package version

import (
	"strconv"
	"strings"
)

// Version and Commit are injected separately at link time via -ldflags (see Makefile / Dockerfile).
// Version is the exact git tag on HEAD (empty if untagged). Commit is the short git hash (empty if unavailable).
var (
	Version = ""
	Commit  = ""
)

func resolve() string {
	if isSemverTag(Version) {
		return Version
	}
	if Commit != "" {
		return Commit
	}
	return "dev"
}

func String() string {
	return resolve()
}

func Display() string {
	return resolve()
}

// isSemverTag reports whether tag looks like semver (optional "v" + major.minor.patch, pre-release suffix allowed).
func isSemverTag(tag string) bool {
	if tag == "" {
		return false
	}
	core := tag
	if i := strings.IndexAny(core, "-+"); i >= 0 {
		core = core[:i]
	}
	core = strings.TrimPrefix(core, "v")
	parts := strings.Split(core, ".")
	if len(parts) != 3 {
		return false
	}
	for _, p := range parts {
		if p == "" {
			return false
		}
		for _, c := range p {
			if c < '0' || c > '9' {
				return false
			}
		}
	}
	return true
}

// Parts splits the git tag (Version) into major/minor/revision for NPM-style API responses.
// Returns zeros when there is no semver tag (commit-only or dev builds).
func Parts() (major, minor, revision int) {
	if !isSemverTag(Version) {
		return 0, 0, 0
	}
	core := Version
	if i := strings.IndexAny(core, "-+"); i >= 0 {
		core = core[:i]
	}
	core = strings.TrimPrefix(core, "v")
	parts := strings.Split(core, ".")
	if len(parts) != 3 {
		return 0, 0, 0
	}
	major, err0 := strconv.Atoi(parts[0])
	minor, err1 := strconv.Atoi(parts[1])
	revision, err2 := strconv.Atoi(parts[2])
	if err0 != nil || err1 != nil || err2 != nil {
		return 0, 0, 0
	}
	return major, minor, revision
}