update cnf/loader to infer parser (config format) from content

internal/cnf/loader.go

@@ -42,11 +42,11 @@ func Load(path string) (ConfigurationFormat, error) {
 
 		// parse
 		_, err = confFormat.ReadFrom(file)
-		if err != nil {
-			return nil, fmt.Errorf("cannot parse file as '%s' | %s", extension, err)
+		if err == nil {
+			return confFormat, nil
 		}
 
-		return confFormat, nil
+		// return nil, fmt.Errorf("cannot parse file as '%s' | %s", extension, err)
 
 	}
 
@@ -72,11 +72,11 @@ func loadFromExtension(ext string) ConfigurationFormat {
 	switch ext {
 	case ".json":
 		return new(json)
-	case ".ini":
+	case ".ini", ".conf":
 		return new(ini)
 	case ".yaml":
 		return new(yaml)
-	case ".conf":
+	case ".nginx":
 		return new(nginx)
 	default:
 		return nil
@@ -85,5 +85,26 @@ func loadFromExtension(ext string) ConfigurationFormat {
 }
 
 func loadFromContent(file io.Reader) ConfigurationFormat {
+
+	// extensions ordered by unicity of the language's syntax
+	extensions := []string{".json", ".yaml", ".nginx", ".ini"}
+
+	// try to load each available extension
+	for _, ext := range extensions {
+
+		// load parser
+		c := loadFromExtension(ext)
+		if c == nil {
+			continue
+		}
+
+		// parse
+		_, err := c.ReadFrom(file)
+		if err == nil {
+			return c
+		}
+
+	}
+
 	return nil
 }