Merge pull request #2 from f4tal-err0r/refactor-oauth

working refactor of oauth

pkgs/client/auth.go

@@ -0,0 +1,160 @@
+package client
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/pkg/browser"
+	"golang.org/x/oauth2"
+)
+
+type DiscordUserAuth struct {
+	Token    *oauth2.Token
+	Config   *oauth2.Config
+	Filepath string
+	Browser  bool
+}
+
+func NewUserAuth(opts ...func(*DiscordUserAuth)) *DiscordUserAuth {
+	context := GetCurrentContext()
+	oauthCfg := &oauth2.Config{
+		ClientID:    context.ClientID,
+		RedirectURL: "http://localhost:8085/callback",
+		Scopes:      []string{"guilds", "guilds.members.read", "identify"},
+		Endpoint: oauth2.Endpoint{
+			AuthURL:  "https://discord.com/oauth2/authorize",
+			TokenURL: "https://discord.com/api/oauth2/token",
+		},
+	}
+
+	return &DiscordUserAuth{
+		Token:    nil,
+		Config:   oauthCfg,
+		Filepath: FetchCacheDir("auth"),
+	}
+}
+
+func WithToken(token *oauth2.Token) func(*DiscordUserAuth) {
+	return func(d *DiscordUserAuth) {
+		d.Token = token
+	}
+}
+
+func generateRand() string {
+	b := make([]byte, 32)
+	rand.Read(b)
+	return base64.RawURLEncoding.EncodeToString(b)
+}
+
+func generateCodeChallenge(codeVerifier string) (string, error) {
+	h := sha256.New()
+	_, err := h.Write([]byte(codeVerifier))
+	if err != nil {
+		return "", err
+	}
+	return base64.RawURLEncoding.EncodeToString(h.Sum(nil)), nil
+}
+
+func (d *DiscordUserAuth) StartAuth() (<-chan *oauth2.Token, error) {
+	tokenChan := make(chan *oauth2.Token)
+	state := generateRand()
+	codeVerifier := generateRand()
+
+	codeChallenge, err := generateCodeChallenge(codeVerifier)
+	if err != nil {
+		log.Fatalf("Unable to generate code challenge: %s", err)
+	}
+
+	url := d.Config.AuthCodeURL(state, oauth2.AccessTypeOffline,
+		oauth2.SetAuthURLParam("code_challenge", codeChallenge),
+		oauth2.SetAuthURLParam("code_challenge_method", "S256"))
+
+	http.HandleFunc("/callback", func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Query().Get("state") != state {
+			log.Fatal("State is not valid")
+			return
+		}
+
+		code := r.URL.Query().Get("code")
+		token, err := d.Config.Exchange(context.Background(), code, oauth2.SetAuthURLParam("code_verifier", codeVerifier))
+		if err != nil {
+			log.Fatal("Failed to exchange token: " + err.Error())
+			return
+		}
+
+		// Send token to channel
+		tokenChan <- token
+	})
+
+	go func() {
+		log.Fatal(http.ListenAndServe(":8085", nil))
+	}()
+
+	// Open the browser to start the auth flow
+	if err := browser.OpenURL(url); err != nil {
+		return nil, fmt.Errorf("open browser: %w", err)
+	}
+
+	// Wait for the auth flow to complete and return the token
+	token := <-tokenChan
+
+	// Save the token to disk
+	if err := d.saveToken(token); err != nil {
+		return nil, fmt.Errorf("save token: %w", err)
+	}
+
+	return tokenChan, nil
+}
+
+func (d *DiscordUserAuth) GetToken() (string, error) {
+
+	f, err := os.Open(d.Filepath)
+	if err != nil {
+		tokench, err := d.StartAuth()
+		if err != nil {
+			log.Fatalf("\nfailed to auth to Discord: %v", err)
+		}
+		token := <-tokench
+		d.Token = token
+	}
+	defer f.Close()
+
+	err = json.NewDecoder(f).Decode(&d.Token)
+	if err != nil {
+		return "", err
+	}
+
+	if d.Token.Expiry.Before(time.Now()) {
+		if tokenSource, err := d.RefreshToken(d.Token).Token(); err != nil {
+			d.Token = tokenSource
+			if err := d.saveToken(d.Token); err != nil {
+				return "", fmt.Errorf("save token: %w", err)
+			}
+		}
+	}
+
+	return d.Token.AccessToken, nil
+}
+
+// RefreshToken refreshes the Oauth2 token
+func (d *DiscordUserAuth) RefreshToken(token *oauth2.Token) oauth2.TokenSource {
+	return d.Config.TokenSource(context.Background(), token)
+}
+
+func (d *DiscordUserAuth) saveToken(token *oauth2.Token) error {
+	f, err := os.Create(d.Filepath)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return json.NewEncoder(f).Encode(token)
+}