/*
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"
)

// AgentReconciler reconciles a Agent object
type AgentReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

// +kubebuilder:rbac:groups=locostack.com,resources=agents,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=locostack.com,resources=agents/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=locostack.com,resources=agents/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 *AgentReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	log := logf.FromContext(ctx)

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

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

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

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

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

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

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

	_, err = controllerutil.CreateOrUpdate(ctx, r.Client, comp, func() error {
		if comp.Labels == nil {
			comp.Labels = make(map[string]string)
		}
		stackName := ""
		if agent.Spec.StackRef != nil {
			stackName = agent.Spec.StackRef.Name
		}
		maps.Copy(comp.Labels, reconciler.ResourceLabels(stackName, "Agent", agent.Name, ""))
		dependencies := make([]corev1.ObjectReference, 0)
		dependencies = append(dependencies, agent.Spec.Model)
		for _, tool := range agent.Spec.Tools {
			dependencies = append(dependencies, tool)
		}
		for _, kb := range agent.Spec.KnowledgeBases {
			dependencies = append(dependencies, kb)
		}
		comp.Spec.Category = "Agent"
		comp.Spec.Template = &tmpl
		comp.Spec.Variables = map[string]string{
			"systemPrompt": agent.Spec.SystemPrompt,
		}
		comp.Spec.Dependencies = dependencies
		if agent.Spec.StackRef != nil {
			comp.Spec.StackRef = &corev1.LocalObjectReference{Name: agent.Spec.StackRef.Name}
		}
		return controllerutil.SetControllerReference(agent, comp, r.Scheme)
	})

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

// SetupWithManager sets up the controller with the Manager.
func (r *AgentReconciler) SetupWithManager(mgr ctrl.Manager) error {
	mapComponentToAgents := 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 == "Agent" {
				reqs = append(reqs, reconcile.Request{
					NamespacedName: types.NamespacedName{
						Name:      em.Name,
						Namespace: em.Namespace,
					},
				})
			}
		}
		return reqs
	}

	return ctrl.NewControllerManagedBy(mgr).
		For(&v1alpha1.Agent{}).
		Owns(&v1alpha1.Component{}).
		Watches(&v1alpha1.Component{}, handler.EnqueueRequestsFromMapFunc(mapComponentToAgents)).
		Named("agent").
		Complete(r)
}