facebookOAuth.go

package main

import (
	"encoding/json"
	"fmt"
	"github.com/gorilla/mux"
	"golang.org/x/oauth2"
	"io/ioutil"
	"log"
	"net/http"
)

var config = &oauth2.Config{
	ClientID:     "YOUR CLIENT ID HERE",
	ClientSecret: "CLIENT SECRET HERE",
	Endpoint: oauth2.Endpoint{
		AuthURL:   "https://graph.facebook.com/oauth/authorize",
		TokenURL:  "https://graph.facebook.com/oauth/access_token",
	},
	RedirectURL:  "http://localhost:8000/auth/facebook/callback",
	Scopes: []string{"email","user_likes","user_birthday","user_gender"},
}

//OAuth handler for facebook OAuth
func facebookLoginHandler(w http.ResponseWriter, r *http.Request){
	url:=config.AuthCodeURL("fileupload")
	http.Redirect(w,r,url,http.StatusTemporaryRedirect)
}

//facebook auth callback
func facebookCallbackHandler(w http.ResponseWriter, r *http.Request){

	state:=r.FormValue("state")
	if state!="fileupload"{
		fmt.Println("Invalid oauth state")
		http.Redirect(w,r,"/",http.StatusTemporaryRedirect)  //307
	}

	code:=r.FormValue("code")
	token,err:=config.Exchange(oauth2.NoContext,r.URL.Query().Get("code"))
	if err!=nil{
		fmt.Println("Code exchange failed %s",err)
		http.Redirect(w,r,"/",http.StatusTemporaryRedirect)
	}

	response,err:=http.Get("https://graph.facebook.com/me?fields=name,email,gender,user&access_token=" + token.AccessToken)
	defer response.Body.Close()


	var facebookResponse interface{}
	contents,err:=ioutil.ReadAll(response.Body)
	json.Unmarshal(contents,&facebookResponse)
	w.Header().Add("Content-Type","application/json")
	w.WriteHeader(200)
	json.NewEncoder(w).Encode(facebookResponse)

	fmt.Println(facebookResponse)
}

func indexHandler(w http.ResponseWriter, r *http.Request){
	fmt.Fprint(w,"WELCOME TO FACEBOOK OAUTH APP")
}

func main(){
	router:=mux.NewRouter()
	router.HandleFunc("/", indexHandler)
	//ouath using facebook
	router.HandleFunc("/auth/facebook",facebookLoginHandler)
	//callback handler
	router.HandleFunc("/auth/facebook/callback",facebookCallbackHandler)
	log.Fatal(http.ListenAndServe(":8000",router))
}