[commithelper-go] Add support for custom commit message templates

.changeset/loud-breads-raise.md

@@ -0,0 +1,7 @@
+---
+"@naverpay/commithelper-go": minor
+---
+
+[commithelper-go] Add support for custom commit message templates
+
+PR: [[commithelper-go] Add support for custom commit message templates](https://github.com/NaverPayDev/cli/pull/50)

packages/commithelper-go/README.md

@@ -96,6 +96,73 @@ This is Basic rule of `.commithelperrc.json`.
 
 - Defines branch prefixes that are blocked from committing. `main`, `master`, `develop` branch is blocked by default.
 
+#### template
+
+- Defines a custom format for commit messages using Go template syntax.
+- If not specified, uses the default format: `[{{.Prefix}}] {{.Message}}`
+- Available template variables:
+  - `{{.Message}}`: Original commit message
+  - `{{.Number}}`: Issue number extracted from branch name
+  - `{{.Repo}}`: Repository name (empty string if not specified in rules)
+  - `{{.Prefix}}`: Full prefix (`#123` or `org/repo#123`)
+
+##### Template Examples
+
+**Example 1: Add issue reference at the end**
+
+```json
+{
+    "rules": {
+        "feature": null
+    },
+    "template": "{{.Message}}\n\nRef. #{{.Number}}"
+}
+```
+
+Result:
+
+```
+:memo: Update documentation
+
+Ref. #123
+```
+
+**Example 2: Custom format with repository**
+
+```json
+{
+    "rules": {
+        "qa": "your-org/your-repo"
+    },
+    "template": "{{.Message}}\n\nSee: {{.Prefix}}"
+}
+```
+
+Result:
+
+```
+:bug: Fix login bug
+
+See: your-org/your-repo#456
+```
+
+**Example 3: Conditional formatting**
+
+```json
+{
+    "rules": {
+        "feature": null
+    },
+    "template": "[{{.Prefix}}] {{.Message}}"
+}
+```
+
+Result:
+
+```
+[#123] :sparkles: Add new feature
+```
+
 ### Example
 
 ```json

packages/commithelper-go/main.go

@@ -1,18 +1,28 @@
 package main
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"regexp"
 	"strings"
+	"text/template"
 )
 
 type Config struct {
-	Rules   map[string]*string `json:"rules"`
-	Protect []string           `json:"protect"`
+	Rules    map[string]*string `json:"rules"`
+	Protect  []string           `json:"protect"`
+	Template *string            `json:"template,omitempty"`
+}
+
+type TemplateData struct {
+	Message string
+	Number  string
+	Repo    string
+	Prefix  string
 }
 
 func main() {
@@ -63,9 +73,9 @@ func main() {
 		os.Exit(1)
 	}
 
-	prefix := generatePrefix(branchName, config)
-	if prefix != "" {
-		commitMessage = fmt.Sprintf("[%s] %s", prefix, commitMessage)
+	templateData := generateTemplateData(branchName, config, commitMessage)
+	if templateData != nil {
+		commitMessage = applyTemplate(config, templateData)
 	}
 
 	if _, err := os.Stat(input); err == nil {
@@ -147,6 +157,63 @@ func generatePrefix(branchName string, config Config) string {
 	return fmt.Sprintf("%s#%s", *repo, issueNumber)
 }
 
+func generateTemplateData(branchName string, config Config, message string) *TemplateData {
+	pattern := regexp.MustCompile(`^(\w+)/(\d+).*`)
+	matches := pattern.FindStringSubmatch(branchName)
+	if len(matches) < 3 {
+		return nil
+	}
+
+	prefixKey := matches[1]
+	issueNumber := matches[2]
+
+	repo, exists := config.Rules[prefixKey]
+	if !exists {
+		return nil
+	}
+
+	var repoName string
+	var prefix string
+	if repo == nil {
+		repoName = ""
+		prefix = fmt.Sprintf("#%s", issueNumber)
+	} else {
+		repoName = *repo
+		prefix = fmt.Sprintf("%s#%s", *repo, issueNumber)
+	}
+
+	return &TemplateData{
+		Message: message,
+		Number:  issueNumber,
+		Repo:    repoName,
+		Prefix:  prefix,
+	}
+}
+
+func applyTemplate(config Config, data *TemplateData) string {
+	// If no template is configured, use default format
+	if config.Template == nil || *config.Template == "" {
+		return fmt.Sprintf("[%s] %s", data.Prefix, data.Message)
+	}
+
+	tmpl, err := template.New("commit").Parse(*config.Template)
+	if err != nil {
+		fmt.Printf("Error parsing template: %v\n", err)
+		// Fallback to default format
+		return fmt.Sprintf("[%s] %s", data.Prefix, data.Message)
+	}
+
+	var buf bytes.Buffer
+	err = tmpl.Execute(&buf, data)
+	if err != nil {
+		fmt.Printf("Error executing template: %v\n", err)
+		// Fallback to default format
+		return fmt.Sprintf("[%s] %s", data.Prefix, data.Message)
+	}
+
+	return buf.String()
+}
+
 func isProtectedBranch(branchName string, protectedBranches []string) bool {
 	for _, protected := range protectedBranches {
 		if branchName == protected {