/*
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"
	"os"
	"path"
	"strings"
	"time"

	"github.com/go-logr/logr"
	"helm.sh/helm/v3/pkg/action"
	"helm.sh/helm/v3/pkg/chartutil"
	"helm.sh/helm/v3/pkg/getter"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	kuberecorder "k8s.io/client-go/tools/record"
	"k8s.io/client-go/tools/reference"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller"

	"github.com/fluxcd/pkg/recorder"
	"github.com/fluxcd/pkg/runtime/predicates"
	"github.com/fluxcd/pkg/untar"

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

// HelmChartReconciler reconciles a HelmChart object
type HelmChartReconciler struct {
	client.Client
	Log                   logr.Logger
	Scheme                *runtime.Scheme
	Storage               *Storage
	Getters               getter.Providers
	EventRecorder         kuberecorder.EventRecorder
	ExternalEventRecorder *recorder.EventRecorder
}

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

func (r *HelmChartReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
	ctx := context.Background()
	start := time.Now()

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

	log := r.Log.WithValues("controller", strings.ToLower(sourcev1.HelmChartKind), "request", req.NamespacedName)

	// Examine if the object is under deletion
	if chart.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(chart.ObjectMeta.Finalizers, sourcev1.SourceFinalizer) {
			chart.ObjectMeta.Finalizers = append(chart.ObjectMeta.Finalizers, sourcev1.SourceFinalizer)
			if err := r.Update(ctx, &chart); err != nil {
				log.Error(err, "unable to register finalizer")
				return ctrl.Result{}, err
			}
		}
	} else {
		// The object is being deleted
		if containsString(chart.ObjectMeta.Finalizers, sourcev1.SourceFinalizer) {
			// Our finalizer is still present, so lets handle garbage collection
			if err := r.gc(chart, true); err != nil {
				r.event(chart, recorder.EventSeverityError, fmt.Sprintf("garbage collection for deleted resource failed: %s", err.Error()))
				// Return the error so we retry the failed garbage collection
				return ctrl.Result{}, err
			}
			// Remove our finalizer from the list and update it
			chart.ObjectMeta.Finalizers = removeString(chart.ObjectMeta.Finalizers, sourcev1.SourceFinalizer)
			if err := r.Update(ctx, &chart); err != nil {
				return ctrl.Result{}, err
			}
			// Stop reconciliation as the object is being deleted
			return ctrl.Result{}, nil
		}
	}

	// Conditionally set progressing condition in status
	resetChart, changed := r.resetStatus(chart)
	if changed {
		chart = resetChart
		if err := r.Status().Update(ctx, &chart); err != nil {
			log.Error(err, "unable to update status")
			return ctrl.Result{Requeue: true}, err
		}
	}

	// Purge all but current artifact from storage
	if err := r.gc(chart, false); err != nil {
		log.Error(err, "unable to purge old artifacts")
	}

	// Perform the reconciliation for the chart source type
	var reconciledChart sourcev1.HelmChart
	var reconcileErr error
	switch chart.Spec.SourceRef.Kind {
	case sourcev1.HelmRepositoryKind:
		repository, err := r.getChartRepositoryWithArtifact(ctx, chart)
		if err != nil {
			chart = sourcev1.HelmChartNotReady(*chart.DeepCopy(), sourcev1.ChartPullFailedReason, err.Error())
			if err := r.Status().Update(ctx, &chart); err != nil {
				log.Error(err, "unable to update status")
			}
			return ctrl.Result{Requeue: true}, err
		}
		reconciledChart, reconcileErr = r.reconcileFromHelmRepository(ctx, repository, *chart.DeepCopy(), changed)
	case sourcev1.GitRepositoryKind:
		repository, err := r.getGitRepositoryWithArtifact(ctx, chart)
		if err != nil {
			chart = sourcev1.HelmChartNotReady(*chart.DeepCopy(), sourcev1.ChartPullFailedReason, err.Error())
			if err := r.Status().Update(ctx, &chart); err != nil {
				log.Error(err, "unable to update status")
			}
			return ctrl.Result{Requeue: true}, err
		}
		reconciledChart, reconcileErr = r.reconcileFromGitRepository(ctx, repository, *chart.DeepCopy(), changed)
	default:
		err := fmt.Errorf("unable to reconcile unsupported source reference kind '%s'", chart.Spec.SourceRef.Kind)
		return ctrl.Result{}, err
	}

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

	// If reconciliation failed, record the failure and requeue immediately
	if reconcileErr != nil {
		r.event(reconciledChart, recorder.EventSeverityError, reconcileErr.Error())
		return ctrl.Result{Requeue: true}, reconcileErr
	}

	// Emit an event if we did not have an artifact before, or the revision has changed
	if chart.Status.Artifact == nil || reconciledChart.Status.Artifact.Revision != chart.Status.Artifact.Revision {
		r.event(reconciledChart, recorder.EventSeverityInfo, sourcev1.HelmChartReadyMessage(reconciledChart))
	}

	log.Info(fmt.Sprintf("Reconciliation finished in %s, next run in %s",
		time.Now().Sub(start).String(),
		chart.GetInterval().Duration.String(),
	))
	return ctrl.Result{RequeueAfter: chart.GetInterval().Duration}, nil
}

type HelmChartReconcilerOptions struct {
	MaxConcurrentReconciles int
}

func (r *HelmChartReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return r.SetupWithManagerAndOptions(mgr, HelmChartReconcilerOptions{})
}

func (r *HelmChartReconciler) SetupWithManagerAndOptions(mgr ctrl.Manager, opts HelmChartReconcilerOptions) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&sourcev1.HelmChart{}).
		WithEventFilter(predicates.ChangePredicate{}).
		WithOptions(controller.Options{MaxConcurrentReconciles: opts.MaxConcurrentReconciles}).
		Complete(r)
}

func (r *HelmChartReconciler) reconcileFromHelmRepository(ctx context.Context,
	repository sourcev1.HelmRepository, chart sourcev1.HelmChart, force bool) (sourcev1.HelmChart, error) {
	cv, err := helm.GetDownloadableChartVersionFromIndex(r.Storage.LocalPath(*repository.GetArtifact()),
		chart.Spec.Chart, chart.Spec.Version)
	if err != nil {
		return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPullFailedReason, err.Error()), err
	}

	// Return early if the revision is still the same as the current artifact
	artifact := r.Storage.NewArtifactFor(chart.Kind, chart.GetObjectMeta(), cv.Version,
		fmt.Sprintf("%s-%s.tgz", cv.Name, cv.Version))
	if !force && repository.GetArtifact() != nil && repository.GetArtifact().Revision == cv.Version {
		if artifact.URL != repository.GetArtifact().URL {
			r.Storage.SetArtifactURL(repository.GetArtifact())
			repository.Status.URL = r.Storage.SetHostname(repository.Status.URL)
		}
		return chart, nil
	}

	// TODO(hidde): according to the Helm source the first item is not
	//  always the correct one to pick, check for updates once in awhile.
	//  Ref: https://github.com/helm/helm/blob/v3.3.0/pkg/downloader/chart_downloader.go#L241
	ref := cv.URLs[0]
	u, err := url.Parse(ref)
	if err != nil {
		err = fmt.Errorf("invalid chart URL format '%s': %w", ref, err)
	}

	// Prepend the chart repository base URL if the URL is relative
	if !u.IsAbs() {
		repoURL, err := url.Parse(repository.Spec.URL)
		if err != nil {
			err = fmt.Errorf("invalid repository URL format '%s': %w", repository.Spec.URL, err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPullFailedReason, err.Error()), err
		}
		q := repoURL.Query()
		// Trailing slash is required for ResolveReference to work
		repoURL.Path = strings.TrimSuffix(repoURL.Path, "/") + "/"
		u = repoURL.ResolveReference(u)
		u.RawQuery = q.Encode()
	}

	// Get the getter for the protocol
	c, err := r.Getters.ByScheme(u.Scheme)
	if err != nil {
		return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPullFailedReason, err.Error()), err
	}

	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(ctx, name, &secret)
		if err != nil {
			err = fmt.Errorf("auth secret error: %w", err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.AuthenticationFailedReason, err.Error()), err
		}

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

	// Ensure artifact directory exists
	err = r.Storage.MkdirAll(artifact)
	if err != nil {
		err = fmt.Errorf("unable to create chart directory: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

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

	// TODO(hidde): implement timeout from the HelmRepository
	//  https://github.com/helm/helm/pull/7950
	res, err := c.Get(u.String(), clientOpts...)
	if err != nil {
		return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPullFailedReason, err.Error()), err
	}

	// Either repackage the chart with the declared default values file,
	// or write the chart directly to storage.
	var (
		readyReason  = sourcev1.ChartPullSucceededReason
		readyMessage = fmt.Sprintf("Fetched revision: %s", artifact.Revision)
	)
	switch {
	case chart.Spec.ValuesFile != "" && chart.Spec.ValuesFile != chartutil.ValuesfileName:
		// Create temporary working directory
		tmpDir, err := ioutil.TempDir("", fmt.Sprintf("%s-%s-", chart.Namespace, chart.Name))
		if err != nil {
			err = fmt.Errorf("tmp dir error: %w", err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
		}
		defer os.RemoveAll(tmpDir)

		// Untar chart into working directory
		if _, err = untar.Untar(res, tmpDir); err != nil {
			err = fmt.Errorf("chart untar error: %w", err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
		}

		// Overwrite values file
		chartPath := path.Join(tmpDir, cv.Name)
		if err := helm.OverwriteChartDefaultValues(chartPath, chart.Spec.ValuesFile); err != nil {
			return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPackageFailedReason, err.Error()), err
		}

		// Package the chart with the new default values
		pkg := action.NewPackage()
		pkg.Destination = tmpDir
		pkgPath, err := pkg.Run(chartPath, nil)
		if err != nil {
			err = fmt.Errorf("chart package error: %w", err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPackageFailedReason, err.Error()), err
		}

		// Copy the packaged chart to the artifact path
		cf, err := os.Open(pkgPath)
		if err != nil {
			err = fmt.Errorf("failed to open chart package: %w", err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
		}
		if err := r.Storage.Copy(&artifact, cf); err != nil {
			cf.Close()
			err = fmt.Errorf("failed to copy chart package to storage: %w", err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
		}
		cf.Close()

		readyMessage = fmt.Sprintf("Fetched and packaged revision: %s", artifact.Revision)
		readyReason = sourcev1.ChartPackageSucceededReason
	default:
		// Write artifact to storage
		if err := r.Storage.AtomicWriteFile(&artifact, res, 0644); err != nil {
			err = fmt.Errorf("unable to write chart file: %w", err)
			return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
		}
	}

	// Update symlink
	chartUrl, err := r.Storage.Symlink(artifact, fmt.Sprintf("%s-latest.tgz", cv.Name))
	if err != nil {
		err = fmt.Errorf("storage error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	return sourcev1.HelmChartReady(chart, artifact, chartUrl, readyReason, readyMessage), nil
}

// getChartRepositoryWithArtifact attempts to get the v1alpha1.HelmRepository
// for the given chart. It returns an error if the HelmRepository could
// not be retrieved or if does not have an artifact.
func (r *HelmChartReconciler) getChartRepositoryWithArtifact(ctx context.Context, chart sourcev1.HelmChart) (sourcev1.HelmRepository, error) {
	if chart.Spec.SourceRef.Name == "" {
		return sourcev1.HelmRepository{}, fmt.Errorf("no HelmRepository reference given")
	}

	name := types.NamespacedName{
		Namespace: chart.GetNamespace(),
		Name:      chart.Spec.SourceRef.Name,
	}

	var repository sourcev1.HelmRepository
	err := r.Client.Get(ctx, name, &repository)
	if err != nil {
		err = fmt.Errorf("failed to get HelmRepository '%s': %w", name, err)
		return repository, err
	}

	if repository.GetArtifact() == nil {
		err = fmt.Errorf("no repository index artifact found for HelmRepository '%s'", name)
	}

	return repository, err
}

func (r *HelmChartReconciler) reconcileFromGitRepository(ctx context.Context,
	repository sourcev1.GitRepository, chart sourcev1.HelmChart, force bool) (sourcev1.HelmChart, error) {
	// Create temporary working directory
	tmpDir, err := ioutil.TempDir("", fmt.Sprintf("%s-%s-", chart.Namespace, chart.Name))
	if err != nil {
		err = fmt.Errorf("tmp dir error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	defer os.RemoveAll(tmpDir)

	// Open GitRepository artifact file and untar files into working directory
	f, err := os.Open(r.Storage.LocalPath(*repository.GetArtifact()))
	if err != nil {
		err = fmt.Errorf("artifact open error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	if _, err = untar.Untar(f, tmpDir); err != nil {
		f.Close()
		err = fmt.Errorf("artifact untar error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	f.Close()

	// Ensure configured path is a chart directory
	chartPath := path.Join(tmpDir, chart.Spec.Chart)
	if _, err := chartutil.IsChartDir(chartPath); err != nil {
		err = fmt.Errorf("chart path error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	// Read the chart metadata
	chartMetadata, err := chartutil.LoadChartfile(path.Join(chartPath, chartutil.ChartfileName))
	if err != nil {
		err = fmt.Errorf("load chart metadata error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	// Return early if the revision is still the same as the current chart artifact
	artifact := r.Storage.NewArtifactFor(chart.Kind, chart.ObjectMeta.GetObjectMeta(), chartMetadata.Version,
		fmt.Sprintf("%s-%s.tgz", chartMetadata.Name, chartMetadata.Version))
	if !force && chart.GetArtifact() != nil && chart.GetArtifact().Revision == chartMetadata.Version {
		if artifact.URL != repository.GetArtifact().URL {
			r.Storage.SetArtifactURL(repository.GetArtifact())
			repository.Status.URL = r.Storage.SetHostname(repository.Status.URL)
		}
		return chart, nil
	}

	// Overwrite default values if instructed to
	if chart.Spec.ValuesFile != "" {
		if err := helm.OverwriteChartDefaultValues(chartPath, chart.Spec.ValuesFile); err != nil {
			return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPackageFailedReason, err.Error()), err
		}
	}

	// Ensure artifact directory exists
	err = r.Storage.MkdirAll(artifact)
	if err != nil {
		err = fmt.Errorf("unable to create artifact directory: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

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

	// Package the chart, we use the action here instead of relying on the
	// chartutil.Save method as the action performs a dependency check for us
	pkg := action.NewPackage()
	pkg.Destination = tmpDir
	pkgPath, err := pkg.Run(chartPath, nil)
	if err != nil {
		err = fmt.Errorf("chart package error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.ChartPackageFailedReason, err.Error()), err
	}

	// Copy the packaged chart to the artifact path
	cf, err := os.Open(pkgPath)
	if err != nil {
		err = fmt.Errorf("failed to open chart package: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	if err := r.Storage.Copy(&artifact, cf); err != nil {
		cf.Close()
		err = fmt.Errorf("failed to copy chart package to storage: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	cf.Close()

	// Update symlink
	cUrl, err := r.Storage.Symlink(artifact, fmt.Sprintf("%s-latest.tgz", chartMetadata.Name))
	if err != nil {
		err = fmt.Errorf("storage error: %w", err)
		return sourcev1.HelmChartNotReady(chart, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	message := fmt.Sprintf("Fetched and packaged revision: %s", artifact.Revision)
	return sourcev1.HelmChartReady(chart, artifact, cUrl, sourcev1.ChartPackageSucceededReason, message), nil
}

// getGitRepositoryWithArtifact attempts to get the GitRepository for the given
// chart. It returns an error if the v1alpha1.GitRepository could not be retrieved
// or does not have an artifact.
func (r *HelmChartReconciler) getGitRepositoryWithArtifact(ctx context.Context, chart sourcev1.HelmChart) (sourcev1.GitRepository, error) {
	if chart.Spec.SourceRef.Name == "" {
		return sourcev1.GitRepository{}, fmt.Errorf("no GitRepository reference given")
	}

	name := types.NamespacedName{
		Namespace: chart.GetNamespace(),
		Name:      chart.Spec.SourceRef.Name,
	}

	var repository sourcev1.GitRepository
	err := r.Client.Get(ctx, name, &repository)
	if err != nil {
		err = fmt.Errorf("failed to get GitRepository '%s': %w", name, err)
		return repository, err
	}

	if repository.GetArtifact() == nil {
		err = fmt.Errorf("no artifact found for GitRepository '%s'", repository.Name)
	}

	return repository, err
}

// resetStatus returns a modified v1alpha1.HelmChart and a boolean indicating
// if the status field has been reset.
func (r *HelmChartReconciler) resetStatus(chart sourcev1.HelmChart) (sourcev1.HelmChart, bool) {
	// The artifact does no longer exist
	if chart.GetArtifact() != nil && !r.Storage.ArtifactExist(*chart.GetArtifact()) {
		chart = sourcev1.HelmChartProgressing(chart)
		chart.Status.Artifact = nil
		return chart, true
	}
	// The chart specification has changed
	if chart.Generation != chart.Status.ObservedGeneration {
		return sourcev1.HelmChartProgressing(chart), true
	}
	return chart, false
}

// gc performs a garbage collection on all but the current artifact of
// the given chart.
func (r *HelmChartReconciler) gc(chart sourcev1.HelmChart, all bool) error {
	if all {
		return r.Storage.RemoveAll(r.Storage.NewArtifactFor(chart.Kind, chart.GetObjectMeta(), "", ""))
	}
	if chart.GetArtifact() != nil {
		return r.Storage.RemoveAllButCurrent(*chart.GetArtifact())
	}
	return nil
}

// event emits a Kubernetes event and forwards the event to notification
// controller if configured.
func (r *HelmChartReconciler) event(chart sourcev1.HelmChart, severity, msg string) {
	if r.EventRecorder != nil {
		r.EventRecorder.Eventf(&chart, "Normal", severity, msg)
	}
	if r.ExternalEventRecorder != nil {
		objRef, err := reference.GetReference(r.Scheme, &chart)
		if err != nil {
			r.Log.WithValues(
				"request",
				fmt.Sprintf("%s/%s", chart.GetNamespace(), chart.GetName()),
			).Error(err, "unable to send event")
			return
		}

		if err := r.ExternalEventRecorder.Eventf(*objRef, nil, severity, severity, msg); err != nil {
			r.Log.WithValues(
				"request",
				fmt.Sprintf("%s/%s", chart.GetNamespace(), chart.GetName()),
			).Error(err, "unable to send event")
			return
		}
	}
}