package serviceadapter

import (
	"context"
	"fmt"
	"log"
	"time"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/client-go/dynamic"
	"k8s.io/client-go/dynamic/dynamicinformer"
	"k8s.io/client-go/tools/cache"
)

// InformerManager watches ServiceAdapter resources and populates the registry.
type InformerManager struct {
	registry   *Registry
	informer   cache.SharedIndexInformer
	stopChan   chan struct{}
	factory    dynamicinformer.DynamicSharedInformerFactory
}

// NewInformerManager creates a new informer that watches ServiceAdapters in the api namespace.
func NewInformerManager(dynamicClient dynamic.Interface, registry *Registry, namespace string) (*InformerManager, error) {
	if registry == nil {
		return nil, fmt.Errorf("registry cannot be nil")
	}

	if namespace == "" {
		namespace = "api"
	}

	// ServiceAdapter GVR
	gvr := schema.GroupVersionResource{
		Group:    "gateway.riotpiao.com",
		Version:  "v1",
		Resource: "serviceadapters",
	}

	// Create informer factory scoped to namespace
	factory := dynamicinformer.NewFilteredDynamicSharedInformerFactory(
		dynamicClient,
		30*time.Second,
		namespace,
		nil,
	)

	// Get the informer for ServiceAdapters
	informer := factory.ForResource(gvr).Informer()

	// Add event handlers
	_, err := informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: func(obj interface{}) {
			unstructObj := obj.(*unstructured.Unstructured)
			if adapter, err := parseServiceAdapter(unstructObj); err == nil {
				if registry.Add(adapter) == nil {
					log.Printf("[INFO] ServiceAdapter added: %s/%s", adapter.Namespace, adapter.ServiceName)
				}
			}
		},
		UpdateFunc: func(oldObj, newObj interface{}) {
			unstructObj := newObj.(*unstructured.Unstructured)
			if adapter, err := parseServiceAdapter(unstructObj); err == nil {
				if registry.Update(adapter) == nil {
					log.Printf("[INFO] ServiceAdapter updated: %s/%s", adapter.Namespace, adapter.ServiceName)
				}
			}
		},
		DeleteFunc: func(obj interface{}) {
			unstructObj, ok := obj.(*unstructured.Unstructured)
			if !ok {
				// Handle tombstone (for objects that were deleted)
				tombstone, ok := obj.(cache.DeletedFinalStateUnknown)
				if !ok {
					return
				}
				unstructObj, ok = tombstone.Obj.(*unstructured.Unstructured)
				if !ok {
					return
				}
			}

			if name, ok := unstructObj.Object["metadata"].(map[string]interface{})["name"]; ok {
				registry.Delete(name.(string))
				log.Printf("[INFO] ServiceAdapter deleted: %s", name)
			}
		},
	})

	if err != nil {
		return nil, err
	}

	return &InformerManager{
		registry: registry,
		informer: informer,
		stopChan: make(chan struct{}),
		factory:  factory,
	}, nil
}

// Start begins watching ServiceAdapter resources.
func (im *InformerManager) Start(ctx context.Context) error {
	im.factory.Start(im.stopChan)

	// Wait for informer cache to sync
	if !cache.WaitForCacheSync(im.stopChan, im.informer.HasSynced) {
		return fmt.Errorf("failed to sync ServiceAdapter informer cache")
	}

	log.Printf("[INFO] ServiceAdapter informer started, synced from cluster")
	return nil
}

// Stop stops watching ServiceAdapter resources.
func (im *InformerManager) Stop() {
	close(im.stopChan)
}

// parseServiceAdapter converts an unstructured object to ServiceAdapter.
func parseServiceAdapter(unstructured *unstructured.Unstructured) (*ServiceAdapter, error) {
	metadata, ok := unstructured.Object["metadata"].(map[string]interface{})
	if !ok {
		return nil, fmt.Errorf("invalid metadata")
	}

	name, ok := metadata["name"].(string)
	if !ok {
		return nil, fmt.Errorf("missing metadata.name")
	}

	namespace, ok := metadata["namespace"].(string)
	if !ok {
		namespace = "default"
	}

	spec, ok := unstructured.Object["spec"].(map[string]interface{})
	if !ok {
		return nil, fmt.Errorf("missing spec")
	}

	// Parse spec fields (simplified - in real implementation would use JSON unmarshaling)
	serviceName, ok := spec["serviceName"].(string)
	if !ok {
		return nil, fmt.Errorf("missing serviceName")
	}

	adapter := &ServiceAdapter{
		Name:        name,
		Namespace:   namespace,
		ServiceName: serviceName,
		CreatedAt:   time.Now(),
	}

	// Parse upstream if present
	if upstreamMap, ok := spec["upstream"].(map[string]interface{}); ok {
		if url, ok := upstreamMap["url"].(string); ok {
			adapter.Spec.Upstream.URL = url
		}
		if timeout, ok := upstreamMap["timeoutSeconds"].(float64); ok {
			adapter.Spec.Upstream.TimeoutSeconds = int32(timeout)
		}
	}

	// Parse auth if present
	if authMap, ok := spec["auth"].(map[string]interface{}); ok {
		if required, ok := authMap["required"].(bool); ok {
			adapter.Spec.Auth.Required = required
		}
		if capability, ok := authMap["capability"].(string); ok {
			adapter.Spec.Auth.Capability = capability
		}
	}

	return adapter, nil
}