refactor: move changelog file to updater interface (#15)

changelog.go

@@ -3,14 +3,8 @@ package rp
 import (
 	"bytes"
 	_ "embed"
-	"fmt"
 	"html/template"
-	"io"
 	"log"
-	"os"
-	"regexp"
-
-	"github.com/go-git/go-git/v5"
 )
 
 const (
@@ -20,8 +14,6 @@ const (
 
 var (
 	changelogTemplate *template.Template
-
-	headerRegex = regexp.MustCompile(`^# Changelog\n`)
 )
 
 //go:embed changelog.md.tpl
@@ -35,60 +27,6 @@ func init() {
 	}
 }
 
-func UpdateChangelogFile(wt *git.Worktree, newEntry string) error {
-	file, err := wt.Filesystem.OpenFile(ChangelogFile, os.O_RDWR|os.O_CREATE, 0644)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	content, err := io.ReadAll(file)
-	if err != nil {
-		return err
-	}
-
-	headerIndex := headerRegex.FindIndex(content)
-	if headerIndex == nil && len(content) != 0 {
-		return fmt.Errorf("unexpected format of CHANGELOG.md, header does not match")
-	}
-	if headerIndex != nil {
-		// Remove the header from the content
-		content = content[headerIndex[1]:]
-	}
-
-	err = file.Truncate(0)
-	if err != nil {
-		return err
-	}
-	_, err = file.Seek(0, io.SeekStart)
-	if err != nil {
-		return err
-	}
-
-	_, err = file.Write([]byte(ChangelogHeader + "\n\n" + newEntry))
-	if err != nil {
-		return err
-	}
-
-	_, err = file.Write(content)
-	if err != nil {
-		return err
-	}
-
-	// Close file to make sure it is written to disk.
-	err = file.Close()
-	if err != nil {
-		return err
-	}
-
-	_, err = wt.Add(ChangelogFile)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
 func NewChangelogEntry(commits []AnalyzedCommit, version, link, prefix, suffix string) (string, error) {
 	features := make([]AnalyzedCommit, 0)
 	fixes := make([]AnalyzedCommit, 0)