♻️ Refactor main.go by extracting window configuration and environment variable handling into dedicated files.

window.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+
+	"fyne.io/fyne/v2"
+)
+
+const (
+	DefaultWindowWidth  = 800.0
+	DefaultWindowHeight = 600.0
+
+	ConfigFileName = "secure-editor-go-config.json"
+)
+
+// windowConfig is persisted to ~/.cache/secure-editor-go-config.json so the
+// editor remembers its window size across runs.
+type windowConfig struct {
+	Width  float32 `json:"width"`
+	Height float32 `json:"height"`
+}
+
+func configPath() (string, error) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(home, ".cache", ConfigFileName), nil
+}
+
+func defaultConfig() windowConfig {
+	return windowConfig{Width: DefaultWindowWidth, Height: DefaultWindowHeight}
+}
+
+func loadConfig() windowConfig {
+	p, err := configPath()
+	if err != nil {
+		return defaultConfig()
+	}
+	data, err := os.ReadFile(p)
+	if err != nil {
+		return defaultConfig()
+	}
+	var c windowConfig
+	if err := json.Unmarshal(data, &c); err != nil {
+		return defaultConfig()
+	}
+	if c.Width <= 0 || c.Height <= 0 {
+		return defaultConfig()
+	}
+	return c
+}
+
+func saveConfig(size fyne.Size) {
+	p, err := configPath()
+	if err != nil {
+		return
+	}
+	if err := os.MkdirAll(filepath.Dir(p), 0755); err != nil {
+		return
+	}
+	c := windowConfig{Width: size.Width, Height: size.Height}
+	data, err := json.MarshalIndent(c, "", "  ")
+	if err != nil {
+		return
+	}
+	_ = os.WriteFile(p, data, 0644)
+}
+
+// clampToScreen shrinks size so it never exceeds the visible desktop area.
+// When the desktop size can't be determined it returns size unchanged.
+func clampToScreen(size fyne.Size) fyne.Size {
+	sw, sh := desktopSize()
+	if sw <= 0 || sh <= 0 {
+		return size
+	}
+	w, h := size.Width, size.Height
+	if w > sw {
+		w = sw
+	}
+	if h > sh {
+		h = sh
+	}
+	return fyne.NewSize(w, h)
+}