Feat: Add frontmatter info in source file

If frontmatter doesn't exist in the sourfe file, add it automatically so
you don't have to remember it.

main.go

@@ -1,14 +1,17 @@
 package main
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
 	"regexp"
 	"strings"
+	"time"
 
 	"github.com/fsnotify/fsnotify"
 	"github.com/gosimple/slug"
@@ -98,6 +101,23 @@ func processModifiedFile(filePath, directory, destDir string) {
 
 	// Copy modified file to the new destination
 	newFilePath := filepath.Join(newDir, "index.md")
+
+	// Check if the file already has frontmatter
+	hasFrontmatter, err := checkFrontmatter(filePath)
+	if err != nil {
+		fmt.Println("Error checking frontmatter:", err)
+		return
+	}
+
+	// If the file doesn't have frontmatter, add it
+	if !hasFrontmatter {
+		err = addFrontmatter(filePath, fileName)
+		if err != nil {
+			fmt.Println("Error adding frontmatter:", err)
+			return
+		}
+	}
+
 	err = copyFile(filePath, newFilePath)
 	if err != nil {
 		fmt.Println("Error copying file:", err)
@@ -112,6 +132,51 @@ func processModifiedFile(filePath, directory, destDir string) {
 	}
 }
 
+// Function to check if the file already has frontmatter
+func checkFrontmatter(filePath string) (bool, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return false, err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "---" {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
+// Function to add frontmatter to the file
+func addFrontmatter(filePath, title string) error {
+	// Read the content of the original file
+	content, err := ioutil.ReadFile(filePath)
+	if err != nil {
+		return err
+	}
+
+	// Create a new temporary file with the frontmatter added
+	tempFilePath := filePath + ".tmp"
+	frontmatter := fmt.Sprintf("---\ntitle: %s\ndate: %s\ndraft: false\ntags: micropost\n---\n\n", title, time.Now().Format("2006-01-02 15:04:05 -0700"))
+	err = ioutil.WriteFile(tempFilePath, []byte(frontmatter+string(content)), os.ModePerm)
+	if err != nil {
+		return err
+	}
+
+	// Replace the original file with the temporary file
+	fmt.Println("Rename:", tempFilePath, filePath)
+	err = os.Rename(tempFilePath, filePath)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func copyFile(src, dst string) error {
 	sourceFile, err := os.Open(src)
 	if err != nil {