From 14e1d2cc61348fb419e56b57ef11ffc244ce7d94 Mon Sep 17 00:00:00 2001
From: Lea Anthony <lea.anthony@gmail.com>
Date: Thu, 27 Oct 2022 05:55:37 +1100
Subject: [PATCH] Support `Addflags`

---
 cli.go      |  6 +++++-
 cli_test.go | 33 +++++++++++++++++++++++++++++++++
 command.go  | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 75 insertions(+), 1 deletion(-)

diff --git a/cli.go b/cli.go
index 4afd5df..ec0959f 100755
--- a/cli.go
+++ b/cli.go
@@ -47,7 +47,6 @@ func (c *Cli) SetErrorFunction(fn func(string, error) error) {
 // Abort - Prints the given error and terminates the application.
 func (c *Cli) Abort(err error) {
 	log.Fatal(err)
-	os.Exit(1)
 }
 
 // AddCommand - Adds a command to the application.
@@ -120,6 +119,11 @@ func (c *Cli) IntFlag(name, description string, variable *int) *Cli {
 	return c
 }
 
+func (c *Cli) AddFlags(flags interface{}) *Cli {
+	c.rootCommand.AddFlags(flags)
+	return c
+}
+
 // Action - Define an action from this command.
 func (c *Cli) Action(callback Action) *Cli {
 	c.rootCommand.Action(callback)
diff --git a/cli_test.go b/cli_test.go
index 63f77ea..38b1962 100644
--- a/cli_test.go
+++ b/cli_test.go
@@ -72,3 +72,36 @@ func TestCli(t *testing.T) {
 		c.LongDescription("long description")
 	})
 }
+
+type testStruct struct {
+	Mode string `name:"mode" description:"The mode of build"`
+}
+
+func TestCli_AddFlags(t *testing.T) {
+	c := NewCli("test", "description", "0")
+
+	ts := &testStruct{}
+	c.AddFlags(ts)
+
+	modeFlag := c.rootCommand.flags.Lookup("mode")
+	if modeFlag == nil {
+		t.Errorf("expected flag mode to be added")
+	}
+	if modeFlag.Name != "mode" {
+		t.Errorf("expected flag name to be added")
+	}
+	if modeFlag.Usage != "The mode of build" {
+		t.Errorf("expected flag description to be added")
+	}
+
+	c.Action(func() error {
+		if ts.Mode != "123" {
+			t.Errorf("expected flag value to be set")
+		}
+		return nil
+	})
+	e := c.Run("-mode", "123")
+	if e != nil {
+		t.Errorf("expected no error, got %v", e)
+	}
+}
diff --git a/command.go b/command.go
index 987aa39..ff81e01 100644
--- a/command.go
+++ b/command.go
@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"reflect"
 	"strings"
 )
 
@@ -221,6 +222,42 @@ func (c *Command) BoolFlag(name, description string, variable *bool) *Command {
 	return c
 }
 
+func (c *Command) AddFlags(optionStruct interface{}) *Command {
+	// use reflection to determine if this is a pointer to a struct
+	// if not, panic
+
+	t := reflect.TypeOf(optionStruct)
+	if t.Kind() != reflect.Ptr {
+		panic("AddFlags requires a pointer to a struct")
+	}
+
+	// Iterate through the fields of the struct reading the struct tags
+	// and adding the flags
+	v := reflect.ValueOf(optionStruct).Elem()
+	for i := 0; i < v.NumField(); i++ {
+		field := v.Field(i)
+		tag := t.Elem().Field(i).Tag
+		name := tag.Get("name")
+		description := tag.Get("description")
+		if name == "" {
+			name = strings.ToLower(t.Elem().Field(i).Name)
+		}
+		if description == "" {
+			description = "No description"
+		}
+		switch field.Kind() {
+		case reflect.Bool:
+			c.BoolFlag(name, description, field.Addr().Interface().(*bool))
+		case reflect.String:
+			c.StringFlag(name, description, field.Addr().Interface().(*string))
+		case reflect.Int:
+			c.IntFlag(name, description, field.Addr().Interface().(*int))
+		}
+	}
+
+	return c
+}
+
 // StringFlag - Adds a string flag to the command
 func (c *Command) StringFlag(name, description string, variable *string) *Command {
 	c.flags.StringVar(variable, name, *variable, description)