/*
 * 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 validation

import (
	"errors"
	"fmt"

	nvidiacomv1alpha1 "github.com/ai-dynamo/dynamo/deploy/cloud/operator/api/v1alpha1"
	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
)

// DynamoGraphDeploymentValidator validates DynamoGraphDeployment resources.
// This validator can be used by both webhooks and controllers for consistent validation.
type DynamoGraphDeploymentValidator struct {
	deployment *nvidiacomv1alpha1.DynamoGraphDeployment
}

// NewDynamoGraphDeploymentValidator creates a new validator for DynamoGraphDeployment.
func NewDynamoGraphDeploymentValidator(deployment *nvidiacomv1alpha1.DynamoGraphDeployment) *DynamoGraphDeploymentValidator {
	return &DynamoGraphDeploymentValidator{
		deployment: deployment,
	}
}

// Validate performs stateless validation on the DynamoGraphDeployment.
// Returns warnings and error.
func (v *DynamoGraphDeploymentValidator) Validate() (admission.Warnings, error) {
	// Validate that at least one service is specified
	if len(v.deployment.Spec.Services) == 0 {
		return nil, fmt.Errorf("spec.services must have at least one service")
	}

	// Validate PVCs
	if err := v.validatePVCs(); err != nil {
		return nil, err
	}

	// Validate each service
	for serviceName, service := range v.deployment.Spec.Services {
		if err := v.validateService(serviceName, service); err != nil {
			return nil, err
		}
	}

	return nil, nil
}

// ValidateUpdate performs stateful validation comparing old and new DynamoGraphDeployment.
// Returns warnings and error.
func (v *DynamoGraphDeploymentValidator) ValidateUpdate(old *nvidiacomv1alpha1.DynamoGraphDeployment) (admission.Warnings, error) {
	// Validate that BackendFramework is not changed (immutable)
	if v.deployment.Spec.BackendFramework != old.Spec.BackendFramework {
		warning := "Changing spec.backendFramework may cause unexpected behavior"
		return admission.Warnings{warning}, fmt.Errorf("spec.backendFramework is immutable and cannot be changed after creation")
	}

	return nil, nil
}

// validateService validates a single service configuration using SharedSpecValidator.
func (v *DynamoGraphDeploymentValidator) validateService(serviceName string, service *nvidiacomv1alpha1.DynamoComponentDeploymentSharedSpec) error {
	// Use SharedSpecValidator to validate service spec (which is a DynamoComponentDeploymentSharedSpec)
	fieldPath := fmt.Sprintf("spec.services[%s]", serviceName)
	sharedValidator := NewSharedSpecValidator(service, fieldPath)
	return sharedValidator.Validate()
}

// validatePVCs validates the PVC configurations.
func (v *DynamoGraphDeploymentValidator) validatePVCs() error {
	for i, pvc := range v.deployment.Spec.PVCs {
		if err := v.validatePVC(i, &pvc); err != nil {
			return err
		}
	}
	return nil
}

// validatePVC validates a single PVC configuration.
func (v *DynamoGraphDeploymentValidator) validatePVC(index int, pvc *nvidiacomv1alpha1.PVC) error {
	var err error

	// Validate name is not nil
	if pvc.Name == nil || *pvc.Name == "" {
		err = errors.Join(err, fmt.Errorf("spec.pvcs[%d].name is required", index))
	}

	// Check if create is true
	if pvc.Create != nil && *pvc.Create {
		// Validate required fields when create is true
		if pvc.StorageClass == "" {
			err = errors.Join(err, fmt.Errorf("spec.pvcs[%d].storageClass is required when create is true", index))
		}

		if pvc.Size.IsZero() {
			err = errors.Join(err, fmt.Errorf("spec.pvcs[%d].size is required when create is true", index))
		}

		if pvc.VolumeAccessMode == "" {
			err = errors.Join(err, fmt.Errorf("spec.pvcs[%d].volumeAccessMode is required when create is true", index))
		}
	}

	return err
}