auth.go

package main

import (
	"crypto/md5"
	"fmt"
	"github.com/markbates/goth/gothic"
	"github.com/stretchr/objx"
	"io"
	"log"
	"net/http"
	"strings"
)

type authHandler struct {
	next http.Handler
}

func (h *authHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	cookie, err := r.Cookie("auth")
	if err == http.ErrNoCookie || cookie.Value == "" {
		// not authenticated
		w.Header().Set("Location", "/login")
		w.WriteHeader(http.StatusTemporaryRedirect)
		return
	}
	if err != nil {
		// some other error
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	// success - call the next handler
	h.next.ServeHTTP(w, r)
}

func MustAuth(handler http.Handler) http.Handler {
	return &authHandler{next: handler}
}

// loginHandler handles the third-party login process.
// format: /auth/{action}/{provider}
func loginHandler(w http.ResponseWriter, r *http.Request) {
	segs := strings.Split(r.URL.Path, "/")
	action := segs[2]
	provider := r.URL.Query().Get("provider")
	switch action {
	case "callback":
		user, err := gothic.CompleteUserAuth(w, r)
		if err != nil {
			fmt.Fprintln(w, err)
			return
		}
		fmt.Printf("user data: %v", user)
		chatUser := &chatUser{User: user}
		m := md5.New()
		_, _ = io.WriteString(m, strings.ToLower(user.Email))
		chatUser.uniqueID = fmt.Sprintf("%x", m.Sum(nil))
		avatarURL, err := avatars.GetAvatarURL(chatUser)
		if err != nil {
			log.Fatalln("Error when trying to GetAvatarURL", "-", err)
		}
		authCookieValue := objx.New(map[string]interface{}{
			"userid":     chatUser.uniqueID,
			"name":       user.Name,
			"avatar_url": avatarURL,
		}).MustBase64()
		http.SetCookie(w, &http.Cookie{
			Name:  "auth",
			Value: authCookieValue,
			Path:  "/"})
		w.Header().Set("Location", "/chat")
		w.WriteHeader(http.StatusTemporaryRedirect)
	case "login":
		log.Println("Started login for", provider)
		gothic.BeginAuthHandler(w, r)
	}
}