feat: add amend functionality to commit command (#35)

- Add a `--amend` boolean flag to `commitCmd` in `cmd/commit.go`
- Add an `--amend` boolean flag to `Command` in `git/git.go`
- Add `WithEnableAmend` option to `WithAmend` in `git/options.go`

fix #32

Author: appleboy

cmd/commit.go

@@ -28,6 +28,7 @@ var (
 	socksProxy     string
 	templateFile   string
 	templateString string
+	commitAmend    bool
 )
 
 func init() {
@@ -41,6 +42,7 @@ func init() {
 	commitCmd.PersistentFlags().StringVar(&socksProxy, "socks", "", "socks proxy")
 	commitCmd.PersistentFlags().StringVar(&templateFile, "template_file", "", "git commit message file")
 	commitCmd.PersistentFlags().StringVar(&templateString, "template_string", "", "git commit message string")
+	commitCmd.PersistentFlags().BoolVar(&commitAmend, "amend", false, "replace the tip of the current branch by creating a new commit.")
 	_ = viper.BindPFlag("output.file", commitCmd.PersistentFlags().Lookup("file"))
 }
 
@@ -78,6 +80,7 @@ var commitCmd = &cobra.Command{
 		g := git.New(
 			git.WithDiffUnified(viper.GetInt("git.diff_unified")),
 			git.WithExcludeList(viper.GetStringSlice("git.exclude_list")),
+			git.WithEnableAmend(commitAmend),
 		)
 		diff, err := g.DiffFiles()
 		if err != nil {

git/git.go

@@ -25,6 +25,7 @@ type Command struct {
 	// Generate diffs with <n> lines of context instead of the usual three
 	diffUnified int
 	excludeList []string
+	isAmend     bool
 }
 
 func (c *Command) excludeFiles() []string {
@@ -39,10 +40,15 @@ func (c *Command) excludeFiles() []string {
 func (c *Command) diffNames() *exec.Cmd {
 	args := []string{
 		"diff",
-		"--staged",
 		"--name-only",
 	}
 
+	if c.isAmend {
+		args = append(args, "HEAD^", "HEAD")
+	} else {
+		args = append(args, "--staged")
+	}
+
 	args = append(args, c.excludeFiles()...)
 
 	return exec.Command(
@@ -54,12 +60,17 @@ func (c *Command) diffNames() *exec.Cmd {
 func (c *Command) diffFiles() *exec.Cmd {
 	args := []string{
 		"diff",
-		"--staged",
 		"--ignore-all-space",
 		"--diff-algorithm=minimal",
 		"--unified=" + strconv.Itoa(c.diffUnified),
 	}
 
+	if c.isAmend {
+		args = append(args, "HEAD^", "HEAD")
+	} else {
+		args = append(args, "--staged")
+	}
+
 	args = append(args, c.excludeFiles()...)
 
 	return exec.Command(
@@ -89,6 +100,10 @@ func (c *Command) commit(val string) *exec.Cmd {
 		fmt.Sprintf("--message=%s", val),
 	}
 
+	if c.isAmend {
+		args = append(args, "--amend")
+	}
+
 	return exec.Command(
 		"git",
 		args...,
@@ -168,5 +183,6 @@ func New(opts ...Option) *Command {
 	return &Command{
 		diffUnified: cfg.diffUnified,
 		excludeList: append(excludeFromDiff, cfg.excludeList...),
+		isAmend:     cfg.isAmend,
 	}
 }

git/options.go

@@ -35,8 +35,15 @@ func WithExcludeList(val []string) Option {
 	})
 }
 
+func WithEnableAmend(val bool) Option {
+	return optionFunc(func(c *config) {
+		c.isAmend = val
+	})
+}
+
 // config is a struct that stores configuration options for the instrumentation.
 type config struct {
 	diffUnified int
 	excludeList []string
+	isAmend     bool
 }