Added authentication keys to start retrieving data from the youtube API

Author: Nyah Check

auth/auth.go

@@ -0,0 +1,179 @@
+// Copyright 2017 YTD Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+// OAuth to Youtube Data API
+
+package auth
+
+import (
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+
+	"code.google.com/p/goauth2/oauth"
+)
+
+const missingClientSecretsMessage = ` OAuth 2.0 not configured `
+
+var (
+	clientSecretsFile = flag.String("secrets", "client_secrets.json", "Client Secrets configuration")
+	cacheFile         = flag.String("cache", "request.token", "Token cache file")
+)
+
+// ClientConfig is a data structure definition for the client_secrets.json file.
+// The code unmarshals the JSON configuration file into this structure.
+type ClientConfig struct {
+	ClientID     string   `json:"client_id"`
+	ClientSecret string   `json:"client_secret"`
+	RedirectURIs []string `json:"redirect_uris"`
+	AuthURI      string   `json:"auth_uri"`
+	TokenURI     string   `json:"token_uri"`
+}
+
+// Config is a root-level configuration object.
+type Config struct {
+	Installed ClientConfig `json:"installed"`
+	Web       ClientConfig `json:"web"`
+}
+
+// openURL opens a browser window to the specified location.
+// This code originally appeared at:
+//   http://stackoverflow.com/questions/10377243/how-can-i-launch-a-process-that-is-not-a-file-in-go
+func openURL(url string) error {
+	var err error
+	switch runtime.GOOS {
+	case "linux":
+		err = exec.Command("xdg-open", url).Start()
+	case "windows":
+		err = exec.Command("rundll32", "url.dll,FileProtocolHandler", "http://localhost:4001/").Start()
+	case "darwin":
+		err = exec.Command("open", url).Start()
+	default:
+		err = fmt.Errorf("Cannot open URL %s on this platform", url)
+	}
+	return err
+}
+
+// readConfig reads the configuration from clientSecretsFile.
+// It returns an oauth configuration object for use with the Google API client.
+func readConfig(scope string) (*oauth.Config, error) {
+	// Read the secrets file
+	data, err := ioutil.ReadFile(*clientSecretsFile)
+	if err != nil {
+		pwd, _ := os.Getwd()
+		fullPath := filepath.Join(pwd, *clientSecretsFile)
+		return nil, fmt.Errorf(missingClientSecretsMessage, fullPath)
+	}
+
+	cfg := new(Config)
+	err = json.Unmarshal(data, &cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	var redirectUri string
+	if len(cfg.Web.RedirectURIs) > 0 {
+		redirectUri = cfg.Web.RedirectURIs[0]
+	} else if len(cfg.Installed.RedirectURIs) > 0 {
+		redirectUri = cfg.Installed.RedirectURIs[0]
+	} else {
+		return nil, errors.New("Must specify a redirect URI in config file or when creating OAuth client")
+	}
+
+	return &oauth.Config{
+		ClientId:     cfg.Installed.ClientID,
+		ClientSecret: cfg.Installed.ClientSecret,
+		Scope:        scope,
+		AuthURL:      cfg.Installed.AuthURI,
+		TokenURL:     cfg.Installed.TokenURI,
+		RedirectURL:  redirectUri,
+		TokenCache:   oauth.CacheFile(*cacheFile),
+		// Get a refresh token so we can use the access token indefinitely
+		AccessType: "offline",
+		// If we want a refresh token, we must set this attribute
+		// to force an approval prompt or the code won't work.
+		ApprovalPrompt: "force",
+	}, nil
+}
+
+// startWebServer starts a web server that listens on http://localhost:8080.
+// The webserver waits for an oauth code in the three-legged auth flow.
+func startWebServer() (codeCh chan string, err error) {
+	listener, err := net.Listen("tcp", "localhost:8080")
+	if err != nil {
+		return nil, err
+	}
+	codeCh = make(chan string)
+	go http.Serve(listener, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		code := r.FormValue("code")
+		codeCh <- code // send code to OAuth flow
+		listener.Close()
+		w.Header().Set("Content-Type", "text/plain")
+		fmt.Fprintf(w, "Received code: %v\r\nYou can now safely close this browser window.", code)
+	}))
+
+	return codeCh, nil
+}
+
+// buildOAuthHTTPClient takes the user through the three-legged OAuth flow.
+// It opens a browser in the native OS or outputs a URL, then blocks until
+// the redirect completes to the /oauth2callback URI.
+// It returns an instance of an HTTP client that can be passed to the
+// constructor of the YouTube client.
+func buildOAuthHTTPClient(scope string) (*http.Client, error) {
+	config, err := readConfig(scope)
+	if err != nil {
+		msg := fmt.Sprintf("Cannot read configuration file: %v", err)
+		return nil, errors.New(msg)
+	}
+
+	transport := &oauth.Transport{Config: config}
+
+	// Try to read the token from the cache file.
+	// If an error occurs, do the three-legged OAuth flow because
+	// the token is invalid or doesn't exist.
+	token, err := config.TokenCache.Token()
+	if err != nil {
+		// Start web server.
+		// This is how this program receives the authorization code
+		// when the browser redirects.
+		codeCh, err := startWebServer()
+		if err != nil {
+			return nil, err
+		}
+
+		// Open url in browser
+		url := config.AuthCodeURL("")
+		err = openURL(url)
+		if err != nil {
+			fmt.Println("Visit the URL below to get a code.",
+				" This program will pause until the site is visted.")
+		} else {
+			fmt.Println("Your browser has been opened to an authorization URL.",
+				" This program will resume once authorization has been provided.\n")
+		}
+		fmt.Println(url)
+
+		// Wait for the web server to get the code.
+		code := <-codeCh
+
+		// This code caches the authorization code on the local
+		// filesystem, if necessary, as long as the TokenCache
+		// attribute in the config is set.
+		token, err = transport.Exchange(code)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	transport.Token = token
+	return transport.Client(), nil
+}

auth/client_secret.json

@@ -0,0 +1 @@
+{"installed":{"client_id":"1023236677559-agfhktgml9nqi1j17ek0vmr6c7cjt87f.apps.googleusercontent.com","project_id":"central-web-175404","auth_uri":"https://accounts.google.com/o/oauth2/auth","token_uri":"https://accounts.google.com/o/oauth2/token","auth_provider_x509_cert_url":"https://www.googleapis.com/oauth2/v1/certs","client_secret":"vqNWDovin1e8vR24HNdxF0_G","redirect_uris":["urn:ietf:wg:oauth:2.0:oob","http://localhost"]}}

auth/ytd-auth.json

@@ -0,0 +1 @@
+{"access_token":"ya29.GluZBJ_ogDg3hhCcldf56ndk6Hx4PTW9y7yfFhFXlyJ4-4zXeXQFRV01-l8ycMFGaLCfHDfLAKsDw5Z8yM1Ns6WVSCoo9IKGngX1f2dxh9dCyM38QYNDCf9lVNgs","token_type":"Bearer","refresh_token":"1/v6zTvG9qcdstbIdQGGtqMvpk1H2QRxi7Z1ioxF66R7Q","expiry":"2017-07-30T23:29:26.611806229-06:00"}