Go oauth github

go-oauth-github.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"time"

	"github.com/dchest/uniuri"
	"github.com/gorilla/mux"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/github"
)

const UserInfoURL = "https://api.github.com/user?access_token="

var githubOauthConfig = &oauth2.Config{
	RedirectURL:  "http://localhost:3000/callback",
	ClientID:     os.Getenv("GITHUB_OAUTH_CLIENT_ID"),
	ClientSecret: os.Getenv("GITHUB_OAUTH_CLIENT_SECRET"),
	Scopes:       []string{"repo", "user"},
	Endpoint:     github.Endpoint,
}

type GithubUser struct {
	Login                   string      `json:"login"`
	ID                      int         `json:"id"`
	NodeID                  string      `json:"node_id"`
	AvatarURL               string      `json:"avatar_url"`
	GravatarID              string      `json:"gravatar_id"`
	URL                     string      `json:"url"`
	HTMLURL                 string      `json:"html_url"`
	FollowersURL            string      `json:"followers_url"`
	FollowingURL            string      `json:"following_url"`
	GistsURL                string      `json:"gists_url"`
	StarredURL              string      `json:"starred_url"`
	SubscriptionsURL        string      `json:"subscriptions_url"`
	OrganizationsURL        string      `json:"organizations_url"`
	ReposURL                string      `json:"repos_url"`
	EventsURL               string      `json:"events_url"`
	ReceivedEventsURL       string      `json:"received_events_url"`
	Type                    string      `json:"type"`
	SiteAdmin               bool        `json:"site_admin"`
	Name                    string      `json:"name"`
	Company                 interface{} `json:"company"`
	Blog                    string      `json:"blog"`
	Location                string      `json:"location"`
	Email                   string      `json:"email"`
	Hireable                bool        `json:"hireable"`
	Bio                     string      `json:"bio"`
	PublicRepos             int         `json:"public_repos"`
	PublicGists             int         `json:"public_gists"`
	Followers               int         `json:"followers"`
	Following               int         `json:"following"`
	CreatedAt               time.Time   `json:"created_at"`
	UpdatedAt               time.Time   `json:"updated_at"`
	PrivateGists            int         `json:"private_gists"`
	TotalPrivateRepos       int         `json:"total_private_repos"`
	OwnedPrivateRepos       int         `json:"owned_private_repos"`
	DiskUsage               int         `json:"disk_usage"`
	Collaborators           int         `json:"collaborators"`
	TwoFactorAuthentication bool        `json:"two_factor_authentication"`
	Plan                    struct {
		Name          string `json:"name"`
		Space         int    `json:"space"`
		Collaborators int    `json:"collaborators"`
		PrivateRepos  int    `json:"private_repos"`
	} `json:"plan"`
}

func main() {
	router := mux.NewRouter().StrictSlash(true)

	router.HandleFunc("/", indexHandler)
	router.HandleFunc("/login", loginHandler)
	router.HandleFunc("/callback", callbackHandler)

	http.ListenAndServe(":3000", router)
}

func indexHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintln(w, "<a href='/login'>Log in with Github</a>")
}

func loginHandler(w http.ResponseWriter, r *http.Request) {
	oauthStateString := uniuri.New()
	url := githubOauthConfig.AuthCodeURL(oauthStateString)
	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
}

func callbackHandler(w http.ResponseWriter, r *http.Request) {
	code := r.FormValue("code")
	token, err := githubOauthConfig.Exchange(oauth2.NoContext, code)
	if err != nil {
		fmt.Fprintf(w, "Code exchange failed with error %s\n", err.Error())
		return
	}

	if !token.Valid() {
		fmt.Fprintln(w, "Retreived invalid token")
		return
	}

	fmt.Fprintln(w, token.AccessToken)

	response, err := http.Get(UserInfoURL + token.AccessToken)
	if err != nil {
		log.Printf("Error getting user from token %s\n", err.Error())
	}

	defer response.Body.Close()
	fmt.Println(response.Body)
	contents, err := ioutil.ReadAll(response.Body)

	var user *GithubUser
	err = json.Unmarshal(contents, &user)
	if err != nil {
		log.Printf("Error unmarshaling Google user %s\n", err.Error())
		return
	}

	fmt.Fprintf(w, "Email: %s\nName: %s\nImage link: %s\n", user.Email, user.Name, user.Login)
}