// internal/controller/deploymentdefaults_controller.go
package controller

import (
	"context"
	"fmt"
	"strings"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/resource"
	"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/handler"
	"sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"

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

// DeploymentDefaultsReconciler reconciles Deployment objects to apply default resources.
type DeploymentDefaultsReconciler struct {
	client.Client
	Scheme   *runtime.Scheme
	Recorder record.EventRecorder
}

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

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

	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 // Requeue on error
	}

	var config configv1alpha1.NodeTainterConfig
	configKey := types.NamespacedName{Name: GlobalTaintConfigName}
	if err := r.Get(ctx, configKey, &config); err != nil {
		if errors.IsNotFound(err) {
			log.Info("Global NodeTainterConfig not found, skipping resource defaulting", "configName", GlobalTaintConfigName)
			return ctrl.Result{}, nil
		}
		log.Error(err, "Failed to get NodeTainterConfig for defaults", "configName", GlobalTaintConfigName)
		r.Recorder.Eventf(&deployment, corev1.EventTypeWarning, "ConfigError", "Failed to get config %s: %v", GlobalTaintConfigName, err)
		return ctrl.Result{}, err
	}

	if config.Spec.ResourceDefaults == nil {
		log.V(1).Info("Resource defaulting is disabled in NodeTainterConfig.")
		return ctrl.Result{}, nil
	}

	optOutKey := strings.TrimSpace(config.Spec.OptOutLabelKey)
	if optOutKey != "" {
		labels := deployment.GetLabels()
		if _, exists := labels[optOutKey]; exists {
			log.Info("Deployment has opt-out label, skipping resource defaulting", "labelKey", optOutKey)
			r.Recorder.Eventf(&deployment, corev1.EventTypeNormal, "OptedOut", "Skipping resource defaulting due to label %s", optOutKey)
			return ctrl.Result{}, nil
		}
	}

	defaults := config.Spec.ResourceDefaults
	defaultCPUReq, errCPUReq := parseQuantity(defaults.CPURequest)
	defaultMemReq, errMemReq := parseQuantity(defaults.MemoryRequest)
	defaultCPULim, errCPULim := parseQuantity(defaults.CPULimit)
	defaultMemLim, errMemLim := parseQuantity(defaults.MemoryLimit)

	var parseErrors []string
	if errCPUReq != nil {
		parseErrors = append(parseErrors, fmt.Sprintf("CPURequest: %v", errCPUReq))
	}
	if errMemReq != nil {
		parseErrors = append(parseErrors, fmt.Sprintf("MemoryRequest: %v", errMemReq))
	}
	if errCPULim != nil {
		parseErrors = append(parseErrors, fmt.Sprintf("CPULimit: %v", errCPULim))
	}
	if errMemLim != nil {
		parseErrors = append(parseErrors, fmt.Sprintf("MemoryLimit: %v", errMemLim))
	}

	if len(parseErrors) > 0 {
		parsingError := fmt.Errorf("invalid resource quantity format in NodeTainterConfig %s: %s", config.Name, strings.Join(parseErrors, "; "))
		log.Error(parsingError, "Default resource parsing failed", "configName", config.Name, "parsingErrors", parseErrors)
		r.Recorder.Eventf(&deployment, corev1.EventTypeWarning, "ConfigError", parsingError.Error())
		return ctrl.Result{}, nil
	}

	deploymentCopy := deployment.DeepCopy()
	mutated := false

	for i, container := range deploymentCopy.Spec.Template.Spec.Containers {
		containerName := container.Name
		log := log.WithValues("container", containerName)

		if deploymentCopy.Spec.Template.Spec.Containers[i].Resources.Requests == nil {
			deploymentCopy.Spec.Template.Spec.Containers[i].Resources.Requests = corev1.ResourceList{}
		}
		if deploymentCopy.Spec.Template.Spec.Containers[i].Resources.Limits == nil {
			deploymentCopy.Spec.Template.Spec.Containers[i].Resources.Limits = corev1.ResourceList{}
		}

		requests := deploymentCopy.Spec.Template.Spec.Containers[i].Resources.Requests
		limits := deploymentCopy.Spec.Template.Spec.Containers[i].Resources.Limits

		if _, exists := requests[corev1.ResourceCPU]; !exists && defaultCPUReq != nil {
			requests[corev1.ResourceCPU] = *defaultCPUReq
			log.V(1).Info("Applied default CPU request", "value", defaultCPUReq.String())
			mutated = true
		}
		if _, exists := requests[corev1.ResourceMemory]; !exists && defaultMemReq != nil {
			requests[corev1.ResourceMemory] = *defaultMemReq
			log.V(1).Info("Applied default Memory request", "value", defaultMemReq.String())
			mutated = true
		}
		if _, exists := limits[corev1.ResourceCPU]; !exists && defaultCPULim != nil {
			limits[corev1.ResourceCPU] = *defaultCPULim
			log.V(1).Info("Applied default CPU limit", "value", defaultCPULim.String())
			mutated = true
		}
		if _, exists := limits[corev1.ResourceMemory]; !exists && defaultMemLim != nil {
			limits[corev1.ResourceMemory] = *defaultMemLim
			log.V(1).Info("Applied default Memory limit", "value", defaultMemLim.String())
			mutated = true
		}
	}

	if mutated {
		log.Info("Applying default resource requests/limits to Deployment")
		if err := r.Patch(ctx, deploymentCopy, client.MergeFrom(&deployment)); err != nil {
			log.Error(err, "Failed to patch Deployment with default resources")
			r.Recorder.Eventf(&deployment, corev1.EventTypeWarning, "UpdateFailed", "Failed to apply default resources: %v", err)
			return ctrl.Result{}, err
		}
		log.Info("Successfully applied default resources")
		r.Recorder.Eventf(&deployment, corev1.EventTypeNormal, "DefaultsApplied", "Default resource requests/limits applied")
	} else {
		log.V(1).Info("Deployment already has necessary resource requests/limits or no defaults configured.")
	}

	return ctrl.Result{}, nil
}

func parseQuantity(s string) (*resource.Quantity, error) {
	s = strings.TrimSpace(s)
	if s == "" {
		return nil, nil
	}
	q, err := resource.ParseQuantity(s)
	if err != nil {
		return nil, fmt.Errorf("invalid quantity format '%s': %w", s, err)
	}
	return &q, nil
}

// Map function for NodeTainterConfig: Trigger reconcile for ALL Deployments when the specific config changes
func (r *DeploymentDefaultsReconciler) mapConfigToDeployments(ctx context.Context, obj client.Object) []reconcile.Request {
	config, ok := obj.(*configv1alpha1.NodeTainterConfig)
	log := log.FromContext(ctx)
	if !ok || config.Name != GlobalTaintConfigName {
		return nil
	}

	log.Info("Global NodeTainterConfig changed, queuing reconciliation for all deployments potentially affected by resource defaults", "configName", config.Name)

	var deploymentList appsv1.DeploymentList
	if err := r.List(ctx, &deploymentList, client.InNamespace("")); err != nil {
		log.Error(err, "Failed to list deployments for config change")
		return nil
	}

	requests := make([]reconcile.Request, 0, len(deploymentList.Items))
	optOutKey := strings.TrimSpace(config.Spec.OptOutLabelKey)

	for _, deployment := range deploymentList.Items {
		if optOutKey != "" {
			labels := deployment.GetLabels()
			if _, exists := labels[optOutKey]; exists {
				continue
			}
		}
		requests = append(requests, reconcile.Request{
			NamespacedName: types.NamespacedName{
				Name:      deployment.Name,
				Namespace: deployment.Namespace,
			},
		})
	}
	log.Info("Queued deployment reconcile requests", "count", len(requests))
	return requests
}

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

	return ctrl.NewControllerManagedBy(mgr).
		Named("deploymentdefaults").
		For(&appsv1.Deployment{}).
		Watches(
			&configv1alpha1.NodeTainterConfig{},
			handler.EnqueueRequestsFromMapFunc(r.mapConfigToDeployments),
		).
		Complete(r)
}