Improve web service related aspects

internal/service/config.go

@@ -0,0 +1,55 @@
+package service
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+var (
+	config     Config
+	configOnce sync.Once
+	configErr  error
+	configPath string
+)
+
+// loadConfig initializes the config from file
+func loadConfig() {
+	exePath, err := os.Executable()
+	configPath := os.Getenv("CONFIG_PATH")
+	if err != nil {
+		configErr = err
+		return
+	}
+	if configPath == "" {
+		exeDir := filepath.Dir(exePath)
+		configPath = filepath.Join(exeDir, "config.json")
+	}
+
+	data, err := os.ReadFile(configPath)
+	if err != nil {
+		configErr = err
+		return
+	}
+
+	err = json.Unmarshal(data, &config)
+	if err != nil {
+		configErr = err
+		return
+	}
+}
+
+// GetConfig returns the singleton instance of the config.
+// It's safe for concurrent use and loads the config only once per process lifetime.
+func GetConfig() (*Config, error) {
+	configOnce.Do(loadConfig)
+	return &config, configErr
+}
+
+// ConfigPath returns the path to the loaded config file (useful for logging or reload later if needed)
+func ConfigPath() string {
+	// Make sure config is at least attempted to be loaded
+	configOnce.Do(loadConfig)
+	return configPath
+}