// Package version holds Jarl's version, set at build time with
//
//	go build -ldflags "-X jarl/internal/version.Version=1.2.3 -X jarl/internal/version.Tag=v1.2.3"
//
// The Makefile sets Version from the VERSION file, and Tag only when the
// build is of that release: HEAD is the tag v<VERSION> and no tracked file
// is changed. Other builds are identified by their commit, which Go
// records from git by itself.
package version

import (
	"runtime/debug"
	"sync"
)

// Version is the Jarl version (the VERSION file).
var Version = "0.1.0-dev"

// Tag is the release tag the build is of ("" when it isn't a release).
var Tag = ""

// Commit is the git commit the build is of. It is read from the build
// information when not set at build time.
var Commit = ""

// Repo is Jarl's source repository.
const Repo = "https://gitea.adbraun.lol/adam/jarl"

// Build describes what a binary was built from.
type Build struct {
	Version  string `json:"version"`
	Tag      string `json:"tag,omitempty"`
	Commit   string `json:"commit,omitempty"`
	Modified bool   `json:"modified,omitempty"` // built with uncommitted changes
	// Label is the short form to show: the tag of a release, otherwise
	// the abbreviated commit (or the version when the commit is unknown).
	Label string `json:"label"`
	// URL is the release or commit in the repository.
	URL string `json:"url"`
}

var info = sync.OnceValue(func() Build {
	commit, modified := Commit, false
	if bi, ok := debug.ReadBuildInfo(); ok {
		for _, s := range bi.Settings {
			switch s.Key {
			case "vcs.revision":
				if commit == "" {
					commit = s.Value
				}
			case "vcs.modified":
				modified = s.Value == "true"
			}
		}
	}
	return describe(Version, Tag, commit, modified)
})

func describe(version, tag, commit string, modified bool) Build {
	b := Build{Version: version, Tag: tag, Commit: commit, Modified: modified}
	switch {
	case tag != "":
		b.Modified = false // the Makefile only sets Tag for clean trees
		b.Label, b.URL = tag, Repo+"/releases/tag/"+tag
	case commit != "":
		b.Label, b.URL = short(commit), Repo+"/commit/"+commit
		if modified {
			b.Label += "-modified"
		}
	default:
		b.Label, b.URL = version, Repo
	}
	return b
}

// Info describes this build.
func Info() Build { return info() }

// String is the version for logs and 'version' commands: "0.2.0" for a
// release, otherwise the version and the commit ("0.2.0-dev (a1b2c3d4e5f6)").
func String() string {
	b := Info()
	if b.Tag != "" || b.Commit == "" {
		return b.Version
	}
	return b.Version + " (" + b.Label + ")"
}

func short(commit string) string {
	if len(commit) > 12 {
		return commit[:12]
	}
	return commit
}