generate falgs based on struct options instead of defining them externally

utils/flags.go

@@ -0,0 +1,122 @@
+package utils
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"reflect"
+	"strings"
+
+	"github.com/codegangsta/cli"
+	"github.com/fatih/structs"
+	"github.com/yudai/hcl"
+)
+
+func GenerateFlags(options ...interface{}) (flags []cli.Flag, mappings map[string]string, err error) {
+	mappings = make(map[string]string)
+
+	for _, struct_ := range options {
+		o := structs.New(struct_)
+		for _, field := range o.Fields() {
+			flagName := field.Tag("flagName")
+			if flagName == "" {
+				continue
+			}
+			envName := "GOTTY_" + strings.ToUpper(strings.Join(strings.Split(flagName, "-"), "_"))
+			mappings[flagName] = field.Name()
+
+			flagShortName := field.Tag("flagSName")
+			if flagShortName != "" {
+				flagName += ", " + flagShortName
+			}
+
+			flagDescription := field.Tag("flagDescribe")
+
+			switch field.Kind() {
+			case reflect.String:
+				flags = append(flags, cli.StringFlag{
+					Name:   flagName,
+					Value:  field.Value().(string),
+					Usage:  flagDescription,
+					EnvVar: envName,
+				})
+			case reflect.Bool:
+				flags = append(flags, cli.BoolFlag{
+					Name:   flagName,
+					Usage:  flagDescription,
+					EnvVar: envName,
+				})
+			case reflect.Int:
+				flags = append(flags, cli.IntFlag{
+					Name:   flagName,
+					Value:  field.Value().(int),
+					Usage:  flagDescription,
+					EnvVar: envName,
+				})
+			}
+		}
+	}
+
+	return
+}
+
+func ApplyFlags(
+	flags []cli.Flag,
+	mappingHint map[string]string,
+	c *cli.Context,
+	options ...interface{},
+) {
+	objects := make([]*structs.Struct, len(options))
+	for i, struct_ := range options {
+		objects[i] = structs.New(struct_)
+	}
+
+	for flagName, fieldName := range mappingHint {
+		if !c.IsSet(flagName) {
+			continue
+		}
+		var field *structs.Field
+		var ok bool
+		for _, o := range objects {
+			field, ok = o.FieldOk(fieldName)
+			if ok {
+				break
+			}
+		}
+		if field == nil {
+			continue
+		}
+		var val interface{}
+		switch field.Kind() {
+		case reflect.String:
+			val = c.String(flagName)
+		case reflect.Bool:
+			val = c.Bool(flagName)
+		case reflect.Int:
+			val = c.Int(flagName)
+		}
+		field.Set(val)
+	}
+}
+
+func ApplyConfigFile(filePath string, options ...interface{}) error {
+	filePath = ExpandHomeDir(filePath)
+	if _, err := os.Stat(filePath); os.IsNotExist(err) {
+		return err
+	}
+
+	fileString := []byte{}
+	log.Printf("Loading config file at: %s", filePath)
+	fileString, err := ioutil.ReadFile(filePath)
+	if err != nil {
+		return err
+	}
+
+	for _, object := range options {
+		if err := hcl.Decode(object, string(fileString)); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}