Refactor API configuration and improve WebSocket handling in frontend and backend

backend/internal/config/config.go

@@ -0,0 +1,141 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/joho/godotenv"
+)
+
+// Config holds all application configuration
+type Config struct {
+	// Server
+	Port        string
+	Environment string // "development", "staging", "production"
+
+	// Database
+	DatabaseURL string
+
+	// Redis (optional)
+	RedisURL string
+
+	// Security
+	JWTSecret    string
+	SecureCookie bool // Derived from Environment
+
+	// CORS
+	AllowedOrigins []string
+
+	// URLs
+	FrontendURL string
+	BackendURL  string // Used to construct OAuth callback URLs
+
+	// OAuth - Google
+	GoogleClientID     string
+	GoogleClientSecret string
+	GoogleRedirectURL  string
+
+	// OAuth - GitHub
+	GitHubClientID     string
+	GitHubClientSecret string
+	GitHubRedirectURL  string
+}
+
+// Load loads configuration from environment variables with optional CLI flag overrides.
+// flagPort overrides the PORT env var if non-empty.
+func Load(flagPort string) (*Config, error) {
+	// Load .env files (ignore errors - files may not exist)
+	_ = godotenv.Load()
+	_ = godotenv.Overload(".env.local")
+
+	cfg := &Config{}
+
+	// Required fields
+	var missing []string
+
+	cfg.DatabaseURL = os.Getenv("DATABASE_URL")
+	if cfg.DatabaseURL == "" {
+		missing = append(missing, "DATABASE_URL")
+	}
+
+	cfg.JWTSecret = os.Getenv("JWT_SECRET")
+	if cfg.JWTSecret == "" {
+		missing = append(missing, "JWT_SECRET")
+	}
+
+	if len(missing) > 0 {
+		return nil, fmt.Errorf("missing required environment variables: %s", strings.Join(missing, ", "))
+	}
+
+	// Port: CLI flag > env var > default
+	cfg.Port = getEnvOrDefault("PORT", "8080")
+	if flagPort != "" {
+		cfg.Port = flagPort
+	}
+
+	// Other optional vars with defaults
+	cfg.Environment = getEnvOrDefault("ENVIRONMENT", "development")
+	cfg.FrontendURL = getEnvOrDefault("FRONTEND_URL", "http://localhost:5173")
+	cfg.BackendURL = getEnvOrDefault("BACKEND_URL", fmt.Sprintf("http://localhost:%s", cfg.Port))
+	cfg.RedisURL = os.Getenv("REDIS_URL")
+
+	// Derived values
+	cfg.SecureCookie = cfg.Environment == "production"
+
+	// CORS origins
+	originsStr := os.Getenv("ALLOWED_ORIGINS")
+	if originsStr != "" {
+		cfg.AllowedOrigins = strings.Split(originsStr, ",")
+		for i := range cfg.AllowedOrigins {
+			cfg.AllowedOrigins[i] = strings.TrimSpace(cfg.AllowedOrigins[i])
+		}
+	} else {
+		cfg.AllowedOrigins = []string{
+			"http://localhost:5173",
+			"http://localhost:3000",
+			"https://realtime-collab-snowy.vercel.app",
+		}
+	}
+
+	// OAuth - Google
+	cfg.GoogleClientID = os.Getenv("GOOGLE_CLIENT_ID")
+	cfg.GoogleClientSecret = os.Getenv("GOOGLE_CLIENT_SECRET")
+	cfg.GoogleRedirectURL = getEnvOrDefault("GOOGLE_REDIRECT_URL",
+		fmt.Sprintf("%s/api/auth/google/callback", cfg.BackendURL))
+
+	// OAuth - GitHub
+	cfg.GitHubClientID = os.Getenv("GITHUB_CLIENT_ID")
+	cfg.GitHubClientSecret = os.Getenv("GITHUB_CLIENT_SECRET")
+	cfg.GitHubRedirectURL = getEnvOrDefault("GITHUB_REDIRECT_URL",
+		fmt.Sprintf("%s/api/auth/github/callback", cfg.BackendURL))
+
+	return cfg, nil
+}
+
+func getEnvOrDefault(key, defaultValue string) string {
+	if value := os.Getenv(key); value != "" {
+		return value
+	}
+	return defaultValue
+}
+
+// IsProduction returns true if running in production environment
+func (c *Config) IsProduction() bool {
+	return c.Environment == "production"
+}
+
+// IsDevelopment returns true if running in development environment
+func (c *Config) IsDevelopment() bool {
+	return c.Environment == "development"
+}
+
+// HasGoogleOAuth returns true if Google OAuth is configured
+func (c *Config) HasGoogleOAuth() bool {
+	return c.GoogleClientID != "" && c.GoogleClientSecret != ""
+}
+
+// HasGitHubOAuth returns true if GitHub OAuth is configured
+func (c *Config) HasGitHubOAuth() bool {
+	return c.GitHubClientID != "" && c.GitHubClientSecret != ""
+}