albttx/main.go

## main.go
package main

// from: https://stackoverflow.com/questions/27368973/golang-facebook-authentication-using-golang-org-x-oauth2

import (
  "fmt"
  "io/ioutil"
  "log"
  "net/http"
  "net/url"
  "strings"

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

var (
  oauthConf = &oauth2.Config{
    ClientID:     "YOUR_CLIENT_ID",
    ClientSecret: "YOUR_CLIENT_SECRET",
    RedirectURL:  "YOUR_REDIRECT_URL_CALLBACK",
    Scopes:       []string{"public_profile"},
    Endpoint:     facebook.Endpoint,
  }
  oauthStateString = "thisshouldberandom"
)

const htmlIndex = `<html><body>
Logged in with <a href="/login">facebook</a>
</body></html>
`

func handleMain(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Type", "text/html; charset=utf-8")
  w.WriteHeader(http.StatusOK)
  w.Write([]byte(htmlIndex))
}

func handleFacebookLogin(w http.ResponseWriter, r *http.Request) {
  Url, err := url.Parse(oauthConf.Endpoint.AuthURL)
  if err != nil {
    log.Fatal("Parse: ", err)
  }
  parameters := url.Values{}
  parameters.Add("client_id", oauthConf.ClientID)
  parameters.Add("scope", strings.Join(oauthConf.Scopes, " "))
  parameters.Add("redirect_uri", oauthConf.RedirectURL)
  parameters.Add("response_type", "code")
  parameters.Add("state", oauthStateString)
  Url.RawQuery = parameters.Encode()
  url := Url.String()
  http.Redirect(w, r, url, http.StatusTemporaryRedirect)
}

func handleFacebookCallback(w http.ResponseWriter, r *http.Request) {
  state := r.FormValue("state")
  if state != oauthStateString {
    fmt.Printf("invalid oauth state, expected '%s', got '%s'\n", oauthStateString, state)
    http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
    return
  }

  code := r.FormValue("code")

  token, err := oauthConf.Exchange(oauth2.NoContext, code)
  if err != nil {
    fmt.Printf("oauthConf.Exchange() failed with '%s'\n", err)
    http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
    return
  }

  resp, err := http.Get("https://graph.facebook.com/me?access_token=" +
    url.QueryEscape(token.AccessToken))
  if err != nil {
    fmt.Printf("Get: %s\n", err)
    http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
    return
  }
  defer resp.Body.Close()

  response, err := ioutil.ReadAll(resp.Body)
  if err != nil {
    fmt.Printf("ReadAll: %s\n", err)
    http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
    return
  }

  log.Printf("parseResponseBody: %s\n", string(response))

  http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
}

func main() {
  http.HandleFunc("/", handleMain)
  http.HandleFunc("/login", handleFacebookLogin)
  http.HandleFunc("/oauth2callback", handleFacebookCallback)
  fmt.Print("Started running on http://localhost:9090\n")
  log.Fatal(http.ListenAndServe(":9090", nil))
}
	package main

	// from: https://stackoverflow.com/questions/27368973/golang-facebook-authentication-using-golang-org-x-oauth2

	import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"strings"

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

	var (
	oauthConf = &oauth2.Config{
	ClientID: "YOUR_CLIENT_ID",
	ClientSecret: "YOUR_CLIENT_SECRET",
	RedirectURL: "YOUR_REDIRECT_URL_CALLBACK",
	Scopes: []string{"public_profile"},
	Endpoint: facebook.Endpoint,
	}
	oauthStateString = "thisshouldberandom"
	)

	const htmlIndex = `<html><body>
	Logged in with <a href="/login">facebook</a>
	</body></html>
	`

	func handleMain(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.WriteHeader(http.StatusOK)
	w.Write([]byte(htmlIndex))
	}

	func handleFacebookLogin(w http.ResponseWriter, r *http.Request) {
	Url, err := url.Parse(oauthConf.Endpoint.AuthURL)
	if err != nil {
	log.Fatal("Parse: ", err)
	}
	parameters := url.Values{}
	parameters.Add("client_id", oauthConf.ClientID)
	parameters.Add("scope", strings.Join(oauthConf.Scopes, " "))
	parameters.Add("redirect_uri", oauthConf.RedirectURL)
	parameters.Add("response_type", "code")
	parameters.Add("state", oauthStateString)
	Url.RawQuery = parameters.Encode()
	url := Url.String()
	http.Redirect(w, r, url, http.StatusTemporaryRedirect)
	}

	func handleFacebookCallback(w http.ResponseWriter, r *http.Request) {
	state := r.FormValue("state")
	if state != oauthStateString {
	fmt.Printf("invalid oauth state, expected '%s', got '%s'\n", oauthStateString, state)
	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
	return
	}

	code := r.FormValue("code")

	token, err := oauthConf.Exchange(oauth2.NoContext, code)
	if err != nil {
	fmt.Printf("oauthConf.Exchange() failed with '%s'\n", err)
	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
	return
	}

	resp, err := http.Get("https://graph.facebook.com/me?access_token=" +
	url.QueryEscape(token.AccessToken))
	if err != nil {
	fmt.Printf("Get: %s\n", err)
	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
	return
	}
	defer resp.Body.Close()

	response, err := ioutil.ReadAll(resp.Body)
	if err != nil {
	fmt.Printf("ReadAll: %s\n", err)
	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
	return
	}

	log.Printf("parseResponseBody: %s\n", string(response))

	http.Redirect(w, r, "/", http.StatusTemporaryRedirect)
	}

	func main() {
	http.HandleFunc("/", handleMain)
	http.HandleFunc("/login", handleFacebookLogin)
	http.HandleFunc("/oauth2callback", handleFacebookCallback)
	fmt.Print("Started running on http://localhost:9090\n")
	log.Fatal(http.ListenAndServe(":9090", nil))
	}