package resourcehelper

import (
	"fmt"
	"strings"

	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/util/validation"
)

// This code is directly lifted from the Kubernetes codebase in order to avoid relying on the k8s.io/kubernetes package.
// For reference: https://github.com/kubernetes/kubernetes/blob/release-1.22/pkg/apis/core/v1/helper/helpers.go,
// https://github.com/kubernetes/kubernetes/blob/release-1.22/pkg/scheduler/util/utils.go#L144

// IsExtendedResourceName returns true if:
// 1. the resource name is not in the default namespace;
// 2. resource name does not have "requests." prefix,
// to avoid confusion with the convention in quota
// 3. it satisfies the rules in IsQualifiedName() after converted into quota resource name
func IsExtendedResourceName(name corev1.ResourceName) bool {
	if IsNativeResource(name) || strings.HasPrefix(string(name), corev1.DefaultResourceRequestsPrefix) {
		return false
	}
	// Ensure it satisfies the rules in IsQualifiedName() after converted into quota resource name
	nameForQuota := fmt.Sprintf("%s%s", corev1.DefaultResourceRequestsPrefix, string(name))
	if errs := validation.IsQualifiedName(string(nameForQuota)); len(errs) != 0 {
		return false
	}
	return true
}

// IsPrefixedNativeResource returns true if the resource name is in the
// *kubernetes.io/ namespace.
func IsPrefixedNativeResource(name corev1.ResourceName) bool {
	return strings.Contains(string(name), corev1.ResourceDefaultNamespacePrefix)
}

// IsNativeResource returns true if the resource name is in the
// *kubernetes.io/ namespace. Partially-qualified (unprefixed) names are
// implicitly in the kubernetes.io/ namespace.
func IsNativeResource(name corev1.ResourceName) bool {
	return !strings.Contains(string(name), "/") ||
		IsPrefixedNativeResource(name)
}

// IsHugePageResourceName returns true if the resource name has the huge page
// resource prefix.
func IsHugePageResourceName(name corev1.ResourceName) bool {
	return strings.HasPrefix(string(name), corev1.ResourceHugePagesPrefix)
}

// IsAttachableVolumeResourceName returns true when the resource name is prefixed in attachable volume
func IsAttachableVolumeResourceName(name corev1.ResourceName) bool {
	return strings.HasPrefix(string(name), corev1.ResourceAttachableVolumesPrefix)
}

// IsScalarResourceName validates the resource for Extended, Hugepages, Native and AttachableVolume resources
func IsScalarResourceName(name corev1.ResourceName) bool {
	return IsExtendedResourceName(name) || IsHugePageResourceName(name) ||
		IsPrefixedNativeResource(name) || IsAttachableVolumeResourceName(name)
}