package datekeys

import (
	"reflect"
	"runtime/debug"
)

// SpecVersion is the version of the DateKeys Protocol Specification that this
// module implements: spec/DateKeys_Protocol_Specification_v0.11.md, tagged
// spec-v0.11 in its repository. It is neither the version of the module (see
// Version) nor the versions inside the objects: the capsule format, 1 to 3,
// and the schema versions (spec §22, §70).
const SpecVersion = "0.15"

// modulePath is the path of this module: the import path of its root
// package, whatever the module is called.
var modulePath = reflect.TypeFor[Error]().PkgPath()

// Version returns the version of this module in the running program, as the
// go command recorded it: a release tag such as v0.1.0; a pseudo-version,
// which names the commit, for a program built in a checkout of the module;
// or "(devel)" when it is unknown, as in tests or under a replace directive
// that points to a directory.
func Version() string {
	info, ok := debug.ReadBuildInfo()
	if !ok {
		return "(devel)"
	}
	return versionIn(info)
}

func versionIn(info *debug.BuildInfo) string {
	m := &info.Main
	if m.Path != modulePath {
		m = nil
		for _, d := range info.Deps {
			if d.Path == modulePath {
				m = d
				break
			}
		}
	}
	if m != nil && m.Replace != nil {
		m = m.Replace
	}
	if m == nil || m.Version == "" {
		return "(devel)"
	}
	return m.Version
}