// SPDX-License-Identifier: AGPL-3.0-only

package version

import (
	"regexp"
	"runtime/debug"
	"strings"
)

const developmentVersion = "v0.1.0-dev"

var (
	Version = developmentVersion
	Commit  = "unknown"
	Date    = "unknown"
)

var (
	taggedVersionPattern       = regexp.MustCompile(`^v(?:0|[1-9][0-9]*)\.(?:0|[1-9][0-9]*)\.(?:0|[1-9][0-9]*)(?:-([0-9A-Za-z-]+(?:\.[0-9A-Za-z-]+)*))?$`)
	pseudoVersionSuffixPattern = regexp.MustCompile(`(?:^|[.-])(?:0\.)?[0-9]{14}-[0-9a-f]{12,}$`)
)

func init() {
	information, ok := debug.ReadBuildInfo()
	if !ok {
		return
	}
	Version = selectVersion(Version, information.Main.Version)
	for _, setting := range information.Settings {
		switch setting.Key {
		case "vcs.revision":
			if Commit == "unknown" && setting.Value != "" {
				Commit = setting.Value
			}
		case "vcs.time":
			if Date == "unknown" && setting.Value != "" {
				Date = setting.Value
			}
		}
	}
}

func selectVersion(linkerValue, moduleVersion string) string {
	if linkerValue != developmentVersion {
		return linkerValue
	}
	moduleVersion = strings.TrimSpace(moduleVersion)
	if !isTaggedVersion(moduleVersion) {
		return linkerValue
	}
	return moduleVersion
}

func isTaggedVersion(value string) bool {
	matches := taggedVersionPattern.FindStringSubmatch(value)
	if matches == nil {
		return false
	}
	prerelease := matches[1]
	if pseudoVersionSuffixPattern.MatchString(prerelease) {
		return false
	}
	for _, identifier := range strings.Split(prerelease, ".") {
		if len(identifier) > 1 && identifier[0] == '0' && allDecimal(identifier) {
			return false
		}
	}
	return true
}

func allDecimal(value string) bool {
	if value == "" {
		return false
	}
	for _, character := range value {
		if character < '0' || character > '9' {
			return false
		}
	}
	return true
}