add twitch API stuff, add follow/sub/cheer labels

twitch/oauth/oauth.go

@@ -0,0 +1,77 @@
+package oauth
+
+import (
+	"context"
+	"crypto/rand"
+	"fmt"
+	"log"
+	"net/http"
+	"sync"
+
+	"golang.org/x/oauth2"
+)
+
+func GenerateToken(
+	ctx *context.Context,
+	oauth2Config *oauth2.Config,
+) (*oauth2.Token, error) {
+	verifier := oauth2.GenerateVerifier()
+
+	state := rand.Text()
+
+	var token *oauth2.Token
+	wg := sync.WaitGroup{}
+
+	var server http.Server
+	server.Addr = "127.0.0.1"
+	server.Handler = http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			code := r.URL.Query().Get("code")
+			scope := r.URL.Query().Get("scope")
+			resState := r.URL.Query().Get("state")
+
+			if len(code) == 0 || len(scope) == 0 || resState != state {
+				http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
+				return
+			}
+
+			t, err := oauth2Config.Exchange(*ctx, code, oauth2.VerifierOption(verifier))
+			if err != nil {
+				log.Fatalf("Could not exchange OAuth2 code: %v", err)
+				http.Error( w,
+					fmt.Sprintf("Could not exchange OAuth2 code: %v", err),
+					http.StatusBadRequest,
+				)
+				return
+			}
+
+			token = t
+			http.Error(
+				w,
+				"Authentication successful! You may now close this tab.",
+				http.StatusOK,
+			)
+			if f, ok := w.(http.Flusher); ok {
+				f.Flush()
+			}
+
+			wg.Done()
+			server.Close()
+		},
+	)
+
+	url := oauth2Config.AuthCodeURL(
+		state,
+		oauth2.AccessTypeOffline,
+		oauth2.S256ChallengeOption(verifier),
+	)
+	log.Printf("Log in with Twitch: %s\n\n", url)
+
+	wg.Add(1)
+	if err := server.ListenAndServe(); err != http.ErrServerClosed {
+		return nil, fmt.Errorf("http: %v", err)
+	}
+	wg.Wait()
+
+	return token, nil
+}