// Package controlname validates identifiers used as control-plane key segments.
package controlname

import (
	"regexp"
	"strings"
)

var (
	account = regexp.MustCompile(`^[a-z]{3,16}$`)
	app     = regexp.MustCompile(`^[a-z][a-z0-9-]{0,31}$`)
	label   = regexp.MustCompile(`^[a-z0-9]([a-z0-9-]{0,61}[a-z0-9])?$`)
)

func ValidAccount(s string) bool { return account.MatchString(s) }
func ValidApp(s string) bool     { return app.MatchString(s) }
func ValidLabel(s string) bool   { return label.MatchString(s) }
func ValidHostShape(host string) bool {
	if host == "" || len(host) > 253 {
		return false
	}
	for _, part := range strings.Split(host, ".") {
		if !ValidLabel(part) {
			return false
		}
	}
	return true
}