/*
Copyright 2018 The Jetstack cert-manager contributors.

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 acmechallenges

import (
	"context"
	"fmt"
	"sync"
	"time"

	"github.com/golang/glog"
	k8sErrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	corelisters "k8s.io/client-go/listers/core/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/util/workqueue"

	"github.com/jetstack/cert-manager/pkg/acme"
	cmlisters "github.com/jetstack/cert-manager/pkg/client/listers/certmanager/v1alpha1"
	controllerpkg "github.com/jetstack/cert-manager/pkg/controller"
	"github.com/jetstack/cert-manager/pkg/issuer/acme/dns"
	"github.com/jetstack/cert-manager/pkg/issuer/acme/http"
	"github.com/jetstack/cert-manager/pkg/util"
)

type Controller struct {
	controllerpkg.Context

	helper     controllerpkg.Helper
	acmeHelper acme.Helper

	// To allow injection for testing.
	syncHandler func(ctx context.Context, key string) error

	challengeLister     cmlisters.ChallengeLister
	issuerLister        cmlisters.IssuerLister
	clusterIssuerLister cmlisters.ClusterIssuerLister
	secretLister        corelisters.SecretLister

	// ACME challenge solvers are instantiated once at the time of controller
	// construction.
	// This also allows for easy mocking of the different challenge mechanisms.
	dnsSolver  solver
	httpSolver solver

	watchedInformers []cache.InformerSynced
	queue            workqueue.RateLimitingInterface
}

func New(ctx *controllerpkg.Context) *Controller {
	ctrl := &Controller{Context: *ctx}
	ctrl.syncHandler = ctrl.processNextWorkItem

	// exponentially back-off self checks, with a base of 2s and max wait of 20s
	ctrl.queue = workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(time.Second*2, time.Second*20), "challenges")

	challengeInformer := ctrl.SharedInformerFactory.Certmanager().V1alpha1().Challenges()
	challengeInformer.Informer().AddEventHandler(&controllerpkg.QueuingEventHandler{Queue: ctrl.queue})
	ctrl.watchedInformers = append(ctrl.watchedInformers, challengeInformer.Informer().HasSynced)
	ctrl.challengeLister = challengeInformer.Lister()

	// issuerInformer.Informer().AddEventHandler(&controllerpkg.QueuingEventHandler{Queue: ctrl.queue})
	issuerInformer := ctrl.SharedInformerFactory.Certmanager().V1alpha1().Issuers()
	ctrl.watchedInformers = append(ctrl.watchedInformers, issuerInformer.Informer().HasSynced)
	ctrl.issuerLister = issuerInformer.Lister()

	// clusterIssuerInformer.Informer().AddEventHandler(&controllerpkg.QueuingEventHandler{Queue: ctrl.queue})
	clusterIssuerInformer := ctrl.SharedInformerFactory.Certmanager().V1alpha1().ClusterIssuers()
	ctrl.watchedInformers = append(ctrl.watchedInformers, clusterIssuerInformer.Informer().HasSynced)
	ctrl.clusterIssuerLister = clusterIssuerInformer.Lister()

	secretInformer := ctrl.KubeSharedInformerFactory.Core().V1().Secrets()
	ctrl.watchedInformers = append(ctrl.watchedInformers, secretInformer.Informer().HasSynced)
	ctrl.secretLister = secretInformer.Lister()

	// instantiate listers used by the http01 solver
	podInformer := ctrl.KubeSharedInformerFactory.Core().V1().Pods()
	serviceInformer := ctrl.KubeSharedInformerFactory.Core().V1().Services()
	ingressInformer := ctrl.KubeSharedInformerFactory.Extensions().V1beta1().Ingresses()
	ctrl.watchedInformers = append(ctrl.watchedInformers, podInformer.Informer().HasSynced)
	ctrl.watchedInformers = append(ctrl.watchedInformers, serviceInformer.Informer().HasSynced)
	ctrl.watchedInformers = append(ctrl.watchedInformers, ingressInformer.Informer().HasSynced)

	ctrl.helper = controllerpkg.NewHelper(ctrl.issuerLister, ctrl.clusterIssuerLister)
	ctrl.acmeHelper = acme.NewHelper(ctrl.secretLister, ctrl.Context.ClusterResourceNamespace)

	ctrl.httpSolver = http.NewSolver(ctx)
	ctrl.dnsSolver = dns.NewSolver(ctx)

	return ctrl
}

func (c *Controller) Run(workers int, stopCh <-chan struct{}) error {
	glog.V(4).Infof("Starting %s control loop", ControllerName)
	// wait for all the informer caches we depend on are synced
	if !cache.WaitForCacheSync(stopCh, c.watchedInformers...) {
		// c.challengeInformerSynced) {
		return fmt.Errorf("error waiting for informer caches to sync")
	}

	var wg sync.WaitGroup
	for i := 0; i < workers; i++ {
		wg.Add(1)
		// TODO (@munnerz): make time.Second duration configurable
		go wait.Until(func() {
			defer wg.Done()
			c.worker(stopCh)
		},
			time.Second, stopCh)
	}
	<-stopCh
	glog.V(4).Infof("Shutting down queue as workqueue signaled shutdown")
	c.queue.ShutDown()
	glog.V(4).Infof("Waiting for workers to exit...")
	wg.Wait()
	glog.V(4).Infof("Workers exited.")
	return nil
}

func (c *Controller) worker(stopCh <-chan struct{}) {
	glog.V(4).Infof("Starting %q worker", ControllerName)
	for {
		obj, shutdown := c.queue.Get()
		if shutdown {
			break
		}

		var key string
		err := func(obj interface{}) error {
			defer c.queue.Done(obj)
			var ok bool
			if key, ok = obj.(string); !ok {
				return nil
			}
			ctx, cancel := context.WithCancel(context.Background())
			defer cancel()
			ctx = util.ContextWithStopCh(ctx, stopCh)
			glog.Infof("%s controller: syncing item '%s'", ControllerName, key)
			if err := c.syncHandler(ctx, key); err != nil {
				return err
			}
			c.queue.Forget(obj)
			return nil
		}(obj)

		if err != nil {
			glog.Errorf("%s controller: Re-queuing item %q due to error processing: %s", ControllerName, key, err.Error())
			c.queue.AddRateLimited(obj)
			continue
		}

		glog.Infof("%s controller: Finished processing work item %q", ControllerName, key)
	}
	glog.V(4).Infof("Exiting %q worker loop", ControllerName)
}

func (c *Controller) processNextWorkItem(ctx context.Context, key string) error {
	namespace, name, err := cache.SplitMetaNamespaceKey(key)
	if err != nil {
		runtime.HandleError(fmt.Errorf("invalid resource key: %s", key))
		return nil
	}

	ch, err := c.challengeLister.Challenges(namespace).Get(name)

	if err != nil {
		if k8sErrors.IsNotFound(err) {
			runtime.HandleError(fmt.Errorf("ch '%s' in work queue no longer exists", key))
			return nil
		}

		return err
	}

	return c.Sync(ctx, ch)
}

var keyFunc = controllerpkg.KeyFunc

const (
	ControllerName = "challenges"
)

func init() {
	controllerpkg.Register(ControllerName, func(ctx *controllerpkg.Context) controllerpkg.Interface {
		return New(ctx).Run
	})
}