package underlay

import (
	"context"
	"fmt"

	"go.uber.org/zap"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"

	"github.com/guildhouse-co/kedge/internal/config"
	"github.com/guildhouse-co/kedge/internal/quartermaster"
)

// Watcher watches for YANG instance data changes in ConfigMaps and triggers
// compilation and SDK dispatch for underlay device configuration.
type Watcher struct {
	cfg       config.UnderlayConfig
	qm        *quartermaster.Client
	log       *zap.SugaredLogger
	clientset kubernetes.Interface
}

// NewWatcher creates a new underlay YANG watcher.
func NewWatcher(cfg config.UnderlayConfig, qm *quartermaster.Client, log *zap.SugaredLogger) *Watcher {
	return &Watcher{cfg: cfg, qm: qm, log: log}
}

// Run starts watching for YANG instance data changes.
func (w *Watcher) Run(ctx context.Context) error {
	if !w.cfg.Enabled {
		w.log.Info("underlay mode disabled, watcher idle")
		<-ctx.Done()
		return nil
	}

	// Build in-cluster K8s client.
	k8sConfig, err := rest.InClusterConfig()
	if err != nil {
		return fmt.Errorf("failed to get in-cluster config: %w", err)
	}
	w.clientset, err = kubernetes.NewForConfig(k8sConfig)
	if err != nil {
		return fmt.Errorf("failed to create k8s client: %w", err)
	}

	w.log.Infof("watching ConfigMap %s/%s for YANG instance data changes",
		w.cfg.Namespace, w.cfg.ConfigMapName)

	// TODO: Set up informer to watch ConfigMap for changes.
	// On change: trigger YANG compilation, then dispatch SDK calls via Bascule.
	// Each mutation is notarized via Quartermaster.

	<-ctx.Done()
	return nil
}