main: switch to urfave/cli/v2

For now this is a drop in replacement for all the flags curently
implemented

Fixes: #171

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

vendor/github.com/urfave/cli/v2/flag.go

@@ -0,0 +1,444 @@
+package cli
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"reflect"
+	"regexp"
+	"runtime"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+)
+
+const defaultPlaceholder = "value"
+
+var (
+	slPfx = fmt.Sprintf("sl:::%d:::", time.Now().UTC().UnixNano())
+
+	commaWhitespace = regexp.MustCompile("[, ]+.*")
+)
+
+// BashCompletionFlag enables bash-completion for all commands and subcommands
+var BashCompletionFlag Flag = &BoolFlag{
+	Name:   "generate-bash-completion",
+	Hidden: true,
+}
+
+// VersionFlag prints the version for the application
+var VersionFlag Flag = &BoolFlag{
+	Name:    "version",
+	Aliases: []string{"v"},
+	Usage:   "print the version",
+}
+
+// HelpFlag prints the help for all commands and subcommands.
+// Set to nil to disable the flag.  The subcommand
+// will still be added unless HideHelp or HideHelpCommand is set to true.
+var HelpFlag Flag = &BoolFlag{
+	Name:    "help",
+	Aliases: []string{"h"},
+	Usage:   "show help",
+}
+
+// FlagStringer converts a flag definition to a string. This is used by help
+// to display a flag.
+var FlagStringer FlagStringFunc = stringifyFlag
+
+// Serializer is used to circumvent the limitations of flag.FlagSet.Set
+type Serializer interface {
+	Serialize() string
+}
+
+// FlagNamePrefixer converts a full flag name and its placeholder into the help
+// message flag prefix. This is used by the default FlagStringer.
+var FlagNamePrefixer FlagNamePrefixFunc = prefixedNames
+
+// FlagEnvHinter annotates flag help message with the environment variable
+// details. This is used by the default FlagStringer.
+var FlagEnvHinter FlagEnvHintFunc = withEnvHint
+
+// FlagFileHinter annotates flag help message with the environment variable
+// details. This is used by the default FlagStringer.
+var FlagFileHinter FlagFileHintFunc = withFileHint
+
+// FlagsByName is a slice of Flag.
+type FlagsByName []Flag
+
+func (f FlagsByName) Len() int {
+	return len(f)
+}
+
+func (f FlagsByName) Less(i, j int) bool {
+	if len(f[j].Names()) == 0 {
+		return false
+	} else if len(f[i].Names()) == 0 {
+		return true
+	}
+	return lexicographicLess(f[i].Names()[0], f[j].Names()[0])
+}
+
+func (f FlagsByName) Swap(i, j int) {
+	f[i], f[j] = f[j], f[i]
+}
+
+// Flag is a common interface related to parsing flags in cli.
+// For more advanced flag parsing techniques, it is recommended that
+// this interface be implemented.
+type Flag interface {
+	fmt.Stringer
+	// Apply Flag settings to the given flag set
+	Apply(*flag.FlagSet) error
+	Names() []string
+	IsSet() bool
+}
+
+// RequiredFlag is an interface that allows us to mark flags as required
+// it allows flags required flags to be backwards compatible with the Flag interface
+type RequiredFlag interface {
+	Flag
+
+	IsRequired() bool
+}
+
+// DocGenerationFlag is an interface that allows documentation generation for the flag
+type DocGenerationFlag interface {
+	Flag
+
+	// TakesValue returns true if the flag takes a value, otherwise false
+	TakesValue() bool
+
+	// GetUsage returns the usage string for the flag
+	GetUsage() string
+
+	// GetValue returns the flags value as string representation and an empty
+	// string if the flag takes no value at all.
+	GetValue() string
+}
+
+// VisibleFlag is an interface that allows to check if a flag is visible
+type VisibleFlag interface {
+	Flag
+
+	// IsVisible returns true if the flag is not hidden, otherwise false
+	IsVisible() bool
+}
+
+func flagSet(name string, flags []Flag) (*flag.FlagSet, error) {
+	set := flag.NewFlagSet(name, flag.ContinueOnError)
+
+	for _, f := range flags {
+		if err := f.Apply(set); err != nil {
+			return nil, err
+		}
+	}
+	set.SetOutput(ioutil.Discard)
+	return set, nil
+}
+
+func copyFlag(name string, ff *flag.Flag, set *flag.FlagSet) {
+	switch ff.Value.(type) {
+	case Serializer:
+		_ = set.Set(name, ff.Value.(Serializer).Serialize())
+	default:
+		_ = set.Set(name, ff.Value.String())
+	}
+}
+
+func normalizeFlags(flags []Flag, set *flag.FlagSet) error {
+	visited := make(map[string]bool)
+	set.Visit(func(f *flag.Flag) {
+		visited[f.Name] = true
+	})
+	for _, f := range flags {
+		parts := f.Names()
+		if len(parts) == 1 {
+			continue
+		}
+		var ff *flag.Flag
+		for _, name := range parts {
+			name = strings.Trim(name, " ")
+			if visited[name] {
+				if ff != nil {
+					return errors.New("Cannot use two forms of the same flag: " + name + " " + ff.Name)
+				}
+				ff = set.Lookup(name)
+			}
+		}
+		if ff == nil {
+			continue
+		}
+		for _, name := range parts {
+			name = strings.Trim(name, " ")
+			if !visited[name] {
+				copyFlag(name, ff, set)
+			}
+		}
+	}
+	return nil
+}
+
+func visibleFlags(fl []Flag) []Flag {
+	var visible []Flag
+	for _, f := range fl {
+		if vf, ok := f.(VisibleFlag); ok && vf.IsVisible() {
+			visible = append(visible, f)
+		}
+	}
+	return visible
+}
+
+func prefixFor(name string) (prefix string) {
+	if len(name) == 1 {
+		prefix = "-"
+	} else {
+		prefix = "--"
+	}
+
+	return
+}
+
+// Returns the placeholder, if any, and the unquoted usage string.
+func unquoteUsage(usage string) (string, string) {
+	for i := 0; i < len(usage); i++ {
+		if usage[i] == '`' {
+			for j := i + 1; j < len(usage); j++ {
+				if usage[j] == '`' {
+					name := usage[i+1 : j]
+					usage = usage[:i] + name + usage[j+1:]
+					return name, usage
+				}
+			}
+			break
+		}
+	}
+	return "", usage
+}
+
+func prefixedNames(names []string, placeholder string) string {
+	var prefixed string
+	for i, name := range names {
+		if name == "" {
+			continue
+		}
+
+		prefixed += prefixFor(name) + name
+		if placeholder != "" {
+			prefixed += " " + placeholder
+		}
+		if i < len(names)-1 {
+			prefixed += ", "
+		}
+	}
+	return prefixed
+}
+
+func withEnvHint(envVars []string, str string) string {
+	envText := ""
+	if envVars != nil && len(envVars) > 0 {
+		prefix := "$"
+		suffix := ""
+		sep := ", $"
+		if runtime.GOOS == "windows" {
+			prefix = "%"
+			suffix = "%"
+			sep = "%, %"
+		}
+
+		envText = fmt.Sprintf(" [%s%s%s]", prefix, strings.Join(envVars, sep), suffix)
+	}
+	return str + envText
+}
+
+func flagNames(name string, aliases []string) []string {
+	var ret []string
+
+	for _, part := range append([]string{name}, aliases...) {
+		// v1 -> v2 migration warning zone:
+		// Strip off anything after the first found comma or space, which
+		// *hopefully* makes it a tiny bit more obvious that unexpected behavior is
+		// caused by using the v1 form of stringly typed "Name".
+		ret = append(ret, commaWhitespace.ReplaceAllString(part, ""))
+	}
+
+	return ret
+}
+
+func flagStringSliceField(f Flag, name string) []string {
+	fv := flagValue(f)
+	field := fv.FieldByName(name)
+
+	if field.IsValid() {
+		return field.Interface().([]string)
+	}
+
+	return []string{}
+}
+
+func withFileHint(filePath, str string) string {
+	fileText := ""
+	if filePath != "" {
+		fileText = fmt.Sprintf(" [%s]", filePath)
+	}
+	return str + fileText
+}
+
+func flagValue(f Flag) reflect.Value {
+	fv := reflect.ValueOf(f)
+	for fv.Kind() == reflect.Ptr {
+		fv = reflect.Indirect(fv)
+	}
+	return fv
+}
+
+func formatDefault(format string) string {
+	return " (default: " + format + ")"
+}
+
+func stringifyFlag(f Flag) string {
+	fv := flagValue(f)
+
+	switch f := f.(type) {
+	case *IntSliceFlag:
+		return withEnvHint(flagStringSliceField(f, "EnvVars"),
+			stringifyIntSliceFlag(f))
+	case *Int64SliceFlag:
+		return withEnvHint(flagStringSliceField(f, "EnvVars"),
+			stringifyInt64SliceFlag(f))
+	case *Float64SliceFlag:
+		return withEnvHint(flagStringSliceField(f, "EnvVars"),
+			stringifyFloat64SliceFlag(f))
+	case *StringSliceFlag:
+		return withEnvHint(flagStringSliceField(f, "EnvVars"),
+			stringifyStringSliceFlag(f))
+	}
+
+	placeholder, usage := unquoteUsage(fv.FieldByName("Usage").String())
+
+	needsPlaceholder := false
+	defaultValueString := ""
+	val := fv.FieldByName("Value")
+	if val.IsValid() {
+		needsPlaceholder = val.Kind() != reflect.Bool
+		defaultValueString = fmt.Sprintf(formatDefault("%v"), val.Interface())
+
+		if val.Kind() == reflect.String && val.String() != "" {
+			defaultValueString = fmt.Sprintf(formatDefault("%q"), val.String())
+		}
+	}
+
+	helpText := fv.FieldByName("DefaultText")
+	if helpText.IsValid() && helpText.String() != "" {
+		needsPlaceholder = val.Kind() != reflect.Bool
+		defaultValueString = fmt.Sprintf(formatDefault("%s"), helpText.String())
+	}
+
+	if defaultValueString == formatDefault("") {
+		defaultValueString = ""
+	}
+
+	if needsPlaceholder && placeholder == "" {
+		placeholder = defaultPlaceholder
+	}
+
+	usageWithDefault := strings.TrimSpace(usage + defaultValueString)
+
+	return withEnvHint(flagStringSliceField(f, "EnvVars"),
+		fmt.Sprintf("%s\t%s", prefixedNames(f.Names(), placeholder), usageWithDefault))
+}
+
+func stringifyIntSliceFlag(f *IntSliceFlag) string {
+	var defaultVals []string
+	if f.Value != nil && len(f.Value.Value()) > 0 {
+		for _, i := range f.Value.Value() {
+			defaultVals = append(defaultVals, strconv.Itoa(i))
+		}
+	}
+
+	return stringifySliceFlag(f.Usage, f.Names(), defaultVals)
+}
+
+func stringifyInt64SliceFlag(f *Int64SliceFlag) string {
+	var defaultVals []string
+	if f.Value != nil && len(f.Value.Value()) > 0 {
+		for _, i := range f.Value.Value() {
+			defaultVals = append(defaultVals, strconv.FormatInt(i, 10))
+		}
+	}
+
+	return stringifySliceFlag(f.Usage, f.Names(), defaultVals)
+}
+
+func stringifyFloat64SliceFlag(f *Float64SliceFlag) string {
+	var defaultVals []string
+
+	if f.Value != nil && len(f.Value.Value()) > 0 {
+		for _, i := range f.Value.Value() {
+			defaultVals = append(defaultVals, strings.TrimRight(strings.TrimRight(fmt.Sprintf("%f", i), "0"), "."))
+		}
+	}
+
+	return stringifySliceFlag(f.Usage, f.Names(), defaultVals)
+}
+
+func stringifyStringSliceFlag(f *StringSliceFlag) string {
+	var defaultVals []string
+	if f.Value != nil && len(f.Value.Value()) > 0 {
+		for _, s := range f.Value.Value() {
+			if len(s) > 0 {
+				defaultVals = append(defaultVals, strconv.Quote(s))
+			}
+		}
+	}
+
+	return stringifySliceFlag(f.Usage, f.Names(), defaultVals)
+}
+
+func stringifySliceFlag(usage string, names, defaultVals []string) string {
+	placeholder, usage := unquoteUsage(usage)
+	if placeholder == "" {
+		placeholder = defaultPlaceholder
+	}
+
+	defaultVal := ""
+	if len(defaultVals) > 0 {
+		defaultVal = fmt.Sprintf(formatDefault("%s"), strings.Join(defaultVals, ", "))
+	}
+
+	usageWithDefault := strings.TrimSpace(fmt.Sprintf("%s%s", usage, defaultVal))
+	multiInputString := "(accepts multiple inputs)"
+	if usageWithDefault != "" {
+		multiInputString = "\t" + multiInputString
+	}
+	return fmt.Sprintf("%s\t%s%s", prefixedNames(names, placeholder), usageWithDefault, multiInputString)
+}
+
+func hasFlag(flags []Flag, fl Flag) bool {
+	for _, existing := range flags {
+		if fl == existing {
+			return true
+		}
+	}
+
+	return false
+}
+
+func flagFromEnvOrFile(envVars []string, filePath string) (val string, ok bool) {
+	for _, envVar := range envVars {
+		envVar = strings.TrimSpace(envVar)
+		if val, ok := syscall.Getenv(envVar); ok {
+			return val, true
+		}
+	}
+	for _, fileVar := range strings.Split(filePath, ",") {
+		if fileVar != "" {
+			if data, err := ioutil.ReadFile(fileVar); err == nil {
+				return string(data), true
+			}
+		}
+	}
+	return "", false
+}