YouTube OAuth 2 golang

main.go

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/youtube/v3"
)

func redirectionHandler(w http.ResponseWriter, req *http.Request) {
	code := req.FormValue("code")
	if code != "" {
		w.Write([]byte("Copy the following auth code and paste it to the terminal:\n\n" + code))
	} else {
		w.Write([]byte("Error: " + req.FormValue("error")))
	}
}

func main() {
	srv := &http.Server{Addr: ":8090"}
	http.HandleFunc("/", redirectionHandler)
	go func() {
		err := srv.ListenAndServe()
		fmt.Println(err)
	}()

	// Only needed in first try
	fmt.Println("Creating OAuth 2 token file...")
	err := CreateOauthToken()
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	} else {
		fmt.Println("Create the oauth 2 token file at ~/.credentials successfully")
	}
	srv.Close()
}

func CreateOauthToken() error {
	b, err := os.ReadFile("client_secret.json")
	if err != nil {
		return err
	}

	// If modifying the scope, delete your previously saved credentials
	// at ./yt-token.json
	config, err := google.ConfigFromJSON(b, youtube.YoutubeReadonlyScope, youtube.YoutubeUploadScope, youtube.YoutubeScope)
	if err != nil {
		return err
	}

	// Use a redirect URI like this for a web app. The redirect URI must be a
	// valid one for your OAuth2 credentials.
	config.RedirectURL = "http://localhost:8090"

	tok := getTokenFromWeb(config)

	_, err = saveToken("yt-token.json", tok)
	return err
}

// getTokenFromWeb uses Config to request a Token.
// It returns the retrieved Token.
func getTokenFromWeb(config *oauth2.Config) *oauth2.Token {
	authURL := config.AuthCodeURL("state-token", oauth2.AccessTypeOffline)
	fmt.Printf("Go to the following link in your browser then type the "+
		"authorization code: \n%v\n", authURL)

	var code string
	if _, err := fmt.Scan(&code); err != nil {
		log.Fatalf("Unable to read authorization code %v", err)
	}

	tok, err := config.Exchange(context.Background(), code)
	if err != nil {
		log.Fatalf("Unable to retrieve token from web %v", err)
	}
	return tok
}

// tokenFromFile retrieves a Token from a given file path.
// It returns the retrieved Token and any read error encountered.
func tokenFromFile(file string) (*oauth2.Token, error) {
	f, err := os.Open(file)
	if err != nil {
		return nil, err
	}
	t := &oauth2.Token{}
	err = json.NewDecoder(f).Decode(t)
	defer f.Close()
	return t, err
}

// saveToken uses a file path to create a file and store the
// token in it.
func saveToken(file string, token *oauth2.Token) (string, error) {
	f, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
	if err != nil {
		return "", err
	}
	defer f.Close()
	err = json.NewEncoder(f).Encode(token)

	return fmt.Sprintf("Saving credential file to: %s", file), err
}