Refactor config handling

- Replace low-level operations like file existance checks, file io with viper calls.
That also allows to get rid of manual config structure initialization.
- Split out UserHome() into itil/home.go to reduce code duplicacy.
- Better error handling and general readbility.

lib/config/config.go

@@ -4,9 +4,9 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/go-i2p/go-i2p/lib/util"
 	"github.com/go-i2p/logger"
 	"github.com/spf13/viper"
-	"gopkg.in/yaml.v3"
 )
 
 var (
@@ -17,47 +17,13 @@ var (
 const GOI2P_BASE_DIR = ".go-i2p"
 
 func InitConfig() {
-	defaultConfigDir := filepath.Join(os.Getenv("HOME"), GOI2P_BASE_DIR)
-	defaultConfigFile := filepath.Join(defaultConfigDir, "config.yaml")
+	defaultConfigDir := filepath.Join(util.UserHome(), GOI2P_BASE_DIR)
 
 	if CfgFile != "" {
 		// Use config file from the flag
 		viper.SetConfigFile(CfgFile)
 	} else {
-		// Create default config if it doesn't exist
-		if _, err := os.Stat(defaultConfigFile); os.IsNotExist(err) {
-			// Ensure directory exists
-			if err := os.MkdirAll(defaultConfigDir, 0o755); err != nil {
-				log.Fatalf("Could not create config directory: %s", err)
-			}
-
-			// Create default configuration
-			defaultConfig := struct {
-				BaseDir    string          `yaml:"base_dir"`
-				WorkingDir string          `yaml:"working_dir"`
-				NetDB      NetDbConfig     `yaml:"netdb"`
-				Bootstrap  BootstrapConfig `yaml:"bootstrap"`
-			}{
-				BaseDir:    DefaultRouterConfig().BaseDir,
-				WorkingDir: DefaultRouterConfig().WorkingDir,
-				NetDB:      *DefaultRouterConfig().NetDb,
-				Bootstrap:  *DefaultRouterConfig().Bootstrap,
-			}
-
-			yamlData, err := yaml.Marshal(defaultConfig)
-			if err != nil {
-				log.Fatalf("Could not marshal default config: %s", err)
-			}
-
-			// Write default config file
-			if err := os.WriteFile(defaultConfigFile, yamlData, 0o644); err != nil {
-				log.Fatalf("Could not write default config file: %s", err)
-			}
-
-			log.Debugf("Created default configuration at: %s", defaultConfigFile)
-		}
-
-		// Set up viper to use the config file
+		// Set up viper to use the default config file: $HOME/.go-ip/config.yaml
 		viper.AddConfigPath(defaultConfigDir)
 		viper.SetConfigName("config")
 		viper.SetConfigType("yaml")
@@ -67,7 +33,15 @@ func InitConfig() {
 	setDefaults()
 
 	if err := viper.ReadInConfig(); err != nil {
-		log.Warnf("Error reading config file: %s", err)
+		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
+			if CfgFile != "" {
+				log.Fatalf("Config file %s is not found: %s", CfgFile, err)
+			} else {
+				createDefaultConfig(defaultConfigDir)
+			}
+		} else {
+			log.Fatalf("Error reading config file: %s", err)
+		}
 	} else {
 		log.Debugf("Using config file: %s", viper.ConfigFileUsed())
 	}
@@ -111,3 +85,20 @@ func UpdateRouterConfig() {
 		ReseedServers:    reseedServers,
 	}
 }
+
+func createDefaultConfig(defaultConfigDir string) {
+
+	defaultConfigFile := filepath.Join(defaultConfigDir, "config.yaml")
+	// Ensure directory exists
+	if err := os.MkdirAll(defaultConfigDir, 0o755); err != nil {
+		log.Fatalf("Could not create config directory: %s", err)
+	}
+
+	// Write current config file
+	if err := viper.WriteConfig(); err != nil {
+		log.Fatalf("Could not write default config file: %s", err)
+	}
+
+	log.Debugf("Created default configuration at: %s", defaultConfigFile)
+
+}

lib/config/router.go

@@ -1,8 +1,9 @@
 package config
 
 import (
-	"os"
 	"path/filepath"
+
+	"github.com/go-i2p/go-i2p/lib/util"
 )
 
 // router.config options
@@ -17,20 +18,12 @@ type RouterConfig struct {
 	Bootstrap *BootstrapConfig
 }
 
-func home() string {
-	h, err := os.UserHomeDir()
-	if err != nil {
-		panic(err)
-	}
-	return h
-}
-
 func defaultBase() string {
-	return filepath.Join(home(), GOI2P_BASE_DIR, "base")
+	return filepath.Join(util.UserHome(), GOI2P_BASE_DIR, "base")
 }
 
 func defaultConfig() string {
-	return filepath.Join(home(), GOI2P_BASE_DIR, "config")
+	return filepath.Join(util.UserHome(), GOI2P_BASE_DIR, "config")
 }
 
 // defaults for router

lib/util/home.go

@@ -0,0 +1,15 @@
+package util
+
+import (
+	"log"
+	"os"
+)
+
+func UserHome() string {
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		log.Fatalf("Unable to get current user's home directory. $HOME environment variable issue? %s", err)
+	}
+
+	return homeDir
+}