package class

import (
	"fmt"
	"strings"

	corev1 "k8s.io/api/core/v1"
)

const (
	// DeviceClassPrefix is the label prefix for classed devices (grouped)
	DeviceClassPrefix = "device-system.class.edge.ncr.com"
	// deviceClassFmt is formatted string to device-system.class.edge.ncr.com/<class-name>
	deviceClassFmt = "%s/%s"
)

// DefaultClass is default set of devices required by containers
var DefaultClass = FmtClassLabel("default")

// formats label for devices based on grouped classes
func FmtClassLabel(name string) string {
	return fmt.Sprintf(deviceClassFmt, DeviceClassPrefix, name)
}

// IsDeviceClass returns true if the request name is
// of a Edge managed device
func IsDeviceClass(className string) bool {
	return strings.Contains(className, DeviceClassPrefix)
}

// BaseName returns the class name without the device class prefix
func BaseName(className string) (string, error) {
	if !IsDeviceClass(className) {
		return "", fmt.Errorf("%s is not a device class with prefix %s", className, DeviceClassPrefix)
	}
	classSplit := strings.Split(className, "/")
	if len(classSplit) != 2 {
		return "", fmt.Errorf("%s is an invalid class name", className)
	}
	return classSplit[1], nil
}

// FetchPodDeviceRequests returns a list of device classes
// that a pod requests within its list of containers
func FetchPodDeviceRequests(ctrs []corev1.Container) []string {
	requests := []string{}
	for _, ctr := range ctrs {
		for reqName := range ctr.Resources.Requests {
			if IsDeviceClass(reqName.String()) {
				requests = append(requests, reqName.String())
			}
		}
	}
	return requests
}