// Package version reports which commit the binary was built from. Docker
// builds stamp it via -ldflags (the build context has no .git, so Go's
// automatic VCS stamp is absent there); host builds fall back to that
// automatic stamp.
package version

import "runtime/debug"

// Commit is set at link time via
// -ldflags "-X <module>/internal/version.Commit=<hash>".
var Commit string

// Resolve returns the commit the binary was built from, or "unknown" when
// neither the ldflags stamp nor build info is available (e.g. go test).
func Resolve() string {
	return resolve(Commit, debug.ReadBuildInfo)
}

func resolve(ldflagsCommit string, readBuildInfo func() (*debug.BuildInfo, bool)) string {
	if ldflagsCommit != "" {
		return ldflagsCommit
	}
	bi, ok := readBuildInfo()
	if !ok {
		return "unknown"
	}
	var revision string
	var modified bool
	for _, s := range bi.Settings {
		switch s.Key {
		case "vcs.revision":
			revision = s.Value
		case "vcs.modified":
			modified = s.Value == "true"
		}
	}
	if revision == "" {
		return "unknown"
	}
	if len(revision) > 12 {
		revision = revision[:12]
	}
	if modified {
		revision += "-dirty"
	}
	return revision
}