Frontend Editor Hugo - Go Backend Introduction

Backend  

The backend with the HTTP API is defined for now all in the main.go file in the adminEditor folder.

1. Structures:

   • Tag: Represents a tag with a name and count.

   • Category: Represents a category with a name and count.

   • ShortcodeData: Represents the data for a shortcode.

   • ShortcodeFunc: Represents a function for rendering a shortcode.

   • Shortcodes: Represents a map of shortcode names to their corresponding functions.

   • ServerConfig: Represents the configuration for the server, including image resizing options and asset folder paths.

   • adminEditor/main.go

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   package main import ( "encoding/json" "fmt" "image" "io" "io/ioutil" "log" "net/http" "os" "path/filepath" "regexp" "strings" "time" _ "markdown-editor/docs" "github.com/disintegration/imaging" "github.com/gosimple/slug" httpSwagger "github.com/swaggo/http-swagger" // swagger UI handler _ "github.com/swaggo/swag" // swagger embed files ) var config Config func main() { // Load configuration loadConfig() // Serve static files from the "static" directory fs := http.FileServer(http.Dir("static")) http.Handle("/", fs) // API endpoints http.HandleFunc("/api/config", handleConfig) http.HandleFunc("/api/save", handleSave) http.HandleFunc("/api/load", handleLoad) http.HandleFunc("/api/list", handleList) http.HandleFunc("/api/media-list", handleMediaList) http.HandleFunc("/api/process-media", handleProcessMedia) http.HandleFunc("/api/create-post", handleCreatePost) http.HandleFunc("/api/tags", handleGetTags) http.HandleFunc("/api/categories", handleGetCategories) http.HandleFunc("/api/delete-media", handleDeleteMedia) http.HandleFunc("/api/upload-media", handleUploadMediaFolder) // Updated Swagger handler http.Handle("/swagger/", httpSwagger.Handler( httpSwagger.URL("/docs/swagger.json"), // The url pointing to API definition httpSwagger.DeepLinking(true), httpSwagger.DocExpansion("none"), httpSwagger.DomID("swagger-ui"), )) // Determine the address to listen on addr := fmt.Sprintf(":%d", config.Server.Port) // Show URL on start if configured if config.Server.ShowURLOnStart { log.Printf("Server starting on http://localhost%s", addr) log.Printf("Swagger UI available at http://localhost%s/swagger/index.html", addr) } else { log.Printf("Server starting on port %d", config.Server.Port) } // Start the server log.Fatal(http.ListenAndServe(addr, nil)) } func loadConfig() { file, err := ioutil.ReadFile("config.json") if err != nil { log.Fatal("Error reading config file:", err) } err = json.Unmarshal(file, &config) if err != nil { log.Fatal("Error parsing config file:", err) } // Set default values if not specified if config.Server.Port == 0 { config.Server.Port = 8080 } if config.Server.GermanFolder == "" { config.Server.GermanFolder = "../content/de/blog" } if config.Server.EnglishFolder == "" { config.Server.EnglishFolder = "../content/en/blog" } // Convert relative paths to absolute paths absGermanFolder, err := filepath.Abs(config.Server.GermanFolder) if err != nil { log.Fatalf("Error converting relative path to absolute path for German folder: %v", err) } config.Server.GermanFolder = absGermanFolder absEnglishFolder, err := filepath.Abs(config.Server.EnglishFolder) if err != nil { log.Fatalf("Error converting relative path to absolute path for English folder: %v", err) } config.Server.EnglishFolder = absEnglishFolder } func handleConfig(w http.ResponseWriter, r *http.Request) { w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(config) } func handleSave(w http.ResponseWriter, r *http.Request) { if r.Method != http.MethodPost { http.Error(w, "Method not allowed", http.StatusMethodNotAllowed) return } filename := r.URL.Query().Get("file") if filename == "" { http.Error(w, "Filename is required", http.StatusBadRequest) return } content, err := ioutil.ReadAll(r.Body) if err != nil { http.Error(w, "Error reading request body", http.StatusInternalServerError) return } fullPath := getFullPath(filename) err = ioutil.WriteFile(fullPath, content, 0644) if err != nil { http.Error(w, "Error saving file", http.StatusInternalServerError) return } w.WriteHeader(http.StatusOK) } func handleLoad(w http.ResponseWriter, r *http.Request) { filename := r.URL.Query().Get("file") if filename == "" { http.Error(w, "Filename is required", http.StatusBadRequest) return } fullPath := getFullPath(filename) content, err := ioutil.ReadFile(fullPath) if err != nil { if os.IsNotExist(err) { http.Error(w, "File not found", http.StatusNotFound) } else { http.Error(w, "Error reading file", http.StatusInternalServerError) } return } w.Header().Set("Content-Type", "text/plain") w.Write(content) } func handleList(w http.ResponseWriter, r *http.Request) { files := make(map[string][]string) germanFiles, err := listFiles(config.Server.GermanFolder) if err != nil { http.Error(w, "Error reading German directory", http.StatusInternalServerError) return } files["de"] = germanFiles englishFiles, err := listFiles(config.Server.EnglishFolder) if err != nil { http.Error(w, "Error reading English directory", http.StatusInternalServerError) return } files["en"] = englishFiles files["en"] = englishFiles w.Header().Set("Content-Type", "application/json") lang := r.URL.Query().Get("lang") switch lang { case "de": json.NewEncoder(w).Encode(germanFiles) case "en": json.NewEncoder(w).Encode(englishFiles) default: json.NewEncoder(w).Encode(files) } w.Header().Set("Content-Type", "application/json") } func handleMediaList(w http.ResponseWriter, r *http.Request) { files, err := ioutil.ReadDir(config.Server.MediaFolder) if err != nil { http.Error(w, "Error reading media directory", http.StatusInternalServerError) return } var mediaFiles []string for _, file := range files { if !file.IsDir() { mediaFiles = append(mediaFiles, file.Name()) } } w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(mediaFiles) } func handleProcessMedia(w http.ResponseWriter, r *http.Request) { if r.Method != http.MethodPost { http.Error(w, "Method not allowed", http.StatusMethodNotAllowed) return } var request struct { File string `json:"file"` NewName string `json:"newName"` } if err := json.NewDecoder(r.Body).Decode(&request); err != nil { http.Error(w, "Invalid request body", http.StatusBadRequest) return } newFileName, err := processMediaFile(request) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } response := struct { Filename string `json:"filename"` }{ Filename: newFileName, } w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(response) } func handleCreatePost(w http.ResponseWriter, r *http.Request) { if r.Method != http.MethodPost { http.Error(w, "Method not allowed", http.StatusMethodNotAllowed) return } var request NewPostRequest if err := json.NewDecoder(r.Body).Decode(&request); err != nil { http.Error(w, "Invalid request body", http.StatusBadRequest) return } // Validate required fields if request.Title == "" || request.Date == "" { http.Error(w, "Title and date are required", http.StatusBadRequest) return } // Create filename from title filename := createSlug(request.Title) + ".md" if request.Thumbnail.LocalFile != "" && request.Thumbnail.URL == "" { if request.Slug == "" { request.Slug = slug.Make(request.Title) } // Create a variable of the struct type var reqMediaFile struct { File string `json:"file"` NewName string `json:"newName"` } reqMediaFile.File = request.Thumbnail.LocalFile reqMediaFile.NewName = request.Slug // Log the processing of the media file log.Printf("Processing media file: %s\n", request.Thumbnail.LocalFile) newFileName, err := processMediaFile(reqMediaFile) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } // Log the result of the media file processing log.Printf("Processed media file: %s -> %s\n", request.Thumbnail.LocalFile, newFileName) request.Thumbnail.URL = "/img/blog/" + newFileName } // Determine the target folder based on language var targetFolder string switch request.Language { case "de": targetFolder = config.Server.GermanFolder case "en": targetFolder = config.Server.EnglishFolder default: http.Error(w, "Invalid language", http.StatusBadRequest) return } // Generate markdown content content := generateMarkdownContent(request) // Save the file fullPath := filepath.Join(targetFolder, filename) if err := ioutil.WriteFile(fullPath, []byte(content), 0644); err != nil { http.Error(w, "Error saving file", http.StatusInternalServerError) return } // Update tags and categories in config updateTagsAndCategories(request.Tags, request.Categories) w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(map[string]string{"filename": filename}) } func handleGetTags(w http.ResponseWriter, r *http.Request) { tags, err := getAllTags() if err != nil { http.Error(w, "Error reading tags", http.StatusInternalServerError) return } w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(tags) } func handleGetCategories(w http.ResponseWriter, r *http.Request) { categories, err := getAllCategories() if err != nil { http.Error(w, "Error reading categories", http.StatusInternalServerError) return } w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(categories) } func createSlug(title string) string { // Convert to lowercase and replace spaces with hyphens slug := strings.ToLower(title) slug = strings.ReplaceAll(slug, " ", "-") // Remove special characters slug = regexp.MustCompile(`[^a-z0-9-]`).ReplaceAllString(slug, "") return slug } func generateMarkdownContent(post NewPostRequest) string { var sb strings.Builder sb.WriteString("---\n") sb.WriteString(fmt.Sprintf("title: '%s'\n", post.Title)) if post.Slug == "" { post.Slug = slug.Make(post.Title) } sb.WriteString(fmt.Sprintf("slug: %s\n", post.Slug)) if post.Description != "" { sb.WriteString(fmt.Sprintf("description: '%s'\n", post.Description)) } // Convert date string to time.Time date, err := time.Parse("2024-11-06T13:53", post.Date) if err != nil { log.Printf("Error parsing date: %v", err) date = time.Now() } // Convert date to UTC utcDate := date.UTC() sb.WriteString(fmt.Sprintf("date: %s\n", utcDate.Format(time.RFC3339))) if len(post.Tags) > 0 { tags, _ := json.Marshal(post.Tags) sb.WriteString(fmt.Sprintf("tags: %s\n", strings.ReplaceAll(string(tags), "\"", ""))) } if len(post.Categories) > 0 { categories, _ := json.Marshal(post.Categories) sb.WriteString(fmt.Sprintf("categories: %s\n", strings.ReplaceAll(string(categories), "\"", ""))) } if post.Thumbnail.URL != "" { sb.WriteString("thumbnail:\n") sb.WriteString(fmt.Sprintf(" url: %s\n", post.Thumbnail.URL)) if post.Thumbnail.Author != "" { sb.WriteString(fmt.Sprintf(" author: %s\n", post.Thumbnail.Author)) } if post.Thumbnail.AuthorURL != "" { sb.WriteString(fmt.Sprintf(" authorUrl: %s\n", post.Thumbnail.AuthorURL)) } if post.Thumbnail.Origin != "" { sb.WriteString(fmt.Sprintf(" origin: %s\n", post.Thumbnail.Origin)) } } sb.WriteString("draft: true\n") sb.WriteString("---\n") return sb.String() } // getAllTags reads and returns all tags from the tags data file func getAllTags() ([]Tag, error) { // Read tags from a JSON file file, err := ioutil.ReadFile("data/tags.json") if err != nil { if os.IsNotExist(err) { // Return empty array if file doesn't exist return []Tag{}, nil } return nil, err } var tagsData TagsData err = json.Unmarshal(file, &tagsData) if err != nil { return nil, err } return tagsData.Tags, nil } // getAllCategories reads and returns all categories from the categories data file func getAllCategories() ([]Category, error) { // Read categories from a JSON file file, err := ioutil.ReadFile("data/categories.json") if err != nil { if os.IsNotExist(err) { // Return empty array if file doesn't exist return []Category{}, nil } return nil, err } var categoriesData CategoriesData err = json.Unmarshal(file, &categoriesData) if err != nil { return nil, err } return categoriesData.Categories, nil } // updateTagsAndCategories updates the tags and categories data files with new entries func updateTagsAndCategories(newTags []string, newCategories []string) error { // Update tags if err := updateTags(newTags); err != nil { return err } // Update categories if err := updateCategories(newCategories); err != nil { return err } return nil } // updateTags updates the tags data file with new tags func updateTags(newTags []string) error { existingTags, err := getAllTags() if err != nil { return err } // Create a map for existing tags for easy lookup tagMap := make(map[string]*Tag) for i := range existingTags { tagMap[existingTags[i].Name] = &existingTags[i] } // Update counts for existing tags and add new ones for _, newTag := range newTags { if tag, exists := tagMap[newTag]; exists { tag.Count++ } else { existingTags = append(existingTags, Tag{ Name: newTag, Count: 1, }) } } // Create data directory if it doesn't exist if err := os.MkdirAll("data", 0755); err != nil { return err } // Save updated tags to file tagsData := TagsData{Tags: existingTags} jsonData, err := json.MarshalIndent(tagsData, "", " ") if err != nil { return err } return ioutil.WriteFile("data/tags.json", jsonData, 0644) } // updateCategories updates the categories data file with new categories func updateCategories(newCategories []string) error { existingCategories, err := getAllCategories() if err != nil { return err } // Create a map for existing categories for easy lookup categoryMap := make(map[string]*Category) for i := range existingCategories { categoryMap[existingCategories[i].Name] = &existingCategories[i] } // Update counts for existing categories and add new ones for _, newCategory := range newCategories { if category, exists := categoryMap[newCategory]; exists { category.Count++ } else { existingCategories = append(existingCategories, Category{ Name: newCategory, Count: 1, }) } } // Create data directory if it doesn't exist if err := os.MkdirAll("data", 0755); err != nil { return err } // Save updated categories to file categoriesData := CategoriesData{Categories: existingCategories} jsonData, err := json.MarshalIndent(categoriesData, "", " ") if err != nil { return err } return ioutil.WriteFile("data/categories.json", jsonData, 0644) } func processMediaFile(request struct { File string `json:"file"` NewName string `json:"newName"` }) (string, error) { sourceFile := filepath.Join(config.Server.MediaFolder, request.File) ext := filepath.Ext(request.File) newFileName := request.NewName + ext destFile := filepath.Join(config.Server.AssetFolder, newFileName) // Open the source image src, err := imaging.Open(sourceFile) if err != nil { return "", fmt.Errorf("error opening source image: %w", err) } // Get the dimensions of the source image srcWidth := src.Bounds().Dx() srcHeight := src.Bounds().Dy() // Calculate the new height to maintain the aspect ratio newHeight := (config.Server.ImageResize.MaxWidth * srcHeight) / srcWidth // Resize the image var resized image.Image if config.Server.ImageResize.Method == "fit" { resized = imaging.Fit(src, config.Server.ImageResize.MaxWidth, newHeight, imaging.Lanczos) } else { resized = imaging.Fill(src, config.Server.ImageResize.MaxWidth, newHeight, imaging.Center, imaging.Lanczos) } // Save the resized image err = imaging.Save(resized, destFile) if err != nil { return "", fmt.Errorf("error saving resized image: %w", err) } // Create and save thumbnail var thumbnail image.Image if config.Server.ThumbnailResize.Method == "fit" { thumbnail = imaging.Fit(src, config.Server.ThumbnailResize.MaxWidth, newHeight, imaging.Lanczos) } else { thumbnail = imaging.Fill(src, config.Server.ThumbnailResize.MaxWidth, newHeight, imaging.Center, imaging.Lanczos) } thumbnailFile := filepath.Join(config.Server.AssetFolder, "thumb_"+newFileName) err = imaging.Save(thumbnail, thumbnailFile) if err != nil { return "", fmt.Errorf("error saving thumbnail: %w", err) } return newFileName, nil } func handleUploadMediaFolder(w http.ResponseWriter, r *http.Request) { if r.Method != http.MethodPost { http.Error(w, "Method not allowed", http.StatusMethodNotAllowed) return } // Parse the multipart form data with a 32MB limit err := r.ParseMultipartForm(32 << 20) if err != nil { http.Error(w, "Error parsing form data", http.StatusBadRequest) return } file, header, err := r.FormFile("file") if err != nil { http.Error(w, "Error retrieving file", http.StatusBadRequest) return } defer file.Close() // Generate a unique filename ext := filepath.Ext(header.Filename) filename := fmt.Sprintf("%d%s", time.Now().UnixNano(), ext) // Create the full path for the new file fullPath := filepath.Join(config.Server.MediaFolder, filename) // Create a new file in the media folder dst, err := os.Create(fullPath) if err != nil { http.Error(w, "Error creating file", http.StatusInternalServerError) return } defer dst.Close() // Copy the uploaded file to the destination _, err = io.Copy(dst, file) if err != nil { http.Error(w, "Error saving file", http.StatusInternalServerError) return } // Return the filename in the response response := struct { Filename string `json:"filename"` }{ Filename: filename, } w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(response) } func handleUploadMedia(w http.ResponseWriter, r *http.Request) { if r.Method != http.MethodPost { http.Error(w, "Method not allowed", http.StatusMethodNotAllowed) return } // Parse the multipart form data with a 32MB limit err := r.ParseMultipartForm(32 << 20) if err != nil { http.Error(w, "Error parsing form data", http.StatusBadRequest) return } file, header, err := r.FormFile("file") if err != nil { http.Error(w, "Error retrieving file", http.StatusBadRequest) return } defer file.Close() // Generate a unique filename ext := filepath.Ext(header.Filename) filename := fmt.Sprintf("%d%s", time.Now().UnixNano(), ext) // Create the full path for the new file fullPath := filepath.Join(config.Server.MediaFolder, filename) // Create a new file in the media folder dst, err := os.Create(fullPath) if err != nil { http.Error(w, "Error creating file", http.StatusInternalServerError) return } defer dst.Close() // Copy the uploaded file to the destination _, err = io.Copy(dst, file) if err != nil { http.Error(w, "Error saving file", http.StatusInternalServerError) return } // Return the filename in the response response := struct { Filename string `json:"filename"` }{ Filename: filename, } w.Header().Set("Content-Type", "application/json") json.NewEncoder(w).Encode(response) } func handleDeleteMedia(w http.ResponseWriter, r *http.Request) { if r.Method != http.MethodDelete { http.Error(w, "Method not allowed", http.StatusMethodNotAllowed) return } filename := r.URL.Query().Get("file") if filename == "" { http.Error(w, "Filename is required", http.StatusBadRequest) return } // Ensure the filename is safe if strings.Contains(filename, "..") { http.Error(w, "Invalid filename", http.StatusBadRequest) return } // Create the full path for the file fullPath := filepath.Join(config.Server.MediaFolder, filename) // Check if file exists if _, err := os.Stat(fullPath); os.IsNotExist(err) { http.Error(w, "File not found", http.StatusNotFound) return } // Delete the file err := os.Remove(fullPath) if err != nil { http.Error(w, "Error deleting file", http.StatusInternalServerError) return } // Also delete thumbnail if it exists thumbPath := filepath.Join(config.Server.MediaFolder, "thumb_"+filename) _ = os.Remove(thumbPath) // Ignore error as thumbnail might not exist w.WriteHeader(http.StatusOK) json.NewEncoder(w).Encode(map[string]string{"status": "success"}) }

   ...

2. Functions:

   • main: The entry point of the program. It sets up the server routes, initializes the server configuration, and starts the server.

   • initShortcodes: Initializes the shortcodes map with the provided shortcode functions.

   • handleCreatePost: Handles the creation of a new blog post. It extracts the necessary data from the request, generates the markdown content, saves the file, updates the tags and categories, and returns the filename.

   • handleUploadMediaFolder: Handles the uploading of a media folder. It extracts the files from the request, generates unique filenames, saves the files in the media folder, and returns the filenames.

   • handleUploadMedia: Handles the uploading of a single media file. It extracts the file from the request, generates a unique filename, saves the file in the media folder, and returns the filename.

   • handleDeleteMedia: Handles the deletion of a media file. It extracts the filename from the request, checks if the file exists, deletes the file, and returns a success status.

   • processMediaFile: Processes a media file by resizing it and saving it in the asset folder. It returns the new filename.

   • createSlug: Creates a URL-friendly slug from a given title.

   • generateMarkdownContent: Generates the markdown content for a blog post based on the provided data.

   • updateTagsAndCategories: Updates the tags and categories data files with new entries.

   • getAllTags: Retrieves all tags from the tags data file.

   • getAllCategories: Retrieves all categories from the categories data file.

   • resizeImage: Resizes an image using the provided dimensions and resampling method.

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