/*

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package controllers

import (
	"context"
	"fmt"

	"github.com/go-logr/logr"
	hydrav1alpha1 "github.com/ory/hydra-maester/api/v1alpha1"
	"github.com/ory/hydra-maester/hydra"
	"github.com/pkg/errors"
	apiv1 "k8s.io/api/core/v1"
	apierrs "k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/types"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

const (
	ClientIDKey     = "client_id"
	ClientSecretKey = "client_secret"
	FinalizerName   = "finalizer.ory.hydra.sh"
)

type HydraClientMakerFunc func(hydrav1alpha1.OAuth2ClientSpec) (HydraClientInterface, error)

type clientMapKey struct {
	url            string
	port           int
	endpoint       string
	forwardedProto string
}

type HydraClientInterface interface {
	GetOAuth2Client(id string) (*hydra.OAuth2ClientJSON, bool, error)
	ListOAuth2Client() ([]*hydra.OAuth2ClientJSON, error)
	PostOAuth2Client(o *hydra.OAuth2ClientJSON) (*hydra.OAuth2ClientJSON, error)
	PutOAuth2Client(o *hydra.OAuth2ClientJSON) (*hydra.OAuth2ClientJSON, error)
	DeleteOAuth2Client(id string) error
}

// OAuth2ClientReconciler reconciles a OAuth2Client object
type OAuth2ClientReconciler struct {
	HydraClient      HydraClientInterface
	HydraClientMaker HydraClientMakerFunc
	Log              logr.Logger
	otherClients     map[clientMapKey]HydraClientInterface
	client.Client
}

// +kubebuilder:rbac:groups=hydra.ory.sh,resources=oauth2clients,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=hydra.ory.sh,resources=oauth2clients/status,verbs=get;update;patch
// +kubebuilder:rbac:groups="",resources=secrets,verbs=get;list;watch;create;update;patch;delete

func (r *OAuth2ClientReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	_ = r.Log.WithValues("oauth2client", req.NamespacedName)

	var oauth2client hydrav1alpha1.OAuth2Client
	if err := r.Get(ctx, req.NamespacedName, &oauth2client); err != nil {
		if apierrs.IsNotFound(err) {
			if registerErr := r.unregisterOAuth2Clients(ctx, &oauth2client); registerErr != nil {
				return ctrl.Result{}, registerErr
			}
			return ctrl.Result{}, nil
		}
		return ctrl.Result{}, err
	}

	// examine DeletionTimestamp to determine if object is under deletion
	if oauth2client.ObjectMeta.DeletionTimestamp.IsZero() {
		// The object is not being deleted, so if it does not have our finalizer,
		// then lets add the finalizer and update the object. This is equivalent
		// registering our finalizer.
		if !containsString(oauth2client.ObjectMeta.Finalizers, FinalizerName) {
			typeMeta := oauth2client.TypeMeta
			oauth2client.ObjectMeta.Finalizers = append(oauth2client.ObjectMeta.Finalizers, FinalizerName)
			if err := r.Update(ctx, &oauth2client); err != nil {
				return ctrl.Result{}, err
			}
			// restore the TypeMeta object as it is removed during Update, but need to be accessed later
			oauth2client.TypeMeta = typeMeta
		}
	} else {
		// The object is being deleted
		if containsString(oauth2client.ObjectMeta.Finalizers, FinalizerName) {
			// our finalizer is present, so lets handle any external dependency
			if err := r.unregisterOAuth2Clients(ctx, &oauth2client); err != nil {
				// if fail to delete the external dependency here, return with error
				// so that it can be retried
				return ctrl.Result{}, err
			}

			// remove our finalizer from the list and update it.
			oauth2client.ObjectMeta.Finalizers = removeString(oauth2client.ObjectMeta.Finalizers, FinalizerName)
			if err := r.Update(ctx, &oauth2client); err != nil {
				return ctrl.Result{}, err
			}
		}

		return ctrl.Result{}, nil

	}

	var secret apiv1.Secret
	if err := r.Get(ctx, types.NamespacedName{Name: oauth2client.Spec.SecretName, Namespace: req.Namespace}, &secret); err != nil {
		if apierrs.IsNotFound(err) {
			if registerErr := r.registerOAuth2Client(ctx, &oauth2client, nil); registerErr != nil {
				return ctrl.Result{}, registerErr
			}
			return ctrl.Result{}, nil
		}
		return ctrl.Result{}, err
	}

	credentials, err := parseSecret(secret, oauth2client.Spec.TokenEndpointAuthMethod)
	if err != nil {
		r.Log.Error(err, fmt.Sprintf("secret %s/%s is invalid", secret.Name, secret.Namespace))
		if updateErr := r.updateReconciliationStatusError(ctx, &oauth2client, hydrav1alpha1.StatusInvalidSecret, err); updateErr != nil {
			return ctrl.Result{}, updateErr
		}
		return ctrl.Result{}, nil
	}

	hydraClient, err := r.getHydraClientForClient(oauth2client)
	if err != nil {
		r.Log.Error(err, fmt.Sprintf(
			"hydra address %s:%d%s is invalid",
			oauth2client.Spec.HydraAdmin.URL,
			oauth2client.Spec.HydraAdmin.Port,
			oauth2client.Spec.HydraAdmin.Endpoint,
		))
		if updateErr := r.updateReconciliationStatusError(ctx, &oauth2client, hydrav1alpha1.StatusInvalidHydraAddress, err); updateErr != nil {
			return ctrl.Result{}, updateErr
		}
		return ctrl.Result{}, nil
	}

	fetched, found, err := hydraClient.GetOAuth2Client(string(credentials.ID))
	if err != nil {
		return ctrl.Result{}, err

	}

	if found {
		//conclude reconciliation if the client exists and has not been updated
		if oauth2client.Generation == oauth2client.Status.ObservedGeneration {
			return ctrl.Result{}, nil
		}

		if fetched.Owner != fmt.Sprintf("%s/%s", oauth2client.Name, oauth2client.Namespace) {
			conflictErr := errors.Errorf("ID provided in secret %s/%s is assigned to another resource", secret.Name, secret.Namespace)
			if updateErr := r.updateReconciliationStatusError(ctx, &oauth2client, hydrav1alpha1.StatusInvalidSecret, conflictErr); updateErr != nil {
				return ctrl.Result{}, updateErr
			}
			return ctrl.Result{}, nil
		}

		if updateErr := r.updateRegisteredOAuth2Client(ctx, &oauth2client, credentials); updateErr != nil {
			return ctrl.Result{}, updateErr
		}
		return ctrl.Result{}, nil
	}

	if registerErr := r.registerOAuth2Client(ctx, &oauth2client, credentials); registerErr != nil {
		return ctrl.Result{}, registerErr
	}

	return ctrl.Result{}, nil
}

func (r *OAuth2ClientReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&hydrav1alpha1.OAuth2Client{}).
		Complete(r)
}

func (r *OAuth2ClientReconciler) registerOAuth2Client(ctx context.Context, c *hydrav1alpha1.OAuth2Client, credentials *hydra.Oauth2ClientCredentials) error {
	if err := r.unregisterOAuth2Clients(ctx, c); err != nil {
		return err
	}

	hydra, err := r.getHydraClientForClient(*c)
	if err != nil {
		return err
	}

	if credentials != nil {
		if _, err := hydra.PostOAuth2Client(c.ToOAuth2ClientJSON().WithCredentials(credentials)); err != nil {
			if updateErr := r.updateReconciliationStatusError(ctx, c, hydrav1alpha1.StatusRegistrationFailed, err); updateErr != nil {
				return updateErr
			}
		}
		return r.ensureEmptyStatusError(ctx, c)
	}

	created, err := hydra.PostOAuth2Client(c.ToOAuth2ClientJSON())
	if err != nil {
		if updateErr := r.updateReconciliationStatusError(ctx, c, hydrav1alpha1.StatusRegistrationFailed, err); updateErr != nil {
			return updateErr
		}
		return nil
	}

	clientSecret := apiv1.Secret{
		ObjectMeta: metav1.ObjectMeta{
			Name:      c.Spec.SecretName,
			Namespace: c.Namespace,
			OwnerReferences: []metav1.OwnerReference{{
				APIVersion: c.TypeMeta.APIVersion,
				Kind:       c.TypeMeta.Kind,
				Name:       c.ObjectMeta.Name,
				UID:        c.ObjectMeta.UID,
			}},
		},
		Data: map[string][]byte{
			ClientIDKey: []byte(*created.ClientID),
		},
	}

	if created.Secret != nil {
		clientSecret.Data[ClientSecretKey] = []byte(*created.Secret)
	}

	if err := r.Create(ctx, &clientSecret); err != nil {
		if updateErr := r.updateReconciliationStatusError(ctx, c, hydrav1alpha1.StatusCreateSecretFailed, err); updateErr != nil {
			return updateErr
		}
	}

	return r.ensureEmptyStatusError(ctx, c)
}

func (r *OAuth2ClientReconciler) updateRegisteredOAuth2Client(ctx context.Context, c *hydrav1alpha1.OAuth2Client, credentials *hydra.Oauth2ClientCredentials) error {
	hydra, err := r.getHydraClientForClient(*c)
	if err != nil {
		return err
	}

	if _, err := hydra.PutOAuth2Client(c.ToOAuth2ClientJSON().WithCredentials(credentials)); err != nil {
		if updateErr := r.updateReconciliationStatusError(ctx, c, hydrav1alpha1.StatusUpdateFailed, err); updateErr != nil {
			return updateErr
		}
	}
	return r.ensureEmptyStatusError(ctx, c)
}

func (r *OAuth2ClientReconciler) unregisterOAuth2Clients(ctx context.Context, c *hydrav1alpha1.OAuth2Client) error {

	// if a reqired field is empty, that means this is a delete after
	// the finalizers have done their job, so just return
	if c.Spec.Scope == "" || c.Spec.SecretName == "" {
		return nil
	}

	hydra, err := r.getHydraClientForClient(*c)
	if err != nil {
		return err
	}

	clients, err := hydra.ListOAuth2Client()
	if err != nil {
		return err
	}

	for _, cJSON := range clients {
		if cJSON.Owner == fmt.Sprintf("%s/%s", c.Name, c.Namespace) {
			if err := hydra.DeleteOAuth2Client(*cJSON.ClientID); err != nil {
				return err
			}
		}
	}

	return nil
}

func (r *OAuth2ClientReconciler) updateReconciliationStatusError(ctx context.Context, c *hydrav1alpha1.OAuth2Client, code hydrav1alpha1.StatusCode, err error) error {
	r.Log.Error(err, fmt.Sprintf("error processing client %s/%s ", c.Name, c.Namespace), "oauth2client", "register")
	c.Status.ReconciliationError = hydrav1alpha1.ReconciliationError{
		Code:        code,
		Description: err.Error(),
	}

	return r.updateClientStatus(ctx, c)
}

func (r *OAuth2ClientReconciler) ensureEmptyStatusError(ctx context.Context, c *hydrav1alpha1.OAuth2Client) error {
	c.Status.ReconciliationError = hydrav1alpha1.ReconciliationError{}
	return r.updateClientStatus(ctx, c)
}

func (r *OAuth2ClientReconciler) updateClientStatus(ctx context.Context, c *hydrav1alpha1.OAuth2Client) error {
	c.Status.ObservedGeneration = c.Generation
	if err := r.Status().Update(ctx, c); err != nil {
		r.Log.Error(err, fmt.Sprintf("status update failed for client %s/%s ", c.Name, c.Namespace), "oauth2client", "update status")
		return err
	}
	return nil
}

func parseSecret(secret apiv1.Secret, authMethod hydrav1alpha1.TokenEndpointAuthMethod) (*hydra.Oauth2ClientCredentials, error) {

	id, found := secret.Data[ClientIDKey]
	if !found {
		return nil, errors.New(`"client_id property missing"`)
	}

	psw, found := secret.Data[ClientSecretKey]
	if !found && authMethod != "none" {
		return nil, errors.New(`"client_secret property missing"`)
	}

	return &hydra.Oauth2ClientCredentials{
		ID:       id,
		Password: psw,
	}, nil
}

func (r *OAuth2ClientReconciler) getHydraClientForClient(oauth2client hydrav1alpha1.OAuth2Client) (HydraClientInterface, error) {
	spec := oauth2client.Spec
	if spec.HydraAdmin == (hydrav1alpha1.HydraAdmin{}) {
		r.Log.Info(fmt.Sprintf("using default client"))
		return r.HydraClient, nil
	}
	key := clientMapKey{
		url:            spec.HydraAdmin.URL,
		port:           spec.HydraAdmin.Port,
		endpoint:       spec.HydraAdmin.Endpoint,
		forwardedProto: spec.HydraAdmin.ForwardedProto,
	}
	if c, ok := r.otherClients[key]; ok {
		return c, nil
	}
	return r.HydraClientMaker(spec)
}

// Helper functions to check and remove string from a slice of strings.
func containsString(slice []string, s string) bool {
	for _, item := range slice {
		if item == s {
			return true
		}
	}
	return false
}

func removeString(slice []string, s string) (result []string) {
	for _, item := range slice {
		if item == s {
			continue
		}
		result = append(result, item)
	}
	return
}