/*
 * SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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_common

import (
	"context"
	"strings"
	"time"

	"k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/client-go/discovery"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/predicate"
)

// ExcludedNamespacesInterface defines the interface for checking namespace exclusions
type ExcludedNamespacesInterface interface {
	Contains(namespace string) bool
}

type GroveConfig struct {
	// Enabled is automatically determined by checking if Grove CRDs are installed in the cluster
	Enabled bool
	// TerminationDelay configures the termination delay for Grove PodCliqueSets
	TerminationDelay time.Duration
}

type LWSConfig struct {
	// Enabled is automatically determined by checking if LWS CRDs are installed in the cluster
	Enabled bool
}

type KaiSchedulerConfig struct {
	// Enabled is automatically determined by checking if Kai-scheduler CRDs are installed in the cluster
	Enabled bool
}

type MpiRunConfig struct {
	// SecretName is the name of the secret containing the SSH key for MPI Run
	SecretName string
}

type Config struct {
	// Enable resources filtering, only the resources belonging to the given namespace will be handled.
	RestrictedNamespace string
	Grove               GroveConfig
	LWS                 LWSConfig
	KaiScheduler        KaiSchedulerConfig
	EtcdAddress         string
	NatsAddress         string
	IngressConfig       IngressConfig
	// ModelExpressURL is the URL of the Model Express server to inject into all pods
	ModelExpressURL string
	// PrometheusEndpoint is the URL of the Prometheus endpoint to use for metrics
	PrometheusEndpoint string
	MpiRun             MpiRunConfig
	// RBAC configuration for cross-namespace resource management
	RBAC RBACConfig
	// ExcludedNamespaces is a thread-safe set of namespaces to exclude (cluster-wide mode only)
	ExcludedNamespaces ExcludedNamespacesInterface
}

// RBACConfig holds configuration for RBAC management
type RBACConfig struct {
	// PlannerClusterRoleName is the name of the ClusterRole for planner (cluster-wide mode only)
	PlannerClusterRoleName string
	// DGDRProfilingClusterRoleName is the name of the ClusterRole for DGDR profiling jobs (cluster-wide mode only)
	DGDRProfilingClusterRoleName string
}

type IngressConfig struct {
	VirtualServiceGateway      string
	IngressControllerClassName string
	IngressControllerTLSSecret string
	IngressHostSuffix          string
}

func (i *IngressConfig) UseVirtualService() bool {
	return i.VirtualServiceGateway != ""
}

// DetectGroveAvailability checks if Grove is available by checking if the Grove API group is registered
// This approach uses the discovery client which is simpler and more reliable
func DetectGroveAvailability(ctx context.Context, mgr ctrl.Manager) bool {
	return detectAPIGroupAvailability(ctx, mgr, "grove.io")
}

// DetectLWSAvailability checks if LWS is available by checking if the LWS API group is registered
// This approach uses the discovery client which is simpler and more reliable
func DetectLWSAvailability(ctx context.Context, mgr ctrl.Manager) bool {
	return detectAPIGroupAvailability(ctx, mgr, "leaderworkerset.x-k8s.io")
}

// detectVolcanoAvailability checks if Volcano is available by checking if the Volcano API group is registered
// This approach uses the discovery client which is simpler and more reliable
func DetectVolcanoAvailability(ctx context.Context, mgr ctrl.Manager) bool {
	return detectAPIGroupAvailability(ctx, mgr, "scheduling.volcano.sh")
}

// DetectKaiSchedulerAvailability checks if Kai-scheduler is available by checking if the scheduling.run.ai API group is registered
// This approach uses the discovery client which is simpler and more reliable
func DetectKaiSchedulerAvailability(ctx context.Context, mgr ctrl.Manager) bool {
	return detectAPIGroupAvailability(ctx, mgr, "scheduling.run.ai")
}

// detectAPIGroupAvailability checks if a specific API group is registered in the cluster
func detectAPIGroupAvailability(ctx context.Context, mgr ctrl.Manager, groupName string) bool {
	logger := log.FromContext(ctx)

	cfg := mgr.GetConfig()
	if cfg == nil {
		logger.Info("detection failed, no discovery client available", "group", groupName)
		return false
	}

	discoveryClient, err := discovery.NewDiscoveryClientForConfig(cfg)
	if err != nil {
		logger.Error(err, "detection failed, could not create discovery client", "group", groupName)
		return false
	}

	apiGroups, err := discoveryClient.ServerGroups()
	if err != nil {
		logger.Error(err, "detection failed, could not list server groups", "group", groupName)
		return false
	}

	for _, group := range apiGroups.Groups {
		if group.Name == groupName {
			logger.Info("API group is available", "group", groupName)
			return true
		}
	}

	logger.Info("API group not available", "group", groupName)
	return false
}

func EphemeralDeploymentEventFilter(config Config) predicate.Predicate {
	return predicate.NewPredicateFuncs(func(o client.Object) bool {
		l := log.FromContext(context.Background())
		objMeta, err := meta.Accessor(o)
		if err != nil {
			l.Error(err, "Error extracting object metadata")
			return false
		}
		if config.RestrictedNamespace != "" {
			// in case of a restricted namespace, we only want to process the events that are in the restricted namespace
			return objMeta.GetNamespace() == config.RestrictedNamespace
		}

		// Cluster-wide mode: check if namespace is excluded
		if config.ExcludedNamespaces != nil && config.ExcludedNamespaces.Contains(objMeta.GetNamespace()) {
			l.V(1).Info("Skipping resource - namespace is excluded",
				"namespace", objMeta.GetNamespace(),
				"resource", objMeta.GetName(),
				"kind", o.GetObjectKind().GroupVersionKind().Kind)
			return false
		}

		// in all other cases, discard the event if it is destined to an ephemeral deployment
		if strings.Contains(objMeta.GetNamespace(), "ephemeral") {
			return false
		}
		return true
	})
}
