/*
Copyright 2020 The Flux CD 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 controllers

import (
	"context"
	"fmt"
	"io/ioutil"
	"net/url"
	"path"
	"time"

	"github.com/go-logr/logr"
	"helm.sh/helm/v3/pkg/getter"
	"helm.sh/helm/v3/pkg/repo"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/yaml"

	sourcev1 "github.com/fluxcd/source-controller/api/v1alpha1"
	"github.com/fluxcd/source-controller/internal/helm"
)

// HelmRepositoryReconciler reconciles a HelmRepository object
type HelmRepositoryReconciler struct {
	client.Client
	Log     logr.Logger
	Scheme  *runtime.Scheme
	Storage *Storage
	Getters getter.Providers
}

// +kubebuilder:rbac:groups=source.fluxcd.io,resources=helmrepositories,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=source.fluxcd.io,resources=helmrepositories/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=source.fluxcd.io,resources=helmcharts/finalizers,verbs=get;update;patch

func (r *HelmRepositoryReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
	defer cancel()

	var repository sourcev1.HelmRepository
	if err := r.Get(ctx, req.NamespacedName, &repository); err != nil {
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	log := r.Log.WithValues(repository.Kind, req.NamespacedName)

	// set initial status
	if reset, status := r.shouldResetStatus(repository); reset {
		log.Info("Initializing Helm repository")
		repository.Status = status
		if err := r.Status().Update(ctx, &repository); err != nil {
			log.Error(err, "unable to update HelmRepository status")
			return ctrl.Result{Requeue: true}, err
		}
	}

	// try to remove old artifacts
	if err := r.gc(repository); err != nil {
		log.Error(err, "artifacts GC failed")
	}

	// try to download index
	syncedRepo, err := r.sync(*repository.DeepCopy())
	if err != nil {
		log.Error(err, "Helm repository sync failed")
	}

	// update status
	if err := r.Status().Update(ctx, &syncedRepo); err != nil {
		log.Error(err, "unable to update HelmRepository status")
		return ctrl.Result{Requeue: true}, err
	}

	log.Info("Helm repository sync succeeded", "msg", sourcev1.HelmRepositoryReadyMessage(syncedRepo))

	// requeue repository
	return ctrl.Result{RequeueAfter: repository.GetInterval().Duration}, nil
}

func (r *HelmRepositoryReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&sourcev1.HelmRepository{}).
		WithEventFilter(SourceChangePredicate{}).
		WithEventFilter(GarbageCollectPredicate{Scheme: r.Scheme, Log: r.Log, Storage: r.Storage}).
		Complete(r)
}

func (r *HelmRepositoryReconciler) sync(repository sourcev1.HelmRepository) (sourcev1.HelmRepository, error) {
	u, err := url.Parse(repository.Spec.URL)
	if err != nil {
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.URLInvalidReason, err.Error()), err
	}

	c, err := r.Getters.ByScheme(u.Scheme)
	if err != nil {
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.URLInvalidReason, err.Error()), err
	}

	u.RawPath = path.Join(u.RawPath, "index.yaml")
	u.Path = path.Join(u.Path, "index.yaml")

	var clientOpts []getter.Option
	if repository.Spec.SecretRef != nil {
		name := types.NamespacedName{
			Namespace: repository.GetNamespace(),
			Name:      repository.Spec.SecretRef.Name,
		}

		var secret corev1.Secret
		err := r.Client.Get(context.TODO(), name, &secret)
		if err != nil {
			err = fmt.Errorf("auth secret error: %w", err)
			return sourcev1.HelmRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
		}

		opts, cleanup, err := helm.ClientOptionsFromSecret(secret)
		if err != nil {
			err = fmt.Errorf("auth options error: %w", err)
			return sourcev1.HelmRepositoryNotReady(repository, sourcev1.AuthenticationFailedReason, err.Error()), err
		}
		if cleanup != nil {
			defer cleanup()
		}
		clientOpts = opts
	}

	res, err := c.Get(u.String(), clientOpts...)
	if err != nil {
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.IndexationFailedReason, err.Error()), err
	}

	data, err := ioutil.ReadAll(res)
	if err != nil {
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.IndexationFailedReason, err.Error()), err
	}

	i := &repo.IndexFile{}
	if err := yaml.Unmarshal(data, i); err != nil {
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.IndexationFailedReason, err.Error()), err
	}

	index, err := yaml.Marshal(i)
	if err != nil {
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.IndexationFailedReason, err.Error()), err
	}

	sum := r.Storage.Checksum(index)
	artifact := r.Storage.ArtifactFor(repository.Kind, repository.ObjectMeta.GetObjectMeta(),
		fmt.Sprintf("index-%s.yaml", sum), sum)

	// create artifact dir
	err = r.Storage.MkdirAll(artifact)
	if err != nil {
		err = fmt.Errorf("unable to create repository index directory: %w", err)
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	// acquire lock
	unlock, err := r.Storage.Lock(artifact)
	if err != nil {
		err = fmt.Errorf("unable to acquire lock: %w", err)
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	defer unlock()

	// save artifact to storage
	err = r.Storage.WriteFile(artifact, index)
	if err != nil {
		err = fmt.Errorf("unable to write repository index file: %w", err)
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	// update index symlink
	indexURL, err := r.Storage.Symlink(artifact, "index.yaml")
	if err != nil {
		err = fmt.Errorf("storage error: %w", err)
		return sourcev1.HelmRepositoryNotReady(repository, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	message := fmt.Sprintf("Helm repository index is available at: %s", artifact.Path)
	return sourcev1.HelmRepositoryReady(repository, artifact, indexURL, sourcev1.IndexationSucceededReason, message), nil
}

func (r *HelmRepositoryReconciler) shouldResetStatus(repository sourcev1.HelmRepository) (bool, sourcev1.HelmRepositoryStatus) {
	resetStatus := false
	if repository.Status.Artifact != nil {
		if !r.Storage.ArtifactExist(*repository.Status.Artifact) {
			resetStatus = true
		}
	}

	// set initial status
	if len(repository.Status.Conditions) == 0 || resetStatus {
		resetStatus = true
	}

	return resetStatus, sourcev1.HelmRepositoryStatus{
		Conditions: []sourcev1.SourceCondition{
			{
				Type:               sourcev1.ReadyCondition,
				Status:             corev1.ConditionUnknown,
				Reason:             sourcev1.InitializingReason,
				LastTransitionTime: metav1.Now(),
			},
		},
	}
}

func (r *HelmRepositoryReconciler) gc(repository sourcev1.HelmRepository) error {
	if repository.Status.Artifact != nil {
		return r.Storage.RemoveAllButCurrent(*repository.Status.Artifact)
	}
	return nil
}