version.go

package walletmain

import (
	"bytes"
	"fmt"
	"strings"
)

const (
	// semanticAlphabet
	semanticAlphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-"
	// These constants define the application version and follow the semantic versioning 2.0.0 spec
	// (http://semver.org/).
	appMajor uint = 0
	appMinor uint = 8
	appPatch uint = 0
	// appPreRelease MUST only contain characters from semanticAlphabet per the semantic versioning spec.
	appPreRelease = "beta"
)

// appBuild is defined as a variable so it can be overridden during the build process with '-ldflags "-X main.appBuild
// foo' if needed. It MUST only contain characters from semanticAlphabet per the semantic versioning spec.
var appBuild string

// Version returns the application version as a properly formed string per the semantic versioning 2.0.0 spec
// (http://semver.org/).
func Version() string {
	// Start with the major, minor, and path versions.
	version := fmt.Sprintf("%d.%d.%d", appMajor, appMinor, appPatch)
	// Append pre-release version if there is one. The hyphen called for by the semantic versioning spec is
	// automatically appended and should not be contained in the pre-release string. The pre-release version is not
	// appended if it contains invalid characters.
	preRelease := normalizeVerString(appPreRelease)
	if preRelease != "" {
		version = fmt.Sprintf("%s-%s", version, preRelease)
	}
	// Append build metadata if there is any. The plus called for by the semantic versioning spec is automatically
	// appended and should not be contained in the build metadata string. The build metadata string is not appended if
	// it contains invalid characters.
	build := normalizeVerString(appBuild)
	if build != "" {
		version = fmt.Sprintf("%s+%s", version, build)
	}
	return version
}

// normalizeVerString returns the passed string stripped of all characters which are not valid according to the semantic
// versioning guidelines for pre-release version and build metadata strings. In particular they MUST only contain
// characters in semanticAlphabet.
func normalizeVerString(str string) string {
	result := bytes.Buffer{}
	for _, r := range str {
		if strings.ContainsRune(semanticAlphabet, r) {
			_, err := result.WriteRune(r)
			// Writing to a bytes.Buffer panics on OOM, and all errors are unexpected.
			if err != nil {
				Error(err)
				panic(err)
			}
		}
	}
	return result.String()
}