Flag support in kubectl plugins

pkg/kubectl/plugins/plugins.go

@@ -19,6 +19,15 @@ package plugins
 import (
 	"fmt"
 	"strings"
+	"unicode"
+)
+
+var (
+	IncompletePluginError     = fmt.Errorf("incomplete plugin descriptor: name, shortDesc and command fields are required")
+	InvalidPluginNameError    = fmt.Errorf("plugin name can't contain spaces")
+	IncompleteFlagError       = fmt.Errorf("incomplete flag descriptor: name and desc fields are required")
+	InvalidFlagNameError      = fmt.Errorf("flag name can't contain spaces")
+	InvalidFlagShorthandError = fmt.Errorf("flag shorthand must be only one letter")
 )
 
 // Plugin is the representation of a CLI extension (plugin).
@@ -31,12 +40,13 @@ type Plugin struct {
 // PluginDescription holds everything needed to register a
 // plugin as a command. Usually comes from a descriptor file.
 type Description struct {
-	Name      string    `json:"name"`
-	ShortDesc string    `json:"shortDesc"`
-	LongDesc  string    `json:"longDesc,omitempty"`
-	Example   string    `json:"example,omitempty"`
-	Command   string    `json:"command"`
-	Tree      []*Plugin `json:"tree,omitempty"`
+	Name      string  `json:"name"`
+	ShortDesc string  `json:"shortDesc"`
+	LongDesc  string  `json:"longDesc,omitempty"`
+	Example   string  `json:"example,omitempty"`
+	Command   string  `json:"command"`
+	Flags     []Flag  `json:"flags,omitempty"`
+	Tree      Plugins `json:"tree,omitempty"`
 }
 
 // PluginSource holds the location of a given plugin in the filesystem.
@@ -45,17 +55,17 @@ type Source struct {
 	DescriptorName string `json:"-"`
 }
 
-var (
-	IncompleteError  = fmt.Errorf("incomplete plugin descriptor: name, shortDesc and command fields are required")
-	InvalidNameError = fmt.Errorf("plugin name can't contain spaces")
-)
-
 func (p Plugin) Validate() error {
 	if len(p.Name) == 0 || len(p.ShortDesc) == 0 || (len(p.Command) == 0 && len(p.Tree) == 0) {
-		return IncompleteError
+		return IncompletePluginError
 	}
 	if strings.Index(p.Name, " ") > -1 {
-		return InvalidNameError
+		return InvalidPluginNameError
+	}
+	for _, flag := range p.Flags {
+		if err := flag.Validate(); err != nil {
+			return err
+		}
 	}
 	for _, child := range p.Tree {
 		if err := child.Validate(); err != nil {
@@ -71,3 +81,33 @@ func (p Plugin) IsValid() bool {
 
 // Plugins is a list of plugins.
 type Plugins []*Plugin
+
+// Flag describes a single flag supported by a given plugin.
+type Flag struct {
+	Name      string `json:"name"`
+	Shorthand string `json:"shorthand,omitempty"`
+	Desc      string `json:"desc"`
+	DefValue  string `json:"defValue,omitempty"`
+}
+
+func (f Flag) Validate() error {
+	if len(f.Name) == 0 || len(f.Desc) == 0 {
+		return IncompleteFlagError
+	}
+	if strings.Index(f.Name, " ") > -1 {
+		return InvalidFlagNameError
+	}
+	return f.ValidateShorthand()
+}
+
+func (f Flag) ValidateShorthand() error {
+	length := len(f.Shorthand)
+	if length == 0 || (length == 1 && unicode.IsLetter(rune(f.Shorthand[0]))) {
+		return nil
+	}
+	return InvalidFlagShorthandError
+}
+
+func (f Flag) Shorthanded() bool {
+	return f.ValidateShorthand() == nil
+}