Simplify GUI settings and build flags

internal/config/config.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"bufio"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -13,6 +14,7 @@ import (
 type Config struct {
 	OSC    OSCConfig
 	VrcLog VrcLogConfig
+	GUI    GUIConfig
 }
 
 type OSCConfig struct {
@@ -29,9 +31,15 @@ type VrcLogConfig struct {
 	LogPatterns  []string
 }
 
+type GUIConfig struct {
+	TopMost  bool
+	FontSize int
+}
+
 func Load(path string) (*Config, error) {
 	cfg := &Config{
 		OSC: OSCConfig{Host: "127.0.0.1", Port: 9001},
+		GUI: GUIConfig{FontSize: 18},
 	}
 	if path == "" {
 		path = filepath.Join(common.RootDir(), "config", "config.toml")
@@ -98,6 +106,15 @@ func Load(path string) (*Config, error) {
 			case "file":
 				cfg.VrcLog.GuestFile = val
 			}
+		case "gui":
+			switch key {
+			case "top_most":
+				cfg.GUI.TopMost = parseBool(val, cfg.GUI.TopMost)
+			case "font_size":
+				if n, err := strconv.Atoi(val); err == nil && n > 0 {
+					cfg.GUI.FontSize = n
+				}
+			}
 		}
 	}
 	if cfg.VrcLog.GuestFile != "" {
@@ -111,6 +128,19 @@ func Load(path string) (*Config, error) {
 	return cfg, scanner.Err()
 }
 
+func SaveGUI(path string, gui GUIConfig) error {
+	path = resolvePath(path)
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+	data, err := os.ReadFile(path)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+	content := upsertGUISection(string(data), gui)
+	return os.WriteFile(path, []byte(content), 0o644)
+}
+
 func parseList(value string) []string {
 	value = strings.TrimSpace(value)
 	value = strings.TrimPrefix(value, "[")
@@ -129,6 +159,76 @@ func parseList(value string) []string {
 	return out
 }
 
+func parseBool(value string, fallback bool) bool {
+	switch strings.ToLower(strings.TrimSpace(value)) {
+	case "true", "1", "on", "yes":
+		return true
+	case "false", "0", "off", "no":
+		return false
+	default:
+		return fallback
+	}
+}
+
+func resolvePath(path string) string {
+	if path == "" {
+		return filepath.Join(common.RootDir(), "config", "config.toml")
+	}
+	if !filepath.IsAbs(path) {
+		return filepath.Join(common.RootDir(), path)
+	}
+	return path
+}
+
+func upsertGUISection(existing string, gui GUIConfig) string {
+	normalized := strings.ReplaceAll(existing, "\r\n", "\n")
+	lines := strings.Split(normalized, "\n")
+	out := make([]string, 0, len(lines)+6)
+	inGUI := false
+	replaced := false
+	for _, raw := range lines {
+		line := raw
+		trimmed := strings.TrimSpace(strings.TrimPrefix(line, "\ufeff"))
+		if strings.HasPrefix(trimmed, "[") && strings.HasSuffix(trimmed, "]") {
+			section := strings.Trim(trimmed, "[]")
+			if section == "gui" {
+				if !replaced {
+					appendGUISection(&out, gui)
+					replaced = true
+				}
+				inGUI = true
+				continue
+			}
+			if inGUI {
+				inGUI = false
+			}
+			out = append(out, line)
+			continue
+		}
+		if inGUI {
+			continue
+		}
+		out = append(out, line)
+	}
+	if !replaced {
+		if len(out) > 0 && strings.TrimSpace(out[len(out)-1]) != "" {
+			out = append(out, "")
+		}
+		appendGUISection(&out, gui)
+	}
+	content := strings.Join(out, "\n")
+	content = strings.TrimRight(content, "\n")
+	return content + "\n"
+}
+
+func appendGUISection(out *[]string, gui GUIConfig) {
+	*out = append(*out,
+		"[gui]",
+		fmt.Sprintf("top_most = %t", gui.TopMost),
+		fmt.Sprintf("font_size = %d", gui.FontSize),
+	)
+}
+
 func loadLines(path string) ([]string, error) {
 	data, err := os.ReadFile(path)
 	if err != nil {