refactor: simplify config validation

internal/config/config.go

@@ -3,97 +3,70 @@ package config
 import (
 	"fmt"
 	"os"
-
-	"gopkg.in/yaml.v3"
+	"strconv"
 )
 
 // Config is the top-level server configuration.
 type Config struct {
-	Server  ServerConfig  `yaml:"server"`
-	Auth    AuthConfig    `yaml:"auth"`
-	Storage StorageConfig `yaml:"storage"`
-	TLS     TLSConfig     `yaml:"tls"`
-	Logging LoggingConfig `yaml:"logging"`
+	Server  ServerConfig
+	Auth    AuthConfig
+	Storage StorageConfig
+	Logging LoggingConfig
 }
 
 type ServerConfig struct {
-	Host string `yaml:"host"`
-	Port int    `yaml:"port"`
-	// Base URL used in DAV responses (e.g. https://dav.example.com)
-	BaseURL string `yaml:"base_url"`
+	Host    string
+	Port    int
+	BaseURL string
 }
 
 type AuthConfig struct {
-	// Realm shown in WWW-Authenticate header
-	Realm string `yaml:"realm"`
+	Realm string
 }
 
 type StorageConfig struct {
-	// Root directory for all data
-	DataDir string `yaml:"data_dir"`
-}
-
-type TLSConfig struct {
-	Enabled  bool   `yaml:"enabled"`
-	CertFile string `yaml:"cert_file"`
-	KeyFile  string `yaml:"key_file"`
+	DataDir string
 }
 
 type LoggingConfig struct {
-	Level  string `yaml:"level"`  // debug | info | warn | error
-	Format string `yaml:"format"` // text | json
-}
-
-// Load reads and parses a YAML config file.
-func Load(path string) (*Config, error) {
-	data, err := os.ReadFile(path)
-	if err != nil {
-		return nil, fmt.Errorf("reading config %q: %w", path, err)
+	Level  string
+	Format string
 }
 
+// Load reads and parses environment variables to create the configuration.
+func Load() (*Config, error) {
 	cfg := &Config{}
-	if err := yaml.Unmarshal(data, cfg); err != nil {
-		return nil, fmt.Errorf("parsing config %q: %w", path, err)
-	}
-
 	cfg.applyDefaults()
-
-	return cfg, cfg.validate()
+	return cfg, nil
 }
 
 func (c *Config) applyDefaults() {
-	if c.Server.Host == "" {
-		c.Server.Host = "0.0.0.0"
-	}
-	if c.Server.Port == 0 {
-		c.Server.Port = 8080
-	}
+	c.Server.Host = getEnv("NIDUS_HOST", "0.0.0.0")
+	c.Server.Port = getEnvInt("NIDUS_PORT", 8080)
+	c.Server.BaseURL = getEnv("NIDUS_BASE_URL", "")
+
 	if c.Server.BaseURL == "" {
-		scheme := "http"
-		if c.TLS.Enabled {
-			scheme = "https"
-		}
-		c.Server.BaseURL = fmt.Sprintf("%s://%s:%d", scheme, c.Server.Host, c.Server.Port)
-	}
-	if c.Auth.Realm == "" {
-		c.Auth.Realm = "DAV Server"
-	}
-	if c.Storage.DataDir == "" {
-		c.Storage.DataDir = "./data"
-	}
-	if c.Logging.Level == "" {
-		c.Logging.Level = "info"
-	}
-	if c.Logging.Format == "" {
-		c.Logging.Format = "text"
-	}
+		c.Server.BaseURL = fmt.Sprintf("http://%s:%d", c.Server.Host, c.Server.Port)
 	}
 
-func (c *Config) validate() error {
-	if c.TLS.Enabled {
-		if c.TLS.CertFile == "" || c.TLS.KeyFile == "" {
-			return fmt.Errorf("tls.cert_file and tls.key_file are required when tls is enabled")
+	c.Auth.Realm = getEnv("NIDUS_AUTH_REALM", "DAV Server")
+	c.Storage.DataDir = getEnv("NIDUS_DATA_DIR", "./data")
+	c.Logging.Level = getEnv("NIDUS_LOG_LEVEL", "info")
+	c.Logging.Format = getEnv("NIDUS_LOG_FORMAT", "text")
+}
+
+func getEnv(key string, defaultValue string) string {
+	if val := os.Getenv(key); val != "" {
+		return val
+	}
+	return defaultValue
+}
+
+func getEnvInt(key string, defaultValue int) int {
+	if val := os.Getenv(key); val != "" {
+		if intVal, err := strconv.Atoi(val); err == nil {
+			return intVal
 		}
 	}
-	return nil
+	return defaultValue
 }