/*
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"

	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	apimeta "k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	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"
)

// ManagedKnowledgeBaseReconciler reconciles a ManagedKnowledgeBase object
type ManagedKnowledgeBaseReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

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

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

	mkb := &v1alpha1.ManagedKnowledgeBase{}
	if err := r.Get(ctx, req.NamespacedName, mkb); err != nil {
		if apierrors.IsNotFound(err) {
			return ctrl.Result{}, nil
		}
		log.Error(err, "Failed to get ManagedKnowledgeBase", "namespace", req.NamespacedName.Namespace, "name", req.NamespacedName.Name)
		return ctrl.Result{}, err
	}

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

	componentAvailable, err := r.reconcileComponent(ctx, mkb)
	if err != nil {
		return ctrl.Result{}, err
	}
	if !componentAvailable {
		apimeta.SetStatusCondition(&mkb.Status.Conditions, metav1.Condition{
			Type:               "Available",
			Status:             metav1.ConditionFalse,
			Reason:             "KnowledgeBaseUnavailable",
			Message:            "ManagedKnowledgeBase is not available",
			ObservedGeneration: mkb.Generation,
		})
	} else {
		apimeta.SetStatusCondition(&mkb.Status.Conditions, metav1.Condition{
			Type:               "Available",
			Status:             metav1.ConditionTrue,
			Reason:             "KnowledgeBaseAvailable",
			Message:            "ManagedKnowledgeBase is available",
			ObservedGeneration: mkb.Generation,
		})
	}

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

	log.Info("Reconciled ManagedKnowledgeBase", "namespace", req.NamespacedName.Namespace, "name", req.NamespacedName.Name)
	return ctrl.Result{}, nil
}

func (r *ManagedKnowledgeBaseReconciler) reconcileComponent(ctx context.Context, mkb *v1alpha1.ManagedKnowledgeBase) (bool, error) {
	compName := fmt.Sprintf("kb-%s", mkb.Name)
	comp := &v1alpha1.Component{
		ObjectMeta: metav1.ObjectMeta{
			Name:      compName,
			Namespace: mkb.Namespace,
		},
	}
	err := r.Get(ctx, client.ObjectKey{Namespace: mkb.Namespace, Name: compName}, comp)

	tmpl, err := templates.Manager.ResolveTemplate(mkb.Spec.Template, "")
	if err != nil {
		apimeta.SetStatusCondition(&mkb.Status.Conditions, metav1.Condition{
			Type:               "KnowledgeBaseRuntimeResolved",
			Status:             metav1.ConditionFalse,
			Reason:             "TemplateNotResolved",
			Message:            fmt.Sprintf("Failed to reconcile template for ManagedKnowledgeBase: %v", err),
			ObservedGeneration: mkb.Generation,
		})
		return false, nil
	}
	apimeta.SetStatusCondition(&mkb.Status.Conditions, metav1.Condition{
		Type:               "KnowledgeBaseRuntimeResolved",
		Status:             metav1.ConditionTrue,
		Reason:             "TemplateResolved",
		Message:            fmt.Sprintf("Successfully resolved template for ManagedKnowledgeBase: %v", tmpl.Name),
		ObservedGeneration: mkb.Generation,
	})

	_, err = controllerutil.CreateOrUpdate(ctx, r.Client, comp, func() error {
		if comp.Labels == nil {
			comp.Labels = make(map[string]string)
		}
		stackName := ""
		if mkb.Spec.StackRef != nil {
			stackName = mkb.Spec.StackRef.Name
		}
		maps.Copy(comp.Labels, reconciler.ResourceLabels(stackName, "KnowledgeBase", mkb.Name, ""))
		dependencies := make([]corev1.ObjectReference, 0)
		if mkb.Spec.EmbeddingModelRef != nil {
			dependencies = append(dependencies, *mkb.Spec.EmbeddingModelRef)
		}
		if mkb.Spec.RerankerModelRef != nil {
			dependencies = append(dependencies, *mkb.Spec.RerankerModelRef)
		}
		comp.Spec.Category = "KnowledgeBase"
		comp.Spec.Template = &tmpl
		comp.Spec.Dependencies = dependencies
		if mkb.Spec.StackRef != nil {
			comp.Spec.StackRef = &corev1.LocalObjectReference{Name: mkb.Spec.StackRef.Name}
		}
		return controllerutil.SetControllerReference(mkb, comp, r.Scheme)
	})

	available := apimeta.IsStatusConditionTrue(comp.Status.Conditions, "Available")
	if available {
		mkb.Status.Endpoint = comp.Status.Endpoint
		apimeta.SetStatusCondition(&mkb.Status.Conditions, metav1.Condition{
			Type:               "Ready",
			Status:             metav1.ConditionTrue,
			Reason:             "ComponentAvailable",
			Message:            "Component is available",
			ObservedGeneration: mkb.Generation,
		})
	} else {
		apimeta.SetStatusCondition(&mkb.Status.Conditions, metav1.Condition{
			Type:               "Ready",
			Status:             metav1.ConditionFalse,
			Reason:             "ComponentUnavailable",
			Message:            "Component is not available",
			ObservedGeneration: mkb.Generation,
		})
	}
	return available, err
}

// SetupWithManager sets up the controller with the Manager.
func (r *ManagedKnowledgeBaseReconciler) SetupWithManager(mgr ctrl.Manager) error {
	mapComponentToManagedKnowledgeBases := func(ctx context.Context, obj client.Object) []reconcile.Request {
		comp, ok := obj.(*v1alpha1.Component)
		if !ok {
			return nil
		}
		var reqs []reconcile.Request
		for _, em := range comp.Spec.Dependencies {
			if em.APIVersion == v1alpha1.GroupVersion.Group && em.Kind == "ManagedKnowledgeBase" {
				reqs = append(reqs, reconcile.Request{
					NamespacedName: types.NamespacedName{
						Name:      em.Name,
						Namespace: em.Namespace,
					},
				})
			}
		}
		return reqs
	}

	return ctrl.NewControllerManagedBy(mgr).
		For(&v1alpha1.ManagedKnowledgeBase{}).
		Owns(&v1alpha1.Component{}).
		Watches(&v1alpha1.Component{}, handler.EnqueueRequestsFromMapFunc(mapComponentToManagedKnowledgeBases)).
		Named("managedknowledgebase").
		Complete(r)
}