err()
		case <-time.After(250 * time.Millisecond):
		}
	}
}

// secretNameFor returns the Secret name holding a key's material.
func secretNameFor(key *bindv1alpha1.BindTSIGKey) string {
	if key.Status.SecretName != "" {
		return key.Status.SecretName
	}
	if key.Spec.SecretName != "" {
		return key.Spec.SecretName
	}
	return key.Name + "-tsig"
}