refactoring: move logic in different files

wallpaper.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"go.i3wm.org/i3"
+)
+
+func GetWorkspaceWallpaper(workspace string, config Config) string {
+	file := config.Default
+	workspaceFile := config.Workspaces[workspace]
+
+	if workspaceFile != "" {
+		file = workspaceFile
+	}
+
+	return file
+}
+
+func GetOutputsWallpapers(config Config) ([]string, error) {
+	files := []string{}
+	outputs, err := i3.GetOutputs()
+
+	if err != nil {
+		return files, err
+	}
+
+	for _, output := range outputs {
+		if output.CurrentWorkspace != "" {
+			file := GetWorkspaceWallpaper(output.CurrentWorkspace, config)
+
+			if file != "" {
+				files = append(files, file)
+			}
+		}
+	}
+
+	return files, nil
+}