package main import ( "net/http" "io/ioutil" "log" "regexp" "text/template" ) const lenPath = len("/view/") var titleValidator = regexp.MustCompile("^[a-zA-Z0-9]+$") var templates = make(map[string]*template.Template) var err error type Page struct { Title string Body []byte } func init() { for _, tmpl := range []string{"edit", "view"} { templates[tmpl] = template.Must(template.ParseFiles(tmpl + ".html")) } } func main() { http.HandleFunc("/view/", makeHandler(viewHandler)) http.HandleFunc("/edit/", makeHandler(editHandler)) http.HandleFunc("/save/", makeHandler(saveHandler)) err := http.ListenAndServe("localhost:8080", nil) if err != nil { log.Fatal("ListenAndServe: ", err.Error()) } } func makeHandler(fn func(http.ResponseWriter, *http.Request, string)) http.HandlerFunc { return func(w http.ResponseWriter, r *http.Request) { title := r.URL.Path[lenPath:] if !titleValidator.MatchString(title) { http.NotFound(w, r) return } fn(w, r, title) } } func viewHandler(w http.ResponseWriter, r *http.Request, title string) { p, err := load(title) if err != nil { // page not found http.Redirect(w, r, "/edit/"+title, http.StatusFound) return } renderTemplate(w, "view", p) } func editHandler(w http.ResponseWriter, r *http.Request, title string) { p, err := load(title) if err != nil { p = &Page{Title: title} } renderTemplate(w, "edit", p) } func saveHandler(w http.ResponseWriter, r *http.Request, title string) { body := r.FormValue("body") p := &Page{Title: title, Body: []byte(body)} err := p.save() if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) return } http.Redirect(w, r, "/view/"+title, http.StatusFound) } func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) { err := templates[tmpl].Execute(w, p) if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError) } } func (p *Page) save() error { filename := p.Title + ".txt" // file created with read-write permissions for the current user only return ioutil.WriteFile(filename, p.Body, 0600) } func load(title string) (*Page, error) { filename := title + ".txt" body, err := ioutil.ReadFile(filename) if err != nil { return nil, err } return &Page{Title: title, Body: body}, nil }