Impliment StartupTesting and started OAuth Server

Testing for IRC & Channels connection for debugging
OAuth Server (because it's better to roll my own for this)
internal/auth/oauth.go
tests/startup_checks.go

More tests to come for debugging

Plan to impliment Logging in internal/stoage/logs for internal & UI
debugging

internal/auth/oauth.go

@@ -0,0 +1,46 @@
+package oauth
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+)
+
+var (
+	clientID = os.Getenv("TWITCH_CLIENT_ID")
+	clientSecret = os.Getenv("TWITCH_CLIENT_SECRET")
+	redirectURI = "http://localhost:8080/callback"
+
+	scopes = []string{
+		"chat:read",
+		"chat:edit",
+		"channel:read:subscriptions",
+		"user:read:email",
+	}
+)
+
+type TokenResponse struct {
+	AccessToken string `json:"access_token"`
+	RefreshToken string `json:"refresh_token"`
+	ExpiresIn int `json:"expires_in"`
+	Scope []string `json:"scope"`
+	TokenType string `json:"token_type"`
+}
+
+// start http server for oauth login & callback
+func StartOAuthServer(addr string) error {
+	if clientID == "" || clientSecret == "" {
+		return fmt.Errorf("TWITCH_CLIENT_ID and TWITCH_CLIENT_SECRET must be set")
+	}
+
+	http.HandleFunc("/", handleIndex)
+	http.HandleFunc("/callback", handleCallback)
+
+	log.Printf("OAuth server listening on %s", addr)
+	return http.ListenAndServe(addr, nil)
+}
+

internal/tests/startup_checks.go

@@ -0,0 +1,52 @@
+package tests
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	twitch "github.com/gempir/go-twitch-irc/v4"
+	twitchapi "streambot_twitch/internal/twitchapi"
+)
+
+// check Twitch API connectivity
+func TestTwitchAPI(client *twitchapi.Client, streamerChannel string) error {
+	_, err := client.GetUserID(streamerChannel)
+	if err != nil {
+		return fmt.Errorf("Twitch API test failed: %w", err)
+	}
+	log.Println("Twitch API connection successful")
+	return nil
+}
+
+// check IRC connection to channels
+func TestIRCConnection(botClient *twitch.Client, channels []string) error {
+	ctx, channel := context.WithTimeout(context.Background(), 15*time.Second)
+	defer cancel()
+
+	connected := make(chan struct{})
+
+	botClient.OnConnect(func() {
+		log.Println("IRC connected successfully")
+		close(connected)
+	})
+
+	for _, ch := range channels {
+		botClient.Join(ch)
+	}
+
+	go func() {
+		if err := botClient.Connect(); err != nil {
+			log.Printf("IRC connection error: %v", err)
+		}
+	}()
+
+	select{
+		case <-connected:
+			log.Println("IRC connecton test successful")
+			return nil
+		case <-ctx.Done():
+			return fmt.Errorf("IRC connection test timed out")
+	}
+}