// Package runtimeinfo implements the private runtime version state used by the
// public buildinfo facade.
package runtimeinfo

import (
	"runtime/debug"
	"sync"
)

var injectedVersion string

// Version returns the injected version or the running executable's main module
// version, falling back to "dev" when neither provides a release identifier.
func Version() string {
	if injectedVersion != "" {
		return injectedVersion
	}
	return fallbackVersion()
}

var fallbackVersion = newFallbackVersion(debug.ReadBuildInfo)

func newFallbackVersion(readBuildInfo func() (*debug.BuildInfo, bool)) func() string {
	return sync.OnceValue(func() string { return version("", readBuildInfo) })
}

func version(injected string, readBuildInfo func() (*debug.BuildInfo, bool)) string {
	if injected != "" {
		return injected
	}

	info, ok := readBuildInfo()
	if ok && info != nil && info.Main.Version != "" && info.Main.Version != "(devel)" {
		return info.Main.Version
	}

	return "dev"
}