ewalk153 · August 29, 2015 14:00
diff --git a/demo_login.go b/demo_login.go
 package main

 import (
 	"bytes"
 	"fmt"
 	"github.com/gorilla/sessions"
 	"html/template"
 	"net/http"
 	"strconv"
 )

 const (
 	authCookie    = "foo_loggedin"
 	encryptSecret = "supersecret-change-me-please"
 )

 const bodyTmpt = `<html>
 <body>
 <div>
 <a href="/">Home</a>
 <a href="/trips">Trips</a>
 {{if not .Page.LoggedIn}}
 <a href="/login">Login</a>
 {{else}}
 <a href="/logout">Logout</a>
 {{end}}
 </div>
 {{.Body}}
 </body>
 </html>
 `

 var (
 	store = sessions.NewCookieStore([]byte(encryptSecret))
 )

 type content struct {
 	Body template.HTML
 	Page interface{}
 }

 // Page holds core page information
 type Page struct {
 	UserID int64
 	Data   interface{}
 }

 // NewPage returns a preset page
 func NewPage(r *http.Request) *Page {
 	p := &Page{}
 	p.Authenticate(r)
 	return p
 }

 // StoreID stores the user's id
 func StoreID(w http.ResponseWriter, r *http.Request, id string) {
 	session, _ := store.Get(r, authCookie)
 	session.Values["UserID"] = id
 	session.Save(r, w)
 }

 // Authenticate checks if a cookie is a valid login
 func (p *Page) Authenticate(r *http.Request) bool {
 	session, _ := store.Get(r, authCookie)
 	id, ok := session.Values["UserID"]
 	if !ok {
 		return false
 	}
 	var err error
 	p.UserID, err = strconv.ParseInt(id.(string), 10, 0)
 	if err != nil {
 		return false
 	}
 	return true
 }

 // LoggedIn returns if a users is logged in
 func (p *Page) LoggedIn() bool {
 	return p.UserID > 0
 }

 func parseTemplate(body string, data interface{}) (out []byte, e error) {
 	var buf bytes.Buffer
 	t, err := template.New("page").Parse(body)
 	if err != nil {
 		return nil, err
 	}
 	err = t.Execute(&buf, data)
 	if err != nil {
 		return nil, err
 	}
 	return buf.Bytes(), nil
 }

 func getPage(pageBody string, data interface{}) string {
 	page, err := parseTemplate(pageBody, data)
 	if err != nil {
 		return err.Error()
 	}
 	base, err := parseTemplate(bodyTmpt, content{Body: template.HTML(page), Page: data})
 	if err != nil {
 		return err.Error()
 	}
 	return string(base)
 }

 type engine struct{}

 // User sample struct
 type User struct {
 	Email string
 }

 // ProtectPage redirects to login, if user not authed
 func (e *engine) ProtectPage(handler func(w http.ResponseWriter, r *http.Request)) func(w http.ResponseWriter, r *http.Request) {
 	return http.HandlerFunc(
 		func(w http.ResponseWriter, r *http.Request) {
 			p := NewPage(r)
 			if !p.LoggedIn() {
 				http.Redirect(w, r, "/login?not_auth", http.StatusSeeOther)
 				return
 			}
 			handler(w, r)
 		})
 }

 //Authenticate is a dummy authenication
 func (e *engine) Authenticate(email, password string) *User {
 	if email == "bob" && password == "pass" {
 		return &User{Email: email}
 	}
 	return nil
 }

 // Index page
 func (e *engine) Index(w http.ResponseWriter, r *http.Request) {
 	p := NewPage(r)
 	fmt.Fprint(w, getPage("<h1>welcome home</h1>", p))
 }

 // Trips page
 func (e *engine) Trips(w http.ResponseWriter, r *http.Request) {
 	p := NewPage(r)
 	p.Data = struct{ Trips []int }{[]int{1, 2, 3}}
 	fmt.Fprint(w, getPage("<h1>All Trips</h1> showing all trips {{range .Data.Trips}}Trip id: {{.}}<br>{{end}}", p))
 }

 // Login page
 func (e *engine) Login(w http.ResponseWriter, r *http.Request) {
 	p := NewPage(r)
 	if p.LoggedIn() {
 		http.Redirect(w, r, "/?dude_already_logged_in", http.StatusSeeOther)
 	}
 	fmt.Fprint(w, getPage(`
 		<h1>Login Now</h1>
 		<form action="/auth" method="post">
 		<input name="email" value="bob" />
 		<input name="pass" value="pass" type="password" />
 		<input type="submit" value="Login">
 		</form>
 		`, p))
 }

 // Auth action
 func (e *engine) Auth(w http.ResponseWriter, r *http.Request) {
 	if e.Authenticate(r.FormValue("email"), r.FormValue("pass")) != nil {
 		StoreID(w, r, "1")
 		http.Redirect(w, r, "/?logged_in", http.StatusSeeOther)
 		return
 	}
 	e.Login(w, r)
 }

 // Logout action
 func (e *engine) Logout(w http.ResponseWriter, r *http.Request) {
 	http.SetCookie(w, &http.Cookie{
 		Name:   authCookie,
 		Value:  "logginoff",
 		MaxAge: -1,
 	})
 	http.Redirect(w, r, "/?logged_out", http.StatusSeeOther)
 }

 func main() {
 	e := engine{}
 	http.HandleFunc("/", e.Index)
 	http.HandleFunc("/trips", e.ProtectPage(e.Trips))
 	http.HandleFunc("/login", e.Login)
 	http.HandleFunc("/auth", e.Auth)
 	http.HandleFunc("/logout", e.Logout)

 	http.ListenAndServe(":5050", nil)
 }
	package main

	import (
	"bytes"
	"fmt"
	"github.com/gorilla/sessions"
	"html/template"
	"net/http"
	"strconv"
	)

	const (
	authCookie = "foo_loggedin"
	encryptSecret = "supersecret-change-me-please"
	)

	const bodyTmpt = `<html>
	<body>
	<div>
	<a href="/">Home</a>
	<a href="/trips">Trips</a>
	{{if not .Page.LoggedIn}}
	<a href="/login">Login</a>
	{{else}}
	<a href="/logout">Logout</a>
	{{end}}
	</div>
	{{.Body}}
	</body>
	</html>
	`

	var (
	store = sessions.NewCookieStore([]byte(encryptSecret))
	)

	type content struct {
	Body template.HTML
	Page interface{}
	}

	// Page holds core page information
	type Page struct {
	UserID int64
	Data interface{}
	}

	// NewPage returns a preset page
	func NewPage(r http.Request) Page {
	p := &Page{}
	p.Authenticate(r)
	return p
	}

	// StoreID stores the user's id
	func StoreID(w http.ResponseWriter, r *http.Request, id string) {
	session, _ := store.Get(r, authCookie)
	session.Values["UserID"] = id
	session.Save(r, w)
	}

	// Authenticate checks if a cookie is a valid login
	func (p Page) Authenticate(r http.Request) bool {
	session, _ := store.Get(r, authCookie)
	id, ok := session.Values["UserID"]
	if !ok {
	return false
	}
	var err error
	p.UserID, err = strconv.ParseInt(id.(string), 10, 0)
	if err != nil {
	return false
	}
	return true
	}

	// LoggedIn returns if a users is logged in
	func (p *Page) LoggedIn() bool {
	return p.UserID > 0
	}

	func parseTemplate(body string, data interface{}) (out []byte, e error) {
	var buf bytes.Buffer
	t, err := template.New("page").Parse(body)
	if err != nil {
	return nil, err
	}
	err = t.Execute(&buf, data)
	if err != nil {
	return nil, err
	}
	return buf.Bytes(), nil
	}

	func getPage(pageBody string, data interface{}) string {
	page, err := parseTemplate(pageBody, data)
	if err != nil {
	return err.Error()
	}
	base, err := parseTemplate(bodyTmpt, content{Body: template.HTML(page), Page: data})
	if err != nil {
	return err.Error()
	}
	return string(base)
	}

	type engine struct{}

	// User sample struct
	type User struct {
	Email string
	}

	// ProtectPage redirects to login, if user not authed
	func (e engine) ProtectPage(handler func(w http.ResponseWriter, r http.Request)) func(w http.ResponseWriter, r *http.Request) {
	return http.HandlerFunc(
	func(w http.ResponseWriter, r *http.Request) {
	p := NewPage(r)
	if !p.LoggedIn() {
	http.Redirect(w, r, "/login?not_auth", http.StatusSeeOther)
	return
	}
	handler(w, r)
	})
	}

	//Authenticate is a dummy authenication
	func (e engine) Authenticate(email, password string) User {
	if email == "bob" && password == "pass" {
	return &User{Email: email}
	}
	return nil
	}

	// Index page
	func (e engine) Index(w http.ResponseWriter, r http.Request) {
	p := NewPage(r)
	fmt.Fprint(w, getPage("<h1>welcome home</h1>", p))
	}

	// Trips page
	func (e engine) Trips(w http.ResponseWriter, r http.Request) {
	p := NewPage(r)
	p.Data = struct{ Trips []int }{[]int{1, 2, 3}}
	fmt.Fprint(w, getPage("<h1>All Trips</h1> showing all trips {{range .Data.Trips}}Trip id: {{.}}<br>{{end}}", p))
	}

	// Login page
	func (e engine) Login(w http.ResponseWriter, r http.Request) {
	p := NewPage(r)
	if p.LoggedIn() {
	http.Redirect(w, r, "/?dude_already_logged_in", http.StatusSeeOther)
	}
	fmt.Fprint(w, getPage(`
	<h1>Login Now</h1>
	<form action="/auth" method="post">
	<input name="email" value="bob" />
	<input name="pass" value="pass" type="password" />
	<input type="submit" value="Login">
	</form>
	`, p))
	}

	// Auth action
	func (e engine) Auth(w http.ResponseWriter, r http.Request) {
	if e.Authenticate(r.FormValue("email"), r.FormValue("pass")) != nil {
	StoreID(w, r, "1")
	http.Redirect(w, r, "/?logged_in", http.StatusSeeOther)
	return
	}
	e.Login(w, r)
	}

	// Logout action
	func (e engine) Logout(w http.ResponseWriter, r http.Request) {
	http.SetCookie(w, &http.Cookie{
	Name: authCookie,
	Value: "logginoff",
	MaxAge: -1,
	})
	http.Redirect(w, r, "/?logged_out", http.StatusSeeOther)
	}

	func main() {
	e := engine{}
	http.HandleFunc("/", e.Index)
	http.HandleFunc("/trips", e.ProtectPage(e.Trips))
	http.HandleFunc("/login", e.Login)
	http.HandleFunc("/auth", e.Auth)
	http.HandleFunc("/logout", e.Logout)

	http.ListenAndServe(":5050", nil)
	}
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