package briefversion

import (
    "log"
    "runtime/debug"
    "time"

    "pkg.jfrech.com/brief/internal/crumbs"
)

// Does NOT add a "brief " or "Brief " prefix.
//
// Used in "brief version".
func Version() string {
    if version == "" || version[0] != 'v' {
        return "vQ"
    }

    return version
}

// Used in internal/manpages.
func VersionDate() time.Time {
    if versionDate.IsZero() {
        return time.Time{}
    }

    return versionDate
}

var (
    version string
    versionDate time.Time
)

func init() {
    // Cf. https://pkg.go.dev/runtime/debug@go1.21.5#BuildSetting [accessed 2023-12-11]
    const (
        vcsRevision = "vcs.revision"
        vcsModified = "vcs.modified"
        vcsTime = "vcs.time"
        vcsTimeLayout = time.RFC3339
    )

    take := crumbs.StringTake

    info, ok := debug.ReadBuildInfo()
    if !ok {
        log.Printf("warning: Brief built without build info") // [2024-01-01, jfrech] TODO consider
        return
    }

    h := make(map[string]string)
    for _, kv := range info.Settings {
        h[kv.Key] += kv.Value
    }

    version = info.Main.Version
    if version == "(devel)" {
        version = "v" + take(8, h[vcsRevision])
        if h[vcsModified] != "false" {
            version += "*"
        }
    }

    if t, err := time.Parse(vcsTimeLayout, h[vcsTime]); err == nil && !t.IsZero() {
        if loc, err := time.LoadLocation("Europe/Berlin"); err == nil {
            t = t.In(loc)
        } else if true {
            t = t.In(time.FixedZone("CET", +01*60*60))
        }

        versionDate = t
    }
}

func XMailer() string {
    return "Brief " + Version() + " (https://brief.software.jfrech.com/)"
}