add optional config preview with confirmation

internal/engine/config/compositor.go

@@ -45,6 +45,7 @@ func (c *Compositor) LoadConf(path string) error {
 	// defaults
 	v.SetDefault("node.name", "noname")
 	v.SetDefault("node.mode", "dev")
+	v.SetDefault("node.show_config", "false")
 	v.SetDefault("node.com_dir", "./com/")
 	v.SetDefault("http_server.address", "0.0.0.0")
 	v.SetDefault("http_server.port", "8080")

internal/engine/config/config.go

@@ -27,9 +27,10 @@ type Conf struct {
 }
 
 type Node struct {
-	Mode   *string `mapstructure:"mode"`
-	Name   *string `mapstructure:"name"`
-	ComDir *string `mapstructure:"com_dir"`
+	Mode       *string `mapstructure:"mode"`
+	Name       *string `mapstructure:"name"`
+	ShowConfig *bool   `mapstructure:"show_config"`
+	ComDir     *string `mapstructure:"com_dir"`
 }
 
 type HTTPServer struct {

internal/engine/config/print.go

@@ -0,0 +1,58 @@
+package config
+
+import (
+	"fmt"
+	"reflect"
+	"time"
+)
+
+func (c *Compositor) Print(v any) {
+	c.printConfig(v, "  ")
+}
+
+func (c *Compositor) printConfig(v any, prefix string) {
+	val := reflect.ValueOf(v)
+	if val.Kind() == reflect.Ptr {
+		val = val.Elem()
+	}
+
+	typ := val.Type()
+
+	for i := 0; i < val.NumField(); i++ {
+		field := val.Field(i)
+		fieldType := typ.Field(i)
+
+		fieldName := fieldType.Name
+		if tag, ok := fieldType.Tag.Lookup("mapstructure"); ok {
+			if tag != "" {
+				fieldName = tag
+			}
+		}
+
+		if field.Kind() == reflect.Ptr {
+			if field.IsNil() {
+				fmt.Printf("%s%s: <nil>\n", prefix, fieldName)
+				continue
+			}
+			field = field.Elem()
+		}
+
+		if field.Kind() == reflect.Struct {
+			if field.Type() == reflect.TypeOf(time.Duration(0)) {
+				duration := field.Interface().(time.Duration)
+				fmt.Printf("%s%s: %s\n", prefix, fieldName, duration.String())
+			} else {
+				fmt.Printf("%s%s:\n", prefix, fieldName)
+				c.printConfig(field.Addr().Interface(), prefix+"  ")
+			}
+		} else if field.Kind() == reflect.Slice {
+			fmt.Printf("%s%s: %v\n", prefix, fieldName, field.Interface())
+		} else {
+			value := field.Interface()
+			if field.Kind() == reflect.String {
+				value = fmt.Sprintf("\"%s\"", value)
+			}
+			fmt.Printf("%s%s: %v\n", prefix, fieldName, value)
+		}
+	}
+}