1 // Copyright 2010 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package main 6 7 import ( 8 "errors" 9 "html/template" 10 "io/ioutil" 11 "net/http" 12 "regexp" 13 ) 14 15 type Page struct { 16 Title string 17 Body []byte 18 } 19 20 func (p *Page) save() error { 21 filename := p.Title + ".txt" 22 return ioutil.WriteFile(filename, p.Body, 0600) 23 } 24 25 func loadPage(title string) (*Page, error) { 26 filename := title + ".txt" 27 body, err := ioutil.ReadFile(filename) 28 if err != nil { 29 return nil, err 30 } 31 return &Page{Title: title, Body: body}, nil 32 } 33 34 func viewHandler(w http.ResponseWriter, r *http.Request) { 35 title, err := getTitle(w, r) 36 if err != nil { 37 return 38 } 39 p, err := loadPage(title) 40 if err != nil { 41 http.Redirect(w, r, "/edit/"+title, http.StatusFound) 42 return 43 } 44 renderTemplate(w, "view", p) 45 } 46 47 func editHandler(w http.ResponseWriter, r *http.Request) { 48 title, err := getTitle(w, r) 49 if err != nil { 50 return 51 } 52 p, err := loadPage(title) 53 if err != nil { 54 p = &Page{Title: title} 55 } 56 renderTemplate(w, "edit", p) 57 } 58 59 func saveHandler(w http.ResponseWriter, r *http.Request) { 60 title, err := getTitle(w, r) 61 if err != nil { 62 return 63 } 64 body := r.FormValue("body") 65 p := &Page{Title: title, Body: []byte(body)} 66 err = p.save() 67 if err != nil { 68 http.Error(w, err.Error(), http.StatusInternalServerError) 69 return 70 } 71 http.Redirect(w, r, "/view/"+title, http.StatusFound) 72 } 73 74 func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) { 75 t, err := template.ParseFiles(tmpl + ".html") 76 if err != nil { 77 http.Error(w, err.Error(), http.StatusInternalServerError) 78 return 79 } 80 err = t.Execute(w, p) 81 if err != nil { 82 http.Error(w, err.Error(), http.StatusInternalServerError) 83 } 84 } 85 86 var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$") 87 88 func getTitle(w http.ResponseWriter, r *http.Request) (string, error) { 89 m := validPath.FindStringSubmatch(r.URL.Path) 90 if m == nil { 91 http.NotFound(w, r) 92 return "", errors.New("Invalid Page Title") 93 } 94 return m[2], nil // The title is the second subexpression. 95 } 96 97 func main() { 98 http.HandleFunc("/view/", viewHandler) 99 http.HandleFunc("/edit/", editHandler) 100 http.HandleFunc("/save/", saveHandler) 101 http.ListenAndServe(":8080", nil) 102 } 103
