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 "log" 12 "net/http" 13 "regexp" 14 ) 15 16 type Page struct { 17 Title string 18 Body []byte 19 } 20 21 func (p *Page) save() error { 22 filename := p.Title + ".txt" 23 return ioutil.WriteFile(filename, p.Body, 0600) 24 } 25 26 func loadPage(title string) (*Page, error) { 27 filename := title + ".txt" 28 body, err := ioutil.ReadFile(filename) 29 if err != nil { 30 return nil, err 31 } 32 return &Page{Title: title, Body: body}, nil 33 } 34 35 func viewHandler(w http.ResponseWriter, r *http.Request) { 36 title, err := getTitle(w, r) 37 if err != nil { 38 return 39 } 40 p, err := loadPage(title) 41 if err != nil { 42 http.Redirect(w, r, "/edit/"+title, http.StatusFound) 43 return 44 } 45 renderTemplate(w, "view", p) 46 } 47 48 func editHandler(w http.ResponseWriter, r *http.Request) { 49 title, err := getTitle(w, r) 50 if err != nil { 51 return 52 } 53 p, err := loadPage(title) 54 if err != nil { 55 p = &Page{Title: title} 56 } 57 renderTemplate(w, "edit", p) 58 } 59 60 func saveHandler(w http.ResponseWriter, r *http.Request) { 61 title, err := getTitle(w, r) 62 if err != nil { 63 return 64 } 65 body := r.FormValue("body") 66 p := &Page{Title: title, Body: []byte(body)} 67 err = p.save() 68 if err != nil { 69 http.Error(w, err.Error(), http.StatusInternalServerError) 70 return 71 } 72 http.Redirect(w, r, "/view/"+title, http.StatusFound) 73 } 74 75 func renderTemplate(w http.ResponseWriter, tmpl string, p *Page) { 76 t, err := template.ParseFiles(tmpl + ".html") 77 if err != nil { 78 http.Error(w, err.Error(), http.StatusInternalServerError) 79 return 80 } 81 err = t.Execute(w, p) 82 if err != nil { 83 http.Error(w, err.Error(), http.StatusInternalServerError) 84 } 85 } 86 87 var validPath = regexp.MustCompile("^/(edit|save|view)/([a-zA-Z0-9]+)$") 88 89 func getTitle(w http.ResponseWriter, r *http.Request) (string, error) { 90 m := validPath.FindStringSubmatch(r.URL.Path) 91 if m == nil { 92 http.NotFound(w, r) 93 return "", errors.New("Invalid Page Title") 94 } 95 return m[2], nil // The title is the second subexpression. 96 } 97 98 func main() { 99 http.HandleFunc("/view/", viewHandler) 100 http.HandleFunc("/edit/", editHandler) 101 http.HandleFunc("/save/", saveHandler) 102 log.Fatal(http.ListenAndServe(":8080", nil)) 103 } 104
