/*
Copyright 2025 Scott Scoble. Licensed under the MIT License.
*/

package controller

import (
	"context"
	"fmt"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/resource"
	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/log"

	kubeclawv1alpha1 "github.com/sscoble/kubeclaw/api/v1alpha1"
)

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

func (r *AgentReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	logger := log.FromContext(ctx)
	logger.Info("reconciling Agent", "name", req.Name, "namespace", req.Namespace)

	agent := &kubeclawv1alpha1.Agent{}
	if err := r.Get(ctx, req.NamespacedName, agent); err != nil {
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	// Handle deletion
	if !agent.DeletionTimestamp.IsZero() {
		if controllerutil.ContainsFinalizer(agent, "kubeclaw.scoble.me/finalizer") {
			podName := fmt.Sprintf("kubeclaw-agent-%s", agent.Spec.AgentID)
			pod := &corev1.Pod{ObjectMeta: metav1.ObjectMeta{Name: podName, Namespace: req.Namespace}}
			if err := r.Delete(ctx, pod); err != nil && !errors.IsNotFound(err) {
				return ctrl.Result{}, err
			}
			controllerutil.RemoveFinalizer(agent, "kubeclaw.scoble.me/finalizer")
			if err := r.Update(ctx, agent); err != nil {
				return ctrl.Result{}, err
			}
		}
		return ctrl.Result{}, nil
	}

	// Ensure finalizer
	if !controllerutil.ContainsFinalizer(agent, "kubeclaw.scoble.me/finalizer") {
		controllerutil.AddFinalizer(agent, "kubeclaw.scoble.me/finalizer")
		if err := r.Update(ctx, agent); err != nil {
			return ctrl.Result{}, err
		}
		return ctrl.Result{Requeue: true}, nil
	}

	// Resolve AgentConfig
	if agent.Spec.AgentConfigRef != "" {
		acfg := &kubeclawv1alpha1.AgentConfig{}
		if err := r.Get(ctx, types.NamespacedName{Name: agent.Spec.AgentConfigRef, Namespace: req.Namespace}, acfg); err != nil {
			logger.Error(err, "cannot fetch AgentConfig", "ref", agent.Spec.AgentConfigRef)
			agent.Status.Phase = "ConfigError"
			_ = r.Status().Update(ctx, agent)
			return ctrl.Result{}, err
		}
		if agent.Spec.Model == "" && acfg.Spec.Model != "" {
			agent.Spec.Model = acfg.Spec.Model
		}
		if agent.Spec.Thinking == "" && acfg.Spec.Thinking != "" {
			agent.Spec.Thinking = acfg.Spec.Thinking
		}
	}

	image := agent.Spec.Image
	if image == "" {
		image = "ghcr.io/sscoble/kubeclaw-agent:latest"
	}

	podName := fmt.Sprintf("kubeclaw-agent-%s", agent.Spec.AgentID)

	pod := &corev1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			Name:      podName,
			Namespace: req.Namespace,
			Labels: map[string]string{
				"app.kubernetes.io/name":      "kubeclaw-agent",
				"app.kubernetes.io/instance":  podName,
				"app.kubernetes.io/part-of":   "scobleclaw",
				"kubeclaw.scoble.me/agent-id": agent.Spec.AgentID,
			},
		},
		Spec: corev1.PodSpec{
			Containers: []corev1.Container{{
				Name:  "agent",
				Image: image,
				Env:   r.buildEnv(agent),
				Resources: corev1.ResourceRequirements{
					Requests: corev1.ResourceList{
						corev1.ResourceCPU:    resource.MustParse("100m"),
						corev1.ResourceMemory: resource.MustParse("128Mi"),
					},
					Limits: corev1.ResourceList{
						corev1.ResourceCPU:    resource.MustParse("500m"),
						corev1.ResourceMemory: resource.MustParse("256Mi"),
					},
				},
			}},
		},
	}

	// Apply resource overrides
	if agent.Spec.Resources != nil {
		if cpu, ok := agent.Spec.Resources.Requests["cpu"]; ok {
			if q, err := resource.ParseQuantity(cpu); err == nil {
				pod.Spec.Containers[0].Resources.Requests[corev1.ResourceCPU] = q
			}
		}
		if mem, ok := agent.Spec.Resources.Requests["memory"]; ok {
			if q, err := resource.ParseQuantity(mem); err == nil {
				pod.Spec.Containers[0].Resources.Requests[corev1.ResourceMemory] = q
			}
		}
		if cpu, ok := agent.Spec.Resources.Limits["cpu"]; ok {
			if q, err := resource.ParseQuantity(cpu); err == nil {
				pod.Spec.Containers[0].Resources.Limits[corev1.ResourceCPU] = q
			}
		}
		if mem, ok := agent.Spec.Resources.Limits["memory"]; ok {
			if q, err := resource.ParseQuantity(mem); err == nil {
				pod.Spec.Containers[0].Resources.Limits[corev1.ResourceMemory] = q
			}
		}
	}

	// Create or update
	foundPod := &corev1.Pod{}
	err := r.Get(ctx, types.NamespacedName{Name: podName, Namespace: req.Namespace}, foundPod)
	if err != nil && errors.IsNotFound(err) {
		logger.Info("creating Pod", "name", podName)
		if err := r.Create(ctx, pod); err != nil {
			return ctrl.Result{}, err
		}
	} else if err == nil {
		foundPod.Spec = pod.Spec
		foundPod.Labels = pod.Labels
		if err := r.Update(ctx, foundPod); err != nil {
			return ctrl.Result{}, err
		}
	}

	agent.Status.Phase = "Running"
	agent.Status.ReadyReplicas = 1
	if err := r.Status().Update(ctx, agent); err != nil {
		return ctrl.Result{}, err
	}

	return ctrl.Result{}, nil
}

func (r *AgentReconciler) buildEnv(agent *kubeclawv1alpha1.Agent) []corev1.EnvVar {
	env := []corev1.EnvVar{{Name: "KUBECLAW_AGENT_ID", Value: agent.Spec.AgentID}}
	if agent.Spec.Model != "" {
		env = append(env, corev1.EnvVar{Name: "KUBECLAW_MODEL", Value: agent.Spec.Model})
	}
	if agent.Spec.Thinking != "" {
		env = append(env, corev1.EnvVar{Name: "KUBECLAW_THINKING", Value: agent.Spec.Thinking})
	}
	if agent.Spec.DefaultTemplate != "" {
		env = append(env, corev1.EnvVar{Name: "KUBECLAW_DEFAULT_TEMPLATE", Value: agent.Spec.DefaultTemplate})
	}
	if len(agent.Spec.AllowedTemplates) > 0 {
		env = append(env, corev1.EnvVar{Name: "KUBECLAW_ALLOWED_TEMPLATES", Value: joinSlice(agent.Spec.AllowedTemplates, ",")})
	}
	return env
}

func (r *AgentReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&kubeclawv1alpha1.Agent{}).
		Owns(&corev1.Pod{}).
		Complete(r)
}