feat: Add JWT configuration to environment and refactor JWT middleware to use new config structure

backend/internal/config/config.go

@@ -6,6 +6,7 @@ import (
 	"log"
 	"os"
 	"strconv"
+	"time"
 
 	"github.com/joho/godotenv"
 	"github.com/timetracker/backend/internal/models"
@@ -14,8 +15,9 @@ import (
 
 // Config represents the application configuration
 type Config struct {
-	Database models.DatabaseConfig
-	APIKey   string
+	Database  models.DatabaseConfig
+	JWTConfig models.JWTConfig
+	APIKey    string
 }
 
 // LoadConfig loads configuration from environment variables and .env file
@@ -24,7 +26,8 @@ func LoadConfig() (*Config, error) {
 	_ = godotenv.Load()
 
 	cfg := &Config{
-		Database: models.DefaultDatabaseConfig(),
+		Database:  models.DefaultDatabaseConfig(),
+		JWTConfig: models.JWTConfig{},
 	}
 
 	// Load database configuration
@@ -32,12 +35,41 @@ func LoadConfig() (*Config, error) {
 		return nil, fmt.Errorf("failed to load database config: %w", err)
 	}
 
+	// Load JWT configuration
+	if err := loadJWTConfig(cfg); err != nil {
+		return nil, fmt.Errorf("failed to load JWT config: %w", err)
+	}
+
 	// Load API key
 	cfg.APIKey = getEnv("API_KEY", "")
 
 	return cfg, nil
 }
 
+// loadJWTConfig loads JWT configuration from environment
+func loadJWTConfig(cfg *Config) error {
+	cfg.JWTConfig.Secret = getEnv("JWT_SECRET", "default-secret")
+	defaultDuration := 24 * time.Hour
+	durationStr := getEnv("JWT_TOKEN_DURATION", defaultDuration.String())
+
+	duration, err := time.ParseDuration(durationStr)
+	if err != nil {
+		return fmt.Errorf("invalid JWT_TOKEN_DURATION: %w", err)
+	}
+	cfg.JWTConfig.TokenDuration = duration
+
+	keyGenerateStr := getEnv("JWT_KEY_GENERATE", "false")
+	keyGenerate, err := strconv.ParseBool(keyGenerateStr)
+	if err != nil {
+		return fmt.Errorf("invalid JWT_KEY_GENERATE: %w", err)
+	}
+	cfg.JWTConfig.KeyGenerate = keyGenerate
+
+	cfg.JWTConfig.KeyDir = getEnv("JWT_KEY_DIR", "./keys")
+
+	return nil
+}
+
 // loadDatabaseConfig loads database configuration from environment
 func loadDatabaseConfig(cfg *Config) error {
 	// Required fields