// internal/controller/imageupdate_controller.go
package controller

import (
	"context"
	"fmt"
	"strings"
	"time"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/tools/record"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/log"

	configv1alpha1 "git.vendetti.ru/andy/operator/api/v1alpha1"

	"github.com/google/go-containerregistry/pkg/crane"
	"github.com/google/go-containerregistry/pkg/name"
)

const (
	DefaultRestartAnnotation = "andy.vendetti.ru/restartedAt"
)

// ImageUpdateReconciler reconciles Deployment objects to check for image updates.
type ImageUpdateReconciler struct {
	client.Client
	Scheme   *runtime.Scheme
	Recorder record.EventRecorder
}

// +kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;update;patch
// +kubebuilder:rbac:groups="",resources=pods,verbs=get;list;watch
// +kubebuilder:rbac:groups=operator.andy.vendetti.ru,resources=nodetainterconfigs,verbs=get;list;watch
// +kubebuilder:rbac:groups="",resources=events,verbs=create;patch

func (r *ImageUpdateReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	log := log.FromContext(ctx).WithValues("deployment", req.NamespacedName)

	var config configv1alpha1.NodeTainterConfig
	configKey := types.NamespacedName{Name: GlobalTaintConfigName}
	if err := r.Get(ctx, configKey, &config); err != nil {
		if !errors.IsNotFound(err) {
			log.Error(err, "Failed to get NodeTainterConfig for image updates", "configName", GlobalTaintConfigName)
			return ctrl.Result{}, err
		}
		log.V(1).Info("Global NodeTainterConfig not found, image update checks skipped.", "configName", GlobalTaintConfigName)
		return ctrl.Result{}, nil
	}

	if config.Spec.ImageUpdatePolicy == nil || !config.Spec.ImageUpdatePolicy.Enabled {
		log.V(1).Info("Image update policy is disabled in NodeTainterConfig.")
		return ctrl.Result{}, nil
	}

	policy := config.Spec.ImageUpdatePolicy
	if len(policy.MonitoredTags) == 0 {
		log.V(1).Info("No monitored tags configured in ImageUpdatePolicy.")
		return ctrl.Result{}, nil
	}

	var deployment appsv1.Deployment
	if err := r.Get(ctx, req.NamespacedName, &deployment); err != nil {
		if errors.IsNotFound(err) {
			log.Info("Deployment not found. Ignoring.")
			return ctrl.Result{}, nil
		}
		log.Error(err, "Failed to get Deployment")
		return ctrl.Result{}, err
	}

	log.V(1).Info("Checking deployment for image updates")
	needsRestart := false
	restartAnnotation := policy.RestartAnnotation
	if restartAnnotation == "" {
		restartAnnotation = DefaultRestartAnnotation
	}

	podList, err := r.findPodsForDeployment(ctx, &deployment)
	if err != nil {
		log.Error(err, "Failed to list pods for deployment")
		return ctrl.Result{RequeueAfter: 1 * time.Minute}, nil
	}

	for _, container := range deployment.Spec.Template.Spec.Containers {
		containerLog := log.WithValues("container", container.Name, "image", container.Image)

		imageName, imageTag, isMonitored := r.parseImageAndCheckTag(container.Image, policy.MonitoredTags)
		if !isMonitored {
			containerLog.V(1).Info("Image tag is not monitored, skipping.")
			continue
		}

		currentDigest, err := r.findCurrentImageDigest(container.Name, podList)
		if err != nil {
			containerLog.Error(err, "Could not determine current image digest from running pods")
			continue
		}
		if currentDigest == "" {
			containerLog.V(1).Info("No running pods found with imageID for this container, skipping check.")
			continue
		}
		containerLog = containerLog.WithValues("currentDigest", currentDigest)

		latestDigest, err := crane.Digest(imageName + ":" + imageTag)
		if err != nil {
			containerLog.Error(err, "Failed to get latest digest from registry", "image", imageName+":"+imageTag)
			r.Recorder.Eventf(&deployment, corev1.EventTypeWarning, "RegistryError", "Failed to fetch digest for %s:%s: %v", imageName, imageTag, err)
			continue
		}
		containerLog = containerLog.WithValues("latestDigest", latestDigest)

		if currentDigest != latestDigest {
			containerLog.Info("Image update detected!", "image", imageName+":"+imageTag)
			r.Recorder.Eventf(&deployment, corev1.EventTypeNormal, "UpdateAvailable", "New digest %s detected for image %s:%s (current: %s)", latestDigest, imageName, imageTag, currentDigest)
			needsRestart = true
			break
		} else {
			containerLog.V(1).Info("Image is up-to-date.")
		}
	}

	if needsRestart {
		deploymentCopy := deployment.DeepCopy()
		if deploymentCopy.Spec.Template.Annotations == nil {
			deploymentCopy.Spec.Template.Annotations = make(map[string]string)
		}
		restartValue := time.Now().Format(time.RFC3339)
		deploymentCopy.Spec.Template.Annotations[restartAnnotation] = restartValue

		log.Info("Triggering deployment restart due to image update", "annotationKey", restartAnnotation, "annotationValue", restartValue)
		if err := r.Patch(ctx, deploymentCopy, client.MergeFrom(&deployment)); err != nil {
			log.Error(err, "Failed to patch Deployment to trigger restart")
			r.Recorder.Eventf(&deployment, corev1.EventTypeWarning, "UpdateFailed", "Failed to trigger restart: %v", err)
			return ctrl.Result{}, err
		}
		log.Info("Deployment patched successfully to trigger restart.")
		r.Recorder.Eventf(&deployment, corev1.EventTypeNormal, "RestartTriggered", "Triggered restart due to updated image")
	}

	checkInterval, err := time.ParseDuration(policy.CheckInterval)
	if err != nil {
		log.Error(err, "Failed to parse CheckInterval from config, using default 1h", "configuredInterval", policy.CheckInterval)
		checkInterval = time.Hour // Fallback
	}

	log.V(1).Info("Requeuing deployment for next check", "after", checkInterval.String())
	return ctrl.Result{RequeueAfter: checkInterval}, nil
}

func (r *ImageUpdateReconciler) parseImageAndCheckTag(image string, monitoredTags []string) (imgName, imgTag string, monitored bool) {
	ref, err := name.ParseReference(image, name.WeakValidation)
	if err != nil {
		return "", "", false
	}

	imgName = ref.Context().Name()
	imgTag = ref.Identifier()

	if strings.HasPrefix(imgTag, "sha256:") {
		return imgName, imgTag, false
	}

	for _, monitoredKeyword := range monitoredTags {
		if strings.Contains(imgTag, monitoredKeyword) {
			return imgName, imgTag, true
		}
	}

	return imgName, imgTag, false
}

func (r *ImageUpdateReconciler) findPodsForDeployment(ctx context.Context, deployment *appsv1.Deployment) (*corev1.PodList, error) {
	selector, err := metav1.LabelSelectorAsSelector(deployment.Spec.Selector)
	if err != nil {
		return nil, fmt.Errorf("failed to convert deployment selector: %w", err)
	}

	podList := &corev1.PodList{}
	err = r.List(ctx, podList, client.InNamespace(deployment.Namespace), client.MatchingLabelsSelector{Selector: selector})
	if err != nil {
		return nil, fmt.Errorf("failed to list pods: %w", err)
	}
	return podList, nil
}

func (r *ImageUpdateReconciler) findCurrentImageDigest(containerName string, podList *corev1.PodList) (string, error) {
	for _, pod := range podList.Items {
		if pod.Status.Phase != corev1.PodRunning && pod.Status.Phase != corev1.PodPending {
			continue
		}
		for _, cs := range pod.Status.ContainerStatuses {
			if cs.Name == containerName && cs.ImageID != "" {
				parts := strings.SplitN(cs.ImageID, "@", 2)
				if len(parts) == 2 && strings.HasPrefix(parts[1], "sha256:") {
					return parts[1], nil
				}
				if strings.HasPrefix(cs.ImageID, "sha256:") {
					return cs.ImageID, nil
				}
				return "", fmt.Errorf("unrecognized imageID format in pod %s: %s", pod.Name, cs.ImageID)
			}
		}
	}
	return "", nil
}

func (r *ImageUpdateReconciler) SetupWithManager(mgr ctrl.Manager) error {
	r.Recorder = mgr.GetEventRecorderFor("imageupdate-controller")

	return ctrl.NewControllerManagedBy(mgr).
		Named("imageupdate").
		For(&appsv1.Deployment{}).
		Complete(r)
}