/*
Copyright 2026 LocoStack.

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 controller

import (
	"context"
	"fmt"
	"maps"
	"strings"

	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	apimeta "k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/apimachinery/pkg/api/resource"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/utils/ptr"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"

	"github.com/LocoStack/loco-operator/api/v1alpha1"
	"github.com/LocoStack/loco-operator/internal/reconciler"
	"github.com/LocoStack/loco-operator/pkg/templates"
)

// StackReconciler reconciles a Stack object
type StackReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

// +kubebuilder:rbac:groups=locostack.com,resources=stacks,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=locostack.com,resources=stacks/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=locostack.com,resources=stacks/finalizers,verbs=update
// +kubebuilder:rbac:groups=locostack.com,resources=components,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups="",resources=persistentvolumes,verbs=get;list;watch;create;update;patch
// +kubebuilder:rbac:groups="",resources=persistentvolumeclaims,verbs=get;list;watch;create;update;patch

func (r *StackReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	log := logf.FromContext(ctx)

	s := &v1alpha1.Stack{}
	if err := r.Get(ctx, req.NamespacedName, s); err != nil {
		if apierrors.IsNotFound(err) {
			return ctrl.Result{}, nil
		}
		return ctrl.Result{}, err
	}

	patch := client.MergeFrom(s.DeepCopy())

	if err := r.reconcileSharedVolumes(ctx, s); err != nil {
		return ctrl.Result{}, err
	}
	if err := r.reconcileComponents(ctx, s); err != nil {
		return ctrl.Result{}, err
	}
	if err := r.reconcileGateways(ctx, s); err != nil {
		return ctrl.Result{}, err
	}

	s.Status.ObservedGeneration = s.Generation
	if err := r.Status().Patch(ctx, s, patch); err != nil {
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	log.Info("Reconciled Stack", "namespace", s.Namespace, "name", s.Name)
	return ctrl.Result{}, nil
}

// reconcileSharedVolumes ensures all PVC-backed shared volumes declared in the Stack spec exist.
func (r *StackReconciler) reconcileSharedVolumes(ctx context.Context, s *v1alpha1.Stack) error {
	failedVolumes := make([]string, 0)
	for _, volume := range s.Spec.SharedVolumes {
		claimName := fmt.Sprintf("%s-%s", s.Name, volume)
		pvc := &corev1.PersistentVolumeClaim{
			ObjectMeta: metav1.ObjectMeta{
				Name:      claimName,
				Namespace: s.Namespace,
			},
		}

		pv := &corev1.PersistentVolume{}
		if err := r.Get(ctx, client.ObjectKey{Name: volume}, pv); err != nil {
			if apierrors.IsNotFound(err) {
				apimeta.SetStatusCondition(&s.Status.Conditions, metav1.Condition{
					Type:               "SharedVolumesResolved",
					Status:             metav1.ConditionFalse,
					Reason:             "ReconcileFailed",
					Message:            fmt.Sprintf("Could not find shared volume %s: %v", volume, err),
					ObservedGeneration: s.Generation,
				})
				return nil
			}
			return err
		}

		_, err := controllerutil.CreateOrUpdate(ctx, r.Client, pvc, func() error {
			if pvc.Labels == nil {
				pvc.Labels = map[string]string{}
			}
			maps.Copy(pvc.Labels, reconciler.ResourceLabels(s.Name, "SharedVolume", volume, ""))

			pvc.Spec.VolumeName = volume
			pvc.Spec.StorageClassName = ptr.To("")

			pvc.Spec.AccessModes = []corev1.PersistentVolumeAccessMode{corev1.ReadWriteMany}
			if pvc.Spec.Resources.Requests == nil {
				pvc.Spec.Resources.Requests = corev1.ResourceList{}
			}
			if _, ok := pvc.Spec.Resources.Requests[corev1.ResourceStorage]; !ok {
				pvc.Spec.Resources.Requests[corev1.ResourceStorage] = resource.MustParse("1Gi")
			}

			return controllerutil.SetControllerReference(s, pvc, r.Scheme)
		})
		if err != nil {
			failedVolumes = append(failedVolumes, volume)
		}
	}
	if len(failedVolumes) > 0 {
		apimeta.SetStatusCondition(&s.Status.Conditions, metav1.Condition{
			Type:               "SharedVolumesResolved",
			Status:             metav1.ConditionFalse,
			Reason:             "ReconcileFailed",
			Message:            fmt.Sprintf("Could not reconcile shared volume(s): %v", failedVolumes),
			ObservedGeneration: s.Generation,
		})
	} else {
		apimeta.SetStatusCondition(&s.Status.Conditions, metav1.Condition{
			Type:               "SharedVolumesResolved",
			Status:             metav1.ConditionTrue,
			Reason:             "ReconcileSucceeded",
			Message:            "All shared volumes reconciled successfully",
			ObservedGeneration: s.Generation,
		})
	}
	return nil
}

func (r *StackReconciler) reconcileComponents(ctx context.Context, s *v1alpha1.Stack) error {
	components := getComponents(s)
	failedComponents := make([]string, 0)
	errList := make([]error, 0)
	for _, comp := range components {
		resolvedTemplateName, reconciled, err := r.reconcileComponent(ctx, s, comp)
		setResolvedTemplateName(&s.Status, comp.name, resolvedTemplateName)
		if !reconciled {
			failedComponents = append(failedComponents, comp.name)
		}
		if err != nil {
			errList = append(errList, err)
		}
	}

	if len(failedComponents) > 0 {
		apimeta.SetStatusCondition(&s.Status.Conditions, metav1.Condition{
			Type:               "ComponentsReconciled",
			Status:             metav1.ConditionFalse,
			Reason:             "ReconcileFailed",
			Message:            fmt.Sprintf("%d component(s) failed to reconcile: %v", len(failedComponents), failedComponents),
			ObservedGeneration: s.Generation,
		})
	} else {
		apimeta.SetStatusCondition(&s.Status.Conditions, metav1.Condition{
			Type:               "ComponentsReconciled",
			Status:             metav1.ConditionTrue,
			Reason:             "ReconcileSucceeded",
			Message:            "All enabled components were reconciled successfully",
			ObservedGeneration: s.Generation,
		})
	}

	if len(errList) > 0 {
		return fmt.Errorf("failed with errors: %v", errList)
	}
	return nil
}

type componentConfig struct {
	name        string
	defaultTmpl string
	template    *v1alpha1.Template
	enabled     bool
}

func newComponentConfig(name, defaultTmpl string, enabled bool, optional *v1alpha1.OptionalComponent) componentConfig {
	var tmpl *v1alpha1.Template

	if optional != nil {
		enabled = optional.Enabled
		tmpl = optional.Template
	}

	return componentConfig{
		name:        name,
		defaultTmpl: defaultTmpl,
		template:    tmpl,
		enabled:     enabled,
	}
}

func getComponents(s *v1alpha1.Stack) []componentConfig {
	return []componentConfig{
		newComponentConfig("Gateway", "litellm", true, s.Spec.Gateway),
		newComponentConfig("VectorStore", "qdrant", true, s.Spec.VectorStore),
		newComponentConfig("GraphStore", "neo4j", false, s.Spec.GraphStore),
		newComponentConfig("Database", "postgresql", true, s.Spec.Database),
		newComponentConfig("Observability", "phoenix", false, s.Spec.Observability),
	}
}

func setResolvedTemplateName(status *v1alpha1.StackStatus, name string, templateName string) {
	switch name {
	case "Gateway":
		status.ComponentStatus.Gateway = templateName
	case "VectorStore":
		status.ComponentStatus.VectorStore = templateName
	case "GraphStore":
		status.ComponentStatus.GraphStore = templateName
	case "Database":
		status.ComponentStatus.Database = templateName
	case "Observability":
		status.ComponentStatus.Observability = templateName
	}
}

func (r *StackReconciler) reconcileComponent(ctx context.Context, s *v1alpha1.Stack, compCfg componentConfig) (string, bool, error) {
	compName := fmt.Sprintf("%s-%s", strings.ToLower(compCfg.name), s.Name)
	comp := &v1alpha1.Component{
		ObjectMeta: metav1.ObjectMeta{
			Name:      compName,
			Namespace: s.Namespace,
		},
	}
	err := r.Get(ctx, client.ObjectKey{Namespace: s.Namespace, Name: compName}, comp)
	if !compCfg.enabled {
		tmpl := "disabled"
		if err == nil {
			if err := r.Delete(ctx, comp); err != nil {
				return tmpl, false, err
			}
			return tmpl, true, nil
		}
		if apierrors.IsNotFound(err) {
			return tmpl, true, nil
		}
		return tmpl, false, err
	}

	tmpl, err := templates.Manager.ResolveTemplate(compCfg.template, compCfg.defaultTmpl)
	if err != nil {
		return "unknown", false, err
	}

	_, err = controllerutil.CreateOrUpdate(ctx, r.Client, comp, func() error {
		if comp.Labels == nil {
			comp.Labels = make(map[string]string)
		}
		maps.Copy(comp.Labels, reconciler.ResourceLabels(s.Name, compCfg.name, s.Name, ""))
		comp.Labels["stack.locostack.com/default"] = "true"
		comp.Spec.Category = compCfg.name
		comp.Spec.Template = &tmpl
		comp.Spec.StackRef = &corev1.LocalObjectReference{Name: s.Name}
		return controllerutil.SetControllerReference(s, comp, r.Scheme)
	})
	available := apimeta.IsStatusConditionTrue(comp.Status.Conditions, "Available")
	return tmpl.Name, available, err
}

func (r *StackReconciler) reconcileGateways(ctx context.Context, s *v1alpha1.Stack) error {
	log := logf.FromContext(ctx)

	gwList := &v1alpha1.ComponentList{}
	err := r.List(ctx, gwList, client.InNamespace(s.Namespace), client.MatchingLabels{"locostack.com/stack": s.Name, "locostack.com/component": "Gateway"})
	if err != nil {
		return fmt.Errorf("failed to list gateway components: %v", err)
	}
	if len(gwList.Items) == 0 {
		log.Info("No gateways found for stack", "namespace", s.Namespace, "stack", s.Name)
		return nil
	}

	dependencies := make([]corev1.ObjectReference, 0)

	emList := &v1alpha1.ExternalModelList{}
	if err := r.List(ctx, emList, client.InNamespace(s.Namespace)); err != nil {
		return fmt.Errorf("Failed to list external models: %v", err)
	}
	for _, em := range emList.Items {
		if em.Spec.StackRef.Name == s.Name {
			dependencies = append(dependencies, corev1.ObjectReference{
				Kind:      "ExternalModel",
				Name:      em.Name,
				Namespace: em.Namespace,
			})
		}
	}

	mmList := &v1alpha1.ManagedModelList{}
	if err := r.List(ctx, mmList, client.InNamespace(s.Namespace)); err != nil {
		return fmt.Errorf("Failed to list managed models: %v", err)
	}
	for _, em := range mmList.Items {
		if em.Spec.StackRef.Name == s.Name {
			dependencies = append(dependencies, corev1.ObjectReference{
				Kind:      "ManagedModel",
				Name:      em.Name,
				Namespace: em.Namespace,
			})
		}
	}

	etList := &v1alpha1.ExternalToolList{}
	if err := r.List(ctx, etList, client.InNamespace(s.Namespace)); err != nil {
		return fmt.Errorf("Failed to list external tools: %v", err)
	}
	for _, em := range etList.Items {
		if em.Spec.StackRef.Name == s.Name {
			dependencies = append(dependencies, corev1.ObjectReference{
				Kind:      "ExternalTool",
				Name:      em.Name,
				Namespace: em.Namespace,
			})
		}
	}

	mtList := &v1alpha1.ManagedToolList{}
	if err := r.List(ctx, mtList, client.InNamespace(s.Namespace)); err != nil {
		return fmt.Errorf("Failed to list managed tools: %v", err)
	}
	for _, em := range mtList.Items {
		if em.Spec.StackRef.Name == s.Name {
			dependencies = append(dependencies, corev1.ObjectReference{
				Kind:      "ManagedTool",
				Name:      em.Name,
				Namespace: em.Namespace,
			})
		}
	}

	if len(dependencies) == 0 {
		return nil
	}

	for _, gw := range gwList.Items {
		gw.Spec.Dependencies = dependencies
		if err := r.Update(ctx, &gw); err != nil {
			return fmt.Errorf("Failed to update gateway %s with dependencies: %v", gw.Name, err)
		}
	}

	return nil
}

// SetupWithManager sets up the controller with the Manager.
func (r *StackReconciler) SetupWithManager(mgr ctrl.Manager) error {
	mapToStack := func(ctx context.Context, obj client.Object) []reconcile.Request {
		var stackName string
		switch typed := obj.(type) {
		case *v1alpha1.ExternalModel:
			stackName = typed.Spec.StackRef.Name
		case *v1alpha1.ManagedModel:
			stackName = typed.Spec.StackRef.Name
		case *v1alpha1.ExternalTool:
			stackName = typed.Spec.StackRef.Name
		case *v1alpha1.ManagedTool:
			stackName = typed.Spec.StackRef.Name
		default:
			return nil
		}
		stackList := &v1alpha1.StackList{}
		if err := mgr.GetClient().List(ctx, stackList, client.InNamespace(obj.GetNamespace())); err != nil {
			return nil
		}
		var reqs []reconcile.Request
		for _, stack := range stackList.Items {
			if stackName == stack.Name {
				reqs = append(reqs, reconcile.Request{
					NamespacedName: types.NamespacedName{Name: stack.Name, Namespace: stack.Namespace},
				})
			}
		}
		return reqs
	}

	return ctrl.NewControllerManagedBy(mgr).
		For(&v1alpha1.Stack{}).
		Owns(&v1alpha1.Component{}).
		Owns(&corev1.PersistentVolumeClaim{}).
		Watches(&v1alpha1.ExternalModel{}, handler.EnqueueRequestsFromMapFunc(mapToStack)).
		Watches(&v1alpha1.ManagedModel{}, handler.EnqueueRequestsFromMapFunc(mapToStack)).
		Watches(&v1alpha1.ExternalTool{}, handler.EnqueueRequestsFromMapFunc(mapToStack)).
		Watches(&v1alpha1.ManagedTool{}, handler.EnqueueRequestsFromMapFunc(mapToStack)).
		Named("stack").
		Complete(r)
}