/*
Copyright 2020 The Flux authors

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"
	"crypto/sha1"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/fluxcd/pkg/apis/meta"
	"github.com/go-logr/logr"
	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
	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"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"

	"github.com/fluxcd/pkg/runtime/events"
	"github.com/fluxcd/pkg/runtime/metrics"
	"github.com/fluxcd/pkg/runtime/predicates"

	sourcev1 "github.com/fluxcd/source-controller/api/v1beta1"
)

// BucketReconciler reconciles a Bucket object
type BucketReconciler struct {
	client.Client
	Log                   logr.Logger
	Scheme                *runtime.Scheme
	Storage               *Storage
	EventRecorder         kuberecorder.EventRecorder
	ExternalEventRecorder *events.Recorder
	MetricsRecorder       *metrics.Recorder
}

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

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

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

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

	// Add our finalizer if it does not exist
	if !controllerutil.ContainsFinalizer(&bucket, sourcev1.SourceFinalizer) {
		controllerutil.AddFinalizer(&bucket, sourcev1.SourceFinalizer)
		if err := r.Update(ctx, &bucket); err != nil {
			log.Error(err, "unable to register finalizer")
			return ctrl.Result{}, err
		}
	}

	// Examine if the object is under deletion
	if !bucket.ObjectMeta.DeletionTimestamp.IsZero() {
		return r.reconcileDelete(ctx, bucket)
	}

	// record reconciliation duration
	if r.MetricsRecorder != nil {
		objRef, err := reference.GetReference(r.Scheme, &bucket)
		if err != nil {
			return ctrl.Result{}, err
		}
		defer r.MetricsRecorder.RecordDuration(*objRef, start)
	}

	// set initial status
	if resetBucket, ok := r.resetStatus(bucket); ok {
		bucket = resetBucket
		if err := r.Status().Update(ctx, &bucket); err != nil {
			log.Error(err, "unable to update status")
			return ctrl.Result{Requeue: true}, err
		}
		r.recordReadiness(bucket, false)
	}

	// purge old artifacts from storage
	if err := r.gc(bucket, false); err != nil {
		log.Error(err, "unable to purge old artifacts")
	}

	// reconcile bucket by downloading its content
	reconciledBucket, reconcileErr := r.reconcile(ctx, *bucket.DeepCopy())

	// update status with the reconciliation result
	if err := r.Status().Update(ctx, &reconciledBucket); 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(reconciledBucket, events.EventSeverityError, reconcileErr.Error())
		r.recordReadiness(reconciledBucket, false)
		return ctrl.Result{Requeue: true}, reconcileErr
	}

	// emit revision change event
	if bucket.Status.Artifact == nil || reconciledBucket.Status.Artifact.Revision != bucket.Status.Artifact.Revision {
		r.event(reconciledBucket, events.EventSeverityInfo, sourcev1.BucketReadyMessage(reconciledBucket))
	}
	r.recordReadiness(reconciledBucket, false)

	log.Info(fmt.Sprintf("Reconciliation finished in %s, next run in %s",
		time.Now().Sub(start).String(),
		bucket.GetInterval().Duration.String(),
	))

	return ctrl.Result{RequeueAfter: bucket.GetInterval().Duration}, nil
}

type BucketReconcilerOptions struct {
	MaxConcurrentReconciles int
}

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

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

func (r *BucketReconciler) reconcile(ctx context.Context, bucket sourcev1.Bucket) (sourcev1.Bucket, error) {
	s3Client, err := r.auth(ctx, bucket)
	if err != nil {
		err = fmt.Errorf("auth error: %w", err)
		return sourcev1.BucketNotReady(bucket, sourcev1.AuthenticationFailedReason, err.Error()), err
	}

	// create tmp dir
	tempDir, err := ioutil.TempDir("", bucket.Name)
	if err != nil {
		err = fmt.Errorf("tmp dir error: %w", err)
		return sourcev1.BucketNotReady(bucket, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	defer os.RemoveAll(tempDir)

	ctxTimeout, cancel := context.WithTimeout(ctx, bucket.GetTimeout())
	defer cancel()

	exists, err := s3Client.BucketExists(ctxTimeout, bucket.Spec.BucketName)
	if err != nil {
		return sourcev1.BucketNotReady(bucket, sourcev1.BucketOperationFailedReason, err.Error()), err
	}
	if !exists {
		err = fmt.Errorf("bucket '%s' not found", bucket.Spec.BucketName)
		return sourcev1.BucketNotReady(bucket, sourcev1.BucketOperationFailedReason, err.Error()), err
	}

	// download bucket content
	for object := range s3Client.ListObjects(ctxTimeout, bucket.Spec.BucketName, minio.ListObjectsOptions{Recursive: true}) {
		if object.Err != nil {
			err = fmt.Errorf("listing objects from bucket '%s' failed: %w", bucket.Spec.BucketName, object.Err)
			return sourcev1.BucketNotReady(bucket, sourcev1.BucketOperationFailedReason, err.Error()), err
		}

		if strings.HasSuffix(object.Key, "/") {
			continue
		}

		localPath := filepath.Join(tempDir, object.Key)
		err := s3Client.FGetObject(ctxTimeout, bucket.Spec.BucketName, object.Key, localPath, minio.GetObjectOptions{})
		if err != nil {
			err = fmt.Errorf("downloading object from bucket '%s' failed: %w", bucket.Spec.BucketName, err)
			return sourcev1.BucketNotReady(bucket, sourcev1.BucketOperationFailedReason, err.Error()), err
		}
	}

	revision, err := r.checksum(tempDir)
	if err != nil {
		return sourcev1.BucketNotReady(bucket, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	// return early on unchanged revision
	artifact := r.Storage.NewArtifactFor(bucket.Kind, bucket.GetObjectMeta(), revision, fmt.Sprintf("%s.tar.gz", revision))
	if meta.HasReadyCondition(bucket.Status.Conditions) && bucket.GetArtifact().HasRevision(artifact.Revision) {
		if artifact.URL != bucket.GetArtifact().URL {
			r.Storage.SetArtifactURL(bucket.GetArtifact())
			bucket.Status.URL = r.Storage.SetHostname(bucket.Status.URL)
		}
		return bucket, nil
	}

	// create artifact dir
	err = r.Storage.MkdirAll(artifact)
	if err != nil {
		err = fmt.Errorf("mkdir dir error: %w", err)
		return sourcev1.BucketNotReady(bucket, 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.BucketNotReady(bucket, sourcev1.StorageOperationFailedReason, err.Error()), err
	}
	defer unlock()

	// archive artifact and check integrity
	if err := r.Storage.Archive(&artifact, tempDir, bucket.Spec.Ignore); err != nil {
		err = fmt.Errorf("storage archive error: %w", err)
		return sourcev1.BucketNotReady(bucket, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	// update latest symlink
	url, err := r.Storage.Symlink(artifact, "latest.tar.gz")
	if err != nil {
		err = fmt.Errorf("storage symlink error: %w", err)
		return sourcev1.BucketNotReady(bucket, sourcev1.StorageOperationFailedReason, err.Error()), err
	}

	message := fmt.Sprintf("Fetched revision: %s", artifact.Revision)
	return sourcev1.BucketReady(bucket, artifact, url, sourcev1.BucketOperationSucceedReason, message), nil
}

func (r *BucketReconciler) reconcileDelete(ctx context.Context, bucket sourcev1.Bucket) (ctrl.Result, error) {
	if err := r.gc(bucket, true); err != nil {
		r.event(bucket, events.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
	}

	// Record deleted status
	r.recordReadiness(bucket, true)

	// Remove our finalizer from the list and update it
	controllerutil.RemoveFinalizer(&bucket, sourcev1.SourceFinalizer)
	if err := r.Update(ctx, &bucket); err != nil {
		return ctrl.Result{}, err
	}

	// Stop reconciliation as the object is being deleted
	return ctrl.Result{}, nil
}

func (r *BucketReconciler) auth(ctx context.Context, bucket sourcev1.Bucket) (*minio.Client, error) {
	opt := minio.Options{
		Region: bucket.Spec.Region,
		Secure: !bucket.Spec.Insecure,
	}

	if bucket.Spec.SecretRef != nil {
		secretName := types.NamespacedName{
			Namespace: bucket.GetNamespace(),
			Name:      bucket.Spec.SecretRef.Name,
		}

		var secret corev1.Secret
		if err := r.Get(ctx, secretName, &secret); err != nil {
			return nil, fmt.Errorf("credentials secret error: %w", err)
		}

		accesskey := ""
		secretkey := ""
		if k, ok := secret.Data["accesskey"]; ok {
			accesskey = string(k)
		}
		if k, ok := secret.Data["secretkey"]; ok {
			secretkey = string(k)
		}
		if accesskey == "" || secretkey == "" {
			return nil, fmt.Errorf("invalid '%s' secret data: required fields 'accesskey' and 'secretkey'", secret.Name)
		}
		opt.Creds = credentials.NewStaticV4(accesskey, secretkey, "")
	} else if bucket.Spec.Provider == sourcev1.AmazonBucketProvider {
		opt.Creds = credentials.NewIAM("")
	}

	if opt.Creds == nil {
		return nil, fmt.Errorf("no bucket credentials found")
	}

	return minio.New(bucket.Spec.Endpoint, &opt)
}

func (r *BucketReconciler) checksum(root string) (string, error) {
	checksum := ""
	err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !info.Mode().IsRegular() {
			return nil
		}
		data, err := ioutil.ReadFile(path)
		if err != nil {
			return err
		}
		checksum += fmt.Sprintf("%x", sha1.Sum(data))
		return nil
	})
	if err != nil {
		return "", err
	}

	return fmt.Sprintf("%x", sha1.Sum([]byte(checksum))), nil
}

// resetStatus returns a modified v1beta1.Bucket and a boolean indicating
// if the status field has been reset.
func (r *BucketReconciler) resetStatus(bucket sourcev1.Bucket) (sourcev1.Bucket, bool) {
	// We do not have an artifact, or it does no longer exist
	if bucket.GetArtifact() == nil || !r.Storage.ArtifactExist(*bucket.GetArtifact()) {
		bucket = sourcev1.BucketProgressing(bucket)
		bucket.Status.Artifact = nil
		return bucket, true
	}
	if bucket.Generation != bucket.Status.ObservedGeneration {
		return sourcev1.BucketProgressing(bucket), true
	}
	return bucket, false
}

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

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

func (r *BucketReconciler) recordReadiness(bucket sourcev1.Bucket, deleted bool) {
	if r.MetricsRecorder == nil {
		return
	}

	objRef, err := reference.GetReference(r.Scheme, &bucket)
	if err != nil {
		r.Log.WithValues(
			strings.ToLower(bucket.Kind),
			fmt.Sprintf("%s/%s", bucket.GetNamespace(), bucket.GetName()),
		).Error(err, "unable to record readiness metric")
		return
	}
	if rc := meta.GetCondition(bucket.Status.Conditions, meta.ReadyCondition); rc != nil {
		r.MetricsRecorder.RecordCondition(*objRef, *rc, deleted)
	} else {
		r.MetricsRecorder.RecordCondition(*objRef, meta.Condition{
			Type:   meta.ReadyCondition,
			Status: corev1.ConditionUnknown,
		}, deleted)
	}
}